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AJNR - American Journal of Neuroradiology

Published ahead of print on May 8, 2008
doi: 10.3174/ajnr.A1000

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An Acute Ischemic Stroke Classification Instrument That Includes CT or MR Angiography: The Boston Acute Stroke Imaging Scale

F. Torres-Mozqueda^a, J. He^a, I.B. Yeh^a, L.H. Schwamm^b, M.H. Lev^a, P.W. Schaefer^a and R.G. González^a

^a Neuroradiology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Mass
^b Stroke Service, Massachusetts General Hospital, Harvard Medical School, Boston, Mass

View larger version (16K): [in this window] [in a new window]   Fig 1. Classification algorithm. Proximal cerebral artery occlusions are depicted in the drawing on the left and are defined as including the following arteries: distal (intracranial) ICA, proximal (M1 or M2) MCA, and/or basilar artery (BA). As shown in the algorithm on the right, the first step was evaluation of CTA or MRA data to identify apparent proximal cerebral artery occlusions. If no proximal cerebral artery occlusion was found, the noncontrast CT or diffusion MR imaging data were reviewed for evidence of a large acute ischemic infarct as defined in the "Materials and Methods" section. If a large CT or DWI abnormality was detected, the patient was classified as having a major stroke. All other circumstances resulted in classification as a minor stroke by imaging.

View larger version (14K): [in this window] [in a new window]   Fig 2. Kaplan-Meier curve of time to discharge. The Kaplan-Meier graph depicts the probability of discharge from hospital in days for patients classified as having major strokes by BASIS and ASPECT (solid line), major by BASIS but minor by ASPECT (dot and dash line), and minor by both classification instruments (dashed line). Overall, a highly significant difference (P < .0001) between the groups was found. In isolating the differences, both the BASIS major/ASPECT major and the BASIS major/ASPECT minor were significantly different from the BASIS and ASPECT minor group (P < .0001). However, there was no significant difference between the BASIS major/ASPECT major (solid line) and the BASIS major/ASPECT minor groups (P = .077).