Objective:To 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.Methods:The clinical and imaging data of 70 patients suspected of meniscus injury and scheduled for arthroscopy in Shandong Medical Imaging Research Institute, Cheeloo College of Medicine, Shandong University 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. According to the results of arthroscopy, the patients was divided into meniscus degeneration and meniscus tear groups, respectively. 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. Results:The 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). The magnetic susceptibility values of 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 -0.062 5 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. Conclusion:QSM can quantitatively evaluate meniscus injury and can be used as an effective supplement method to conventional MRI, which is helpful to improve the diagnosis of meniscus tear.

Objective:To evaluate the feasibility of high resolution MRI for the measurement of anterior cartilaginous acetabulum-head-index (A-CAHI) and the value of A-CAHI for predicting hip clinical function after treatment in developmental dysplasia of the hip (DDH).Methods:The imaging data of 92 hips from 61 children with treated DDH were retrospectively reviewed in Shandong Medical Imaging Research Institute from January 2019 to January 2020. All children underwent conservative treatments or surgical interventions 3 years ago. Hip function after treatment was evaluated clinically based on the modified MacKay criteria. The hips were divided into satisfactory clinical function group (McKay rating excellent or good, n=46) and unsatisfactory group (McKay rating fair or poor, n=46). All patients were imaged with conventional MRI, high resolution fat suppressed proton density weighted image (FS-PDWI) of the unilateral hip joint in oblique sagittal view, and anteroposterior hip radiographs. A-CAHI and lateral cartilaginous acetabulum-head-index (L-CAHI) were measured respectively on high-resolution oblique sagittal PDWI and conventional coronal T 1WI. Acetabulum head index (AHI) was also measured on anteroposterior hip radiograph. Mann-Whitney U test or independent-samples t test was used to compare the difference of A-CAHI, L-CAHI and AHI between satisfactory and unsatisfactory clinical function groups. The diagnostic value using A-CAHI, L-CAHI, AHI, or A-CAHI combined with L-CAHI for unsatisfactory clinical function were investigated by the ROC curve. The area under the curve (AUC) and the Z statistic were used to compare diagnostic performance. Results:The values of A-CAHI, L-CAHI and AHI were significantly higher in satisfactory clinical function group compared with the unsatisfactory group ( Z=-7.746, -7.735, t=-7.199, all P<0.001).A-CAHI combined with L-CAHI had the significant highest diagnostic accuracy compared with A-CAHI, L-CAHI and AHI (AUC were 0.994, 0.969, 0.968, 0.861, respectively), with significant differences ( Z=1.975, 2.006, 3.553, P=0.048, 0.051,<0.001). The sensitivity and specificity of A-CAHI combined with L-CAHI for the diagnosis of prognosis were 95.7% and 97.8%, respectively. Conclusions:A-CAHI measured by high resolution MRI was found to have the highest diagnostic accuracy for prediction of hip clinical function in the treated DDH, and combined with L-CAHI can improve the diagnostic accuracy significantly.

Objective:To investigate the correlation of age with diffusion tensor imaging (DTI) values as fractional anisotropy (FA), apparent diffusion coefficient (ADC) and contrast to noise ratio (CNR) of three-dimensional nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation imaging (3D SHINKEI) of the brachial plexus in normal adults.Methods:A total of 54 adult healthy volunteers and 6 patients with Guillain-Barre syndrome were prospectively enrolled from October 2018 to April 2019. Healthy volunteers were divided into 3 groups according to age as 21-40 years old group ( n=20), 41-60 years old group ( n=20), and ≥61 years old group ( n=14). All of them underwent MRI examination of the brachial plexus, including DTI and 3D SHINKEI sequences. The average FA and ADC values of the brachial plexus were measured and calculated through the fusion of DTI and 3D SHINKEI by 2 physicians independently. The contrast to noise ratio (CNR) of brachial plexus nerve was measured in 3D SHINKEI sequence images. Intraclass correlation efficient (ICC) was used to analyze the consistency between the two physicians. A simple linear regression model and Pearson correlation analysis were used to detect the correlation between FA, ADC, CNR and age. One-way analysis of variance was used to compare the differences of FA, ADC and CNR in different age groups. The FA and ADC values in different genders were compared by independent sample t-test. Results:Inter-observer agreements of the 2 physicians were good for FA and ADC values with ICC values of 0.811 and 0.901, respectively. For different groups, FA values were 0.397±0.023, 0.368±0.023, and 0.334±0.018 and ADC values were (1.376±0.072) × 10 -3 mm 2/s, (1.466±0.086) × 10 -3 mm 2/s, (1.486±0.080) × 10 -3 mm 2/s, for 21-40, 41-60, and ≥61 years old groups, respectively with statistical significant difference ( F=25.311, P<0.001; F=9.948, P<0.001). The CNR of the brachial plexus were 510.583±192.846, 502.581±128.821, and 426.782±113.648 for 21-40, 41-60, and ≥61 years old group without statistical difference ( F=1.429, P=0.249). The FA value of brachial plexus was highly negatively correlated with age ( r=-0.745, P<0.001), while the ADC value was moderately positively correlated with age ( r=0.596, P<0.001). The CNR of 3D SHINKEI sequence was negatively correlated with age ( r=-0.292, P=0.033). There was no statistically significant difference in brachial plexus FA and ADC values between male and female subjects ( t=1.496, P=0.141; t=-1.557, P=0.126). The FA value of Guillain-Barre syndrome patients was lower than that of healthy volanteers in the same age group ( t=6.129, P<0.001), and the ADC value had no statistical diference ( t=-1.335, P=0.186). Conclusion:The values of FA, ADC and CNR of brachial plexus in normal adults change with age. Among them, FA value is more significant.