RT Journal Article
SR Electronic
T1 High-b-value Diffusion-weighted MR Imaging of Suspected Brain Infarction
JF American Journal of Neuroradiology
JO Am. J. Neuroradiol.
FD American Society of Neuroradiology
SP 1821
OP 1829
VO 21
IS 10
A1 Joel R. Meyer
A1 Arturo Gutierrez
A1 Bryan Mock
A1 Delon Hebron
A1 Jordan M. Prager
A1 Michael T. Gorey
A1 Daniel Homer
YR 2000
UL http://www.ajnr.org/content/21/10/1821.abstract
AB BACKGROUND AND PURPOSE: Recent technological advances in MR instrumentation allow acquisition of whole-brain diffusion-weighted MR scans to be obtained with b values greater than 1000. Our purpose was to determine whether high-b-value diffusion-weighted MR imaging improved contrast and detection of signal changes in acute and chronic brain infarction.METHODS: We prospectively evaluated the MR scans of 30 subjects with a history of possible brain infarction on a 1.5-T MR imager with 40 mT/meter gradients (slew rate 150 T/m/s) by use of the following single-shot echo-planar diffusion-weighted MR sequences: 1) 7999/71.4/1 (TR/TE/excitations, b = 1000; 2) 999/ 88.1/3, b = 2500; and 3) 7999/ 92.1/4, b = 3000. Diffusion-weighted MR imaging was performed in three orthogonal directions during all sequences. All subjects were scanned with fast fluid-attenuated inversion recovery (FLAIR) (10,006/145/2200/1 [TR/TE/TI/excitations]) and fast spin-echo T2-weighted (3650/95/3 [TR/TE/excitations], echo train length, 8). The diagnosis of brain infarction was established by clinical criteria.RESULTS: Twenty women and 10 men with a mean age of 67.7 years were enrolled in the study. One subject was excluded owing to poor image quality. Twelve of 29 subjects had a clinical diagnosis of acute infarction. All 12 had lesions that were hyperintense on diffusion-weighted images at all three b values; five were cortical and seven subcortical. There was increased contrast of all lesions on high-b-value scans (b = 2500 and 3000). Lesions that were hypointense on diffusion-weighted images were identified and evaluated at the three different b values. At b = 1000, there were 19 hypointense lesions, whereas at b = 2500 and 3000 there were 48 and 55 lesions, respectively. On FLAIR and T2-weighted images, these low-signal lesions were predominantly chronic, subcortical, ischemic lesions and lacunar infarcts, but four chronic cortical infarcts, one porencephalic cyst, and one primary brain tumor were also found. Low-signal lesions were also noted to have increased contrast on high-b-value diffusion-weighted scans.CONCLUSION: High-b-value diffusion-weighted MR imaging (b = 2500 or b = 3000) had no impact on diagnosis of acute infarction. High-b-value diffusion-weighted MR imaging (b = 2500) combined with diffusion-weighted MR imaging at b = 1000 improves tissue characterization by increasing the spectrum of observed imaging abnormalities in patients with suspected brain infarction.