In vivo evaluation of human patellar tendon microstructure and microcirculation with diffusion MRI

Area of Science:

• Musculoskeletal MRI
• Diffusion Tensor Imaging (DTI)
• Intravoxel Incoherent Motion (IVIM) imaging

Background:

• Patellar tendon (PT) integrity and microcirculation are vital for tendinopathy progression and repair.
• Noninvasive assessment methods are needed to evaluate PT microstructure and microcirculation.

Purpose of the Study:

• To evaluate the feasibility and robustness of stimulated-echo based diffusion-weighted MRI with readout-segmented echo-planar imaging (ste-RS-EPI).
• To assess human PT microstructure and microcirculation noninvasively using ste-RS-EPI.

Main Methods:

• Acquired PT diffusion tensor imaging (DTI) and intravoxel incoherent motion (IVIM) using an ste-RS-EPI protocol on a 3T MRI scanner.
• Calculated DTI parameters (AD, RD, MD, FA) and IVIM parameters (fp, D*×fp, Vb, D*×Vb) in different PT regions.
• Assessed intra- and intersession reproducibility of DTI and IVIM parameters.

Main Results:

• DTI parameters for healthy PT were established (e.g., MD: 1.18 × 10⁻³ mm²/s).
• Significantly higher IVIM parameters (fp and D*×fp) were observed in the outer-two thirds compared to the central-third of the PT (P < 0.05).
• Good test-retest and interrater reproducibility were demonstrated for both DTI and IVIM parameters.

Conclusions:

• Diffusion MRI of the PT using the ste-RS-EPI protocol is clinically feasible.
• The technique provides reproducible DTI- and IVIM-derived parameters for assessing PT microstructure and microcirculation.
• This method holds promise for noninvasive evaluation of patellar tendon health.