Lesson 1Perfusion imaging interpretation: core vs penumbra, Tmax, CBF, CBV thresholds and pitfallsThis part explains CT and MR perfusion analysis, separating core from penumbra using CBF, CBV, and Tmax maps, examining usual numerical thresholds, vendor variations, artefacts, and clinical traps that might mislead treatment choices in local practice.
Physiologic basis of core and penumbraTmax, CBF, and CBV map interpretationCommon numeric thresholds and caveatsArtifacts, motion, and truncation errorsChronic infarct and leukoaraiosis pitfallsLesson 2Guidelines and decision thresholds: major society recommendations for imaging selection and treatment windowsThis part sums up key guideline advice for acute stroke imaging, covering time frames for IV thrombolysis and thrombectomy, imaging choices beyond standard times, and applying decision thresholds in everyday Botswana clinical scenarios.
Key AHA/ASA and ESO imaging guidanceImaging criteria for IV thrombolysisImaging criteria for thrombectomyLate-window and wake-up stroke imagingReconciling guidelines with local practiceLesson 3Communication with stroke team: phrasing for thrombolysis and thrombectomy eligibility, recommended next imaging and monitoringThis part centres on brief, effective talks with the stroke team, including standard wording for thrombolysis and thrombectomy suitability, statements of doubt, suggested next scans, and advice on monitoring and repeat tests in resource-limited environments.
Key elements of the stroke phone reportPhrasing eligibility for IV thrombolysisPhrasing eligibility for thrombectomyRecommending next imaging stepsDocumenting uncertainty and follow-upLesson 4MRI protocols for hyperacute stroke: DWI, ADC, FLAIR, SWI, TOF/MRA, perfusion MRI parametersThis part describes MRI protocol setup for hyperacute stroke, detailing DWI and ADC for core, FLAIR for onset guess, SWI for bleeding and clot, TOF/MRA for vessels, and perfusion MRI settings suited to urgent decisions in Botswana hospitals.
Optimizing DWI and ADC for ischemic coreFLAIR mismatch and stroke onset estimationSWI for microbleeds and susceptibility vessel signTOF and contrast MRA for vessel imagingPerfusion MRI: sequence choice and timingLesson 5Reporting structure for stroke code: critical findings, side and vascular territory, estimated core/penumbra, time-sensitive recommendationsThis part lays out a structured report for stroke code, highlighting clear notes on bleeding, ischemic core and penumbra, blockage spot, side and vascular area, and direct, urgent suggestions for thrombolysis, thrombectomy, and follow-up scans.
Standardized report headings and sequenceDocumenting hemorrhage and ischemic coreSide, vascular territory, and ASPECTS scoringStating thrombectomy and lysis eligibilityTime-stamped, actionable recommendationsLesson 6CT protocols: slice thickness, reconstruction, contrast timing for CTA, coverage for perfusionThis part looks at noncontrast CT, CTA, and CT perfusion setup in acute stroke, focusing on slice thickness, reconstruction types, contrast timing, and perfusion range to balance speed, radiation, and accuracy in Botswana facilities.
Noncontrast CT slice thickness and kernelsCTA acquisition timing and contrast bolusCT perfusion coverage and slab selectionRadiation dose, ASIR, and artifact reductionMotion management and patient positioningLesson 7Selecting emergency imaging: noncontrast CT, CT angiography, CT perfusion and MRI alternativesThis part reviews choosing emergency imaging paths, comparing noncontrast CT, CTA, CT perfusion, and MRI based on time from start, patient state, restrictions, and local resources to build efficient, evidence-based plans for Botswana.
Baseline noncontrast CT indicationsWhen to add CTA in the first scanRole of CT perfusion in triageWhen MRI is preferred or essentialBuilding site-specific imaging algorithmsLesson 8Vascular occlusion assessment: site of occlusion, collateral status, thrombus length and clot burden scoreThis part explains step-by-step check of vascular blockage, including spotting blockage site, clot length, collateral flow, and clot burden scores on CTA and MRA, and how these affect thrombectomy choices and outlook in local cases.
Identifying proximal versus distal occlusionsMeasuring thrombus length on CTACollateral grading systems and scoringClot burden score and prognosisImaging predictors of recanalizationLesson 9False negatives and mimics: seizure, migraine, hypoglycemia, posterior fossa limitations and strategies to reduce errorsThis part tackles false negatives and stroke look-alikes, like seizures, migraines, low blood sugar, functional issues, and back brain strokes, offering imaging plans and tweaks to cut diagnostic mistakes in urgent Botswana settings.
Common clinical and imaging stroke mimicsSeizure and postictal imaging appearancesMigraine aura and perfusion abnormalitiesPosterior fossa stroke CT limitationsStrategies to reduce false negativesLesson 10Key acute imaging signs: early ischemic changes, hyperdense vessel sign, territorial infarction patternsThis part covers main CT and MRI signs of acute ischemia, including early tissue changes, dense vessel sign, loss of grey-white difference, groove flattening, and typical area infarct shapes linked to specific vessel paths.
Early ischemic CT signs and ASPECTS useHyperdense artery sign and variantsLoss of gray–white differentiation patternsTerritorial infarct patterns by vascular territoryPosterior circulation and lacunar stroke signs
