The patterns that keep coming back
Tap a card to reveal the diagnosis and the exam clue.
Did it stick? Six exam-style questions
Every wrong option is explained.
Written summary of the session
A reading version for revision on the ward or on the train. Chapter times refer to the recording above.
Part A — Reading a CT head (00:00 – 40:08)
CT vs MRI: identify the scan first
- CT shows bone as bright white, uses a single grey scale (density), and is the first-line scan in trauma, suspected haemorrhage and acute stroke.
- MRI has several sequences (T1, T2, FLAIR, DWI, ADC), shows cortical bone as dark, and gives far better soft-tissue detail. If the same slice looks different in two images, you are looking at MRI sequences.
CT densities and haemorrhage
- Acute blood is hyperdense (bright) on CT; over roughly two to three weeks it becomes isodense and then hypodense (dark). Air and fat are the darkest; calcification and metal the brightest.
Subdural haematoma (SDH)
- Crescent-shaped collection that follows the curve of the hemisphere and can cross suture lines. Think of the elderly, anticoagulants, alcohol and minor falls — tearing of bridging veins.
- Acute-on-chronic SDH: mixed density, often with a fluid level — fresh bright blood layering within an older dark collection.
Extradural haematoma (EDH) and contrecoup injury
- Lentiform (biconvex, lens-shaped) collection that is limited by the sutures, usually after a temporal bone fracture with middle meningeal artery injury; the classic stem mentions a lucid interval.
- Contrecoup: contusion on the side of the brain opposite to the point of impact.
Subarachnoid haemorrhage (SAH)
- Bright blood in the sulci, Sylvian fissures and basal cisterns after a thunderclap headache. CT within six hours is highly sensitive; if CT is normal and suspicion remains, lumbar puncture at twelve hours looks for xanthochromia.
Pneumocephalus and the Mount Fuji sign
- Intracranial air appears jet-black on CT (darker than CSF) — after trauma, surgery or sinus fracture.
- Mount Fuji sign: bilateral subdural air separating and compressing the frontal lobes, the hallmark of tension pneumocephalus, a neurosurgical emergency.
Hydrocephalus
- Dilated ventricles out of proportion to the sulci; early rounding of the temporal horns and periventricular low density from transependymal CSF flow.
MCA territory infarction on CT
- Early signs: hyperdense MCA sign, loss of grey–white differentiation, insular ribbon sign, obscured lentiform nucleus and sulcal effacement. Later: a wedge-shaped hypodensity in the MCA territory.
Calcifications: pathological vs normal
- Neurocysticercosis: multiple small calcified lesions in a patient with seizures and an endemic travel or residence history.
- Normal calcification is expected in the pineal gland, choroid plexus, basal ganglia (age-related), falx and habenula — do not call these disease.
Part B — Reading an MRI brain (40:08 – 74:54)
T1 vs T2
- T1: CSF is dark, white matter is brighter than grey matter — the "anatomy" sequence. Fat, subacute blood and gadolinium are bright.
- T2: CSF is bright — the "pathology" sequence; most oedema and lesions appear bright.
FLAIR — why CSF goes dark
- FLAIR is a T2 image with the free-water signal suppressed, so CSF turns dark while periventricular and cortical lesions stay bright. It is the sequence for multiple sclerosis plaques and subtle oedema.
DWI and ADC — restricted diffusion
- True restricted diffusion is bright on DWI and dark on ADC. It appears within minutes of an acute infarct and is also seen in abscess pus and in prion disease.
DWI-FLAIR mismatch and acute stroke imaging
- An infarct shows on DWI almost immediately but takes hours to appear on FLAIR. DWI positive, FLAIR negative suggests the stroke is likely under about 4.5 hours old — the basis for considering thrombolysis in wake-up or unknown-onset stroke under UK guidance.
CT perfusion — core and penumbra
- Perfusion maps separate the infarct core (dead tissue) from the penumbra (salvageable tissue). A small core with a large penumbra is the mismatch that supports mechanical thrombectomy in the extended window.
Multiple sclerosis and Dawson's fingers
- Ovoid periventricular lesions arranged perpendicular to the ventricles on sagittal FLAIR — Dawson's fingers — with involvement of the corpus callosum, juxtacortical white matter, brainstem and spinal cord.
MCA infarction on MRI; brain abscess
- An acute MCA infarct is a territorial area of DWI brightness with matching ADC darkness.
- A brain abscess is a ring-enhancing lesion whose centre restricts diffusion; a necrotic tumour's centre usually does not.
Part C — Exam strategy (74:54 – 91:56)
Ring-enhancing lesions: the differential
- Abscess, glioblastoma, metastases, toxoplasmosis (immunosuppressed), primary CNS lymphoma, tuberculoma and resolving haematoma. The stem decides: fever and a source point to abscess; known cancer to metastases; HIV with multiple lesions to toxoplasmosis or lymphoma.
How to approach any neuroimaging stem in MRCP Part 2
- Name the modality and sequence first. Then ask: is there blood, is there a mass, is there oedema, is the midline shifted, are the ventricles the right size?
- Match the image to the clinical stem before you look at the options — age, onset, trauma, anticoagulation, fever, immune status.
- Eliminate options by the one feature that does not fit; the examiners build look-alike pairs on purpose.
Rapid-fire revision
- The final minutes run a quick-fire set of cases to check the system works under time pressure, followed by details of the MRCP Part 2 course and a question-and-answer discussion.
Who taught it, and how to go further
Dr Chirag Madaan is the founder of Intellect Medicos, Course Director at Pastest, former ICU in-charge at Apollo Hospitals Delhi and author of Be an ECG Xpert. More than 1,000 doctors have cleared MRCP under his teaching.
Neuroimaging is one module of the Intellect Medicos MRCP Part 2 course, which also covers ECG mastery, chest and abdominal radiology, dermatology and ophthalmology images, weekly previous-year question classes, a timed weekly mock with full discussion and a 150-MCQ-per-system question bank. The next live batch starts on 22 November 2026.
