Improving the clinical efficiency of T2⁎ mapping of ligament integrity

• Published in: Journal of biomechanics Vol. 47; no. 10; pp. 2522 - 2525
• Main Authors: Biercevicz, A.M, Walsh, E.G, Murray, M.M, Akelman, M.R, Fleming, B.C
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 18.07.2014
• Subjects: Algorithms; Animals; Biomechanical Phenomena; Computation; Computer Simulation; Gold; Integrity; Joints - pathology; Joints - physiology; Least squares method; Least-Squares Analysis; Ligaments; Ligaments - physiology; Magnetic Resonance Imaging; MRI; Physical Medicine and Rehabilitation; Post-processing; Posterior cruciate ligament; Posterior Cruciate Ligament - physiology; Reproducibility of Results; Sheep; T2⁎ relaxometry; T 2 ⁎ relaxometry; MRI; Posterior cruciate ligament; T2⁎ relaxometry; T(⁎) relaxometry
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2014.03.037

Abstract Current MR methods use T2⁎ relaxation time as a surrogate measure of ligament strength. Currently, a multi-echo voxel-wise least squares fit is the gold standard to create T2⁎ maps; however, the post-processing is time-intensive and serves as a stopgap for clinical use. The study objective was to determine if an alternative method could improve post-processing time without sacrificing fidelity of T2⁎ values for eventual translational use in the clinic. Using a 6 echo FLASH sequence, three different methods were used to determine intact posterior cruciate ligament (PCL) median T2⁎ Two of these methods utilized a voxel-wise method to establish T2⁎ maps: (1) a current “gold standard” method using a voxel-wise 6 echo least-squares fit (6LS) and (2) a voxel-wise 2 echo point T2⁎ determination (2MM). The third method used median ligament signal intensity and a single nonlinear least-squares fit (6LSROI ) instead of a voxel-wise basis. The resulting median T2⁎ values of the PCL and computational time were compared. The median T2⁎ values were 42% higher using the 2MM compared to the 6LS method ( p <0.0001). However, a strong correlation was found for the median T2⁎ values between the 2MM and 6LS methods ( R2 =0.80). The median T2⁎ values were not significantly different between the 6LS and 6LSROI methods ( p =0.519). Using the 2MM (which provides a regional map) and the 6LSROI (which efficiently provides the median T2⁎ value) methods in tandem would take only minutes of post-processing computational time compared to the 6LS method (~540 min), and hence would facilitate clinical application of T2⁎ maps to predict ligament structural properties as a patient outcome measure.