(Stroke. 1999;30:1974-1981.)
© 1999 American Heart Association, Inc.
Letters to the Editor |
A Standardized MRI Stroke Protocol: Comparison with CT in Hyperacute Intracerebral Hemorrhage
Department of Neurology, Stanford Stroke Center
Departments of Neurology, and Neurological Sciences & Neurosurgery, Stanford Stroke Center
Department of Radiology, Stanford University Medical Center, Palo Alto, California
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To the Editor:
We read with great interest the article by Schellinger et al1 regarding the use of MRI for detection of intracranial hemorrhage and applaud the efforts of the authors in performing these difficult studies. We have also observed that MRI is capable of detecting early acute cerebral hemorrhage and find the potential of MRI in this setting extremely promising. However, although we strongly agree that there is growing evidence that MRI is more sensitive than previously believed for the detection of acute intracranial hemorrhage, we also urge caution. It may be somewhat premature to declare that MRI is "as good as CT"1 for the exclusion of parenchymal hemorrhage in acute stroke patients.
Current evidence supporting the use of MRI alone in this situation is based on only a handful of patients.1 2 In addition, the hemorrhages detected to date, including the hemorrhages in this series, have been relatively large (>2.0 cm in diameter), which increases the probability of detection. No data have been reported on smaller, less-easily detected hemorrhages, which could still be at risk for worsening if a thrombolytic is administered. In addition, the possibility of MRI overestimating the degree of bleeding in patients with petechial hemorrhage undetectable on CT has not been studied. This could potentially lead to exclusion of patients who might otherwise benefit from thrombolysis. The problem of ruling out subarachnoid hemorrhage is also a concern, as appropriately pointed out by the authors.
We strongly agree that the use of MRI instead of CT for the assessment of acute stroke patients would substantially simplify patient management, and we have advocated the use of MRI, especially diffusion-weighted imaging (DWI), in the assessment of acute stroke patients. DWI is highly accurate in identifying ischemia, and both initial DWI and perfusion-weighted imaging (PWI) volumes are highly correlated with stroke outcome.3 4 5 In addition, its clinical utility in this setting appears to be substantial.6 If MRI is also acceptably accurate at identifying acute cerebral hemorrhage, this would vastly improve our ability to rapidly assess and treat acute stroke patients. However, we also believe that these promising observations need to be further substantiated in larger studies. We and others are currently organizing such investigations.
In the interim, we believe that MRI alone for the exclusion of hemorrhage should be used with care, particularly in patients being considered for thrombolytic therapy. Hopefully, future studies will confirm the promising results of Schellinger et al and greatly improve our ability to evaluate acute stroke patients.
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1. Schellinger P, Jansen O, Fiebach J, Hacke W, Sartor K. A standardized MRI stroke protocol: comparison with CT in hyperacute intracerebral hemorrhage. Stroke. 1999;30:765–768.
2.
Patel MR, Edelman RR, Warach S. Detection of
hyperacute primary intraparenchymal hemorrhage by magnetic
resonance imaging. Stroke. 1996;27:2321–2324.
3.
Tong DC, Yenari MA, Albers GW, O'Brien M, Marks MP,
Moseley ME. Correlation of perfusion- and diffusion-weighted MRI with
NIHSS score in acute (<6.5 hour) ischemic stroke.
Neurology. 1998;50:864–870.
4.
Marks M, Tong D, Beaulieu C, Albers G, Moseley M.
Evaluation of early reperfusion and intravenous rt-PA
therapy using diffusion and perfusion weighted MRI.
Neurology. 1999;52:1792–1798.
5. Beaulieu C, deCrespigny A, Tong D, Moseley M, Albers G, Marks M. Longitudinal MRI study of perfusion and diffusion in stroke: evolution of lesion volume and correlation with clinical outcome. Ann Neurol. In press.
6. Albers GW, Lansberg MG, Norbash AM, Woolfenden AR, O'Brien MW, Tong DC, Marks MP, Kemp SM, Moseley ME. Yield of diffusion-weighted MRI for detection of potentially clinically relevant findings in stroke patients. Stroke. 1999;30:235. Abstract 20.
Response
Department of Neurology
Department of Neuroradiology, University of Heidelberg, Heidelberg, Germany
Key Words: intracerebral hemorrhage • magnetic resonance imaging
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We appreciated the letter of Drs Tong, Albers, Yenari, and Marks. There is obvious agreement with several aspects and conclusions of our study.1 We agree that to date few patients with hyperacute intracerebral hemorrhage have been evaluated with MRI1 2 and that microhemorrhages and subarachnoid hemorrhages have not yet been a subject of multicenter clinical investigations.3 On the other hand, animal experimental data on the use of MRI in intracerebral hemorrhage4 5 6 and data on the efficiency of MRI in the diagnosis of subarachnoid hemorrhage7 become more and more available. We firmly believe that the use of stroke MRI with diffusion- and perfusion-weighted MR images, MR angiography, T2-weighted fast spin-echo, and perhaps FLAIR images alone (instead of CT) would optimize patient management. Without doubt, further studies such as large multicenter trials are needed and are now underway in Europe and the United States to obtain sufficient data to allow the broad application of stroke MRI. We also agree that missing tiny hemorrhages could lead to complications if thrombolytic therapy8 were performed. However, the inexperienced investigator may confuse small basal ganglia calcifications seen on CT with small hemorrhages and therefore withhold thrombolytic therapy.
Despite the generally accepted inability to differentiate intracerebral hemorrhage and ischemia by clinical signs and symptoms,8 we do not believe that there is a relevant risk of withholding a potentially effective thrombolytic therapy from eligible patients with inconclusive stroke MRI findings. Differentiation between hemorrhagic and ischemic stroke, and therefore candidacy for recanalization therapy, may very well be achieved by stroke MRI findings. Stroke MRI findings of cerebral hemorrhage and ischemia differ significantly, and, in our experience with more than 70 patients (not to speak of those who receive stroke MRI within the clinical routine), cannot be confused. Cerebral ischemia appears on stroke MRI as a hyperintensity on diffusion-weighted MRI, an area of disturbed perfusion on perfusion-weighted MRI equal to or exceeding that of the diffusion-weighted imaging lesion, and a potential vessel occlusion by MRA.9 Thrombolysis ideally is performed when there is evidence of a large tissue at risk (volume difference between the lesions on diffusion- and perfusion-weighted imaging, respectively) and a vessel occlusion.9 Petechial hemorrhage is seen in vasculitic lesions, which are no indication for thrombolytic therapy, or in hemorrhagic transformation of ischemic strokes. The latter does not typically occur in the time window accepted for thrombolysis. We agree, however, that those facilities not familiar with stroke MRI should perform an additional CT scan in doubtful cases before applying thrombolysis.
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References |
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TopIntroductionReferencesIntroduction References |
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1. Schellinger PD, Jansen O, Fiebach JB, Hacke W, Sartor K. A Standardized MRI stroke protocol: comparison with CT in hyperacute intracerebral hemorrhage. Stroke. 1999;30:765–768.
2. Patel MR, Edelman RR, Warach S. Detection of hyperacute primary intraparenchymal hemorrhage by magnetic resonance imaging. Stroke. 1996;27:2321–2324.
3.
Busch E, Beaulieu C, de Crespigny A, Moseley ME.
Diffusion MR imaging during acute subarachnoid
hemorrhage in rats. Stroke. 1998;29:2155–2161.
4. Deinsberger W, Hartmann M, Vogel J, Jansen O, Kuschinsky W, Sartor K, Boeker DK. Local fibrinolysis and aspiration of intracerebral hematomas in rats: an experimental study using MR monitoring. Neurol Res. 1998;20:349–352.[Medline] [Order article via Infotrieve]
5. Deinsberger W, Vogel J, Kuschinsky W, Auer LM, Boker DK. Experimental intracerebral hemorrhage: description of a double injection model in rats. Neurol Res. 1996;18:475–477.[Medline] [Order article via Infotrieve]
6. Bellon RJ, Kastrup A, Beaulieu C, Moseley ME, Marks MP. Magnetic resonance imaging of hyperacute intracerebral hemorrhage in a rabbit model. Presented at: Joint Annual Meeting of the American Society of Neuroradiology; May 23–28, 1999; San Diego, Calif.
7. Wiesmann M, Mayer T, Yousri I, Seelos K, Missler U, Medele R, Stummer W, Steiger HJ, Brueckmann H. Comparison of FLAIR and fast spin-echo MR imaging at 1.5 T for detection of acute subarachnoid hemorrhage. Presented at: Joint Annual Meeting of the American Society of Neuroradiology; May 23–28, 1999; San Diego, Calif.
8. Hacke W, Kaste M, Fieschi C, von Kummer R, Davalos A, Meier D, Larrue V, Bluhmki E, Davis S, Donnan G, Schneider D, Diez-Tejedor E, Trouillas P. Randomised double-blind placebo-controlled trial of thrombolytic therapy with intravenous alteplase in acute ischaemic stroke (ECASS II). Lancet. 1998;352:1245–1251.[Medline] [Order article via Infotrieve]
9. Jansen O, Schellinger PD, Fiebach JB, Hacke W, Sartor K. Early recanalization in acute ischemic stroke saves tissue at risk defined by MRI. Lancet. 1999;353:2036–2037.[Medline] [Order article via Infotrieve]
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