Diffusion tensor imaging of the normal foot at 3 T.

Area of Science:

• Musculoskeletal imaging
• Biomedical engineering
• Neuroimaging

Background:

• Diffusion tensor imaging (DTI) is a powerful MRI technique for assessing tissue microstructure.
• Understanding normative DTI values in foot muscles is crucial for diagnosing pathologies.
• Previous DTI studies have focused on larger skeletal muscles, with limited data on intrinsic foot muscles.

Purpose of the Study:

• To establish normative diffusion tensor imaging (DTI) eigenvalues, apparent diffusion coefficient (ADC), and fractional anisotropy (FA) in asymptomatic foot muscles.
• To assess the feasibility of DTI for evaluating water diffusion anisotropy in intrinsic foot muscles.
• To compare DTI metrics between different intrinsic foot muscles.

Main Methods:

• Ten healthy adults underwent 3-T MRI with DTI sequences.
• DTI indices were calculated for five intrinsic foot muscles: quadratus plantae, abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, and abductor digiti minimi.
• Signal-to-noise ratio (SNR) was measured to assess image quality.

Main Results:

• Normative ranges for DTI eigenvalues (λ1, λ2, λ3), ADC, and FA were established for the intrinsic foot muscles.
• Apparent diffusion coefficient ranged from 1.48 × 10⁻³ to 1.55 × 10⁻³ mm²/s.
• Fractional anisotropy ranged from 0.21 to 0.40, indicating measurable diffusion anisotropy.
• Mean SNR varied between 47.5 and 69.1 across the examined muscles.

Conclusions:

• Diffusion tensor imaging (DTI) is a feasible technique for assessing water diffusion anisotropy in intrinsic foot muscles.
• The established DTI metrics provide normative reference values for healthy foot musculature.
• DTI findings in foot muscles are comparable to those reported for calf and thigh skeletal muscles, suggesting consistency across different muscle groups.