Diffusion Tensor Imaging of Short T₂ Tissues Using Quantitative Ultrashort Echo Time Double-Echo Steady-State: A...

Area of Science:

• Biomedical Imaging
• Musculoskeletal MRI
• Diffusion Tensor Imaging

Background:

• Conventional diffusion tensor imaging (DTI) struggles with short T2 tissues due to signal loss from long echo times.
• Accurate microstructural assessment of musculoskeletal tissues requires imaging techniques sensitive to both long and short T2 components.
• Quantitative ultrashort echo time double-echo steady-state (qUTE-DESS) MRI is a novel sequence designed to address these limitations.

Purpose of the Study:

• To evaluate the feasibility and performance of quantitative ultrashort echo time double-echo steady-state (qUTE-DESS) MRI for imaging short T2 musculoskeletal tissues.
• To validate the qUTE-DESS sequence in phantoms, an ex vivo porcine hoof, and an in vivo human knee.
• To assess the capability of qUTE-DESS to generate quantitative parameter maps (T1, T2, diffusivity, mean diffusivity (MD), fractional anisotropy (FA)) in diverse musculoskeletal tissues.

Main Methods:

• Implementation of the qUTE-DESS sequence on a clinical 3T MRI system.
• Acquisition of data with six diffusion-weighting orientations to enable calculation of MD and FA.
• Validation using sucrose, agarose, and celery phantoms, followed by ex vivo porcine hoof and in vivo human knee imaging.

Main Results:

• Phantoms showed linear relationships between T1, T2, diffusivity, and concentration (R2 > 0.88), and anisotropic diffusion in fibrous structures.
• qUTE-DESS generated high-resolution MD and FA maps in porcine hoof and human knee tissues (cartilage, meniscus, tendon, ligament, muscle).
• The technique effectively captured short T2 components missed by conventional DTI, overcoming spin-echo limitations.

Conclusions:

• qUTE-DESS MRI is a feasible and valuable tool for quantitative microstructural assessment of musculoskeletal tissues, including those with short T2 relaxation times.
• This approach overcomes limitations of conventional DTI, offering potential for improved detection and evaluation of joint abnormalities and degenerative changes.
• Further studies are warranted to assess the diagnostic utility of qUTE-DESS in larger patient cohorts with musculoskeletal pathologies.