Clinical experience with diffusion-weighted MR in patients with acute stroke.
OBJECTIVE
Our purpose was to evaluate the clinical efficacy, sensitivity, and specificity of echo-planar diffusion-weighted MR imaging in patients with acute infarction.


METHODS
We retrospectively analyzed 194 cases of acute ischemic stroke diagnosed clinically within 24 hours of onset and studied with echo-planar diffusion-weighted MR imaging. Examinations were considered to be positive for infarction when an increase in signal was noted on images acquired at a high b value but absent on images with a low b value. A final clinical diagnosis of acute stroke was used as the standard of reference. A subset of 48 patients scanned within 6 hours was also analyzed.


RESULTS
Diffusion-weighted MR imaging studies were positive in 133 of 151 cases of infarction (88% sensitivity) and negative in 41 of 43 cases with no infarction (95% specificity). Two cases identified as positive on diffusion-weighted images had nonischemic diagnoses (1.5% false-positive rate). Diffusion-weighted imaging had a positive predictive value of 98.5% and a negative predictive value of 69.5%. Use of T2-weighted sequences as well as diffusion-weighted imaging produced no false-positive findings. Of the negative scans, 69.5% corresponded to transient ischemic attacks or infarcts (mostly small brain stem infarcts). When only cases scanned within 6 hours of onset were considered, the sensitivity rose to 94% and the specificity to 100%.


CONCLUSIONS
Despite bias due to dependence between diffusion-weighted imaging and the final diagnosis, this analysis suggests high sensitivity and specificity for echo-planar diffusion-weighted imaging in the diagnosis of acute cerebral infarction, although negative scans did not rule out an ischemic pathogenesis.
Lövblad
K O
KO
Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass, USA.
Laubach
H J
HJ
Baird
A E
AE
Curtin
F
F
Schlaug
G
G
Edelman
R R
RR
Warach
S
S
D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology; D002545:Brain Ischemia / Q000175:diagnosis*; D002544:Cerebral Infarction / Q000175:diagnosis*; D004058:Diffusion; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D012680:Sensitivity and Specificity