A unique anisotropic R2 of collagen degeneration (ARCADE) mapping as an efficient alternative to composite relaxation metric (R2‐R1ρ) in human knee cartilage study. Issue 6 (22nd February 2019)

• Record Type: Journal Article
• Authors: Pang, Yuxi; Palmieri‐Smith, Riann M.; Malyarenko, Dariya I.; Swanson, Scott D.; Chenevert, Thomas L.
• Is Part Of: Magnetic resonance in medicine. Volume 81:Issue 6(2019)
• Page Start: 3763
• Page End: 3774
• Publication Date: 2019-02-22
• Subjects: anisotropic R2 -- chemical exchange effect -- composite relaxation metric R2 − R1ρ -- human knee cartilage -- magic angle effect; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.27621
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: Anisotropic transverse R 2 (1/ T 2 ) relaxation of water proton is sensitive to cartilage degenerative changes. The purpose is to develop an efficient method to extract this relaxation metric in clinical studies. Methods: Anisotropic R 2 can be measured inefficiently by standard R 2 mapping after removing an isotropic contribution obtained from R 1 ρ mapping. In the proposed method, named as a unique anisotropic R 2 of collagen degeneration (ARCADE) mapping, an assumed uniform isotropic R 2 was estimated at magic angle locations in the deep cartilage, and an anisotropic R 2 was thus isolated in a single T2W sagittal image. Five human knees from 4 volunteers were studied with standard R 2 and R 1 ρ mappings at 3T, and anisotropic R 2 derived from ARCADE on the T2W (TE = 48.8 ms) image from R 2 mapping was compared with the composite relaxation ( R 2 – R 1 ρ ) using statistical analysis including Student's t‐test and Pearson's correlation coefficient. Results: Anisotropic R 2 (1/s) from ARCADE was highly positively correlated with but not significantly different from standard R 2 – R 1 ρ (1/s) in the segmented deep ( r = 0.83 ± 0.06; 8.3 ± 2.9 vs. 7.3 ± 1.9, P = .50) and the superficial ( r = 0.82 ± 0.05; 3.5 ± 2.4 vs. 4.5 ± 1.6, P = .39) zones. However, after eliminating systematic errors by the normalization in terms of zonal contrast, anisotropic R 2 was significantly higher (60.2 ± 18.5% vs. 38.4 ± 16.6%, P < .01) than R 2 – R 1 ρ as predicted. Conclusion: The proposed anisotropic R 2 mapping could be an efficient alternative to the conventional approach, holding great promise in providing both high‐resolution morphological and more sensitive transverse relaxation imaging from a single T2W scan in a clinical setting.