7 Tesla quantitative hip MRI: a comparison between TESS and CPMG for T2 mapping

Area of Science:

• Magnetic Resonance Imaging
• Quantitative Imaging
• Biomedical Engineering

Background:

• Quantitative assessment of hip joint cartilage is crucial for diagnosing and monitoring joint diseases.
• Conventional multi-echo-spin-echo (CPMG) T2 mapping is established but can be time-consuming and sensitive to magnetic field inhomogeneities.
• Advancements in MRI techniques are needed to improve efficiency and robustness in cartilage imaging.

Purpose of the Study:

• To evaluate the feasibility of triple-echo steady state (TESS) T2 mapping as an alternative to CPMG T2 mapping.
• To compare the quantitative accuracy, reproducibility, and image quality of TESS and CPMG T2 mapping for hip joint cartilage at 7 Tesla (7T).

Main Methods:

• TESS and CPMG T2 mapping were performed on eight healthy volunteers and three patients at 7T.
• Reproducibility was assessed in five volunteers over five scans.
• T2 relaxation times were measured in multiple hip joint regions, and data were compared using correlation coefficients and repeatability measures. Image quality and artifacts were also evaluated.

Main Results:

• Both TESS and CPMG depicted cartilage and fluid well.
• TESS yielded systematically lower T2 values compared to CPMG for both acetabular and femoral cartilage.
• No correlation was found between the two methods; TESS showed slightly better reproducibility and was insensitive to B1 inhomogeneities, unlike CPMG.

Conclusions:

• TESS T2 mapping is a promising alternative for quantitative hip joint imaging at 7T.
• It allows for reduced acquisition time and improved insensitivity to B1 inhomogeneities.
• TESS offers comparable image quality and good repeatability, making it attractive for clinical applications.