11/1/2018. Disclosure. Imaging in Acute Ischemic Stroke 2018 Neuro Symposium. Is NCCT good enough? Keystone Heart Consultant, Stock Options

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1 Disclosure Imaging in Acute Ischemic Stroke 2018 Neuro Symposium Keystone Heart Consultant, Stock Options Kevin Abrams, M.D. Chief of Radiology Medical Director of Neuroradiology Baptist Hospital, Miami, FL Clinical Associate Professor of Radiology FIU School of Medicine Is NCCT good enough? ICLIC M6 Srinivasan et al, Radiographics 2006 Wake Up Stroke In General ASPECTS > 6 eligible for treatment Evaluate with narrow window and level (eg 10, 30) to increase the sensitivity for detection of early ischemic findings ASPECTS < 3 1

2 Imaging Exclusion Criteria for IV tpa Intracerebral hemorrhage Prior stroke in previous 3 months Hx of prior intracranial hemorrhage Intracranial neoplasm, avm or aneurysm Recent intracranial or spinal surgery CT demonstrates multilobar infarction (hypodensity>1/3 MCA territory) Sx suggests SAH What Are We Looking For? BLEED LARGE OBVIOUS INFARCTS STROKE MIMICS EARLY SIGNS OF INFARCT SALVAGABLE TISSUE (PERFUSION) VESSEL PATENCY (CTA, MRA) CT VS MR FOR ACUTE STROKE Why Assess Collaterals? ADVANTAGES FAST READILY AVAILABLE R/O ACUTE BLEED EASY TO MONITOR PATIENTS NO CONTRA INDICATIONS DISADVANTAGES OLD VS NEW INFARCT NOT ALWAYS EASY NOT SENS. FOR EARLY ACUTE INFARCT PERFUSION ONLY LTD AREA IONIZING RADIATION To try to stratify those patients with ischemic penumbra who may benefit, and, not potentially harmed, by intervention/ revascularization. Some Ways We Can Assess Collateral Circulation in Acute Ischemic Stroke Conventional Angiography CTA Collateral Score Multiphasic CTA CT Perfusion MRI Techniques CTA Collateral Score 1 CS=0: No collateral supply CS=1: >0 but <50% filling of vessels of occluded MCA territory CS=2: >50% but <100% CS=3: 100% filling of vessels of occluded MCA territory Oh Young Bang et al; Collateral Circulation in Ischemic Stroke- Assessment Tools and Therapeutic Strategies, Stroke 2015: 46: IYL Tan et al; CTA clot burden score and collateral score, AJNR Mar

3 Neurophysiology of Perfusion 1 Stroke. Feb 2018 Neurological dysfunction occurs in a tissue after CBF falls below ~ ml/100g of tissue per minute CBF of < 10 can t be tolerated beyond a few minutes before infarction occurs CBF between 10 20, cell death may take minutes to hours. 1.Guidelines and Recommendations for Perfusion Imaging in Cerebral Ischemia; Stroke, April 2003 Which Perfusion Maps Matter? In General: MTT: most sensitive, least specific CBV: most specific, least sensitive CBF: somewhere in between CBV, CBF<30%, DWI MTT minus CBV ~ ischemic penumbra (tissue at risk) Tmax>6 sec. minus CBF<30%~ischemic penumbra Vendor dependent MTT, CBF, Tmax>6 seconds endovasc rx <3 hr onset left hemiparesis Middle age pt 3

4 MTT CBF CBV 4

5 Clot pic Wake up stroke 87 yo female NIHSS 11 on arrival 5

6 MTT CBF CBV 48 hour follow up NIHSS= 3 72 y.o. female, D.M. 3.5 hour onset left hemiparesis

7 Angioplasty and stent after IA tpa MTT CBF CBV Middle age female h/a dizzy ho, nausea, vomiting, pain right side of neck, NIHSS 0 7

8 CLOT C7 RCC INN RSC T 3 T2 T1 MTT CBF CBV N.B.: DAWN trial excluded patients with infarct volume>51ml 8

9 2 days later 9

10 Middle age male Acute onset hemiparesis and aphasia nihss 22 2 week follow up 10

11 MTT CBF CBV N.B.: DEFUSE 3 excluded patients with core infarct >70ml also excluded patients with mismatch ratio < Hour F/U; NIHSS= 3 Reality Check Although we see a great deal of brain detail in neuroimaging, each 1 mm 3 voxel: at least 80,000 neurons 4.5 million synapses 10 MAY 2013 VOL 340 SCIENCE 11

12 Why do perfusion? Helpful, although not perfect, in establishing ischemic penumbra Useful in differentiating stroke mimics (eg seizure). Aids in detecting large vessel occlusion (especially M2, P2, Basilar tip), or partially occlusive thrombus or high grade stenosis. May help in defining etiology (eg borderzone hypoperfusion or borderzone emboli). Possible Stroke with Aphasia and Altered Consciousness in Dr s Ofc? Stroke w/ & Altered Consciousness in Dr s Ofc Hyperperf p sz MTT CBF CBV Hyperperfusion Pattern First make sure you know which side the symptoms are related to. Early Re Perfusion after ischemia/ infarct After Seizure Hyperperfusion syndrome after CEA Severe Migraine 12

13 55 y.o. being evaluated for stroke 55 y.o. being evaluated for stroke B.P. 76/ 42 CBF CBV MTT Borderzone Hypoperfusion pattern Conclusions Hypotension Hi Grade proximal stenosis/ stenoses Emboli We have moved from a time based treatment to a tissue based treatment for AIS. The interventional tools and outcomes have become so encouraging that there is now a paradigm shift: From: which patients benefit from treatment? To: which patients do we withhold treatment? How many neurons are not worth saving? More RCT s are needed Thank You! 13