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pres.title = "Neuroradiology Case Questions for Residents";
pres.subject = "Neuroradiology";
pres.author = "Radiology Teaching Series";

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// ─── CASE DATA ───────────────────────────────────────────────────────────────
// Each case: { num, title, clinical, question, imageTags, answer, findings, teaching }
const cases = [
  {
    num: 1,
    title: "Acute Ischaemic Stroke",
    clinical: "62-year-old male presents with sudden-onset right-sided weakness and aphasia for 2 hours. Non-contrast CT head performed.",
    question: "What is the EARLIEST CT sign of acute MCA territory infarction visible within the first few hours?",
    imageTags: ["Non-contrast CT head", "Early ischaemic changes", "MCA territory"],
    answer: "Hyperdense MCA Sign / Loss of Insular Ribbon",
    findings: [
      "Hyperdense MCA sign (dense artery sign) - thrombus in MCA",
      "Loss of grey-white matter differentiation at insular cortex (insular ribbon sign)",
      "Subtle sulcal effacement in affected territory",
      "ASPECTS scoring used to quantify ischaemic extent (score ≤6 = poor prognosis)",
      "DWI MRI is far more sensitive (restricted diffusion within minutes)"
    ],
    teaching: "Early CT signs of infarction (hyperdense vessel, insular ribbon loss, lentiform nucleus obscuration) appear within 3–6 hours. ASPECTS score <7 predicts poor outcome with thrombolysis. MRI-DWI detects infarction within minutes."
  },
  {
    num: 2,
    title: "Subarachnoid Haemorrhage",
    clinical: "45-year-old female presents with 'worst headache of her life' - thunderclap onset. GCS 14/15. CT head performed urgently.",
    question: "Describe the CT findings and name the most common underlying cause.",
    imageTags: ["Non-contrast CT head", "Basal cisterns", "Subarachnoid space"],
    answer: "Hyperdense blood in subarachnoid space - Berry (Saccular) Aneurysm",
    findings: [
      "Hyperdense (white) blood filling the basal cisterns, sylvian fissures and sulci",
      "Star-shaped pattern around midbrain on axial images",
      "Most common cause: ruptured saccular (berry) aneurysm (85% of cases)",
      "Common aneurysm locations: anterior communicating artery (30%), posterior communicating (25%), MCA bifurcation (20%)",
      "If CT negative but clinical suspicion high → LP for xanthochromia"
    ],
    teaching: "SAH sensitivity on CT is 98% at <6 hours but drops to 50% at 1 week. CT angiography is the next step to localise the aneurysm. Risk of rebleed is highest in first 24h. Modified Fisher scale grades SAH extent and predicts vasospasm risk."
  },
  {
    num: 3,
    title: "Glioblastoma (GBM)",
    clinical: "58-year-old male with 3-week history of progressive headache, confusion and left arm weakness. MRI brain with gadolinium performed.",
    question: "What are the characteristic MRI features of glioblastoma multiforme, and what is its WHO grade?",
    imageTags: ["MRI T1+Gad", "MRI T2/FLAIR", "Ring-enhancing lesion", "White matter"],
    answer: "WHO Grade 4 Glioma - Heterogeneous ring-enhancing mass with central necrosis",
    findings: [
      "T1+Gad: Thick, irregular ring enhancement around a necrotic core",
      "T2/FLAIR: Extensive surrounding vasogenic oedema crossing white matter tracts",
      "Butterfly pattern if crossing corpus callosum (bilateral spread)",
      "Central necrosis (hypointense T1, heterogeneous T2)",
      "Mass effect: midline shift, transtentorial herniation risk",
      "MR spectroscopy: elevated choline, reduced NAA, lipid/lactate peaks"
    ],
    teaching: "GBM is WHO grade 4, median survival 12–15 months with treatment (surgery + temozolomide + radiotherapy - Stupp protocol). The 'butterfly glioma' pattern crossing the corpus callosum is virtually pathognomonic. Pseudoprogression (post-treatment change) can mimic progression on MRI."
  },
  {
    num: 4,
    title: "Meningioma",
    clinical: "67-year-old woman incidentally found to have a dural-based mass on MRI performed for headaches. No focal neurological deficit.",
    question: "What imaging features help distinguish meningioma from other extra-axial masses?",
    imageTags: ["MRI T1+Gad", "Dural-based mass", "Extra-axial", "CSF cleft"],
    answer: "Homogeneous enhancing extra-axial mass with dural tail sign",
    findings: [
      "Extra-axial location with CSF cleft between mass and brain parenchyma",
      "Homogeneous intense enhancement post-gadolinium",
      "Dural tail sign: linear enhancement extending along dura (80% sensitive, not fully specific)",
      "T2: isointense to grey matter (vs. hypointense in WHO grade 2/3)",
      "Hyperostosis or erosion of adjacent bone",
      "May show calcification on CT (psammomatous type)"
    ],
    teaching: "Meningiomas arise from arachnoid cap cells and are extra-axial (not intra-axial). 90% are WHO grade 1 (benign). The CSF cleft separates them from the brain. Dural tail is highly suggestive but not pathognomonic (also seen in dural metastases, lymphoma). Observation is appropriate for incidental, asymptomatic small meningiomas."
  },
  {
    num: 5,
    title: "Multiple Sclerosis",
    clinical: "28-year-old female presents with episodes of right-sided optic neuritis 6 months ago, now with new left leg weakness. MRI brain and spine requested.",
    question: "Describe the MRI features of multiple sclerosis and how lesions are classified.",
    imageTags: ["MRI FLAIR", "Periventricular lesions", "MRI T2", "Spine MRI"],
    answer: "Demyelinating plaques - periventricular, juxtacortical, infratentorial (Dawson fingers on FLAIR)",
    findings: [
      "FLAIR: Periventricular ovoid lesions perpendicular to ventricles (Dawson fingers)",
      "Juxtacortical lesions touching grey-white junction",
      "Infratentorial lesions (brainstem, cerebellar peduncles)",
      "T1: Active plaques enhance with gadolinium (ring or nodular); old lesions are T1 hypointense 'black holes'",
      "Spine: Short (<2 vertebral segments) T2 cord lesions, posterior/lateral columns",
      "McDonald criteria require dissemination in space (DIS) and dissemination in time (DIT)"
    ],
    teaching: "MS lesions are characterised by their periventricular distribution perpendicular to the ventricles (Dawson fingers on sagittal FLAIR). The McDonald 2017 criteria allow diagnosis from a single MRI demonstrating both DIS and DIT. Active lesions enhance for up to 6 weeks. NMOSD (neuromyelitis optica) typically causes long cord lesions (>3 vertebral segments)."
  },
  {
    num: 6,
    title: "Cerebral Metastases",
    clinical: "55-year-old male known to have NSCLC, presenting with headache and right-sided weakness for 2 weeks. MRI brain with gadolinium performed.",
    question: "What are the characteristic features of cerebral metastases, and which primary tumours most commonly metastasise to the brain?",
    imageTags: ["MRI T1+Gad", "Multiple enhancing lesions", "Grey-white junction", "Surrounding oedema"],
    answer: "Multiple ring-enhancing lesions at grey-white junction with disproportionate oedema",
    findings: [
      "Multiple lesions (60–70% cases) at grey-white matter junction (watershed zone)",
      "Ring or nodular enhancement post-gadolinium",
      "Disproportionately large surrounding vasogenic oedema relative to lesion size",
      "Hyperdense on CT if melanoma or haemorrhagic metastases",
      "Most common primaries: Lung (most frequent), Breast, Melanoma, Renal cell, Colorectal",
      "Melanoma, choriocarcinoma, RCC, and thyroid ca are prone to haemorrhage"
    ],
    teaching: "The grey-white junction is a watershed zone where embolic metastases arrest. Disproportionate oedema relative to lesion size helps distinguish mets from primary brain tumours. Single metastasis can be indistinguishable from GBM - tissue diagnosis required. MR spectroscopy and perfusion imaging can help differentiate."
  },
  {
    num: 7,
    title: "Cerebral Abscess",
    clinical: "35-year-old immunocompetent male with fever, headache and drowsiness for 5 days. Recent history of dental extraction. MRI brain performed.",
    question: "How does MRI (specifically DWI) help differentiate a cerebral abscess from a ring-enhancing tumour (necrotic GBM)?",
    imageTags: ["MRI DWI", "MRI ADC map", "Ring-enhancing lesion", "MRI T1+Gad"],
    answer: "Abscess: Restricted diffusion (bright DWI, dark ADC) due to viscous pus",
    findings: [
      "DWI: Bright (restricted diffusion) in abscess cavity - due to viscous pus with high cellularity",
      "ADC map: Dark (low ADC values) in abscess centre",
      "T1+Gad: Smooth thin ring enhancement (vs. thick irregular ring in GBM)",
      "T2: Central cavity hyperintense, surrounding T2 dark capsule (free radicals in macrophages)",
      "Rim may be hypointense on T2 due to paramagnetic free radicals",
      "Adjacent satellite lesions suggest pyogenic abscess spread"
    ],
    teaching: "DWI is the most reliable tool to differentiate abscess (restricted diffusion) from necrotic tumour (no restriction, free diffusion in necrotic centre, high ADC). MR spectroscopy shows amino acid peaks (valine, leucine, isoleucine) in bacterial abscess. Treatment: surgical drainage + antibiotics 6-8 weeks."
  },
  {
    num: 8,
    title: "Epidural Haematoma",
    clinical: "22-year-old male after RTA with brief LOC. GCS 15 then rapid deterioration to GCS 8 (lucid interval). CT head performed.",
    question: "Describe the CT findings and explain the pathophysiology of epidural haematoma.",
    imageTags: ["Non-contrast CT head", "Biconvex hyperdense collection", "Skull fracture", "Temporal region"],
    answer: "Biconvex (lenticular) hyperdense extra-axial collection - Middle Meningeal Artery tear",
    findings: [
      "Biconvex (lenticular) hyperdense collection, does NOT cross suture lines",
      "Most common location: temporal/temporoparietal region (75–80% cases)",
      "Associated temporal bone (squamous) fracture crossing middle meningeal artery groove",
      "Midline shift and ipsilateral uncal herniation risk",
      "Swirl sign: mixed density suggests active bleeding",
      "Lucid interval: artery bleeds slowly, initial LOC from concussion, then rebleeds"
    ],
    teaching: "Epidural haematoma is a neurosurgical emergency. It is arterial in origin (middle meningeal artery) and does not cross suture lines (periosteal dura firmly adherent). The lucid interval is characteristic. Subdural haematoma crosses suture lines, is crescent shaped, and is usually venous (bridging veins). EDH requires urgent surgical evacuation."
  },
  {
    num: 9,
    title: "Chronic Subdural Haematoma",
    clinical: "78-year-old female on warfarin presents with progressive cognitive decline over 3 weeks. Minor fall 4 weeks ago. CT head performed.",
    question: "What is the CT appearance of a chronic subdural haematoma, and how does it differ from an acute SDH?",
    imageTags: ["Non-contrast CT head", "Crescent-shaped collection", "Subdural space", "Bilateral"],
    answer: "Hypodense crescent-shaped collection - blood degradation products become isodense then hypodense",
    findings: [
      "Crescent-shaped collection following brain contour, CROSSES suture lines",
      "Acute SDH (0-3 days): Hyperdense (white) - fresh blood",
      "Subacute SDH (3-21 days): Isodense to brain - easily missed, look for midline shift",
      "Chronic SDH (>21 days): Hypodense (dark) - protein breakdown and reabsorption",
      "Mixed density: Rebleeding into chronic SDH",
      "Bilateral chronic SDHs common in elderly, alcoholic patients, anticoagulated patients"
    ],
    teaching: "SDH results from tearing of bridging cortical veins. In elderly patients, brain atrophy creates a larger subdural space. Isodense chronic SDH on CT is easily missed - MRI is more sensitive. Treatment depends on neurological status: observation vs. burr hole drainage vs. craniotomy."
  },
  {
    num: 10,
    title: "Cerebral Venous Sinus Thrombosis",
    clinical: "28-year-old female, 6 weeks post-partum, presents with headache, papilloedema and seizures. CT head shows subtle hyperdensity in superior sagittal sinus.",
    question: "What is the diagnostic investigation of choice for CVST and what are the key imaging findings?",
    imageTags: ["MRI T1+Gad", "MRV", "Dural sinus", "Delta sign", "DWI"],
    answer: "MR Venography (MRV) - Empty delta sign on CT, filling defect on MRV",
    findings: [
      "CT: Hyperdense cord sign (acute thrombus in sinus), empty delta sign with contrast (filling defect in superior sagittal sinus)",
      "MRV: Absent flow/filling defect in affected sinus",
      "MRI: Loss of normal flow void in dural sinus on T2",
      "Bilateral haemorrhagic infarctions in parasagittal regions (SSS thrombosis)",
      "DWI can show venous infarction with both restricted and facilitated diffusion",
      "Predisposing factors: pregnancy/puerperium, OCP, dehydration, thrombophilia"
    ],
    teaching: "CVST is diagnosed on CT venography or MR venography. The empty delta sign on contrast CT represents clot surrounded by enhancing collateral channels in the SSS. Treatment with anticoagulation (even in haemorrhagic infarcts) is the standard of care. SSS is most commonly involved, followed by transverse sinuses."
  },
  {
    num: 11,
    title: "Hydrocephalus",
    clinical: "4-month-old infant with rapidly increasing head circumference and bulging fontanelle. CT head shows enlarged ventricles.",
    question: "Distinguish obstructive (non-communicating) from communicating hydrocephalus, and give one cause of each.",
    imageTags: ["CT head", "Enlarged ventricles", "CSF pathways", "Periventricular lucency"],
    answer: "Obstructive: block within ventricular system (e.g. aqueduct stenosis); Communicating: impaired CSF reabsorption",
    findings: [
      "Obstructive (non-communicating): CSF obstruction within ventricular pathways",
      "Causes: aqueduct of Sylvius stenosis, colloid cyst of 3rd ventricle, posterior fossa tumour",
      "Communicating: CSF obstruction at arachnoid granulations or in subarachnoid space",
      "Causes: post-SAH, post-meningitis, carcinomatous meningitis",
      "CT: Disproportionate ventricular enlargement, periventricular lucency (transependymal oedema)",
      "Normal pressure hydrocephalus: Hakim triad (gait, cognition, incontinence) in elderly - large ventricles, normal CSF pressure"
    ],
    teaching: "Periventricular lucency on CT indicates transependymal CSF percolation suggesting acute/subacute raised ICP. Disproportionate temporal horn enlargement is an early sign. Evans' ratio (frontal horn width / biparietal diameter >0.3) indicates significant hydrocephalus. MRI phase-contrast can assess CSF flow at aqueduct (aqueductal stenosis)."
  },
  {
    num: 12,
    title: "Arteriovenous Malformation (AVM)",
    clinical: "25-year-old male presents with sudden-onset severe headache and right hemiparesis. CT shows parenchymal haemorrhage in the left parietal lobe.",
    question: "What investigation should follow CT to evaluate for underlying vascular malformation, and what are the key features of an AVM?",
    imageTags: ["CT angiography", "MRI T2", "Tangle of vessels", "Nidus", "Draining vein"],
    answer: "CT/MR Angiography then DSA - Tangle of dilated vessels (nidus) with early draining vein",
    findings: [
      "MRI T2: Flow voids representing the nidus (tangle of abnormal vessels)",
      "No intervening normal brain parenchyma within nidus (distinguishes from cavernoma)",
      "MRA/CTA: Enlarged feeding arteries, nidus, early draining vein (before venous phase)",
      "DSA (gold standard): Defines angioarchitecture, feeding arteries, nidus size, draining veins",
      "Haemosiderin rim on T2/SWI from prior bleeds",
      "Spetzler-Martin grade (I-V): size, eloquent cortex, deep venous drainage - guides treatment"
    ],
    teaching: "AVMs carry 2-4% annual haemorrhage risk. Haemorrhage is the presenting feature in ~50% cases. DSA remains gold standard for characterisation. Treatment options include microsurgery, stereotactic radiosurgery (Gamma knife), or endovascular embolisation (rarely curative alone). AVMs are congenital but symptoms typically appear in 2nd-4th decade."
  },
  {
    num: 13,
    title: "Acoustic Neuroma (Vestibular Schwannoma)",
    clinical: "52-year-old female with progressive unilateral right-sided sensorineural hearing loss and tinnitus for 18 months. MRI IACs performed.",
    question: "Describe the MRI features of a vestibular schwannoma and how it is differentiated from meningioma of the CPA.",
    imageTags: ["MRI T1+Gad", "MRI T2", "CPA angle", "Internal auditory canal", "Ice cream cone shape"],
    answer: "Intracanalicular or CPA mass centred on IAC - Ice cream cone shape on T2",
    findings: [
      "Origin at vestibular division of CN VIII within IAC (80%) or CPA cistern",
      "T2: Hypointense mass in hyperintense CSF - filling the IAC ('ice cream cone' shape)",
      "T1+Gad: Homogeneous or heterogeneous enhancement (larger lesions heterogeneous)",
      "Widening/remodelling of the IAC on CT",
      "CPA meningioma: Broad dural base, NOT centred on IAC, obtuse angle with posterior petrous face, calcification possible",
      "HINT: Schwannoma = acute angle with petrous bone; Meningioma = obtuse angle + dural tail"
    ],
    teaching: "Vestibular schwannomas are benign, slow-growing. T2-weighted sequences (CISS/FIESTA) are optimal for IAC assessment. NF2 (neurofibromatosis type 2) should be suspected with bilateral vestibular schwannomas. Management: 'watch and scan' for small tumours, stereotactic radiosurgery, or microsurgical excision for larger tumours."
  },
  {
    num: 14,
    title: "Pituitary Adenoma",
    clinical: "38-year-old female with bitemporal hemianopia, amenorrhoea and galactorrhoea. MRI pituitary performed.",
    question: "Classify pituitary adenomas by size and describe MRI findings of a macroadenoma with suprasellar extension.",
    imageTags: ["MRI T1 sagittal", "MRI T1+Gad coronal", "Sella turcica", "Optic chiasm", "Figure-of-eight shape"],
    answer: "Macroadenoma (>10mm) - Figure-of-eight shape, compression of optic chiasm, loss of normal pituitary signal",
    findings: [
      "Microadenoma (<10mm): hypointense T1 focus within enhancing pituitary gland; gland height >8mm (F)/>6mm (M)",
      "Macroadenoma (>10mm): Enlarges sella, figure-of-eight shape due to diaphragma sellae constriction",
      "Suprasellar extension compresses optic chiasm → bitemporal hemianopia",
      "Cavernous sinus invasion (Knosp grade ≥3) indicates unresectable disease",
      "T1 bright spot (posterior pituitary) absent or displaced",
      "Prolactinoma most common; treated medically (dopamine agonists); others require surgery"
    ],
    teaching: "The pituitary gland normally enhances intensely. Microadenomas are identified as relatively hypointense foci on dynamic gadolinium imaging. Macroadenomas classically have a figure-of-eight shape caused by the diaphragma sellae waist. Cavernous sinus invasion (Knosp classification) predicts surgical resectability."
  },
  {
    num: 15,
    title: "Spinal Cord Compression",
    clinical: "65-year-old male with known prostate cancer, presenting with progressive bilateral leg weakness, numbness and urinary retention for 3 days.",
    question: "What is the investigation of choice for suspected metastatic spinal cord compression (MSCC) and what are the MRI findings?",
    imageTags: ["MRI spine T2 sagittal", "T1 post-Gad", "Vertebral metastasis", "Epidural extension", "Cord compression"],
    answer: "Urgent whole spine MRI - T1 hypointense vertebral body, epidural mass compressing cord",
    findings: [
      "T1: Vertebral body metastases - hypointense replacing normal bright fatty marrow",
      "T2/STIR: Hyperintense marrow signal in involved vertebrae (oedema/tumour)",
      "Epidural extension compressing thecal sac and cord",
      "T2 cord signal change (myelopathy) = poor prognostic sign",
      "Multiple vertebral levels involved (prostate mets commonly skip-level)",
      "Whole spine MRI mandatory as 30% have multiple levels"
    ],
    teaching: "MSCC is an oncological emergency. MRI of the whole spine (not just symptomatic level) is mandated as multiple segments may be involved. Prostate, lung, breast, myeloma and renal cancers are the most common causes. Treatment: high-dose steroids immediately, followed by radiotherapy or surgical decompression depending on prognosis and stability."
  },
  {
    num: 16,
    title: "Pontine Glioma (DIPG)",
    clinical: "7-year-old girl with 6-week history of facial weakness, diplopia and ataxia. MRI brain and spine performed.",
    question: "What are the MRI characteristics of Diffuse Intrinsic Pontine Glioma (DIPG) and why is biopsy traditionally avoided?",
    imageTags: ["MRI T2 axial", "MRI T1 sagittal", "Pontine enlargement", "T1+Gad"],
    answer: "Diffuse T2 hyperintense expansion of the pons engulfing basilar artery, poor or absent enhancement",
    findings: [
      "T2: Diffuse hyperintense expansion of pons (>60% of pons cross-section)",
      "T1: Hypointense, obliterating normal pontine architecture",
      "Basilar artery encased by tumour but not displaced (intrinsic location distinguishes from extrinsic mass)",
      "Variable (usually minimal) gadolinium enhancement at presentation",
      "No hydrocephalus typically (does not block 4th ventricle early)",
      "H3K27M mutation diagnostic; biopsy now increasing with stereotactic technique but historically avoided due to location risk"
    ],
    teaching: "DIPG (now WHO grade 4 H3K27-altered diffuse midline glioma) carries a median survival of 9-11 months. The basilar artery encased but not displaced is a key radiological feature differentiating it from exophytic brainstem tumours. Radiotherapy is standard (62% temporary improvement). ONC201 (dopamine receptor antagonist) shows promise in H3K27-mutant tumours."
  },
  {
    num: 17,
    title: "Subdural Empyema",
    clinical: "19-year-old male presents with fever, headache, rapidly progressing obtundation and seizures. History of recent frontal sinusitis. MRI brain performed urgently.",
    question: "How does MRI differentiate subdural empyema from a chronic subdural haematoma, and what is the most appropriate urgent treatment?",
    imageTags: ["MRI DWI", "MRI T1+Gad", "Subdural collection", "Adjacent meningeal enhancement"],
    answer: "Subdural empyema: DWI restricted diffusion (bright), rim-enhancing collection - urgent surgical drainage",
    findings: [
      "DWI: Restricted diffusion (bright) in empyema - pus contains inflammatory cells, debris",
      "T1+Gad: Peripheral rim enhancement of the subdural collection",
      "Adjacent leptomeningeal and cortical enhancement (associated meningitis/cerebritis)",
      "T2: Heterogeneous subdural collection with adjacent cortical oedema",
      "Sinusitis or mastoiditis as the source (look at paranasal sinuses on same scan)",
      "Chronic SDH: Hypodense, no restricted DWI, no surrounding inflammation"
    ],
    teaching: "DWI is the critical sequence - restricted diffusion differentiates empyema from hygroma/chronic SDH. Subdural empyema is a neurosurgical emergency requiring urgent craniotomy and drainage (burr holes may not give adequate access). Preceded by sinusitis (70%), otitis media (20%). Pathogens: Streptococcus milleri, anaerobes. Mortality 10-20% even with treatment."
  },
  {
    num: 18,
    title: "Cavernous Malformation (Cavernoma)",
    clinical: "32-year-old female with recurrent seizures. MRI brain performed. T2* GRE sequence shows a specific finding.",
    question: "What is the characteristic MRI appearance of a cerebral cavernous malformation, and which sequence is most sensitive?",
    imageTags: ["MRI T2*/ SWI", "Popcorn appearance", "Haemosiderin ring", "MRI T1"],
    answer: "Popcorn / mulberry appearance with peripheral haemosiderin ring - best seen on SWI/GRE T2*",
    findings: [
      "T1: Mixed signal intensity 'popcorn' lesion - blood products in multiple stages",
      "T2*/ SWI: Blooming black haemosiderin ring (hemosiderin staining from prior microhaemorrhages)",
      "No surrounding oedema (unless acute bleed)",
      "No feeding artery or draining vein on MRA (distinguishes from AVM)",
      "Familial cavernomatosis: multiple lesions, autosomal dominant (CCM1/2/3 genes)",
      "SWI (susceptibility-weighted imaging) is most sensitive - detects microhaemorrhages not visible on conventional sequences"
    ],
    teaching: "Cavernomas are 'angiographically occult' vascular malformations - they do NOT appear on conventional angiography. The haemosiderin ring is pathognomonic. Annual haemorrhage risk: 0.5-1% per year (higher in posterior fossa/brainstem locations: 2-5%/year). SWI identifies many more lesions than T2* GRE and should be the sequence of choice."
  },
  {
    num: 19,
    title: "Posterior Reversible Encephalopathy Syndrome (PRES)",
    clinical: "35-year-old female with eclampsia post-delivery, presenting with seizures and visual disturbance. BP 190/115 mmHg. MRI brain performed.",
    question: "Describe the MRI findings of PRES and explain the underlying pathophysiology.",
    imageTags: ["MRI FLAIR", "Posterior cerebral regions", "Vasogenic oedema", "DWI"],
    answer: "Bilateral symmetric FLAIR hyperintensity in posterior parieto-occipital regions - vasogenic oedema from failed cerebrovascular autoregulation",
    findings: [
      "FLAIR: Bilateral, roughly symmetric hyperintensity in posterior cerebral regions (occipital, parietal)",
      "Posterior predominance due to relative lack of sympathetic innervation in posterior circulation",
      "DWI: Facilitated diffusion (vasogenic oedema, ADC elevated) - distinguishes from infarction",
      "T1+Gad: Variable leptomeningeal enhancement",
      "Anterior/frontal involvement possible in severe cases (20-30%)",
      "Conditions: Eclampsia/pre-eclampsia, hypertensive emergency, CsA/tacrolimus toxicity, sepsis"
    ],
    teaching: "PRES is caused by failed cerebrovascular autoregulation leading to vasogenic (not cytotoxic) oedema. The DWI/ADC pattern is key: PRES = high ADC (vasogenic, reversible), whereas infarction = low ADC (cytotoxic, irreversible). Most cases resolve with BP control and removal of precipitating cause. Atypical cases with restricted DWI indicate true infarction."
  },
  {
    num: 20,
    title: "Neurocysticercosis",
    clinical: "28-year-old immigrant from an endemic country presents with new-onset seizures. CT head shows multiple calcified lesions and one ring-enhancing lesion.",
    question: "Describe the CT and MRI stages of neurocysticercosis and which stage is most likely causing the seizures.",
    imageTags: ["CT head", "Ring-enhancing lesion", "Calcified nodules", "Scolex", "MRI T2"],
    answer: "Vesicular/colloidal vesicular stage (ring-enhancing, viable/dying larva with scolex) causes seizures via perilesional inflammation",
    findings: [
      "Stage 1 - Vesicular: Well-defined cyst with eccentric scolex (white dot sign), no surrounding oedema, no enhancement",
      "Stage 2 - Colloidal vesicular: Ring enhancement, surrounding oedema - dying larvae trigger immune response",
      "Stage 3 - Granular nodular: Nodular enhancement, reducing oedema",
      "Stage 4 - Calcified nodular: Punctate calcifications (end stage), no oedema",
      "Multiple stages may coexist simultaneously in one patient",
      "White dot sign (scolex) on T2 MRI is pathognomonic"
    ],
    teaching: "Neurocysticercosis is the most common cause of new-onset seizures in adults in endemic countries. The scolex (white dot on T2 MRI) within a cyst is pathognomonic. Calcified lesions on CT represent burned-out disease and can cause seizures by focal gliosis. Treatment: albendazole + praziquantel for viable cysts; anti-epileptics; steroids to reduce inflammation. Calcified lesions do not require antiparasitic therapy."
  }
];

// ─── HELPER: Add Question Slide ──────────────────────────────────────────────
function addQuestionSlide(c) {
  const s = pres.addSlide();
  s.background = { color: DARK_BG };
  topBar(s);

  // Case number badge
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  bottomBar(s, `Case ${c.num} of 20  |  Question`);
}

// ─── HELPER: Add Answer Slide ─────────────────────────────────────────────────
function addAnswerSlide(c) {
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  bottomBar(s, `Case ${c.num} of 20  |  Answer`);
}

// ─── BUILD ALL SLIDES ─────────────────────────────────────────────────────────
cases.forEach(c => {
  addQuestionSlide(c);
  addAnswerSlide(c);
});

// ─── FINAL SUMMARY SLIDE ──────────────────────────────────────────────────────
{
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  topBar(s);

  s.addShape(pres.ShapeType.rect, { x: 0, y: 0.06, w: "100%", h: 0.5, fill: { color: MID_BLUE } });
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  });
}

// ─── WRITE FILE ───────────────────────────────────────────────────────────────
pres.writeFile({ fileName: "/home/daytona/workspace/neuroradiology-cases/Neuroradiology_Cases_for_Residents.pptx" })
  .then(() => console.log("SUCCESS: Presentation written."))
  .catch(e => { console.error("ERROR:", e); process.exit(1); });