Improved differentiation between knees with cartilage lesions and controls using 7T relaxation time mapping

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Radiology

Background:

• T1ρ and T2 relaxation mapping are established markers for knee cartilage composition at 3 Tesla (T).
• T1ρ reflects proteoglycan content, while T2 reflects collagen integrity.

Purpose of the Study:

• To assess the feasibility of T1ρ and T2 imaging of knee cartilage at 7T compared to 3T.
• To evaluate the ability of T1ρ and T2 mapping at 7T to distinguish between normal and osteoarthritis (OA) patients.

Main Methods:

• Twenty patients (7 healthy, 13 with OA) underwent knee MRI at both 3T and 7T.
• Cartilage was segmented, and T1ρ and T2 values were analyzed using a two-parameter model.
• Statistical analysis compared healthy and OA groups, with stratification by cartilage lesion presence.

Main Results:

• T1ρ and T2 values were significantly higher in OA patients in the lateral femoral condyle and patella at both field strengths.
• 7T MRI demonstrated greater sensitivity, with more significant differences between healthy and OA groups compared to 3T.
• Signal-to-noise ratio was 60% higher on average at 7T across cartilage and meniscus compartments.

Conclusions:

• T1ρ imaging at 7T is a viable method for differentiating degenerated cartilage, overcoming previous concerns.
• The enhanced sensitivity of T1ρ and T2 imaging at 7T holds potential for future OA development studies.