Diffusion-weighted MRI of ischemic stroke at 3T: Value of synthetic b-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 b = 1000s mm(-2) 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 2000s mm(-2) were acquired. Synthetic images with b-values of 1000, 1500, 2000 and 2500 s mm(-2) were computed. Two readers compared synthetic (syn) and acquired (acq) b = 2000s mm-2 images with acquired b = 1000s mm(-2) 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'. 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 (p < 0.01) and were frequently selected as preferred b-values. Acq2000 images exhibited a similar lesion detection rate and improved lesion conspicuity (p < 0.01) but worse image quality (p < 0.01) than acq1000 images. Syn2000 and syn2500 images performed significantly worse (p < 0.01) than acq1000 images in most or all categories. CR significantly increased with increasing b-values.

Conclusion: Synthetic images at b = 1000 and 1500 s mm(-2) and acquired DWI images at b = 2000 s mm(-2) 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.Y