Diffusion tensor imaging of the normal foot at 3 T

The objective of this study was to establish normative diffusion tensor imaging (DTI) eigenvalues (λ1,λ2,λ3), apparent diffusion coefficient, and fractional anisotropy in asymptomatic foot muscles.

Ten healthy adults (mean [SD], 25.9 [4.3] years) were examined using a 3-T magnetic resonance imaging scanner. Diffusion tensor imaging indices were evaluated in 5 muscles in the foot: quadratus plantae, abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, and abductor digiti minimi. Signal-to-noise ratio was also measured for each muscle.

In the various foot muscles, λ1 ranged from 1.88 × 10 to 2.14 × 10 mm/s, λ2 ranged from 1.39 × 10 to 1.48 × 10 mm/s, and λ3 ranged from 0.91 × 10 to 1.27 × 10 mm/s; apparent diffusion coefficient ranged from 1.48 × 10 to 1.55 × 10 mm/s; and fractional anisotropy ranged from 0.21 to 0.40. Statistical differences were seen in some eigenvalues between muscle pairs. Mean signal-to-noise ranged from 47.5 to 69.1 in the various muscles examined.

Assessment of anisotropy of water diffusion in foot muscles was feasible using DTI. The measured DTI metrics in the foot were similar to those in calf and thigh skeletal muscles.