Differentiation Between Knee Meniscus Degeneration And Tear Using Quantitative Susceptibility Mapping At 3T MRI

ObjectiveTo evaluate the feasibility and the application values of quantitative susceptibility mapping(QSM)for the assessment of meniscal injury and in distinguishing meniscus degeneration and tears.Materials and MethodsThe clinical and imaging data of 70 patients suspected of meniscus injury and scheduled for arthroscopy in Shandong Provincial Hospital from November 2019 to June 2020 were analyzed retrospectively.Thirty age-and sex-matched healthy subjects were also examined as controls.All subjects received knee joint QSM and routine MR imaging.On the basis of the results of arthroscopy,we marked off the meniscus degeneration group and tear group,and the sensitivity and specificity of conventional MRI in the diagnosis of meniscal tear were analyzed.The conventional MR was evaluated by two radiologists.The meniscus injury area was delineated on the original QSM magnitude images(the central area of the posterior corner of the lateral meniscus was selected in the healthy controls)and mapped to the corresponding QSM maps,and the magnetic susceptibility values were measured.Kruskal-Wallis H test was used to analyze the magnetic sensitivity values of meniscal degeneration,meniscal tear and healthy control groups;and Bonferroni was used to correct the pairwise comparison.ROC curve was established to evaluate the threshold and efficacy of magnetic susceptibility value in the diagnosis of meniscal tear.The results were compared with those of conventional MRI.ResultsThe magnetic susceptibility values of meniscus of healthy controls,meniscal degeneration and meniscal tear groups were(0.035±0.016)ppm,-0.031(-0.040,-0.005)ppm,and(-0.122±0.115)ppm,respectively,with significant difference found among the three groups(χ2=44.419,P<0.05).The magnetic susceptibility values of meniscus of healthy controls was significantly higher than those of meniscus degeneration patients and meniscus tear patients(χ2=-23.843,-48.253,P<0.05).meniscus of meniscus tear group was significant lower than those of meniscus degeneration group(χ2=-24.410,P<0.05).Taking magnetic susceptibility values of-0.0625 ppm as threshold,the area under the ROC curve for the diagnosis of meniscal tears was 0.949,with the sensitivity as 87%and the specificity as 100%The sensitivity and specificity of conventional MRI in the diagnosis of meniscal tears were 86.8%and 87.5%,respectively.ConclusionQSM allows in vivo imaging and quantification of the magnetic susceptibility of the knee in patients with meniscal tears at 3T with a clinically ready protocol.QSM can serve as a useful tool for early diagnosis for meniscus degeneration and tear can be used as a supplementary sequence of conventional MRI.