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Published on: August 14, 2019
Intrasession and Intersession Repeatability of Diffusion Tensor Imaging in Healthy Human Liver
Oi Lei Wong1, Thomas Wai Tong Leung, Gladys Goh Lo
1From the *Department of Medical Physics and Applied Radiation Science, McMaster University, Hamilton, Ontario; †Imaging Research Center, St. Joseph's Healthcare, Hamilton Ontario, Canada; ‡Medical Physics and Research Department, §Comprehansive Oncology Center, and ∥Intervention and Radiology Department, Hong Kong Sanatorium & Hospital, Hong Kong Special Administrative Region (SAR), China; ¶School of Biomedical Engineering, and #Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada.
Objective:
The aim of this study was to evaluate the effect of signal to noise ratio (SNR) and number of gradient directions (NGD) on intra- and intersession repeatability of liver diffusion tensor imaging (DTI) metrics.
Methods:
At each of 3 liver DTI scan sessions, liver diffusion was assessed in 5 healthy volunteers using a 6-direction DTI scan performed 9 separate times (ie, number of signal averages [NSA]). In addition, 4 combinations of NSA and NGD were acquired (NSA/NGD = 1/30, 3/10, 3/12, and 5/6) to determine the combined effect to DTI metrics, which was based on intersubject variability and intrasession (Vintra) and intersession (Vinter) repeatability.
Results:
Intersubject variability was less than 20%, whereas Vintra and Vinter repeatability were less than 5% and less than 10%, respectfully. Vinter was not affected by the NGD used. Decreases in Vinter(FA), Vinter(λ1), Vinter(RD), and Vinter(MD) were observed with increasing NSA, and hence SNR.
Conclusion:
Increased SNR may improve intrasession and intersession repeatability of liver DTI metrics. Scan repeatability was not influenced by NGD.

