were assessed with SSE after MRI. The ratio of strain in the target muscle (A) and a nearby normal muscle (B), defined as the strain index value (SR) (B/A), was calculated automatically. Elastograms were assigned an elasticity score according to the degree and distribution of strain induced by manual compression. Ultrasonography and MRI were analyzed in conjunction with clinical information, biochemical data, final clinical diagnosis and grading of pathology. Correlations between SR and qualitative analyses of MRI and ultrasonography, elasticity score, biochemical data and final clinical diagnosis were analyzed using Pearson's correlation coefficient.Results: The SR of the target muscles was high in patients with IM (mean 3.14; range, 0.95-5.93 6 1.42). The correlations between SR and pathologic grading and elasticity score were statistically significant (p , 0.05). There was no significant agreement between SR and other clinical and radiologic parameters. Conclusion: Muscle hardness, as semi-quantitatively measured by SSE, was increased in cases of IM. The correlation between the SR and the pathologic grading suggests that SSE could be an important tool in not only the diagnosis of but also in measuring the degree of muscular inflammation. Advances in knowledge: This work describes a correlation between tissue elasticity and pathology in IM.

Purpose: This study investigated whether shear wave elastography (SWE) could be used to estimate the chronicity of supraspinatus tendon (SST) tears. Methods: A retrospective study was performed. From November 2015 to July 2016, 113 patients (52 men, 61 women; age range, 21 to 79 years) with persistent shoulder pain underwent 119 rotator cuff tendon examinations by routine B-mode ultrasonography, while SST elasticity was measured using SWE. Following the exclusion of eight suboptimal examinations, four examinations with missing SST measurements, and 27 examinations of patients with other conditions, 80 examinations were analyzed. A torn SST was found in 54 examinations (27 with a partial-thickness tear and 27 with a full-thickness tear). Elasticity values were compared in multiple ways. The results were analyzed using the Mann-Whitney U test or Kruskal-Wallis test. Results: No statistically significant difference in elasticity values (in kPa) was found between normal (median, 94.65; interquartile range [IQR], 87.43 to 105.47) and torn SSTs (median, 96.79; IQR, 86.71 to 108.56) or between full-thickness tears (median, 93.80; IQR, 82.50 to 108.33) and partial-thickness tears (median, 96.83; IQR, 90.60 to 112.20). However, there was a statistically significant difference in elasticity according to whether the duration of symptoms was 1 year or less (median, 92.20; IQR, 84.01 to 104.38) or longer than 1 year (median, 105.10; IQR, 100.41 to 116.03; P=0.032). Conclusion: Elasticity values were significantly higher in torn SSTs in patients with chronic shoulder pain that had persisted for more than 1 year. Further studies with larger samples seem warranted to determine whether elasticity values measured by SWE can be used preoperatively as a surrogate marker of the chronicity of a rotator cuff tendon tear.

Medial folds of the PCL are normal synovial structures that can be seen by MRI and in cadaveric studies in a large proportion of the population.

This study aimed to evaluate multiacquisition with variable resonance image combination selective short tau inversion recovery (MAVRIC SL STIR) for metallic artifact reduction in magnetic resonance imaging (MRI) of postoperative cervical spine with artificial disk replacement.Methods: A porcine cervical spine with artificial disk replacement was subject to 3 T MRI with variable fat-suppressed fluid-sensitive sequences. Five volunteers underwent MRI with MAVRIC SL STIR and STIR. Quantitative and qualitative analyses were performed for metallic artifact reduction.Results: MAVRIC SL STIR showed the least signal void areas in the tissue phantom and volunteer study. In the tissue phantom study, MAVRIC SL STIR showed the best visualization of anatomic structure, least distortion, and signal pile-up. However, it ranked last for the homogeneity of fat suppression among sequences. In the volunteer study, MAVRIC SL STIR showed better visualization of anatomic structure and lesser distortion, but showed worse image quality of the spinal cord than STIR in the sagittal plane ( P < 0.05).Conclusions: MAVRIC SL STIR might be useful for visualization of anatomy by reduction of signal void areas and distortion in the operated site but should be used as a complement to STIR for evaluation of the spinal cord signal change.

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