High b-value diffusion-weighted MR imaging of normal brain at 3T.

INTRODUCTION: The purpose of this study was to determine the normative apparent diffusion coefficient (ADC) values at 3T using high b-value (3000 s/mm(2)) diffusion-weighted images (DWI) and compare the signal characteristics of the high b value with standard b-value (1000 s/mm(2)) DWI.

METHODS: Institutional review board approval was obtained for this prospective study which included 20 volunteers (10 M, 10 F, mean age: 38.7+/-14.9) without any known clinical disease or radiological findings. All brain examinations were performed with 3T MR by using similar parameters of b1000 and b3000 DWI sequences. DWI and ADC maps were obtained. Signal intensity, noise, signal to noise ratio (SNR), contrast to noise (CNR), contrast ratio (CR), and ADC values of bilateral posterior limb of internal capsule, frontal white matter, parietal gray matter, pons, thalamus, splenium of corpus callosum were measured on b1000 and b3000 DW images.

RESULTS: In all anatomic locations, MR signal intensity, SNR and ADC values of b3000 images were significantly lower than MR signal intensity, SNR and ADC values of b1000 images (p<0.001). The CNR and CR values at the posterior limb of internal capsule and pons were significantly increased on b3000 images (p<0.001) and decreased in the other regions measured.

CONCLUSION: The ADC values calculated from standard b-value DWI were significantly higher than those calculated from high b-value DWI. These results agree with the previous studies. In the regions where CNR values increase with high b value, b3000 DWI images may provide additional clinical information.