Contribution of high-b-value diffusion-weighted imaging in determination of brain ischemia in transient ischemic attack patients.
OBJECTIVE
High-b-value diffusion-weighted imaging (DWI) (b = 2,000 and b = 3,000 second/mm(2)) offers theoretical advantages over DWI examinations at b = 1,000 second/mm(2) for detection of acute ischemic stroke. The purpose of this study was to determine whether high-b-value DWI are better than b = 1,000 images in TIA patients.


METHODS
We compared DWI obtained with 3 different b-values (1,000, 2,000, and 3,000 second/mm(2)) and fluid-attenuated inversion recovery (FLAIR) sequences in 75 consecutive TIA patients. DWI examinations were performed within 3.25 ± 1.5 days after the onset of symptoms. Presence of ischemic lesion, volume, lesion conspicuity, and lesion distinction were determined.


RESULTS
A total of 40 (53.3%) patients revealed ischemic acute lesions with b = 1,000 while 34 (45.3%) were positive on FLAIR. High-b-value DWI did not increase the sensitivity for the detection of acute brain ischemia. The median lesion value increased as the b-value did: .17 mL (interquartile range [IQR] .12-.78) at b = 1,000; .19 mL (IQR .13-1.00) at b = 2,000; .29 mL (IQR .14-1.02) at b = 3,000; and .12 mL (IQR .04-.62 mL) on FLAIR (P < .001). As b-value increased, we observed hyperintensities in white matter that could erroneously be considered as acute ischemia.


CONCLUSIONS
High-b-value DWI did not improve the conspicuity and distinction of the ischemic lesions.
Hospital Universitari Arnau de Vilanova de Lleida-Stroke Unit, Institut de Recerca Biomèdica, Lleida, Spain. fpurroygarcia@gmail.com
Francisco
F
Purroy
Robert
R
Begue
Alejandro
A
Quílez
Jordi
J
Sanahuja
Maria Isabel
MI
Gil
D000368:Aged; D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D002546:Ischemic Attack, Transient / Q000473:pathology*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index