Effect of Truncated Sampling on Estimated Fiber Directions in Q-Space Imaging

Bryce Wilkins¹, Namgyun Lee¹, Manbir Singh¹

The effect of truncated-sphere sampling commonly used in DSI to estimate single fiber orientation errors is simulated using fully-sampled (7x7x7) q-space data (343 samples), truncated-sphere (203 samples), zero-padding to (21x21x21), noise-free and noisy (SNR = 30) scenarios. We show that the error of resolving a single fiber direction depends on the fiber orientation, and the corners of q-space, which are not sampled when truncated sampling schemes are used, help reduce error (mean error 3.5deg versus 3.9deg for the noise case and zero-padding used). As truncated-sphere sampling requires 40% less time, its use could justify the small increase in error.