Effects of MR parameter changes on the quantification of diffusion anisotropy and apparent diffusion coefficient in diffusion tensor imaging: evaluation using a diffusional anisotropic phantom.
OBJECTIVE
To validate the usefulness of a diffusional anisotropic capillary array phantom and to investigate the effects of diffusion tensor imaging (DTI) parameter changes on diffusion fractional anisotropy (FA) and apparent diffusion coefficient (ADC) using the phantom.


METHODS
Diffusion tensor imaging of a capillary array phantom was performed with imaging parameter changes, including voxel size, number of sensitivity encoding (SENSE) factor, echo time (TE), number of signal acquisitions, b-value, and number of diffusion gradient directions (NDGD), one-at-a-time in a stepwise-incremental fashion. We repeated the entire series of DTI scans thrice. The coefficients of variation (CoV) were evaluated for FA and ADC, and the correlation between each MR imaging parameter and the corresponding FA and ADC was evaluated using Spearman's correlation analysis.


RESULTS
The capillary array phantom CoVs of FA and ADC were 7.1% and 2.4%, respectively. There were significant correlations between FA and SENSE factor, TE, b-value, and NDGD, as well as significant correlations between ADC and SENSE factor, TE, and b-value.


CONCLUSIONS
A capillary array phantom enables repeated measurements of FA and ADC. Both FA and ADC can vary when certain parameters are changed during diffusion experiments. We suggest that the capillary array phantom can be used for quality control in longitudinal or multicenter clinical studies.
Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Korea.
Sang Joon
SJ
Kim
Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Korea.
Choong Gon
CG
Choi
Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Korea.
Jeong Kon
JK
Kim
Department of Biostatistics, University of Ulsan College of Medicine, Seoul 138-736, Korea.
Sung-Cheol
SC
Yun
Department of Radiology, East-West Neomedical Center, Kyung Hee University College of Medicine, Seoul 134-727, Korea.
Geon-Ho
GH
Jahng
Clinical Scientist, MR, Philips Healthcare, Seoul 140-200, Korea.
Ha-Kyu
HK
Jeong
Clinical Scientist, MR, Philips Healthcare, Seoul 140-200, Korea.
Eun Ju
EJ
Kim
D016880:Anisotropy; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000295:instrumentation* / Q000379:methods*; D006801:Humans; D019047:Phantoms, Imaging; D012107:Research Design; D059629:Signal-To-Noise Ratio
Apparent diffusion coefficient; Diffusion tensor imaging; Fractional anisotropy; Magnetic resonance imaging; Phantom study