Purpose: To evaluate if sub-regional analysis could offer higher sensitivity than full-thickness analysis when quantifying dGEMRIC data of the knee.
Materials and methods: A dGEMRIC data set of medial femoral cartilage of the knee, including thirteen patients with osteoarthritis (diseased) and fourteen asymptomatic subjects (control), was reanalyzed with sub-regional analysis, i.e. using two ROIs (regions of interest) representing superficial region and deep region of the cartilage respectively, in addition to full-thickness ROI. Comparisons were made in T1pre (spin-lattice relaxation time without contrast administration), T1Gd (after Gd-DTPA2- administration), and ΔR1 (the change of relaxation rate) obtained with the three analysis methods.
Results: Differences between superficial region and deep region in T1pre, and T1Gd were clearly observed. Superficial region analysis always provided shortest T1Gd and highest ΔR1 in both the diseased and the control, but the diseased-control difference in T1Gd and ΔR1 were quite close with the three analysis methods. Even though superficial region analysis showed slightly higher values of AUC (areas under the curves) of Receiver Operating Characteristic compared to full-thickness analysis, no significant difference in sensitivity was observed for knee dGEMRIC, with either T1Gd (p=0.802) or ΔR1 (p=0.328).
Conclusion: For analyzing dGEMRIC of the knee with reduced cartilage thickness due to OA, there is no significant difference in sensitivity between sub-regional analysis and full-thickness analysis.