Differentials

Pattern-Based Differentials

Quick differential diagnosis lists with practical imaging clues and common traps.

225 patterns

Neuro

NeuroRing-enhancing brain lesion›

Differential

Metastasis
Glioblastoma
Abscess
Tumefactive demyelination
Neurocysticercosis
Subacute infarct

Useful clues

Restricted diffusion favors abscess but is not exclusive
Multiple gray-white junction lesions favor metastases
Open ring may suggest demyelination
Thick irregular wall favors high-grade tumor

Pitfalls

Do not call abscess on ring enhancement alone
Always check immune status and diffusion map

NeuroDiffusion restriction in brain›

Differential

Acute infarct
Abscess
Hypercellular tumor
Encephalitis
Seizure-related change
Creutzfeldt-Jakob disease

Useful clues

Vascular territory favors infarct
Cortical ribbon/basal ganglia may suggest CJD
Temporal lobe pattern suggests HSV
Mass-like restriction can be lymphoma

Pitfalls

T2 shine-through needs ADC confirmation
Post-ictal change can mimic infarct

NeuroWhite matter lesions›

Differential

Chronic microangiopathy
Multiple sclerosis
Migraine
Vasculitis
ADEM
Leukodystrophy

Useful clues

Dawson fingers/callosal lesions favor MS
Deep periventricular punctate lesions common with small vessel disease
Symmetric confluent disease suggests metabolic/toxic

Pitfalls

Avoid diagnosing MS without dissemination pattern and clinical context
Age and vascular risk factors matter

NeuroBasal ganglia T1 hyperintensity›

Differential

Manganese deposition
Chronic liver disease
Hyperglycemia
Calcification
Hemorrhage
Fahr disease

Useful clues

Check T2/SWI/CT
Symmetry favors metabolic cause
Clinical liver disease is key

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroCerebellopontine angle mass›

Differential

Vestibular schwannoma
Meningioma
Epidermoid
Arachnoid cyst
Metastasis
Facial nerve schwannoma

Useful clues

IAC extension favors schwannoma
DWI bright favors epidermoid
Dural tail favors meningioma

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroSellar mass›

Differential

Pituitary macroadenoma
Meningioma
Craniopharyngioma
Rathke cleft cyst
Metastasis
Hypophysitis

Useful clues

Cavernous sinus invasion
Calcification suggests craniopharyngioma
Stalk thickening suggests inflammatory/metastatic

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroIntraventricular mass›

Differential

Ependymoma
Central neurocytoma
Subependymoma
Choroid plexus tumor
Metastasis
Colloid cyst

Useful clues

Location and age narrow list
Foramen of Monro suggests colloid cyst/neurocytoma
Calcification common in several lesions

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroLeptomeningeal enhancement›

Differential

Infection
Carcinomatous meningitis
Inflammatory meningitis
Neurosarcoidosis
Postoperative change
Subarachnoid blood

Useful clues

Basal cisterns suggest TB/fungal/sarcoid
Known malignancy changes priority
FLAIR sulcal signal helps

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroPachymeningeal enhancement›

Differential

Intracranial hypotension
Postoperative change
Meningioma en plaque
Metastasis
IgG4 disease
Granulomatous disease

Useful clues

Brain sagging favors hypotension
Nodular thickening raises neoplasm
Look for venous sinus disease

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroCorpus callosum lesion›

Differential

Multiple sclerosis
Glioblastoma/lymphoma
Marchiafava-Bignami
Trauma/DAI
Infarct
Cytotoxic lesion

Useful clues

Crossing midline mass suggests high grade tumor/lymphoma
Transient splenial lesion can be metabolic/infectious
DAI favors trauma

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroTemporal lobe signal abnormality›

Differential

HSV encephalitis
Glioma
Autoimmune encephalitis
Post-ictal change
Mesial temporal sclerosis
Infarct

Useful clues

Insular/cingulate involvement suggests HSV
Hippocampal volume loss favors sclerosis
DWI and enhancement pattern help

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroCystic brain lesion›

Differential

Arachnoid cyst
Porencephalic cyst
Neuroglial cyst
Cystic tumor
Abscess
Parasitic cyst

Useful clues

CSF signal on all sequences favors benign cyst
DWI restriction suggests epidermoid/abscess
Enhancing mural nodule suggests tumor

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroSkull base lytic lesion›

Differential

Metastasis
Myeloma
Chordoma
Chondrosarcoma
Infection
Fibrous dysplasia

Useful clues

Midline clivus favors chordoma
Chondroid matrix off midline favors chondrosarcoma
Multiple lesions suggest metastasis/myeloma

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroHemorrhagic brain lesion›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroCranial nerve enhancement›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroOptic nerve enlargement›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroCavernous sinus lesion›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroPineal region mass›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

NeuroRestricted diffusion in spinal cord›

Differential

Acute infarct
Demyelination
Cord contusion
Abscess
Hypercellular tumor
Artifact

Useful clues

Vascular territory and abrupt onset favor infarct
Enhancement pattern and lesion length help
Confirm on ADC

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroNon-enhancing T2 brain mass›

Differential

Low-grade glioma
Demyelination
Cortical dysplasia
Subacute infarct
Encephalitis
Gliosis

Useful clues

Mass effect favors tumor
Cortical/subcortical expansion is key
Follow-up helps when indeterminate

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroCortical calcification›

Differential

Sturge-Weber
Old infarct
Infection
Tumor
Vascular malformation
Metabolic disease

Useful clues

Gyriform pattern suggests Sturge-Weber/old infarct
CT confirms calcium
Enhancement/mass changes concern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroDural-based mass›

Differential

Meningioma
Dural metastasis
Solitary fibrous tumor
Lymphoma
Granulomatous disease
Subdural collection mimic

Useful clues

Hyperostosis favors meningioma
Bone destruction favors metastasis
Flow voids suggest SFT

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroBasilar artery occlusion mimic›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroCerebral venous thrombosis mimic›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroDWI-negative stroke›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroBrainstem T2 lesion›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroSubarachnoid FLAIR hyperintensity›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroBilateral thalamic lesions›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroPosterior reversible encephalopathy pattern›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroCerebral microbleeds›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroVentriculomegaly›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NeuroDiffuse dural calcification›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Chest

ChestMultiple pulmonary nodules›

Differential

Metastases
Infection/septic emboli
Granulomatous disease
Rheumatoid nodules
AVMs
Sarcoidosis

Useful clues

Random peripheral nodules favor hematogenous metastases
Cavitation and feeding vessel may suggest septic emboli
Perilymphatic pattern suggests sarcoid

Pitfalls

Distribution is more useful than number alone
Always compare growth

ChestGround-glass opacity›

Differential

Infection
Edema
Hemorrhage
Organizing pneumonia
NSIP
Adenocarcinoma spectrum

Useful clues

Smooth septal thickening favors edema
Peripheral perilobular pattern favors organizing pneumonia
Persistent focal GGO raises adenocarcinoma concern

Pitfalls

Poor inspiration can mimic diffuse GGO
Do not ignore chronic focal GGO

ChestCavitary lung lesion›

Differential

Squamous cell carcinoma
TB
Bacterial abscess
Septic emboli
Fungal infection
Granulomatosis with polyangiitis

Useful clues

Thick irregular wall suggests malignancy
Tree-in-bud/upper lobe favors TB
Multiple peripheral cavitating nodules suggest septic emboli

Pitfalls

Wall thickness is a clue, not a diagnosis
Clinical immune status changes priority

ChestTree-in-bud nodules›

Differential

Endobronchial infection
TB/NTM
Aspiration
Cystic fibrosis
Diffuse panbronchiolitis
Tumor emboli rarely

Useful clues

Dependent distribution favors aspiration
Upper lobe/cavitation favors TB
Bronchiectasis suggests chronic infection

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestCrazy paving›

Differential

Pulmonary edema
Pneumocystis pneumonia
ARDS
Pulmonary alveolar proteinosis
Hemorrhage
Adenocarcinoma

Useful clues

Acute setting often edema/infection
Chronic geographic pattern suggests PAP
Clinical immune status essential

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestMiliary nodules›

Differential

Miliary TB
Fungal infection
Hematogenous metastases
Sarcoidosis
Pneumoconiosis
Hypersensitivity pneumonitis

Useful clues

Random tiny nodules suggest hematogenous spread
Perilymphatic suggests sarcoid
Immune status guides infection

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestMosaic attenuation›

Differential

Small airways disease
Chronic thromboembolic disease
Vascular disease
Hypersensitivity pneumonitis
Asthma/bronchiolitis
Technical expiratory effect

Useful clues

Expiratory air trapping favors airway disease
Vessel size difference suggests vascular cause
CTPA may be needed

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestAnterior mediastinal mass›

Differential

Thymoma
Lymphoma
Germ cell tumor
Thyroid goiter
Thymic cyst
Metastasis

Useful clues

Fat/calcification may suggest teratoma
Invasive features matter
Age and tumor markers help

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestMiddle mediastinal mass›

Differential

Lymphadenopathy
Foregut duplication cyst
Bronchogenic cyst
Vascular aneurysm
Esophageal lesion
Nerve sheath tumor

Useful clues

Cyst attenuation and no enhancement favors duplication/bronchogenic cyst
Vascular continuity suggests aneurysm
Nodes follow lymphatic stations

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestPosterior mediastinal mass›

Differential

Neurogenic tumor
Extramedullary hematopoiesis
Meningocele
Esophageal lesion
Paravertebral abscess
Lymphoma

Useful clues

Neural foraminal widening favors nerve sheath tumor
Bilateral paravertebral masses suggest EMH
Discitis signs suggest abscess

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestPleural thickening›

Differential

Empyema
Mesothelioma
Metastasis
Asbestos-related pleural disease
Prior infection/hemothorax
Fibrothorax

Useful clues

Nodular circumferential thickening suggests malignancy
Split pleura sign suggests empyema
Calcified plaques suggest asbestos exposure

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestBronchiectasis›

Differential

Post-infective
Cystic fibrosis
ABPA
Immunodeficiency
Aspiration
Primary ciliary dyskinesia

Useful clues

Upper lobe central pattern suggests CF/ABPA
Lower lobe dependent suggests aspiration
Situs abnormality suggests ciliary dyskinesia

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestSolitary pulmonary nodule›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestDiffuse cystic lung disease›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestUpper lobe fibrosis›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestLower lobe fibrosis›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestPulmonary artery enlargement›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

ChestHalo sign›

Differential

Angioinvasive fungal infection
Hemorrhagic metastasis
Vasculitis
Septic emboli
Organizing pneumonia
Adenocarcinoma

Useful clues

Immunocompromised patient changes urgency
Nodule plus GGO halo can be hemorrhage
Look for cavitation evolution

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestReverse halo sign›

Differential

Organizing pneumonia
Fungal infection
Pulmonary infarct
TB
Sarcoidosis
Vasculitis

Useful clues

Clinical immune status critical
Peripheral wedge shape suggests infarct
Nodular rim may suggest granulomatous/infection

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestDiffuse alveolar hemorrhage pattern›

Differential

Vasculitis
Anticoagulation
Pulmonary edema
Infection
Goodpasture syndrome
Drug reaction

Useful clues

Rapidly changing GGO/consolidation
Clinical hemoptysis may be absent
Look for renal/systemic clues

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestUnilateral hyperlucent lung›

Differential

Air trapping
Pulmonary embolism
Swyer-James
Technical rotation
Mastectomy effect
Congenital lobar overinflation

Useful clues

Expiratory CT helps air trapping
Small vessels suggest vascular/airway cause
Check prior surgery

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestCalcified pulmonary nodule›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestAirspace consolidation›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestLobar collapse›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestSolitary cavitary nodule›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestPulmonary cysts›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestSeptal thickening›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestPleural effusion unilateral›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestPneumomediastinum›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestPulmonary artery filling defect›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

ChestChest wall mass›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Abdomen

AbdomenHypervascular liver lesion›

Differential

Hemangioma
FNH
Adenoma
HCC
Hypervascular metastasis
Arterioportal shunt

Useful clues

Peripheral nodular discontinuous enhancement favors hemangioma
Central scar favors FNH
Washout/capsule in cirrhosis favors HCC

Pitfalls

Single arterial phase is often insufficient
Background liver disease changes diagnosis

AbdomenCystic pancreatic lesion›

Differential

IPMN
Serous cystadenoma
Mucinous cystic neoplasm
Pseudocyst
Solid pseudopapillary neoplasm
Cystic neuroendocrine tumor

Useful clues

Duct communication favors IPMN
Microcystic scar favors serous cystadenoma
History of pancreatitis favors pseudocyst

Pitfalls

Do not assume pseudocyst without pancreatitis history
Look for mural nodule and duct dilatation

AbdomenBowel wall thickening›

Differential

Infection
Inflammatory bowel disease
Ischemia
Neoplasm
Edema/hypoproteinemia
Radiation enteritis

Useful clues

Long segment symmetric thickening favors benign inflammation
Disproportionate fat stranding suggests inflammation
Reduced enhancement/pneumatosis raises ischemia

Pitfalls

Collapsed bowel can mimic thickening
Pattern and length are essential

AbdomenRim-enhancing liver lesion›

Differential

Abscess
Metastasis
Cholangiocarcinoma
Necrotic HCC
Hemangioma atypical
Inflammatory pseudotumor

Useful clues

Cluster sign/gas favors abscess
Multiple lesions favor metastases
Capsular retraction suggests cholangiocarcinoma

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenDiffuse hepatic steatosis mimics›

Differential

Fatty liver
Iron deposition
Glycogen storage
Chemotherapy effect
Hepatitis
Perfusion alteration

Useful clues

In/out-of-phase MRI confirms fat
Iron drops on T2*
Vessel course helps pseudolesion

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenSplenic multiple lesions›

Differential

Lymphoma
Sarcoidosis
Fungal microabscesses
Metastases
Hemangiomas
Granulomas

Useful clues

Tiny lesions in immunocompromised suggest fungal
Bulky nodes suggest lymphoma
Calcified lesions often healed granulomas

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenAdrenal mass›

Differential

Adenoma
Metastasis
Pheochromocytoma
Myelolipoma
Adrenocortical carcinoma
Hemorrhage

Useful clues

Macroscopic fat suggests myelolipoma
Low HU/washout favors adenoma
Large irregular heterogeneous lesion concerning

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenPeritoneal nodularity›

Differential

Carcinomatosis
TB peritonitis
Peritoneal mesothelioma
Lymphomatosis
Endometriosis
Splenosis

Useful clues

Omental cake suggests carcinomatosis
Smooth thickening/necrotic nodes may suggest TB
History of splenectomy suggests splenosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenMesenteric mass›

Differential

Carcinoid metastasis
Lymphoma
Desmoid
Sclerosing mesenteritis
GIST
Metastasis

Useful clues

Desmoplastic reaction/calcification suggests carcinoid
Encasing vessels without obstruction favors lymphoma
Prior surgery/FAP suggests desmoid

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenRetroperitoneal fibrosis›

Differential

Idiopathic/IgG4
Malignancy
Radiation
Drug-related
Infection
Erdheim-Chester disease

Useful clues

Medial ureteral deviation classic
Bulky nodular mass suggests malignancy
Periaortic rind suggests fibrosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenGallbladder wall thickening›

Differential

Cholecystitis
Hepatitis
Heart failure
Adenomyomatosis
Gallbladder carcinoma
Hypoalbuminemia

Useful clues

Stones/Murphy sign favor cholecystitis
Diffuse systemic edema can thicken wall
Focal mass-like thickening concerning

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenBiliary duct dilatation›

Differential

Choledocholithiasis
Pancreatic head cancer
Cholangiocarcinoma
Benign stricture
Sphincter dysfunction
Post-cholecystectomy state

Useful clues

Abrupt cutoff raises malignancy
Intraductal filling defect suggests stone
Clinical bilirubin important

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenPancreatic duct dilatation›

Differential

Pancreatic cancer
Chronic pancreatitis
IPMN
Ampullary lesion
Post-inflammatory stricture
Stone

Useful clues

Double duct sign raises ampullary/pancreatic lesion
Calcifications favor chronic pancreatitis
Cyst communication suggests IPMN

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenAscites with septations›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenGastric wall thickening›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenColonic mass-like thickening›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenLymphadenopathy abdomen›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenRenal sinus mass›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

AbdomenIntrahepatic biliary strictures›

Differential

PSC
Cholangiocarcinoma
IgG4 cholangitis
Recurrent pyogenic cholangitis
Ischemic cholangiopathy
AIDS cholangiopathy

Useful clues

Multifocal beading suggests PSC
Dominant stricture needs caution
Pancreatic IgG4 features help

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenLiver iron overload›

Differential

Hemochromatosis
Transfusional hemosiderosis
Chronic liver disease
Iron medication
Siderotic nodules
Technical artifact

Useful clues

T2*/R2* quantifies iron
Spleen/pancreas pattern helps primary vs secondary
Fat can confound

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenHyperdense renal lesion noncontrast›

Differential

Hemorrhagic cyst
Proteinaceous cyst
Papillary RCC
Calcified cyst
AML with minimal fat
Pseudoenhancement issue

Useful clues

Enhancement is decisive
Homogeneous high attenuation small cyst may be benign
Use subtraction MRI if needed

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenFat-containing liver lesion›

Differential

HCC with fat
Adenoma
Angiomyolipoma
Lipoma
Teratoma rare
Focal fat

Useful clues

Enhancement and background liver risk matter
Macroscopic vs microscopic fat
Vessel displacement helps lesion vs focal fat

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenPortal vein thrombosis›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenHepatic vein thrombosis›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenDiffuse pancreatic enlargement›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenSplenic infarcts›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenRenal infarct›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenAdrenal hemorrhage›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenPneumatosis intestinalis›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenFree intraperitoneal air›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenOmental infarction›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

AbdomenAppendiceal mucocele›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSK

MSKLytic bone lesion›

Differential

Metastasis
Myeloma
Infection
Giant cell tumor
Aneurysmal bone cyst
Brown tumor

Useful clues

Age is key
Multiple punched-out lesions suggest myeloma
Aggressive periosteal reaction/soft tissue mass raises malignancy

Pitfalls

Do not classify without age and location
Check matrix and zone of transition

MSKBone marrow edema around joint›

Differential

Trauma/stress injury
Osteoarthritis
Inflammatory arthritis
Osteonecrosis
Infection
Transient osteoporosis

Useful clues

Subchondral fracture line favors insufficiency injury
Serpiginous margin favors osteonecrosis
Effusion/synovitis may guide arthritis/infection

Pitfalls

Marrow edema is nonspecific
Always inspect cartilage and subchondral bone

MSKSclerotic bone lesion›

Differential

Bone island
Osteoblastic metastasis
Osteoid osteoma
Paget disease
Bone infarct
Chronic osteomyelitis

Useful clues

Brush border favors bone island
Multiple axial lesions suggest metastases
Nidus suggests osteoid osteoma

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKSoft tissue mass with fat›

Differential

Lipoma
Atypical lipomatous tumor
Liposarcoma
Hemangioma
Fat necrosis
Hibernoma

Useful clues

Thick septa/nodular nonfat tissue concerning
Phleboliths suggest vascular lesion
Deep large lesion needs caution

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKCartilaginous bone lesion›

Differential

Enchondroma
Low-grade chondrosarcoma
Osteochondroma
Chondroblastoma
Chondromyxoid fibroma
Metastasis with chondroid matrix

Useful clues

Pain/endosteal scalloping favors chondrosarcoma
Epiphyseal lesion in young patient suggests chondroblastoma
Ring-and-arc matrix helps

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKPeriosteal reaction›

Differential

Trauma/stress fracture
Osteomyelitis
Osteosarcoma
Ewing sarcoma
Hypertrophic osteoarthropathy
Metastasis

Useful clues

Aggressive interrupted pattern concerning
Solid smooth reaction often benign/chronic
Age and location are key

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKMuscle edema›

Differential

Strain/tear
Myositis
Denervation
Infection
Rhabdomyolysis
Compartment syndrome

Useful clues

Feathery edema follows strain
Nerve territory suggests denervation
Gas/fluid collection suggests infection

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKJoint effusion with synovitis›

Differential

Inflammatory arthritis
Septic arthritis
Crystal arthropathy
PVNS/TGCT
Hemarthrosis
Osteoarthritis flare

Useful clues

Blooming suggests hemosiderin/PVNS
Bone erosions and fever raise septic concern
Crystal disease may calcify

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKAvascular necrosis mimics›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKTendon sheath mass›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKCalcified soft tissue mass›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKEpiphyseal lesion›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKDiaphyseal lesion child›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

MSKBone lesion with fluid-fluid levels›

Differential

Aneurysmal bone cyst
Telangiectatic osteosarcoma
Giant cell tumor with ABC change
Chondroblastoma
Simple bone cyst fracture
Metastasis

Useful clues

Fluid levels are nonspecific
Solid enhancing component concerning
Age/location essential

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKMarrow replacing lesion›

Differential

Metastasis
Myeloma
Lymphoma
Leukemia
Infection
Red marrow reconversion

Useful clues

T1 lower than muscle concerning
Chemical shift helps red marrow
Multiplicity and clinical context key

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKBaker cyst mimic›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKMeniscal cyst›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKACL ganglion›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKShoulder labral cyst›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKTarsal coalition›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKPlantar fascia thickening›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKMorton neuroma mimic›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKHand enchondroma›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKSacral insufficiency fracture›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

MSKRib lesion›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GU

GUEnhancing renal mass›

Differential

Clear cell RCC
Papillary RCC
Oncocytoma
Angiomyolipoma without visible fat
Metastasis
Lymphoma

Useful clues

Macroscopic fat favors AML
Hypovascular mass may be papillary RCC
Central scar can be oncocytoma but overlaps RCC

Pitfalls

Enhancement must be measured
Do not rely on scar alone

GUAdnexal cystic mass›

Differential

Functional cyst
Hemorrhagic cyst
Endometrioma
Dermoid
Cystadenoma
Borderline/malignant epithelial tumor

Useful clues

T1 bright with shading favors endometrioma
Fat-fluid level favors dermoid
Solid vascular nodules raise malignancy concern

Pitfalls

Use age/menopausal status
Simple cyst criteria are modality and size dependent

GUComplex renal cyst›

Differential

Hemorrhagic cyst
Infected cyst
Cystic RCC
Multilocular cystic neoplasm
Abscess
Bosniak IIF/III lesion

Useful clues

Enhancing septa/nodule matters
T1 hyperintensity suggests blood/protein
Subtraction MRI helps enhancement

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUHydronephrosis without stone›

Differential

UPJ obstruction
Ureteric stricture
Tumor
Retroperitoneal fibrosis
Pregnancy
Reflux

Useful clues

Transition point is key
Delayed excretion helps functional obstruction
Bilateral disease suggests bladder/outlet or retroperitoneal cause

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUBladder wall thickening›

Differential

Cystitis
Outlet obstruction
Neoplasm
Radiation cystitis
Neurogenic bladder
Underdistension

Useful clues

Focal enhancing mass suggests tumor
Diffuse trabeculation suggests chronic outlet obstruction
Poor distension mimics thickening

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUProstate peripheral zone lesion›

Differential

Prostate cancer
Prostatitis
Post-biopsy hemorrhage
Granulomatous prostatitis
Fibrosis
Atrophy

Useful clues

Low ADC/high DWI with focal T2 dark lesion concerning
Hemorrhage T1 bright
Inflammation can mimic cancer

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUTesticular mass›

Differential

Seminoma
Non-seminomatous germ cell tumor
Lymphoma
Leydig cell tumor
Epidermoid cyst
Infarct

Useful clues

Older age suggests lymphoma
Onion-ring avascular cyst suggests epidermoid
Wedge-shaped avascular area suggests infarct

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUEndometrial thickening›

Differential

Hyperplasia
Polyp
Carcinoma
Hormonal effect
Tamoxifen change
Blood products

Useful clues

Postmenopausal status changes threshold
Focal vascular lesion suggests polyp
Myometrial invasion requires MRI staging

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUOvarian solid mass›

Differential

Fibroma/fibrothecoma
Brenner tumor
Metastasis
Dysgerminoma
Granulosa cell tumor
Epithelial malignancy

Useful clues

Very low T2 suggests fibrous tumor
Bilateral solid masses suggest metastases
Ascites/peritoneal disease raises malignancy

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUUrethral stricture›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUSeminal vesicle lesion›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUPlacental mass›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUCervical mass›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUVaginal cyst›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

GUMale infertility imaging abnormality›

Differential

Varicocele
Obstructive azoospermia
Testicular atrophy
Epididymal obstruction
Congenital absence vas deferens
Prior infection

Useful clues

Bilateral renal agenesis link with vas deferens anomaly
Scrotal Doppler and TRUS may complement
Volume comparison matters

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GUUterine junctional zone thickening›

Differential

Adenomyosis
Physiologic contraction
Endometrial carcinoma invasion
Fibroid distortion
Postpartum change
Tamoxifen effect

Useful clues

T2 bright foci favor adenomyosis
Transient contraction changes on repeat
Clinical age/context matters

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GUEctopic pregnancy mimics›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GUHematosalpinx›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GUAdnexal torsion mimic›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GUVulvar mass›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GUBladder filling defect›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GUUreteric filling defect›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GURenal papillary necrosis›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GUMedullary nephrocalcinosis›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GUProstatic abscess›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

GUScrotal wall swelling›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & Neck

Head & NeckCystic neck mass›

Differential

Branchial cleft cyst
Necrotic nodal metastasis
Thyroglossal duct cyst
Abscess
Lymphatic malformation
Ranula

Useful clues

Adult lateral cystic neck mass is malignant until proven otherwise
Midline tract near hyoid suggests thyroglossal duct cyst
Rim enhancement and inflammatory fat suggest abscess

Pitfalls

Do not call branchial cyst in older adult without excluding HPV-related nodal metastasis

Head & NeckParotid mass›

Differential

Pleomorphic adenoma
Warthin tumor
Mucoepidermoid carcinoma
Metastatic node
Lymphoma
Inflammatory lesion

Useful clues

Tail of parotid and bilateral/multifocal lesions favor Warthin
Ill-defined invasive lesion raises malignancy
Very T2 bright mass often pleomorphic adenoma

Pitfalls

Imaging overlap is high
Look for facial nerve/perineural spread

Head & NeckSinonasal mass›

Differential

Inflammatory polyp
Inverted papilloma
Squamous carcinoma
Esthesioneuroblastoma
Fungal disease
Lymphoma

Useful clues

Cerebriform pattern suggests inverted papilloma
Bone destruction raises malignancy
Hyperdense allergic fungal mucin is a clue

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

Head & NeckThyroid nodule with suspicious nodes›

Differential

Papillary thyroid carcinoma
Medullary carcinoma
Lymphoma
Metastasis
Thyroiditis with reactive nodes
Anaplastic carcinoma

Useful clues

Microcalcifications/cystic nodes favor papillary carcinoma
Rapid invasive mass concerning anaplastic
Calcitonin context for medullary

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

Head & NeckLaryngeal mass›

Differential

Squamous cell carcinoma
Papillomatosis
Chondrosarcoma
Lymphoma
Inflammatory granuloma
Amyloidosis

Useful clues

Cartilage invasion important
Submucosal calcified mass may be chondrosarcoma
Smoking history matters

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

Head & NeckMasticator space mass›

Differential

Odontogenic infection
Sarcoma
Perineural tumor spread
Lymphoma
Vascular malformation
Benign muscle hypertrophy

Useful clues

Dental source and abscess signs common
Foramen ovale widening suggests perineural spread
Flow voids suggest vascular lesion

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

Head & NeckOrbital apex lesion›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

Head & NeckNasopharyngeal mass›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

Head & NeckOrbital mass adult›

Differential

Cavernous venous malformation
Lymphoma
Metastasis
Inflammatory pseudotumor
Optic nerve sheath meningioma
Lacrimal gland tumor

Useful clues

Location within orbit narrows list
Molding lesion favors lymphoma
Pain favors inflammatory/infectious

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckCavernous sinus enhancement›

Differential

Tolosa-Hunt
Meningioma
Perineural spread
Carotid cavernous fistula
Thrombosis
Metastasis

Useful clues

Flow voids/enlarged SOV suggest fistula
Foraminal spread suggests perineural tumor
Painful ophthalmoplegia can be inflammatory

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckTemporal bone opacification›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckMiddle ear mass›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckPetrous apex lesion›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckLacrimal gland enlargement›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckSubmandibular swelling›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckRetropharyngeal fluid›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckTongue base mass›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckSkull vault lesion›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckDental periapical lucency›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Head & NeckThyroid diffuse enlargement›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Breast

BreastBreast calcifications›

Differential

Benign secretory calcifications
DCIS
Fibroadenoma involution
Fat necrosis
Vascular calcification
Milk of calcium

Useful clues

Fine pleomorphic/linear branching concerning
Layering on true lateral suggests milk of calcium
Distribution matters

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

BreastArchitectural distortion›

Differential

Radial scar
Invasive carcinoma
Postsurgical scar
Sclerosing adenosis
Fat necrosis
Complex sclerosing lesion

Useful clues

No prior surgery raises concern
DBT helps confirm true distortion
US correlate may guide biopsy

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

BreastCircumscribed breast mass›

Differential

Cyst
Fibroadenoma
Papilloma
Phyllodes tumor
Mucinous carcinoma
Metastasis

Useful clues

Anechoic with posterior enhancement is cyst
Rapid growth raises phyllodes
Older age changes concern

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

BreastAxillary lymphadenopathy›

Differential

Reactive node
Breast cancer metastasis
Lymphoma
Melanoma metastasis
Granulomatous disease
Recent vaccination

Useful clues

Cortical thickening/lost hilum concerning
Laterality and vaccine history matter
Known malignancy changes priority

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

BreastNon-mass enhancement breast MRI›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

BreastBloody nipple discharge imaging›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

BreastEnhancing breast focus MRI›

Differential

Background parenchymal enhancement
Papilloma
DCIS
Invasive carcinoma
Fibroadenoma
Inflammation

Useful clues

Kinetics plus morphology matter
New asymmetric focus is more concerning
Correlate with mammogram/US

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastPostoperative breast change vs recurrence›

Differential

Scar
Fat necrosis
Seroma
Recurrent tumor
Radiation change
Infection

Useful clues

Increasing mass/enhancement concerning
Fat signal favors fat necrosis
Time from surgery matters

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastBreast skin thickening›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastRetroareolar mass›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastIntraductal lesion›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastBreast edema›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastImplant peri-capsular fluid›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastFat-containing breast lesion›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastDeveloping asymmetry›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastGrouped calcifications›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastBreast abscess mimic›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

BreastMale breast mass›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Spine

SpineIntradural extramedullary mass›

Differential

Meningioma
Schwannoma
Neurofibroma
Metastasis
Arachnoid cyst
Paraganglioma

Useful clues

Dural tail favors meningioma
Foraminal extension favors nerve sheath tumor
Cauda equina lesion may be paraganglioma

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

SpineIntramedullary cord lesion›

Differential

Ependymoma
Astrocytoma
Demyelination
Hemangioblastoma
Metastasis
Syrinx

Useful clues

Central cord hemorrhagic cap favors ependymoma
Long segment inflammatory lesion suggests demyelination
Flow voids suggest hemangioblastoma

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

SpineVertebral body collapse›

Differential

Osteoporotic fracture
Metastasis
Myeloma
Infection
Kummell disease
Trauma

Useful clues

Posterior convexity/soft tissue mass suggests malignancy
Fluid cleft suggests Kummell
Discitis/endplate destruction suggests infection

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

SpineDiscitis-osteomyelitis mimics›

Differential

Infection
Modic type 1
Inflammatory spondyloarthropathy
Neuropathic spine
Crystal deposition
Postoperative change

Useful clues

Disc enhancement/paraspinal abscess favors infection
Vacuum disc favors degenerative
Clinical markers help

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

SpineCauda equina enhancement›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

SpineEpidural collection›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

SpineFacet joint edema›

Differential

Degenerative facet arthropathy
Septic arthritis
Inflammatory arthritis
Trauma
Crystal disease
Synovial cyst

Useful clues

Paraspinal abscess favors infection
Bilateral/sacroiliac disease suggests inflammatory
Check epidural extension

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

SpineLeptomeningeal spinal enhancement›

Differential

Carcinomatous meningitis
Infection
Inflammatory arachnoiditis
Neurosarcoidosis
Postoperative change
Blood products

Useful clues

Nodular cauda equina enhancement raises malignancy/infection
History and CSF important
Compare brain imaging

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Pediatric

PediatricPediatric abdominal mass›

Differential

Neuroblastoma
Wilms tumor
Hydronephrosis
Lymphoma
Hepatoblastoma
Ovarian mass

Useful clues

Crossing midline/calcification favors neuroblastoma
Renal origin favors Wilms
Age is key

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

PediatricLimping child hip pain›

Differential

Transient synovitis
Septic arthritis
Perthes disease
SCFE
Stress injury
Osteomyelitis

Useful clues

Fever and high markers raise septic arthritis
Epiphyseal flattening suggests Perthes
Adolescent obese patient suggests SCFE

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

PediatricPediatric posterior fossa mass›

Differential

Medulloblastoma
Pilocytic astrocytoma
Ependymoma
ATRT
Brainstem glioma
Metastasis

Useful clues

Midline vermian mass favors medulloblastoma
Cyst with mural nodule favors pilocytic astrocytoma
Fourth ventricle extension favors ependymoma

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

PediatricNeonatal bowel obstruction›

Differential

Malrotation/volvulus
Duodenal atresia
Jejunoileal atresia
Meconium ileus
Hirschsprung disease
Anorectal malformation

Useful clues

Double bubble suggests duodenal obstruction
Microcolon suggests unused colon
Urgent volvulus exclusion is key

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

PediatricPediatric neck mass›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

PediatricPediatric renal cystic lesion›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

PediatricPediatric mediastinal mass›

Differential

Lymphoma
Thymus
Germ cell tumor
Neuroblastoma
Foregut duplication cyst
Infection

Useful clues

Anterior mass with airway compression urgent
Posterior mass suggests neurogenic
Normal thymus can mimic mass

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricPediatric liver mass›

Differential

Hepatoblastoma
Hemangioma
FNH
Abscess
Mesenchymal hamartoma
Metastasis

Useful clues

Age and AFP key
Vascularity helps hemangioma
Cystic multiseptated lesion suggests hamartoma

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricNeonatal adrenal mass›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricPediatric renal mass›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricPediatric bone pain›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricPediatric airway narrowing›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricPediatric abdominal calcification›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricPediatric pelvic mass›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricPediatric chest hyperinflation›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricPediatric skull lesion›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricPediatric liver calcification›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

PediatricPediatric intussusception lead point›

Differential

Common benign entity
Infection or inflammation
Trauma/vascular cause
Primary tumor
Metastatic/systemic disease
Post-treatment or artifact

Useful clues

Use age, location and distribution
Compare prior imaging
Confirm with the best modality for the pattern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Vascular

VascularArterial wall thickening›

Differential

Atherosclerosis
Vasculitis
Dissection
Intramural hematoma
Radiation arteritis
Infection/mycotic aneurysm

Useful clues

Long smooth inflammatory wall enhancement suggests vasculitis
Intimal flap suggests dissection
Calcified plaque favors atherosclerosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

VascularVisceral artery aneurysm›

Differential

Atherosclerotic aneurysm
Pseudoaneurysm pancreatitis/trauma
Mycotic aneurysm
Fibromuscular dysplasia
Vasculitis
Segmental arterial mediolysis

Useful clues

Pseudoaneurysm enhances like artery
Pancreatitis history suggests splenic artery pseudoaneurysm
Multiple beaded vessels suggests FMD/SAM

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

VascularDeep venous thrombosis mimics›

Differential

Acute DVT
Chronic post-thrombotic change
Baker cyst rupture
Cellulitis
Lymphedema
Extrinsic compression

Useful clues

Noncompressibility confirms DVT
Chronic wall thickening/collaterals suggest old clot
Calf fluid suggests ruptured cyst

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

VascularPulmonary embolism mimics›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

VascularAortic mural thrombus›

Differential

Common benign cause
Infection/inflammation
Primary neoplasm
Metastatic disease
Vascular/traumatic cause
Post-treatment change

Useful clues

Use location, age and enhancement pattern
Compare with prior imaging
Clinical context changes the top diagnosis

Pitfalls

Avoid overcalling from one feature alone
Correlate with clinical setting and prior imaging

VascularArterial beading›

Differential

Fibromuscular dysplasia
Vasculitis
Segmental arterial mediolysis
Atherosclerosis mimic
Spasm
Connective tissue disorder

Useful clues

Renal/cervical arteries common in FMD
Aneurysm/dissection suggests SAM
Inflammatory markers help vasculitis

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

VascularVenous collateral pathways›

Differential

Chronic venous occlusion
SVC syndrome
Portal hypertension
IVC obstruction
Congenital venous anomaly
Post-thrombotic change

Useful clues

Collateral map localizes obstruction
Enhancement timing matters
Compare central veins

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Cardiac

CardiacDelayed myocardial enhancement›

Differential

Infarct scar
Myocarditis
Sarcoidosis
Amyloidosis
Hypertrophic cardiomyopathy
Chagas disease

Useful clues

Subendocardial vascular pattern favors infarct
Mid-wall/subepicardial favors nonischemic
Global subendocardial suggests amyloid

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

CardiacPericardial thickening›

Differential

Constrictive pericarditis
Postoperative change
Infection/TB
Malignancy
Radiation
Uremia

Useful clues

Septal bounce and ventricular interdependence help
Calcification supports chronic constriction
Effusive constrictive possible

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

CardiacCardiac mass›

Differential

Thrombus
Myxoma
Metastasis
Papillary fibroelastoma
Lipoma
Sarcoma

Useful clues

Location and mobility matter
No enhancement favors thrombus
Fat signal favors lipoma

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Nuclear

NuclearFocal FDG uptake colon›

Differential

Physiologic uptake
Polyp/cancer
Inflammation
Diverticulitis
Medication/metformin effect
Artifact

Useful clues

Focal intense uptake deserves correlation
Diffuse bowel uptake may be physiologic/metformin
CT correlate changes concern

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NuclearBone scan hot lesion›

Differential

Metastasis
Degenerative change
Fracture
Infection
Paget disease
Stress injury

Useful clues

Pattern and CT/radiograph correlation key
Linear rib uptake often fracture
Superscan suggests extensive disease

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

NuclearCold thyroid nodule›

Differential

Benign nodule
Thyroid carcinoma
Cyst
Thyroiditis focus
Adenoma
Technical artifact

Useful clues

Cold is not diagnostic of malignancy
US risk stratification needed
Functional context matters

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

Intervention

InterventionPost-ablation liver margin enhancement›

Differential

Expected rim enhancement
Residual tumor
Hyperemia
Abscess
Biloma
Hemorrhage

Useful clues

Nodular arterial enhancement suggests residual
Smooth thin rim often expected
Diffusion and serial change help

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available

InterventionPost-biopsy lung opacity›

Differential

Hemorrhage
Pneumothorax
Atelectasis
Air embolism rare
Infection delayed
Tumor progression

Useful clues

Immediate ground-glass around needle path is hemorrhage
Monitor pneumothorax
Neurologic symptoms after biopsy are urgent

Pitfalls

Do not diagnose from one imaging sign alone
Use clinical context, labs and prior imaging when available