Biexponential T_1ρ relaxation mapping of human knee menisci

Abstract

Background Measuring T1ρ in the knee menisci can potentially be used as noninvasive biomarkers in detecting early‐stage osteoarthritis (OA). Purpose To demonstrate the feasibility of biexponential T1ρ relaxation mapping of human knee menisci. Study Type Prospective. Population Eight healthy volunteers with no known inflammation, trauma, or pain in the knee and three symptomatic subjects with early knee OA. Field Strength/Sequence Customized Turbo‐FLASH sequence to acquire 3D‐T1ρ‐weighted images on a 3 T MRI scanner. Assessment T1ρ relaxation values were assessed in 11 meniscal regions of interest (ROIs) using monoexponential and biexponential models. Statistical Tests Nonparametric rank‐sum tests, Kruskal–Wallis test, and coefficient of variation. Results The mean monoexponential T1ρ relaxation in the lateral menisci were 28.05 ± 4.2 msec and 37.06 ± 10.64 msec for healthy subjects and early knee OA patients, respectively, while the short and long components were 8.07 ± 0.5 msec and 72.35 ± 3.2 msec for healthy subjects and 2.63 ± 2.99 msec and 55.27 ± 24.76 msec for early knee OA patients, respectively. The mean monoexponential T1ρ relaxation in the medial menisci were 34.30 ± 3.8 msec and 37.26 ± 11.38 msec for healthy and OA patients, respectively, while the short and long components were 7.76 ± 0.7 msec and 72.19 ± 4.2 msec for healthy subjects and 3.06 ± 3.24 msec and 55.27 ± 24.59 msec for OA patients, respectively. Statistically significant (P ≤ 0.05) differences were observed in the monoexponential relaxation between some of the ROIs. The T1ρ,short was significantly lower (P = 0.02) in the patients than controls. The rmsCV% ranges were 1.51–16.6%, 3.59–14.3%, and 4.91–15.6% for T1ρ‐mono, T1ρ‐short, and T1ρ‐long, respectively. Data Conclusion Our results showed that in all ROIs, T1ρ relaxation times of outer zones (red zones) were less than inner zones (white zones). Monoexponential T1ρ was increased in medial, lateral, and body menisci of early OA while the biexponential numbers were decreased in early OA patients. Level of Evidence: 2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019. J. Magn. Reson. Imaging 2019;50:824–835.

Early detection of myocardial involvement by non-contrast T1ρ mapping of cardiac magnetic resonance in type 2 diabetes mellitus

“…Native T1, T2, and postcontrast T1 maps were produced by importing respective images into their corresponding analysis modules. T1ρ maps were calculated by pixelwise fitting of a monoexponential decay function using a Levenberg–Marquardt algorithm of non-linear estimation ( 14 ) using Matlab (Version R2018b; MathWorks, Natick, MA). For global measurements of native T1, T2, and T1ρ values, the software automatically generated these values once the contours on the basal, middle, and apical slices were delineated.…”

Normal Values of Magnetic Resonance T1ρ Relaxation Times in the Adult Heart at 1.5 T MRI

“…T 1ρ ‐maps were calculated by pixelwise fitting of a monoexponential decay function using Matlab (Version R2018b; Mathworks, Natick, MA). A monoexponential two‐parameter decay model was applied using a Levenberg–Marquardt algorithm of nonlinear estimation to fit the T 1 ρ ‐relaxation time 20–22 . To increase signal‐to‐noise ratio (SNR) of T 1 ρ , we select entire slice ROI so that the small difference can be revealed.…”

“…A monoexponential two-parameter decay model was applied using a Levenberg-Marquardt algorithm of nonlinear estimation to fit the T 1ρ -relaxation time. [20][21][22] To increase signal-to-noise ratio (SNR) of T 1ρ , we select entire slice ROI so that the small difference can be revealed. Mean T 1ρ values were generated automatically by drawing the endocardium and epicardium of the left ventricle on T 1ρ maps created by the Matlab.…”

High angular resolution diffusion imaging (HARDI) of porcine menisci: a comparison of diffusion tensor imaging and generalized q-sampling imaging

“…However, a limitation of most conventional MRI techniques in clinical use is the short T2 relaxation times of many tissues within the knee, including the menisci ( 9 - 12 ). Quantitative MRI (qMRI) techniques, including T2 mapping, T1ρ mapping, and delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC) have been investigated as tools to assess the biochemical alterations in the meniscus before morphological changes occur ( 13 - 18 ). More recently, Ultrashort echo-time T2* (UTE-T2*) mapping has been proposed as a novel quantitative technique with the potential to measure short-T2* relaxation times for joint tissues that are not well captured with standard T2 mapping ( 19 , 20 ).…”