Diffusion Fractional Anisotropy-based Transformation in Skeletal Muscle Caused by Pressure

作者：Hata Junichi^*; Yagi Kazuo; Hikishima Keigo; Komaki Yuji; Goto Masami; Yano Keichi

来源：Magnetic Resonance in Medical Sciences, 2012, 11(3): 179-184.

DOI：10.2463/mrms.11.179

• diffusion tensor
• fractional anisotropy
• pressurization
• skeletal muscle
• stimulated echo

Purpose: We used diffusion tensor imaging (DTI) to evaluate anisotropic changes in skeletal muscle cells under external pressure. %26lt;br%26gt;Materials and Methods: In 6 healthy volunteers, we compared DTI of the tibialis anterior (TA) and soleus (SOL) muscles under pressure. We performed imaging using a 1.5-tesla magnetic resonance (MR) scanner and diffusion-weighted stimulated-echo echo-planar pulse sequences optimized for skeletal muscle. We calculated diffusion tensor eigen-values (A), apparent diffusion coefficients, and fractional anisotropy (FA) values in a series of axially acquired DTI and compared them between the pressurized and nonpressurized lower limbs. We also measured a cross-sectional area of skeletal muscle. %26lt;br%26gt;Results: We observed clear differences in FA and lambda(3) between pressurized muscles and the nonpressurized muscles we used as controls. The mean control FAs were 0.36 +/- 0.02 (TA) and 0.30 +/- 0.02 (SOL). The mean control lambda(3)s were 0.74 +/- 0.02 s/mm(2) (TA) and 0.85 +/- 0.03 s/mm(2) (SQL). FA values in the pressurized (200 mmHg) limbs increased to 0.39 +/- 0.02 (TA) and 0.35 +/- 0.04 (SQL) compared with those values in the nonpressurized controls. lambda(3) values in the pressurized (200 mmHg) limbs decreased to 0.68 +/- 0.05 s/mm(2) (TA) and 0.77 0.06 s/mm(2) (SOL) compared with those in controls. Moreover, the mean value of cross-sectional area of skeletal muscle (control) was 907.3 +/- 140.1 mm(2) (TA) and 1522 +/- 201.0 mm(2) (SQL). The cross-sectional area in the pressurized (200 mmHg) limbs decreased to 590.3 +/- 68.1 mm(2) (TA) and 1131 +/- 112.6 mm(2) (SOL) compared with those in controls. One-way analysis of variance (ANOVA) and post hoc Tukey-Kramer tests showed significant differences. %26lt;br%26gt;Conclusion: Anisotropy changed markedly on pressurizing the lower limb based on the correlation of the cross-sectional area and A3 suggested marked changed in anisotropy following application of pressure to the lower limb. If compression of the cross-sectional area is assumed to represent compression of the cell, change in A3 reflected the change in the size of muscle cells.

• 出版日期2012