GQI validity in DTI-optimized acquisition

[Ahmed Bayoumi]

Hi Frank.

I hope all is well with you.

In one of our experiments, we reconstructed the diffusion sequences using GQI with a diffusion sampling length ratio of 2. Our diffusion-weighted images were acquired using a single-shot spin-echo diffusion-sensitized echo-planar imaging sequence with a balanced Icosa21 tensor encoding scheme. The b=1,000 s mm−2, TR/TE 7,100/65 ms, FOV = 256 × 256 mm, and the slice thickness was 3 mm with a 0 mm gap and a total of 44 slices.

A reviewer has questioned the validity and optimality of GQI in a single-shell, low b-value acquisition. (quoted below)

" ... in the case of DT sequence, requires at least a combination of 2 shells with one with a higher diffusion weight. In this last case the result is sub-optimal for the separation of crossing fiber bundles."

Any ideas on addressing this issue?

Thanks,

Ahmed

[Fang-Cheng Yeh]

It is indeed suboptimal for resolving crossing fiber, and GQI will
produce a similar result with DTI due to (1) low b-value (2) not
enough directions.
It should still be fine if you are not claiming heavily on crossing fibers.
Frank

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