High b value diffusion-weighted images sampled at high angular resolution were analyzed using a composite hindered and restricted model of diffusion (CHARMED).
First, as the tumour outline is usually better delineated on the high b value diffusion-weighted image compared with the ADC map, it is easier to mark out the tumour contour when the ROI is drawn on the b value image (Fig. 6).
High b-value diffusion magnetic resonance imaging (MRI) enables us to detect far smaller architectures, by using q-space analysis, than the resolution in conventional MRI.
To explore the diagnostic usefulness of high b-value diffusion magnetic resonance brain imaging ("q-space" imaging) in multiple sclerosis (MS).
In fact for small width values, diffusion coefficient is highly anisotropic, the component normal to the wall being the smaller one.
Optimizations of the acquisition protocol and the use of a dedicated 32-channel coil with excellent SNR properties based on Wiggins et al. [40], aimed at compensating for some of the unfavorable SNR properties in high b-value diffusion MRI, including averaging of consecutive scans [41].
Diffusion-weighted images were acquired using a spin-echo sequence, with motion correction using a navigator echo and gradient waveforms sensitive to isotropic diffusion, with the following parameters: TR/TE = 4000/47 ms, FOV = 30 mm, matrix size = 128×64, slice thickness = 1 mm and b-values (diffusion weighting) of 120 and 1200 s/mm2.
The low b-value diffusion images and the ADC map were also at the readers' disposal.
At each of the two time-points, an average of the 30 high b-value diffusion weighted images of the SD and KD pups were geometrically aligned with one another, and saved within a common coordinate system.
Data were acquired with multi-directional diffusion weighting mode in each of 30 different directions with a b-value (diffusion weighting factor) of 1,000 s/mm and one reference image (b-value of 0).
