Imaging of Acute Stroke. Noam Eshkar, M.D New Jersey Neuroscience Institute JFK Medical Center Edison Radiology Group

Transcription

1 Imaging of Acute Stroke Noam Eshkar, M.D New Jersey Neuroscience Institute JFK Medical Center Edison Radiology Group

2 Modalities Non Contrast CT (NCCT) Contrast CT Angiography MRI MR Angiography Perfusion Techniques: CT/MR Angiography/Intervention

3 Non Contrast CT Readily available, ER, 24/7 Quick scan times, < one minute Excellent sensitivity to hemorrhage No injections Rules out many non-cva diagnoses CVA takes hours to appear

4 Intervention Triage CT contraindications to thrombolysis Hemorrhage Large visible infarct, >1/3 vascular territory Non infarct pathology Time factors IV: 3 hours IA: 6 hours (longer for basilar) Mechanical: 8 hours or more

5 Early CT Findings Loss of insular ribbon / lentiform nucleus Hyperdense vessel (MCA) Parenchymal lucency Loss grey-white differentiation Edema Decreased blood flow Vascular territory

6 Loss of Insular Ribbon

7 Effacement of lentiform nucleus

8 Hyperdense MCA

9 Hyperdense Basilar

10 Later CT Findings

11 CT Angiography Acute CVA Readily available Arch to circle of willis High resolution/ 3D Intervention planning IV contrast Ionizing radiation

12 CT Angiography - Technique Scan thoracic inlet to vertex Intracranial embolus/stenosis Carotid disease Arch anatomy Arterial phase bolus trigger Acquisition < one minute Effective with impaired/uncooperative patients

13 CT Angiography - Drawbacks Ionizing radiation Automated dose modulation Iodinated Contrast Allergic reaction Extravasation Nephropathy

14 Iodinated Contrast Nephropathy Serum Creatinine: to check or not to check Obtaining value typically delays treatment 60 minutes or more Significant delay in setting of acute stroke Loss of brain parenchyma Change of eligibility for treatment with time Risk = 1-2% Check if + renal/diabetic history?

15 CT Perfusion Repeated scanning first pass effect Multiple locations; multiple passes.

16 artery Contrast vein Time

17 Mean Transit Time Cerebral Blood Flow Cerebral Blood Volume MTT CBF CBV

18 Ischemia Infarct MTT CBV Difference is tissue at risk = penumbra

19 Blood Flow Quantification; ml/100g/min -Relative vs Absolute -Normal (absolute): GM 60/ WM 25

20 Relative Perfusion Penumbra ratio to normal CBF Core infarct: Penumbra - infarct: Penumbra - recovers:.5-.75

21 MTT CBV PENUMBRA

22 Acute CVA - CT work up Radiation Radiation Dose mgy CT head: 45 CT Angio Neck/Head: 30 CT perfusion: 105 California patients over exposed- CT perfusion mgy Skin burns/hair loss/?long term effects Manual override of scanner settings

23 MRI - DWI Diffusion Weighted Imaging Mainstay of stroke imaging Fast : < 1 minute Positive within minutes Other sequences hours Generally irreversible

24 MRI - DWI Measures water mobility Fades over about two weeks Very rare false negatives Few false positives blood, abscess Sort out with other sequences

25 Magnetic Resonance Angiography Time of Flight Blood motion No IV contrast Can be limited Slow flow Tortuosity Patient motion Complex flow: exaggerates stenosis

26 MRA MRA ANGIO

27 Contrast MRA More coverage Faster Better for tortuosity +/- C.O.W Contrast IV access Renal insufficiency NSF

28 MR Perfusion Contrast Time

29 Angiography Generally not for diagnosis Precursor to intervention: Intrarterial thrombolyis - tpa Mechanical Thrombectomy Angioplasty/Stent Risks Dissection, emboli, perforation, hemorrhage.

30 83 yo F RT hemiparesis Ca LT ICA terminus

31 One year prior Current

32 Prior Current

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34 81 yo F Slurred speech RT side weakness Dense L MCA

35 Left MCA bifurcation thrombus CTA

36 Post ia tpa

37 Before intervention 10 days later

38 87 yo F Altered mental status Dense Rt MCA 5 hours onset

39 before ia tpa with thrombectomy after

40 MRI 24 hours post

41 MRA 24 hours post CTA Post intervention angio

42 58 yo M LT weakness NCCT negative

43 CTA RT MCA filling defect

44 6 mg tpa + mechanical thrombectomy

45 24 hours post 6 mg tpa + mechanical thrombectomy

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47 68 yo F Afib RT hemiplegia NCCT: chronic occipital infarct 4 hours post onset

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49 PRE POST 14 mg tpa + thrombectomy

50 36 hours post

51 54 yo F Ongoing TIAs MRI: no acute CVA No flow, RT ICA

52 No flow Right ICA MRA

53 CT Angiography

54 MTT - at risk CBF CBV - mismatch

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56 Post STA-MCA

57 68 yo M RT weakness NCCT neg CTA neck neg

58 4/24

59 5/16 4/24

60 5/16 4/24

61 MTT DWI

62 61 yo F Acute left hemiparesis 5 hours post onset NCCT neg

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64 MTT DWI

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68 8 mg tpa and thrombectomy Started moving arm and leg post procedure Transferred for aortic repair

69 Summary ER: code stroke time is brain CT work up fastest NCCT/CTA Perfusion adds physiologic data Radiation/contrast MR Most sensitive for acute infarct No radiation/contrast More time consuming Difficult for acutely ill patients Angio: intervention

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