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Head CT Interpretation and Advanced Neuroimaging in ED Stroke Patients Andrew Asimos, MD Director of Emergency Stroke Care Carolinas Medical Center Charlotte, NC Adjunct Associate Professor, Department of Emergency Medicine University of North Carolina School of Medicine at Chapel Hill.
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Head CT Interpretation and Advanced Neuroimaging in ED Stroke PatientsAndrew Asimos, MDDirector of Emergency Stroke CareCarolinas Medical CenterCharlotte, NCAdjunct Associate Professor, Department of Emergency MedicineUniversity of North Carolina School of Medicine at Chapel Hill
4th MediterraneanEmergency MedicineCongressSorrento, Italy September 17, 2007
Disclosures • NovoNordisk, Boehringer Ingelheim Advisory Boards • Research support from Boehringer Ingelheim
Session Objectives • Review findings consistent with early ischemic changes on non-contrast CT • Understand the basis for the clinical application of CTA and CTP imaging in acute stroke • Understand the images that comprise a CTA/CTP series • Understand the limitations of CTP imaging
Key Learning Points • Non-contrast CT features of early ischemic stroke are subtle, with considerable inter-reader variability • CTP more accurate than unenhanced CT for detecting stroke and determining the extent of stroke • CTA excellent at detecting large vessel occlusion • CTA and CTP will likely replace non-contrast CT as the imaging standard within the next few years
Case: Patient presentingwithin 3 hour window • 50 yo male • CT less than 2 hours within symptom onset • Awake, alert, dysarthric • Fixed right sided gaze • Left sided weakness
Essential Imaging Questions • Is there hemorrhage? • Are findings consistent with acute ischemic stroke? • Can this imaging modality’s results add to my risk/benefit analysis? • Is there large vessel occlusion? • Is there “irreversibly” infarcted core? • Is there “salvageable” penumbra? • Are other findings present that should be considered • Microbleeds • Leukoaraiosis
The Four P’s of Acute Stroke Imaging Rowley HA et al. Am J Neuroradiol 2001;22:599-601.
Evolution of an Infarct on CT 6hrs 24hrs 48hrs 72hrs 96hrs
Hyperacute Stroke: Subtle Signs on Non-contrast CT • Hyperdense MCA sign • Obscuration of the lentiform nucleus and basal ganglia • Effacement of the subinsular cortex • Subtle crowding of sulci from early edema
Case: Patient presentingwithin 3 hour window • 50 yo male • CT less than 2 hours within symptom onset • Awake, alert, dysarthric • Fixed right sided gaze • Left sided weakness
Case: Patient presentingwithin 3 hour window Initial BF BV TTP
Case:“Wake up” Stroke 0735 at outside hospital
Case: “Wake up” Stroke 1030 at stroke center
Therapeutic Window • Time from symptom onset used for theoretical and practical reasons • Increasingly will rely on imaging studies to determine tissue salvageability and clot burden
Advanced CT Imaging for Acute Stroke: CTP versus MRI Muir KW et al. Lancet Neurology 2006; 5:755-768
CT Perfusion Terminology Blood Flow Blood Volume Mean Transit Time or Time to Peak
Changes in Cerebral Vascular Physiology with Worsening Circulatory Impairment
Relationship between CBV, CBF, and MTT Blood Flow Blood Volume Mean Transit Time or Time to Peak MTT= CBV/CBF
Conclusions • CTP more accurate than unenhanced CT for detecting stroke and determining the extent of stroke • Possible to distinguish penumbra from infarcted tissue • Correlation between PCT/CTA and MRI is excellent • Already used in DIAS and DEDAS Wintermark M et al. Am J Neuroradiol 2005;26(1):104-12. Wintermark M et al. Stroke 2006;37:979-985. Wintermark M et al. Neurology 2007;68(9):694-697.
Important Remaining CTP Questions • What is the interrater reliability of visual estimation of lesion volumes? • Is that variability clinically important? • Can computerization automate measurement of absolute perfusion thresholds and lesion volume in a clinically meaningful way? • Will the current perfusion thresholds for penumbra and infarct be maintained with rigorous future testing?
Questions? www.FERNE.org aasimos@carolinas.org 704 355 4212 ferne_memc_2007_braincourse_asimos_neuroimaging_091707_finalcd 10/1/2014 5:04 AM