Diffusion-weighted MRI of ischemic stroke at 3T: Value of synthetic -values.

OBJECTIVES

Diffusion-weighted imaging (DWI) plays a crucial role in the diagnosis of ischemic stroke. We assessed the value of computed and acquired high b-value DWI in comparison with conventional = 1000 s mm DWI for ischemic stroke at 3T.

METHODS

We included 36 patients with acute ischemic stroke who presented with diffusion abnormalities on DWI performed within 24 h of symptom onset. B-values of 0, 500, 1000 and 2000 s mm were acquired. Synthetic images with b-values of 1000, 1500, 2000 and 2500 s mm were computed. Two readers compared synthetic (syn) and acquired (acq) = 2000 s mm images with acquired = 1000 s mm images in terms of lesion detection rate, image quality, presence of uncertain hyperintensities and lesion conspicuity. Readers also selected their preferred b-value. Contrast ratio (CR) measurements were performed. Non-parametrical statistical tests and weighted Cohens' κ tests were computed.

RESULTS

Syn1000 and syn1500 matched acq1000 images in terms of lesion detection rate, image quality and presence of uncertain hyperintensities but presented with significantly improved lesion conspicuity ( < 0.01) and were frequently selected as preferred b-values. Acq2000 images exhibited a similar lesion detection rate and improved lesion conspicuity ( < 0.01) but worse image quality ( < 0.01) than acq1000 images. Syn2000 and syn2500 images performed significantly worse ( < 0.01) than acq1000 images in most or all categories. CR significantly increased with increasing b-values.

CONCLUSION

Synthetic images at = 1000 and 1500 s mm and acquired DWI images at = 2000 s mm may be of clinical value due to improved lesion conspicuity.

ADVANCES IN KNOWLEDGE

Synthetic b-values enable improved lesion conspicuity for DWI of ischemic stroke.