T2* relaxometry in the human cervical spinal cord at 7T

Motivation: In spinal cord T2* relaxometry, only mono-exponential models have previously been used, neglecting the potential presence of multiple compartments. Goal(s): Determine if a mono- or bi-exponential model is better for T2* relaxometry in the cervical spinal cord white matter (WM) and grey matter (GM). Approach: Mask the ventral half of the GM and WM in a 7-echoes GRE acquisition. Fit a mono-/bi-exponential model to the average signal in the masks for each slice. Compute R2, F-tests and p-values. Results: A bi-exponential model gave statistically better results in WM. No relevant difference between the models was measured in GM for most slices. Impact: A bi-exponential model is statistically better than a mono-exponential one for T2* relaxometry in spinal cord white matter, but not grey matter. The model can be used for contrast optimization, e.g. to improve lesion detection in demyelinating diseases.