High Yield MRI

MRI Differential Diagnosis Guide

MRI Differential Diagnosis Guide

Paste the clinical presentation, choose your working approach, select the sequences performed, and step through a feature-based algorithm to a reasoned, referenced differential.

Educational tool — not a diagnostic device. This guide supports learning and structured reasoning for trained readers. It does not replace formal radiological interpretation, multidisciplinary review, or clinical judgement. Weightings are teaching heuristics, not validated probabilities. Always correlate with the actual images, priors, and the full clinical picture.
1 Choose your approach

Hybrid

History + imaging. Parse the presentation to suggest a pattern, then let the imaging features drive the differential.

Imaging-pattern first

Go straight to the dominant imaging pattern and its discriminators. History only re-ranks.

Clinical-presentation first

Lead with the pasted history; map it to likely patterns, then narrow with sequences and findings.
2 Clinical history / presentation
Optional but recommended — key terms (age, immunosuppression, known primary, trauma, fever, cirrhosis, NF, etc.) are used to suggest a pattern and re-rank the differential.
3 Region & dominant imaging pattern
Body part / anatomy imaged (optional — narrows the patterns to that anatomy):
Select the dominant pattern / problem:
4 Sequences performed
⚑ Diffusion reminder. True restricted diffusion = bright on DWI and dark on ADC. Bright DWI with a bright ADC is T2 shine-through — not true restriction. ADC is the quantitative map, so always confirm restriction on ADC before calling it.
Tick what was actually acquired. The tool flags when a key discriminating sequence is missing. Hover any sequence for a reminder of what it shows.
5 Guided work-up —
6 Differential & reasoning
High Yield MRI · feature-based teaching algorithm · verify against source images and primary literature

High-Yield Summary

The distilled “if you see X → think Y” discriminators behind the interactive guide above. Tap a region to expand.

Signal rules: Restricted diffusion = bright DWI + dark ADC (bright DWI + bright ADC = T2 shine-through, not real). Opposed-phase signal drop = microscopic fat. Fat-sat drop = macroscopic fat. SWI blooming = blood or calcium.
Brain / Neuro

Ring / rim-enhancing lesion

  • Central DWI restriction / dual-rim (SWI) → abscess
  • Thick irregular rim, crosses callosum → GBM
  • Multiple, grey-white junction, known primary → metastases
  • Incomplete ‘open’ ring toward cortex → demyelination
  • Prior RT field, low rCBV → radiation necrosis

Restricted diffusion

  • Arterial territory, acute deficit → infarct
  • Ring + central restriction → abscess
  • Insinuating, non-suppressing on FLAIR → epidermoid
  • Homogeneous periventricular, avid enhancement → CNS lymphoma
  • Cortical ribbon / BG + myoclonus → CJD

Intrinsic T1 hyperintensity

  • Drops on fat-sat → fat (lipoma/dermoid)
  • Blooms on SWI → blood or calcium
  • T1-bright / T2-dark + melanoma → melanotic mets
  • Cyst at foramen of Monro → colloid cyst

Multiple T2/FLAIR white-matter lesions

  • Periventricular perpendicular (Dawson) + juxtacortical + infratentorial → MS
  • Deep, spares U-fibres, older + vascular RF → small-vessel disease
  • Asymmetric subcortical U-fibres, immunosuppressed, no enhancement → PML
  • Child, post-infectious, fluffy → ADEM

Multiple microbleeds (SWI)

  • Strictly lobar, elderly → amyloid angiopathy
  • Deep grey / pons / cerebellum, HTN → hypertensive
  • Grey-white junction / callosum, trauma → DAI
  • Popcorn + complete haemosiderin rim → cavernomas

Extra-axial mass

  • Dural tail, broad base, hyperostosis → meningioma
  • CPA ‘ice-cream cone’ into IAC → vestibular schwannoma
  • Restricts + non-suppressing FLAIR → epidermoid (vs arachnoid cyst = follows CSF)
  • Multiple + bone destruction → dural mets

CPA / IAC mass

  • Extends into IAC, ‘ice-cream cone’, widens porus → vestibular schwannoma
  • Broad dural base, dural tail, acute bony angles → meningioma
  • Restricts diffusion, non-suppressing FLAIR, insinuates → epidermoid
  • Follows CSF, no restriction, no enhancement → arachnoid cyst
  • Enhances along the facial nerve (labyrinthine/geniculate) → facial nerve schwannoma

Paediatric posterior fossa mass

  • Low ADC + midline 4th ventricle → medulloblastoma
  • High ADC + hemisphere cyst + nodule → pilocytic astrocytoma
  • 4th-ventricle floor, through foramina → ependymoma
  • <3y heterogeneous → ATRT; expansile pons → DIPG

Sellar / suprasellar mass

  • Within sella, snowman waist → macroadenoma
  • Suprasellar, cystic + calcified → craniopharyngioma
  • Intrasellar cyst + intracystic nodule → Rathke cleft cyst
  • Flow void / pulsation → aneurysm
    • ⚠ Suspect aneurysm → image the vessels, do NOT biopsy.
Spine

Intramedullary cord lesion

  • Central, symmetric, cleavage plane, cap sign, adult → ependymoma
  • Eccentric, ill-defined, child → astrocytoma
  • Pial nodule + flow voids + cyst, VHL → haemangioblastoma

Cord T2 / non-compressive myelopathy

  • ≥3 segments (LETM), central → NMOSD / TM
  • Short <2 segments, peripheral dorsolateral → MS
  • Anterior ‘owl-eye’, acute, DWI+ → cord infarct
  • Dorsal columns (inverted V) → B12 (SCD)
  • Dorsal serpentine flow voids, older man → dural AV fistula

Intradural-extramedullary mass

  • Dumbbell widening foramen, target sign → schwannoma / neurofibroma
  • Broad dural base, calcified, dural tail → meningioma
  • Multiple leptomeningeal nodules → drop mets
  • Filum/conus sausage + haemorrhage → myxopapillary ependymoma

Vertebral marrow / compression fracture

  • T1 below muscle/disc, pedicle, epidural → malignant
  • Band-like preserved T1, opposed-phase drop → benign fracture
  • Endplate destruction + T2-bright disc + collection → discitis-osteomyelitis
Musculoskeletal

Bone lesion: aggressive vs not

  • Narrow sclerotic zone, solid periosteum → non-aggressive
  • Wide moth-eaten/permeative, interrupted periosteum → aggressive
  • <30 aggressive → primary sarcoma; >40 / multiple → mets / myeloma
  • Rim-enhancing collection / sinus → osteomyelitis

Marrow signal: replacement vs reconversion

  • T1 above muscle & disc, symmetric → benign reconversion
  • T1 below muscle/disc, no opposed-phase drop → replacing tumour
  • Geographic subchondral STIR-bright + fracture line → marrow oedema

Soft-tissue mass

  • Follows fat, thin septa → lipoma; thick/nodular septa → ?ALT/liposarcoma
  • Serpentine vessels, phleboliths → haemangioma
  • Target sign, along a nerve, split-fat → PNST
  • Deep, >5 cm, heterogeneous / growing → indeterminate
    • ⚠ Indeterminate → refer to a sarcoma unit BEFORE biopsy.

Knee internal derangement

  • Linear meniscal signal reaching the articular surface → meniscal tear
  • Displaced fragment in notch / ‘double-PCL’ → bucket-handle tear
  • ACL discontinuity, abnormal angle, anterior tibial translation, pivot-shift bone bruises → ACL tear
  • Focal cartilage defect + subchondral oedema → chondral injury
Body (abdomen / pelvis)

Focal liver lesion

  • Very T2-bright, nodular discontinuous fill-in → haemangioma
  • Central scar, iso-to-hyperintense (retains) on HBP → FNH
  • Intralesional fat (opposed drop), OCP → adenoma
  • Arterial hyper + washout + capsule (at-risk) → HCC
  • Multiple, rim/target, restrict → metastases

Adrenal mass

  • Opposed-phase signal drop → lipid-rich adenoma
  • Macroscopic fat + India-ink margin → myelolipoma
  • Very T2-bright, avid enhancement → phaeochromocytoma
  • No drop + known primary → metastasis
    • ⚠ Suspect phaeo → exclude biochemically before biopsy.

Renal mass

  • Simple, non-enhancing → benign cyst (Bosniak I-II)
  • Enhancing thick septa / nodule → cystic RCC (III-IV)
  • T2-bright, avid, opposed-phase drop → clear cell RCC
  • T2-dark, hypoenhancing, restricts → papillary RCC
  • Macroscopic fat, no calcification → angiomyolipoma

Adnexal mass (O-RADS MRI)

  • Macroscopic fat ± Rokitansky nodule → dermoid
  • T1-bright, no fat-sat drop, T2 shading → endometrioma
  • T2-dark solid, low enhancement → fibroma
  • Solid enhancing tissue, intermediate/high curve, ascites → O-RADS 4-5 malignant

Prostate (PI-RADS v2.1)

  • PZ — focal marked DWI restriction (low ADC), early enhancement → PI-RADS 4-5 (significant cancer)
  • TZ — lenticular / ‘erased-charcoal’, non-circumscribed T2-low, DWI+ → PI-RADS 4-5
  • Round encapsulated T2 nodules (‘organised chaos’) → BPH nodule (benign)
  • Wedge / band-like, mildly T2-low → prostatitis (benign)
    • PZ is DWI-dominant, TZ is T2-dominant; DCE is the tie-breaker.
Cardiac

Late gadolinium enhancement (LGE) pattern

  • Subendocardial / transmural, in a coronary territory → ischaemic (infarct)
  • Mid-wall (septal), dilated LV → non-ischaemic DCM
  • Subepicardial / patchy inferolateral → myocarditis
  • Patchy mid-wall + basal septum, RV involvement → sarcoidosis
  • Global subendocardial + difficult myocardial nulling → amyloid

Myocardial oedema / function

  • Regional T2-high + matching wall-motion abnormality → acute ischaemia / infarct
  • Patchy T2-high + subepicardial LGE, recent viral illness → acute myocarditis
  • Asymmetric septal hypertrophy + patchy LGE → HCM
Breast

Breast lesion (BI-RADS MRI)

  • Irregular shape, spiculated margin, rim enhancement → suspicious (malignant)
  • Type 3 kinetics: fast initial + washout → suspicious
  • Oval/round, circumscribed, dark internal septations, type 1 persistent → fibroadenoma (benign)
  • Non-mass enhancement: segmental / clustered-ring / clumped → suspicious (DCIS)
  • Slow initial + persistent (type 1) curve → favours benign
High Yield MRI · distilled teaching reference · correlate with the full images and primary literature