title: T1ρ magnetic resonance: basic physics principles and applications in knee and intervertebral disc imaging.
abstract: T1ρ relaxation time provides a new contrast mechanism that differs from T1- and T2-weighted contrast, and is useful to study low-frequency motional processes and chemical exchange in biological tissues. T1ρ imaging can be performed in the forms of T1ρ-weighted image, T1ρ mapping and T1ρ dispersion. T1ρ imaging, particularly at low spin-lock frequency, is sensitive to B0 and B1 inhomogeneity. Various composite spin-lock pulses have been proposed to alleviate the influence of field inhomogeneity so as to reduce the banding-like spin-lock artifacts. T1ρ imaging could be specific absorption rate (SAR) intensive and time consuming. Efforts to address these issues and speed-up data acquisition are being explored to facilitate wider clinical applications. This paper reviews the T1ρ imaging's basic physic principles, as well as its application for cartilage imaging and intervertebral disc imaging. Compared to more established T2 relaxation time, it has been shown that T1ρ provides more sensitive detection of proteoglycan (PG) loss at early stages of cartilage degeneration. T1ρ has also been shown to provide more sensitive evaluation of annulus fibrosis (AF) degeneration of the discs.
authors.affiliation: 1 Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, New Territories, Hong Kong SAR, China ; 2 Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands ; 3 Department of Radiology and Biomedical Imaging, University of California, San Francisco, USA ; 4 Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China.
authors.forename: Yì-Xiáng J
authors.initials: YX
authors.lastname: Wáng
authors.affiliation: 1 Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, New Territories, Hong Kong SAR, China ; 2 Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands ; 3 Department of Radiology and Biomedical Imaging, University of California, San Francisco, USA ; 4 Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China.
authors.forename: Qinwei
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: 1 Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, New Territories, Hong Kong SAR, China ; 2 Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands ; 3 Department of Radiology and Biomedical Imaging, University of California, San Francisco, USA ; 4 Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Li
authors.affiliation: 1 Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, New Territories, Hong Kong SAR, China ; 2 Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands ; 3 Department of Radiology and Biomedical Imaging, University of California, San Francisco, USA ; 4 Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China.
authors.forename: Weitian
authors.initials: W
authors.lastname: Chen
authors.affiliation: 1 Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, New Territories, Hong Kong SAR, China ; 2 Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands ; 3 Department of Radiology and Biomedical Imaging, University of California, San Francisco, USA ; 4 Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China.
authors.forename: Anil
authors.initials: A
authors.lastname: Ahuja
authors.affiliation: 1 Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, New Territories, Hong Kong SAR, China ; 2 Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands ; 3 Department of Radiology and Biomedical Imaging, University of California, San Francisco, USA ; 4 Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
keywords: T1ρ; biomarker; cartilage; degeneration; intervertebral disc; musculoskeletal system; osteoarthritis (OA); quantitative