Nian Wang1,2, Farid Badar1, Yang Xia1. 1. 1 Department of Physics and Center for Biomedical Research, Oakland University, Rochester, MI, USA. 2. 2 Center for In Vivo Microscopy, Department of Radiology, Duke University, Durham, NC, USA.
Abstract
OBJECTIVE: To study the experimental influences to the measurement of cartilage thickness by magnetic resonance imaging (MRI). DESIGN: The complete thicknesses of healthy and trypsin-degraded cartilage were measured at high-resolution MRI under different conditions, using two intensity-based imaging sequences (ultra-short echo [UTE] and multislice-multiecho [MSME]) and 3 quantitative relaxation imaging sequences (T1, T2, and T1ρ). Other variables included different orientations in the magnet, 2 soaking solutions (saline and phosphate buffered saline [PBS]), and external loading. RESULTS: With cartilage soaked in saline, UTE and T1 methods yielded complete and consistent measurement of cartilage thickness, while the thickness measurement by T2, T1ρ, and MSME methods were orientation dependent. The effect of external loading on cartilage thickness is also sequence and orientation dependent. All variations in cartilage thickness in MRI could be eliminated with the use of a 100 mM PBS or imaged by UTE sequence. CONCLUSIONS: The appearance of articular cartilage and the measurement accuracy of cartilage thickness in MRI can be influenced by a number of experimental factors in ex vivo MRI, from the use of various pulse sequences and soaking solutions to the health of the tissue. T2-based imaging sequence, both proton-intensity sequence and quantitative relaxation sequence, similarly produced the largest variations. With adequate resolution, the accurate measurement of whole cartilage tissue in clinical MRI could be utilized to detect differences between healthy and osteoarthritic cartilage after compression.
OBJECTIVE: To study the experimental influences to the measurement of cartilage thickness by magnetic resonance imaging (MRI). DESIGN: The complete thicknesses of healthy and trypsin-degraded cartilage were measured at high-resolution MRI under different conditions, using two intensity-based imaging sequences (ultra-short echo [UTE] and multislice-multiecho [MSME]) and 3 quantitative relaxation imaging sequences (T1, T2, and T1ρ). Other variables included different orientations in the magnet, 2 soaking solutions (saline and phosphate buffered saline [PBS]), and external loading. RESULTS: With cartilage soaked in saline, UTE and T1 methods yielded complete and consistent measurement of cartilage thickness, while the thickness measurement by T2, T1ρ, and MSME methods were orientation dependent. The effect of external loading on cartilage thickness is also sequence and orientation dependent. All variations in cartilage thickness in MRI could be eliminated with the use of a 100 mM PBS or imaged by UTE sequence. CONCLUSIONS: The appearance of articular cartilage and the measurement accuracy of cartilage thickness in MRI can be influenced by a number of experimental factors in ex vivo MRI, from the use of various pulse sequences and soaking solutions to the health of the tissue. T2-based imaging sequence, both proton-intensity sequence and quantitative relaxation sequence, similarly produced the largest variations. With adequate resolution, the accurate measurement of whole cartilage tissue in clinical MRI could be utilized to detect differences between healthy and osteoarthritic cartilage after compression.
Authors: Richard B Souza; Thomas Baum; Samuel Wu; Brian T Feeley; Nancy Kadel; Xiaojuan Li; Thomas M Link; Sharmila Majumdar Journal: J Orthop Sports Phys Ther Date: 2012-03-08 Impact factor: 4.751