3-T high-b-value diffusion-weighted MR imaging in hyperacute ischemic stroke

Abstract

In patients with hyperacute ischemic stroke, early demonstration of infarction is essential. Diffusion weighted imaging (DWI) is the key method for detecting hyperacute infarction. The value of high b-value DWI in hyperacute ischemic stroke is controversial at 1.5 T, and is unknown at 3 T. The aim of this study is to explore the value of high b-value versus standard b-value DWI at 3T in hyperacute stroke with quantitative and qualitative analysis. This study prospectively included 104 consecutive patients with hyperacute stroke. At 3 T, conventional MR sequences and DWI were performed. The examination included a standard DWI (b = 1000 s/mm(2)) and two high b-value DWI (b = 3000 s/mm(2) and b = 5000 s/mm(2)). Qualitative and quantitative analysis was performed. With increasing b value, DW images appeared noisier. The number of detected lesions was significantly higher on b = 3000 images than on the other DW images and higher on b = 5000 images than on b = 1000 images. The number of lesions greater than 1 cm was not significantly different. Lesion conspicuity was higher, boundary better seen, lesion extent bigger, and estimation of final infarct size was better on high b-value than on standard b-value DWI. Contrast-to-noise-ratio (CNR) and signal-to-noise-ratio (SNR) decreased and contrast ratio (CR) increased on high b-value DWI compared to standard b-value DWI. At 3 T, high b-value DWI was superior to standard b-value DWI in detection of hyperacute infarction and prediction of final infarct size in spite of increasing imaging artifacts.