nondiffusionweighted

Nondiffusionweighted refers to magnetic resonance imaging data acquired without diffusion-sensitizing gradients, typically corresponding to a diffusion-weighted image with a b-value of zero (b0). Such images provide a baseline reference for diffusion MRI studies and, depending on imaging parameters, can resemble conventional T2-weighted images. In diffusion MRI protocols, multiple images are acquired with different diffusion weightings (b-values) and the b0 image is used to calculate apparent diffusion coefficient (ADC) maps and to calibrate the diffusion model.

Acquisition and interpretation: A nondiffusionweighted image is obtained by turning off the diffusion gradients or setting their strength to the lowest possible value, resulting in minimal diffusion weighting. The image contrast is influenced by T2 relaxation, TE, and susceptibility effects, and may differ from a standard T2-weighted scan. In practice, the b0 image serves as a reference against which diffusion-weighted images with higher b-values are compared; together they enable assessment of tissue microstructure, particularly in brain, spinal cord, and oncologic imaging. Limitations: Because diffusion weighting is near zero, nondiffusionweighted images do not emphasize diffusion differences and can be affected by artifacts such as motion, susceptibility, and geometric distortion in echo-planar imaging.

Clinical use: Nondiffusionweighted (b0) images are essential in calculating ADC maps and in validating lesion conspicuity on diffusion sequences. They are not a separate diagnostic sequence by themselves but provide critical context for diffusion analysis.