Bias of cartilage T2 values related to method of calculation

Purpose: To determine how different methods for calculating T-2 affect the resulting T-2 values of patellar cartilage. Materials and Methods: T-2-weighted images of patellar cartilage for 10 subjects were acquired using two MRI scanners. T-2 values of patellar cartilage were calculated using linear, weighted and nonlinear fitting algorithms for a monoexponential decay equation. T-2 values were also calculated for the superficial, middle and deep zones of the cartilage. Results: All three methods of calculation resulted in significantly different T, values (P <.0001). The weighted calculation produced the highest T-2 values, and the nonlinear calculation produced the lowest T-2 values. The average difference of T-2 value between the methods was under 5 ms. Similar results were found in a zonal analysis of the tissue. The nonlinear calculation of T-2 consistently had the best fit to the acquired data. Conclusion: The T-2 value of patellar cartilage depends on the method of calculation. It is unclear if larger T, value differences would be seen in subjects diagnosed with osteoarthritis. This study highlights the potential difficulty of comparing different studies with one another based on the method of T-2 calculation. (c) 2008 Elsevier Inc. All rights reserved.