Supraspinatus muscle elasticity measured with real time shear wave ultrasound elastography correlates with MRI spectroscopic measured amount of fatty degeneration.

BACKGROUND: Fatty Degeneration (FD) of the rotator cuff muscles influences functional and anatomical outcome after rotator cuff repair. The MRI based estimation of fatty degeneration is the gold standard. There is some evidence that Ultrasound elastography (EUS) can detect local differences of tissue stiffness in muscles and tendons. Shear-wave elastography (SWE) was evaluated to determine the extent to which shear wave velocity was associated with measures of fatty degeneration. MRI-spectroscopic fat measurement was used as a reference to quantify the amount of fat in the muscle belly. METHODS: Forty-two patients underwent SWE of the supraspinatus muscles at its thickest diameter. After ultrasound evaluation an MRI-spectroscopic fat measurement of the supraspinatus muscle was performed using the SPLASH-technique. A gel filled capsule was used to locate the measured area in the MRI. The values of shear wave velocity (SWV) measured with SWE and spectroscopic fat measurement were correlated statistically using Pearson's correlation test. RESULTS: Correlation of the fat amount measured with MRI-spectroscopy and the SWV measured with SWE was ρ =0.82. Spectroscopic measured fat ratio of the supraspinatus muscle ranged from 0% to 77.41% and SWV from 1.59 m/s to 5.32 m/s. In 4 patients no sufficient SWE could be performed, these individuals showed a larger diameter of the overlying soft tissue. SWV measured with SWE showed a good correlation with MRI spectroscopic fat amount of the supraspinatus muscle. CONCLUSION: These preliminary data suggest that SWE may be a sufficient tool in detecting and estimating the amount of fatty degeneration in the supraspinatus muscle in real time. Large overlying soft tissue may be a limitation in performing sufficient EUS. Ethical Committee Approval: Nr: 156/14 Date 12th August 2014. LEVEL OF EVIDENCE: III.

Comparing the MRI-based Goutallier Classification to an experimental quantitative MR spectroscopic fat measurement of the supraspinatus muscle.

BACKGROUND: The Goutallier Classification is a semi quantitative classification system to determine the amount of fatty degeneration in rotator cuff muscles. Although initially proposed for axial computer tomography scans it is currently applied to magnet-resonance-imaging-scans. The role for its clinical use is controversial, as the reliability of the classification has been shown to be inconsistent. The purpose of this study was to compare the semi quantitative MRI-based Goutallier Classification applied by 5 different raters to experimental MR spectroscopic quantitative fat measurement in order to determine the correlation between this classification system and the true extent of fatty degeneration shown by spectroscopy. METHODS: MRI-scans of 42 patients with rotator cuff tears were examined by 5 shoulder surgeons and were graduated according to the MRI-based Goutallier Classification proposed by Fuchs et al. Additionally the fat/water ratio was measured with MR spectroscopy using the experimental SPLASH technique. The semi quantitative grading according to the Goutallier Classification was statistically correlated with the quantitative measured fat/water ratio using Spearman's rank correlation. RESULTS: Statistical analysis of the data revealed only fair correlation of the Goutallier Classification system and the quantitative fat/water ratio with R = 0.35 (p < 0.05). By dichotomizing the scale the correlation was 0.72. The interobserver and intraobserver reliabilities were substantial with R = 0.62 and R = 0.74 (p < 0.01). CONCLUSION: The correlation between the semi quantitative MRI based Goutallier Classification system and MR spectroscopic fat measurement is weak. As an adequate estimation of fatty degeneration based on standard MRI may not be possible, quantitative methods need to be considered in order to increase diagnostic safety and thus provide patients with ideal care in regard to the amount of fatty degeneration. Spectroscopic MR measurement may increase the accuracy of the Goutallier classification and thus improve the prediction of clinical results after rotator cuff repair. However, these techniques are currently only available in an experimental setting.

Arthroscopic prevalence of pulley lesions in 1007 consecutive patients.

This study retrospectively analyzed 1007 diagnostic shoulder arthroscopies. The study included 72 patients with an arthroscopically verified pulley lesion as the main pathologic finding. Epidemiologic data and arthroscopic findings were evaluated in all patients, and 53 were clinically examined with the Constant score after a minimum follow-up of 2 years. We observed an incidence of 7.1% for pulley lesions. An isolated rupture of the superior glenohumeral ligament (SGHL) was seen in 53 patients (73.6%) and a combined partial articular-side tear of the rotator cuff adjacent to rotator interval in 19 (26.4%). Thirty-one patients (43%) had a history of trauma, whereas 41 (57%) had none. Overall, the mean postoperative Constant score adjusted for age and gender was 80.1% (range, 47%-135%). Patients with a SGHL lesion only (85.7%) exhibited a significant (P = .047) higher age- and gender-adjusted Constant score compared with patients with a combined partial surface tendon tear (73.1%). Our epidemiologic data accentuate the need for careful evaluation of the superolateral aspect of rotator interval to avoid underdiagnosis of pulley lesions at shoulder arthroscopy. Our findings provide evidence that the clinical outcome of isolated SGHL lesions is better compared with combined partial articular-side rotator cuff tear. With respect to the progressive pathologic process of pulley lesions, we recommend an early surgical treatment.

2D SPLASH: a new method to determine the fatty infiltration of the rotator cuff muscles.

The objective of this paper is to quantify the fatty degeneration (infiltration) of rotator cuff muscles with a new spectroscopic FLASH (SPLASH) sequence. Before planned surgery (reconstruction or muscle transfer), 20 patients (13 men, 7 women; 35-75 years) with different stages of rotator cuff disease underwent an MR examination in a 1.5-T unit. The protocol consists of imaging sequences and a newly implemented SPLASH, which allows an exact quantification of the fat/water ratio with a high spatial resolution in an arbitrarily shaped region of interest (ROI). The percentages of fat in the rotator cuff muscles were determined. To determine statistically significant differences between the different stages of rotator cuff tear, a Kruskal-Wallis H test was used. Fatty infiltration of the supraspinatus muscle was correlated with cross-sectional area (CSA) measures (Bravais-Pearson). We found significant differences between different stages of rotator cuff disease, the fatty infiltration and the volume loss (determined by the occupation ratio) of the supraspinatus muscle. With the increasing extent of rotator cuff disease, fatty infiltration increases significantly, as does the volume loss of the supraspinatus muscle. Comparing fatty infiltration and the occupation ratio individually, there was only a moderate inverse correlation between fatty infiltration and the occupation ratio, with considerable variation of data. Fatty infiltration of the infraspinatus muscle occurred when the infraspinatus tendon was involved to a lesser extent. The SPLASH sequence allows exact quantification of fatty infiltration in an arbitrarily shaped ROI. The extent of atrophy and fatty infiltration correlates with the size of the tear. Atrophy and fatty infiltration correlate only moderately and should be evaluated separately.