An efficient R1ρ dispersion imaging method for human knee cartilage using constant magnetization prepared turbo‐FLASH. (6th March 2021)

• Record Type: Journal Article
• Authors: Pang, Yuxi; Palmieri‐Smith, Riann M.; Maerz, Tristan
• Is Part Of: NMR in biomedicine. Volume 34:Number 6(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-03-06
• Subjects: fully refocused spin‐lock preparation -- human knee articular cartilage -- magic angle effect -- quantitative R1ρ dispersion imaging -- tailored constant R1ρ weighting -- turbo‐FLASH; Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.4500
• Languages: English
• ISSNs: 0952-3480

Abstract

Abstract : This work aimed to develop an efficient R 1ρ dispersion imaging method for clinical studies of human knee cartilage at 3 T. Eight constant magnetizations ( M prep ) were prepared by tailoring both the duration and amplitude ( ω 1 ) of a fully refocused spin‐lock preparation pulse. The limited M prep dynamic range was expanded by the measure, equivalent to that with ω 1 = ∞, from the magic angle location in the deep femoral cartilage. The developed protocol with M prep = 60% was demonstrated on one subject's bilateral and two subjects' unilateral asymptomatic knees. The repeatability of the proposed protocol was estimated by two repeated scans with a three‐month gap for the last two subjects. The synthetic R 1ρ and R 2 derived from R 1ρ dispersions were compared with the published references using state‐of‐the‐art R 1ρ and R 2 mapping (MAPSS). The proposed protocol demonstrated good (<5%) repeatability quantified by the intra‐ and intersubject coefficients of variation in the femoral and tibial cartilage. The synthetic R 1ρ (1/s) and the references were comparable in the femoral (23.0 ± 5.3 versus 24.1 ± 3.8, P = 0.67) and the tibial (29.1 ± 8.8 versus 27.1 ± 5.1, P = 0.62), but not the patellar (16.5 ± 4.9 versus 22.7 ± 1.6, P < 0.01) cartilage. The same trends were also observed for the current and the previous R 2 . In conclusion, the developed R 1ρ dispersion imaging scheme has been revealed to be not only efficient but also robust for clinical studies of human knee cartilage at 3 T. Abstract : We propose an efficient R 1ρ dispersion imaging method for human knee cartilage studies. A constant magnetization was prepared by tailoring both duration and amplitude of a fully‐refocused spin‐lock preparation pulse, leading to not only an accessible clinical scan time but also less adverse k‐space filtering effect during image readout. The results from repeated scans and from comparisons with the literature suggest that the proposed method is a promising tool to further explore cartilage R 1ρ dispersion in clinical settings.