Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Imaging Modalities in Acute Stroke: Time is Brain
Document related concepts
no text concepts found
Transcript
Jeremiah Scharf Gillian Lieberman, MD April 2001 Imaging Modalities in Acute Stroke: Time is Brain Jeremiah Scharf, Harvard Medical School, MS IV Gillian Lieberman, MD Beth Israel-Deaconess Medical Center Department of Radiology Jeremiah Scharf Gillian Lieberman, MD Stroke - Definition and Statistics Acute, vascular injury to CNS <24 hrs = TIA >24 hrs = stroke (CVA) Affects 600,000 people/ yr (that is 1 stroke per minute!) Is #3 cause of mortality in adults Is #1 cause of disability http://www.swmed.edu/stars/resources/stroke.html 2 Jeremiah Scharf Gillian Lieberman, MD Types of Stroke Hemorrhagic usually hypertensive hemorrhage Ischemic (80%) Thrombotic (20%) (40%) intracerebral atherosclerosis Embolic (60%) Cardiac embolus (thrombus, tumor, septic embolus) artery-to-artery (mainly carotid thrombus) Paradoxical embolus (thrombus, fat, air) 3 Jeremiah Scharf Gillian Lieberman, MD Risk Factors for Stroke Atherosclerosis risk factors Family history of CVA, TIA, or MI Hypertension Smoking Diabetes Hypercholesterolemia Previous CVA, TIA, or MI Atrial fibrillation 4 Jeremiah Scharf Gillian Lieberman, MD Our Patient - BF 86 yo F w/ Hx of HTN, CAD s/p MI, and high cholesterol presented to PCP for routine visit Felt “funny” -> began seizing In ED, unresponsive, L. sided hemiplegia eyes deviated to the right 5 Jeremiah Scharf Gillian Lieberman, MD Differential Diagnosis Many CNS diseases can mimic ischemic stroke Hemorrhage Mass lesion (tumor, abscess, AVM) Seizure (Todd’s paralysis) Hemiplegic migraine MS flare Venous infarct 6 Jeremiah Scharf Gillian Lieberman, MD Goals of Imaging in Acute Stroke 1. Rule in or out other disease processes 2. Define location, extent and age of infarct 3. Do so as rapidly as possible TIME IS BRAIN 7 Jeremiah Scharf Gillian Lieberman, MD Cerebrovascular Anatomy Posterior Circulation Anterior Circulation 8 MGH Handbook of Neurology Jeremiah Scharf Gillian Lieberman, MD Anatomy of the Anterior Circulation Anterior cerebral artery Middle cerebral artery Internal carotid artery Anterior cerebral artery Middle cerebral artery Internal carotid artery MGH Handbook of Neurology High Yield Neuroscience 9 Jeremiah Scharf Gillian Lieberman, MD Vascular territories in the brain 10 MGH Handbook of Neurology Jeremiah Scharf Gillian Lieberman, MD Imaging Modalities in Acute Stroke CT without contrast Conventional MRI Diffusion-Weighted and Perfusion MRI MRA Ultrasound 11 Jeremiah Scharf Gillian Lieberman, MD CT Imaging in Acute Stroke - 1 Initial test of choice Best modality for detecting hemorrhage Identifies mass lesions (tumor, abscess, AVM) Fast and readily available = Crucial for stroke triage (rule in/out other diseases) Patient #2 - LL BIDMC 12 Jeremiah Scharf Gillian Lieberman, MD CT Imaging in Acute Stroke Our - 2Patient HOWEVER, CT is poor at detecting acute infarcts Only 40% sensitivity <24 h Film Findings for our patient, BF: Normal Initial Head CT 2 hours post stroke BIDMC 13 Patient #1 – BF; 1-2 hrs post stroke Jeremiah Scharf Gillian Lieberman, MD Our patient BF: CT#2 – 8 hours later As time passes, classic signs of stroke appear: Normal G/W diff. Loss of gray-white matter differentiation Normal sulci Sulcal effacement BIDMC Patient #1 – BF; 8 hrs post stroke 14 Jeremiah Scharf Gillian Lieberman, MD Our patient BF CT#3 - 2 days later Complete loss of gray-white matter differentiation ? hemorrhagic transformation Sulcal effacement BIDMC Patient #1 – BF; 48 hrs post stroke 15 Jeremiah Scharf Gillian Lieberman, MD Therefore, other imaging modalities are used to detect strokes < 6 hours! 16 Jeremiah Scharf Gillian Lieberman, MD Imaging Modalities in Acute Stroke CT without contrast Conventional MRI Diffusion-Weighted and Perfusion MRI MRA Ultrasound 17 Jeremiah Scharf Gillian Lieberman, MD Conventional MR Imaging in Stroke Our Patient T1 T2 Slight incr. detection rate over CT in early stroke T2 hyperintensity visible at 12-24 hrs (80% +) represents BIDMC edema May see absent flow voids = arterial occlusion BIDMC T1 imaging basics T2 imaging basics CSF is dark Soft tissue is bright Good for mass lesions CSF is bright Soft tissue is dark Good for edema18(bright) Jeremiah Scharf Gillian Lieberman, MD Conventional MR Imaging in Stroke Our patient, BF, underwent an MRI study immediately following her initial CT, 2 hours after her stroke Film Findings: Normal Initial MRI: ? Absent R. MCA Flow Void (suggestive of MCA occlusion) BIDMC T2 image 19 Patient BF; 2 hrs post stroke Jeremiah Scharf Gillian Lieberman, MD Our patient BF - MRI #2 :30 hours later At 30 hrs., classic MR signs of infarct are present Film Findings: T2 hyperintensity in temporal lobe, MCA distribution BIDMC T2 image 20 Patient BF; 30 hrs post stroke Jeremiah Scharf Gillian Lieberman, MD Conclusions - Conventional MR Imaging in Acute Stroke Conventional MRI can detect acute infarcts slightly earlier than CT Nonetheless, additional techniques are still needed for early stroke detection 21 Jeremiah Scharf Gillian Lieberman, MD Imaging Modalities in Acute Stroke CT without contrast Conventional MRI Diffusion-Weighted and Perfusion MRI MRA Ultrasound 22 Jeremiah Scharf Gillian Lieberman, MD Diffusion Weighted MRI Imaging (DWI) Osmotic pump failure is 1st event in ischemia Fluid shift extracellular->intracellular Water in cells now can’t diffuse! Detected as decreased diffusion coefficient (ADC) Increased restriction of diffusion (DWI) Detects change within 30 minutes of onset of stroke Beats T2 signal by 3-6 hours !!! 23 Schaefer et al. Radiology 217:331-345, 2000 Jeremiah Scharf Gillian Lieberman, MD Our Patient had a DWI MRI immediately following the initial routine MRI 24 Jeremiah Scharf Gillian Lieberman, MD DWI in BF at 2 hours post-stroke In our patient, DWI sequences were performed during her initial MRI A faint increase in DWI signal was observed in the temporal and insular cortex. Indicated early ischemia in MCA territory Led to treatment with IV thrombolytic therapy (t-PA) BIDMC Patient BF; 2 hrs post stroke 25 Jeremiah Scharf Gillian Lieberman, MD That’s good, but could we predict how bad her stroke might get? 26 Jeremiah Scharf Gillian Lieberman, MD Imaging the Penumbra: the Holy Grail of Stroke Diagnostics DWI is thought to show the area currently infarcting. But is there an “area at risk” where blood flow is reduced but cells haven’t died yet? Imaging this region (the penumbra) = goal of MR perfusion imaging Uses gadolinium for contrast Changes magnetic properties of perfused tissue vs. non-perfused Measures decreased flow in penumbra! -increased mean-transit-time (MTT) of blood flow to penumbra 27 http://www.swmed.edu/stars/resources/stroke.html Jeremiah Scharf Gillian Lieberman, MD Correlation of Perfusion Imaging with Infarct Progression DWI MTT Early (2h): =small area of injury = area of low/ slow blood flow = area at risk for stroke extension Late (29h): =larger area of injury (correlates w/ 2h MTT) Baird AE and Warach S. J. Cereb. Blood Flow Metab. 18(6): 583-609, 1998. 28 Jeremiah Scharf Gillian Lieberman, MD Progression of Infarct in BF: DWI at 30 hrs post-stroke serial, axial sections demonstrating extent of infarct at 30 hours normal DWI normal brain 29 BIDMC Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 2 normal DWI normal brain BIDMC 30 Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 3 increased DWI injured brain BIDMC 31 Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 4 increased DWI injured brain 32 BIDMC Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 5 increased DWI injured brain 33 BIDMC Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 6 increased DWI injured brain 34 BIDMC Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 7 increased DWI injured brain 35 BIDMC Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 8 increased DWI injured brain 36 BIDMC Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 9 increased DWI injured brain 37 BIDMC Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 10 increased DWI injured brain 38 BIDMC Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 11 increased DWI injured brain 39 BIDMC Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 12 increased DWI injured brain BIDMC 40 Jeremiah Scharf Gillian Lieberman, MD DWI in 3D - 13 increased DWI injured brain BIDMC 41 Jeremiah Scharf Gillian Lieberman, MD Summary – Extent of infarct our patient R. MCA territory R. PCA territory (complete) 42 MGH Handbook of Neurology BIDMC Jeremiah Scharf Gillian Lieberman, MD Imaging Modalities in Acute Stroke CT without contrast Conventional MRI Diffusion-Weighted and Perfusion MRI MRA Ultrasound 43 Jeremiah Scharf Gillian Lieberman, MD MRA/Angiography of occluded MCA our patient – R. MCA companion patient –L. MCA our patient – R. MCA BIDMC Patient BF; R. MCA occlusion BIDMC Patient BF; R. MCA occlusion Bahn et al. JMRI 6:833-845, 1996 L. MCA occlusion -literature 44 Jeremiah Scharf Gillian Lieberman, MD Imaging Modalities in Acute Stroke CT without contrast Conventional MRI Diffusion-Weighted and Perfusion MRI MRA Ultrasound 45 Jeremiah Scharf Gillian Lieberman, MD Ultrasound in Stroke Has a primary role in working up cause of stroke Echocardiography Carotid Ultrasound TEE for LA/LV thrombus Bubble echo study for PFO (paradoxical embolus) Evaluates patency of carotids and degree of stenosis Transcranial Doppler Ultrasound Evaluates patency of intracranial arteries (MCA) 46 Jeremiah Scharf Gillian Lieberman, MD Summary I – Patient Course BF was given t-PA within 3 hours of onset 30% increase in recovery over controls (31% t-PA vs. 20% placebo = minimal/ no disability @ 3 mos.) 6-fold increased risk of bleeding (6% vs. 1%?) Symptoms of stroke did not improve considerably Intubated in ICU for 1 week Transferred to floor with residual weakness Discharged to rehabilitation facility after 10 days 47 Jeremiah Scharf Gillian Lieberman, MD Summary II – Timing of stroke detection in our patient Imaging Modality Time of post-stroke imaging 2h 8h 30h CT without contrast - + + Conventional MRI - ND + DWI MRI + ND + MRA + ND + + = evidence of acute stroke; - = no evidence of acute stroke; ND = not determined 48 Jeremiah Scharf Gillian Lieberman, MD Summary III – Imaging in Stroke Acute Stroke (<6 hours) CT (without contrast!!) Conventional MRI (T1,T2) Excellent for ruling out hemorrhage, other diseases Poor in defining early infarcts Bad for hemorrhage, fair for early infarcts Diffusion-Weighted and Perfusion MRI Excellent for defining early infarcts (1-2 hrs) and for estimating areas at risk 49 Jeremiah Scharf Gillian Lieberman, MD Summary IV - Imaging in Stroke Sub-acute Stroke (>6 hours) CT (without contrast) Excellent in defining late infarcts (>24 h) Conventional MRI (T1,T2) Better than CT at 6-24h; Same as CT in infarcts > 24h sulcal effacement, loss of gray-white differentiation T2 hyperintensity is most indicative of injury Ultrasound Critical for workup of origin of stroke (TEE, TCD, Carotid Doppler) 50 Jeremiah Scharf Gillian Lieberman, MD Summary V - Imaging in Stroke In the near future, there will hopefully be effective treatments for acute stroke. Patients will need to come to the ER at first sign of “brain attack”. Patients will need to be imaged by multiple modalities rapidly. Remember ... TIME IS BRAIN 51 Jeremiah Scharf Gillian Lieberman, MD References AHA Website: http://www.americanheart.org/statistics/stroke.html Bahn MM, Oser AB, Cross DT. CT and MRI of Stroke. JMRI 6:833-845, 1996. Baird AE and Warach S. Magnetic Resonance Imaging in Acute Stroke. J. Cereb. Blood Flow Metab. 18(6): 583-609, 1998. Beauchamp NJ, Barker PB, Yang PY, vanZijl PCM. Imaging of Acute Cerebral Ischemia. Radiology 212:307-324, 1999. Culebras A et al. AHA Scientific Statement: Practice Guidelines for the Use of Imaging in Transient Ischemic Attacks and Acute Stroke. Stroke. 28:1480-1497, 1997. Flaherty AW. MGH Handbook of Neurology. Lippincott Williams and Wilkins 2000. Fix J. High-Yield Anatomy. Lippincott Williams & Wilkins. Philadelphia. 2000. Lev MH, Farkas J, Gemmete JJ, Hossain ST, Hunter GJ, Kroshetz WJ, Gonzalez RG. Acute Stroke: Improved Nonenhanced CT Detection – Benefits of Soft-Copy Interpretation by Using Variable Window Width and Center Level Settings. Radiology 213: 150-155, 1999. Petrella JR and Provenzale JM. MR Perfusion Imaging of the Brain. AJR 175:207-219, 2000. Schaefer PW, Grant PE, Gonzalez RG. Diffusion Weighted MR Imaging of the Brain. Radiology 217:331-345, 2000 Simon RP, Aminoff MJ, Greenberg DA. Clinical Neurology. Appleton & Lange: Connecticut, 1999. UT Southwestern STARS Website: http://www.swmed.edu/stars/resources/stroke.html 52 Jeremiah Scharf Gillian Lieberman, MD Acknowledgments Andru Bageac and Daniel Saurborn - for help with case identification Beverlee Turner -for help with Power point and PACS Gillian Lieberman -for her enthusiasm in teaching medical students My classmates -for enduring this talk 53
