Study on the correlation between shear wave elastography and MRI grading of meniscal degeneration

Abstract

Background: Shear Wave Elastography (SWE) offers quantitative insights into the hardness and elasticity characteristics of tissues. The objective of this study is to investigate the correlation between SWE of the menisci and MRI-assessed degenerative changes in the menisci, with the aim of providing novel reference source for improving non-invasive evaluation of meniscal degenerative alterations.

Methods: The participants in this study were selected from patients who underwent knee joint MRI scans at our hospital from February 2023 to February 2024. The anterior horns of both the medial and lateral menisci were evaluated using SWE technique. The differences in elastic values of meniscus among different MRI grades were compared. The correlation between elastic values and MRI grades, as well as various parameters, was analyzed. Using MRI Grade 3 as the gold standard, the optimal cutoff value for meniscal tear was determined. The intraclass correlation coefficient (ICC) was employed to evaluate the reliability of repeated measurements performed by the same observer.

Results: A total of 104 female participants were enrolled in this study, with 152 lateral menisci (LM) and 144 medial menisci (MM) assessed. For the male group, 83 individuals were included, with 147 LM and 145 MM evaluated. The results demonstrated statistically significant differences in the elasticity values of the menisci at the same anatomical sites across different MRI grades (P < 0.001). Within the same grade, the MM had higher elasticity values than the LM, showing a statistically significant difference (P < 0.001). The elasticity values of the menisci were higher in males compared to females. There were statistically significant positive correlations between the elasticity values of the menisci and age, BMI, and MRI grade. The ICC for repeated measurements within the observer demonstrated good reliability (> 0.79).

Conclusions: The meniscal elasticity values measured by SWE exhibit a significant positive correlation with the grades of degeneration assessed by MRI. Furthermore, the elasticity values of the meniscus are found to increase with advancing age and elevated BMI.

Keywords: Degeneration; Knee joint; Magnetic resonance imaging; Meniscus; Shear wave elastography.

Fig. 1

A 65-year-old male patient presented with a tear in the anterior horn of the medial meniscus (MM) of the left knee joint. Image A shows a proton density-weighted sequence MRI, revealing a torn signal in the coronal plane of the MM anterior horn (indicated by the red circle). Image C presents a 2D grayscale ultrasound image, indicating a torn hypoechoic area in the coronal plane of the MM anterior horn (indicated by the red triangle). Image B displays a shear wave elastography (SWE) confidence map of the meniscus, appearing uniformly green. Image D presents a color-coded SWE map, with deep blue indicating extreme softness and deep red indicating extreme hardness. The torn meniscus exhibits a region with light green coding, indicating increased hardness within the torn area. A region of interest (ROI) with a diameter of 2 mm is placed at the central position of the meniscus for measurement. The reliability index (RLB) is 100%. (F, femur; MM, medial meniscus; T, tibia)

Fig. 2

The patient’s knee arthroscopy image