Brain stroke: CT or MRI? Pr Alexandre Krainik Department of Neuroradiology University Hospital of Grenoble - France
Stroke? Imaging Challenges To treat? Parenchyma ICH / stroke mimics To treat > 3 hr? Perfusion Penumbra To guide treatment? Vessels Thrombosis, stenosis
Parenchyma IntraCranial Hemorrhage Acute ICH NECT = MRI Subacute or chronic hem. MRI > CT No impact (< 5 µbleeds) NECT T2* NECT T2* Fiebach JB et al. Stroke 2004;35:502-6
Parenchyma Ischemic Tissue 42 yo woman. Right hemiplegia since 4 hr NECT Loss of gray-white differentiation Cortex Basal ganglia Swelling of gyri Sulcal effacement Ventricular compression Se. < 33 % for < 3 hr Se. < 66 % for < 6 hr
Parenchyma Ischemic Tissue 80 yo man. Right hemiplegia since 1 hr MRI DWI: hyperintensity + low ADC T2 FLAIR: normal < 3h / hyper > 3 Se. 95-100% for < 6h
Parenchyma Ischemic Tissue 60 yo woman. Amnesia since 6 hr
Parenchyma Ischemic Tissue 60 yo woman. Aphasia since 3 hr 3T B1000 B3000
Parenchyma Ischemic Tissue 73 yo man. Left hand paresia since 4 hr MRI DWI Sensitivity and specificity > 90% for detecting infarct core Latchaw et al. Stroke 2009;40:3646-78 Excellent intra and inter-observer reproducibility Fiebach et al. Stroke, 2002;33:2206-10 MR Diffusion is the gold standard for detecting acute infarction < 3h Limitations of CT: posterior fossa, small infarcts (cortical and lacunar) Schaefer PW et al. Stroke 2008;39:2986-2992, Kunst el al. Radiol Clin N Am 2011;49:1-26
Parenchyma Stroke Mimics 22 yo man. Dizziness, diplopia since 4 hr 5 years earlier: transient motor deficit MS Chalela JA et al. Lancet 2007;369:293-8
Imaging Challenges Parenchyma Parenchyma MRI > CT Perfusion ICH: CT = MR *Ischemia: MR Mimics: MR Vessels Small size Posterior fossa
Perfusion MISMATCH Necrosis CBV CBF MTT Penumbra CBV CBF MTT CBF CBV MTT to treat beyond 3 hr Compensatory mechanisms Autoregulation Vasoreactivity Distinguish between Core: irreversible risk ICH Penumbra: salvageable In clinical practice Perfusion imaging relies on DSC pmri pct Donnan GA et al. Lancet Neurol 2009;8:261-9
Perfusion MISMATCH MR Necrosis: DWI Penumbra: MTT - T0 CT Necrosis: CBV < 2ml/100g Penumbra: MTT > 145% Necrosis Penumbra Necrosis Penumbra Wintermark M at al. Stroke 2006;37:979-985, Schaefer PW et al.stroke 2008;39:2986,92
Perfusion Pitfalls and limits DSC Hemorrhage Bolus Movements Quantification AIF VOF Thresholds Small infarct pct: Radiation exposure 80 kev, 120 mas 2-3 msv (NECT) for max 12 msv Imanishi et al. Eur Radiol 2005;15:41-6
Perfusion MR ASL 64 yo woman. Left hemiplegia since 2 hr ADC ASL STAR Pros No contrast media needed CBF quantification Cons Poor SNR (3T) Evolving technique Sensitive to blood speed Courtesy Dr JC Ferre Deibler AR et al. AJNR 2008;29:1228-34
Perfusion Functional disorder Right MCA stenosis Transient left hemiparesia DSC CBV DSC CBF BOLD CO 2 Impaired vascular reserve Zyieh Stroke 2005; Haller Radiology 2008
Imaging Challenges Perfusion Parenchyma MRI > CT Perfusion pct = pmri Penumbra: CT = MR Functional: MRI Vessels
Vessels Locate thrombosis NECT: white clot T2*: dark clot
Vessels Locate thrombosis CTA MRA Sensitivity and specificity of CTA > 90% for detecting proximal vessel occlusion CTA is more accurate method to evaluate distal vessels and collateral circulation MRA sensitivity increases using 3T, CE-TOF but speficity decreases Lev MH et al. J Comput Assist Tomogr 2001;25:520-8 Nguyen-Huynh el al. Stroke 2008;39:1184-8
Vessels Locate stenosis Dissection CTA CE-MRA NECT T1 SPIR Atherosclerosis CTA T2
Imaging Challenges Vessels Parenchyma MRI > CT Perfusion pct = pmri Thrombosis: CTA>MRA Stenosis: CTA>MRA Vessels CTA > MRA
Stroke Therapeutic Challenges Imaging Answers To treat < 3 hr? Parenchyma MRI > CT To treat > 3 hr? Perfusion pct = pmri Availibility Experience To guide treatment? Vessels CTA > MRA
Acknowledgments Pr Xavier LECLERC CHRU Lille France Dr Virginie LEFOURNIER CHU Grenoble France Dr Sylvie Grand CHU Grenoble France Dr Jean-Christophe FERRE CHU Rennes France Stroke 2009; 40:3646-3678
Perfusion Functional disorder Right MCA stenosis Transient left hemiparesia BOLD CO 2 Impaired vascular reserve papg030211
Perfusion Functional disorder Basillar artery stenosis Dizziness BOLD CO 2 Preserved vascular reserve bilg240311