Table 3. Errors of DTI metrics.

The group mean (± group standard deviation) across the 20 HCP-A subjects of the mean absolute error (MAE) of different DTI metrics derived from the raw data consisting of two b = 0 and 12 diffusion-weighted images (DWIs) (a), the raw data denoised by supervised learning with the ground-truth DWIs as the training target (i.e., supervised denoising) (b), BM4D (c), AONLM (d), MPPCA (e), and SDnDTI (f–i) compared to the ground-truth DTI metrics derived from 14 b = 0 and 93 DWIs. SDnDTI results were generated by an MU-Net trained on the data from 20 HCP-A subjects (f), an MU-Net trained on the data from 20 HCP subjects (g), an MU-Net with parameters from the MU-Net trained on the data from 20 HCP subjects as initialization and further fine-tuned using the data of each HCP-A subject (h), and an MU-Net trained on the data from the data of each HCP-A subject (i).

HCP-A data		Primary eigenvector (°)	Fractional anisotropy	Mean diffusivity (μm2/ms)	Axial diffusivity (μm2/ms)	Radial diffusivity (μm2/ms)
a	Raw	16.17 ± 0.72	0.043 ± 0.0029	0.025 ± 0.0023	0.054 ± 0.0035	0.030 ± 0.0024
b	Supervised	10.14 ± 0.56	0.023 ± 0.00092	0.020 ± 0.0023	0.032 ± 0.0021	0.023 ± 0.0023
c	BM4D	12.78 ± 0.58	0.031 ± 0.0014	0.032 ± 0.0040	0.049 ± 0.0040	0.034 ± 0.0034
d	AONLM	13.04 ± 0.61	0.033 ± 0.0016	0.027 ± 0.0027	0.046 ± 0.0028	0.030 ± 0.0023
e	MPPCA	15.71 ± 0.69	0.036 ± 0.0019	0.025 ± 0.0024	0.047 ± 0.0028	0.028 ± 0.0024
f	SDnDTI (20 subj)	12.63 ± 0.61	0.028 ± 0.0014	0.022 ± 0.0022	0.039 ± 0.0021	0.024 ± 0.0022
g	SDnDTI (HCP MU-Net)	14.06 ± 0.58	0.036 ± 0.0014	0.023 ± 0.0023	0.045 ± 0.0019	0.027 ± 0.0022
h	SDnDTI (fine tuned)	12.66 ± 0.70	0.028 ± 0.0016	0.022 ± 0.0023	0.039 ± 0.0025	0.025 ± 0.0023
i	SDnDTI (1 subj)	13.65 ± 0.65	0.031 ± 0.0015	0.024 ± 0.0024	0.043 ± 0.0025	0.027 ± 0.0023