Disclosure. + Outline. What is a stroke? Role of imaging in stroke Ischemic stroke Venous infarct Current topics

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1 + Kathleen R. Fink, MD University of Washington 5 th Nordic Emergency Radiology Course May 21, Disclosure My spouse receives research salary support from: Bracco BayerHealthcare Guerbet Thank you to my spouse, James Fink For some of these slides! + Outline What is a stroke? Role of imaging in stroke Ischemic stroke Venous infarct Current topics 1

2 + What is a stroke? Stroke is a syndrome of acute neurological dysfunction due to: Ischemia Intracerebral hemorrhage (IPH, IVH) Subarachnoid hemorrhage Venous thrombosis Infarction: brain, spinal cord or retinal cell death due to ischemia Silent stroke: infarction without attributable symptoms Sacco et al Stroke 2013 doi: /STR.0b013e318296aeca + Types of Stroke Ischemic Stroke Most common ~85% Interruption of arterial supply Hemorrhagic Stroke: term falling out of favor ICH most common - Often due to hypertension SAH less common - 85% of spontaneous SAH due to aneurysm rupture Transient Ischemic Attack (TIA): definitions vary Mini-stroke resolving within 24 hours High risk for future stroke - > one-third will have major stroke within 1 year if untreated % will have major stroke within 3 months + Acute Ischemic stroke 2

3 + Early Action Is Important Time Is Brain F.A.S.T. Assessment F = Face Smile > facial droop A = Arms Raise arms > downward drift S = Speech Phrase > slurred/strange speech T = Time If any sign +, note the time and call 911 In 2005, > 90% of those surveyed recognized sudden onset numbness as a stroke symptom, yet < 40% knew all major symptoms and to call ED Arrival: First 15 Minutes Upon Arrival Stat blood draw Finger stick glucose Place 2 large bore Ivs EKG Weigh or estimate weight Initial Stroke Assessment Short history and physical exam Document last time normal Quantify deficits - Glascow Coma Scale - NIH stroke score Call pharmacy (for tpa) + ED Radiology: 30 Minutes Clear a CT scanner STAT head CT - Non-contrast - CTA Blood on head CT? 3

4 + Blood on Head CT? No Blood: CTA neck/head + If No Blood on Head CT Time of last normal < 4 hours, 15 minutes? IF Yes: IV tpa candidate (15 minutes to Rx) IF No: Possible Endovascular Rx candidate Large artery occlusion < 6 hours - ICA, MCA, ACA, Vert, Basilar, PCA Basilar occlusion Rx considered beyond 6 hrs + IV tpa Criteria ( 3 hours) Inclusion Criteria Age 18+ with ischemic stroke 3 hrs to Rx - Measurable deficit (NIHSS) - CT excludes hemorrhage Cautionary Criteria Age < 18 or > 80 Minor symptoms (NIHSS <4) or improving Severe stroke: e.g. coma, NIHSS 20 Early brain ischemia findings on CT Seizure with postictal impairments Known neoplasm, AVM, aneurysm Pregnancy or parturition within previous 30 days 4

5 + IV tpa Criteria ( 3 hours) Exclusion Criteria CT confirms hemorrhage Stroke, MI or TBI within previous 90 days Known prior intracranial bleed/sah Clinical presentation of SAH (even if CT negative) HTN with refractory SBP > 185 or DBP > 110 Presumed septic embolus Surgery or biopsy within past 14 days Trauma with injuries/wounds within past 30 days Active bleeding or acute trauma (e.g. fracture) GI/GU hemorrhage within past 21 days Known hereditary or acquired bleeding diathesis Baseline glucose <50 or >400, plt <100K, hct <25 Non-compressible arterial or venous puncture in last 7 days Other serious, advanced or terminal illness any other condition that would pose a significant hazard to the patient if tpa Rx were initiated + IV tpa (3-4.5 hours) Same Eligibility Criteria as for IV tpa 3 hours, with Additional Exclusion Criteria: Age > 80 Oral anticoagulants (regardless of INR) NIHSS > 25 History of both stroke and diabetes + Ischemic infarct: CT Standard windows Stroke windows 5

6 + Ischemic infarct: MRI MRI DWI Stroke windows + Infarct: Time is helpful: Symptom onset 15:15 15:57 19:39 23:26 + Ischemic infarct: Early infarct often occult on CT. Nonenhanced CT used to: Find alternative or unexpected diagnosis Evaluate for imaging contraindications to giving TPA 6

7 + Ischemic infarct: TPA evaluation Imaging contraindications to TPA: Intracranial hemorrhage *+ Well demarcated infarct of greater than 1/3 MCA territory + Well demarcated infarct by CT may prompt reassessment of symptom timing * NINDs criteria, + ECASS II Criteria Ann Emerg Med 61:2, /3 MCA Territory Involvement > 1/3 <1/3 + Ischemic infarct: Tips Utilize stroke windows Center 32, narrow width Specifically evaluate - Basal ganglia - Insular ribbon Second look at areas based on clinical history Tread cautiously in the brainstem 7

8 + Ischemic infarct: Brainstem or not? Brainstem infarct No infarct + Acute Stroke MRI Diffusion-weighted Imaging Confirms or excludes new ischemia/infarct - Sensitivity %, specificity % - Positive within minutes, remains positive for days - ADC map is independent of T1/T2 effects Low values confirm diffusion restriction in the acute setting Distinguishes from T2 shine through artifact May reveal additional subclinical lesions relating to stroke mechanism Rarely reversible with restoration of perfusion AHA/ASA Guidelines for the Early Management of Patients With Acute Ischemic Stroke. Stroke. 2013;44: Acute Stroke MRI T2/FLAIR Defines extent of prior infarcts May detect early brain ischemia FLAIR may reveal slow flow vascular hyperintensities T2* GRE Defines extent of prior hemorrhages Detects new blood products May show artery susceptibility sign (more sensitive than NECT) AHA/ASA Guidelines for the Early Management of Patients With Acute Ischemic Stroke. Stroke. 2013;44:

9 + Acute Stroke: Diffusion MRI + Clot Signs: T2/FLAIR, T2* FLAIR Hyperintensity Sign T2* Artery Susceptibility Sign Slow Flow Distal to Clot Like Hyperdense Clot on CT + Acute Stroke: CT versus MRI Advantages of CT Lower cost Wider availability Shorter duration Fewer contraindications Advantages of MRI More sensitive for small acute infarcts Distinguishes acute from chronic ischemia/infarct Better spatial resolution Avoids ionizing radiation Accurate for acute blood 9

10 + MRI for TIA (< 24 hours) MRI more sensitive than NECT for both new and pre-existing ischemic lesions DWI positive in ~40% - Pooled data from 19 studies, > 1000K patients - Lesions smaller and multiple in TIA (vs CVA) - Associated with higher risk of recurrent ischemic events AHA/ASA Guidelines for the Early Management of Patients With Acute Ischemic Stroke. Stroke. 2013;44: Dense vessel sign Increased attenuation of an acutely thrombosed vessel Reported attenuation cutoff values vary. Attenuation of affected vessel should be greater than that of other vessels + Dense MCA sign: Dense MCA sign suggests acute MCA occlusion. Associated with large territory infarct and poorer outcome Not very sensitive (As low as 47%*) * Von Kummer

11 + Dense vessel sign: dot sign Smaller hyperdense focus in the Sylvian fissure Represents acute thrombosis of MCA branch + Dense basilar sign Dense basilar sign difficult: Calcified atherosclerotic plaque Beam hardening from the skull base No paired internal control (unlike MCA) Reasonable reported accuracy *+ : - Sensitivity 60-71% - Specificity 81-98% Consider HU cutoff of * * Connell 2012, + Goldmakher Venous thrombosis 11

12 + Dense vessel sign: venous Dense vessel sign can involves dural venous sinuses or veins Suggested HU cut-off value: 62 * OR ratio of attenuation value to hematocrit: >1.5 concerning * Here, HU Hct 32 HU/Hct = 2.0 * Buyck Dural venous sinus thrombosis: False positive Here, HU 65 Hct 46 HU/Hct = Dural Venous thrombosis Predominantly affects patients under 50 OCPs/peripartum Prothrombotic state Malignancy/infection If unrecognized, can result in complications of venous infarct with neurological consequences. Diagnosis can be difficult, both clinically and by imaging 12

13 + Dural venous thrombosis: Complications Noncontrast CT T1 post + Dural venous thrombosis: Complications Presentation 2 Days later + Dural venous sinus thrombosis: Spectrum of complications Venous infarct Vasogenic edema 13

14 + Dural venous sinus thrombosis: Spectrum of complications Venous Congestion + hemorrhage Parenchymal hemorrhage + Dural venous sinus thrombosis CT DWI/ADC + Dural venous sinus thrombosis FLAIR GRE 14

15 + Venous Sinus thrombosis: MR CT T1 T2 GRE + Venous sinus thrombosis: Summary Requires high index of suspicion for diagnosis Consider if you see Unusual infarct Unusual vasogenic edema Unusual hemorrhage Dense sinus sign Remember to look at flow voids on MRI + Current topics, headache 15

16 + Penumbra Imaging? Concept of salvageable ischemic tissue ( Penumbra ) - Ideal target is large ischemic zone surrounding small infarct core - Selection based on pattern of insult in addition to time of onset Penumbra = Ischemic Zone Infarct Core MRI: (Perfusion Diffusion) Mismatch CT: (Mean Transit Time Cerebral Blood Volume) Mismatch Lack of Standardization Techniques, Thresholds, Parameters, Processing Lack of Evidence Increased reperfusion in patients with large mismatches Selection based on penumbra imaging (MRI or CT) may not result in clinical benefit or improved outcome AHA/ASA Guidelines for the Early Management of Patients With Acute Ischemic Stroke. Stroke. 2013;44: Perfusion-Diffusion Mismatch DWI: Infarct Core Perfusion CT: Prolonged MTT + Intra-arterial tpa Intra-arterial Fibrinolysis (IA tpa) Considered for those ineligible for IV tpa Outcomes highly time-dependent, as with IV Combination IV + IA Fibrinolysis Large-vessel occlusions may benefit most, as they are more likely to fail with IV tpa alone IV tpa should be given to those eligible, even if IA treatments are considered Optimal dose of IA tpa is not well-established tpa not FDA approved for IA use AHA/ASA Guidelines for the Early Management of Patients With Acute Ischemic Stroke. Stroke. 2013;44:

17 + Endovascular Devices Mechanical Clot Disruption/Extraction Acute Angioplasty/Stenting Intracranial or extracranial Variety of devices, need for comparative data Reduced time from onset to reperfusion is highly correlated with better outcomes AHA/ASA Guidelines for the Early Management of Patients With Acute Ischemic Stroke. Stroke. 2013;44: Recent endovascular therapy trials EXTEND 1A ICA or MCA occlusion; all received TPA CTP showed penumbra Mechanical thrombectomy Solitaire device, started by 6 and ended by 8 hrs. Early neurological improvement and better functional outcome at 90 days ESCAPE: NIHSS > 5 Occlusion of MCA trunk Small infarct core (ASPECT 6-10) Moderate to good collaterals on CTA SWIFT-PRIME ICA or MCA occlusion; all received tpa NIHSS 8-29 ASPECTS > 6 MR CLEAN Usual care vs. Usual care + endovascular (within 6 hrs) Most received IV tpa Anterior cerebral proximal occlusion IA thrombolytic, mechanical thrombectomy or both + Endovascular Therapy Before Mechanical Extraction After Clot 4.5 hrs 17

18 + Outline What is a stroke? Role of imaging in stroke Ischemic stroke Venous infarct Current topics Thank you! Kathleen Fink ktozer@uw.edu The Seattle skyline as seen from Seacrest park in West Seattle. Sunset on Friday January 3rd, Photo by Katherine B. Turner 18