Using chemical-shift MR imaging to quantify fatty degeneration within supraspinatus muscle due to supraspinatus tendon injuries

Muscle Health & Fatty Infiltration with Advanced Rotator Cuff Pathology

PURPOSE OF REVIEW

Fatty infiltration (FI) of the rotator cuff is a critical determinant of clinical outcomes following rotator cuff injuries and repairs. This review examines the natural history, pathophysiology, imaging evaluation, and treatment strategies for FI, highlighting recent insights into its cellular mechanisms and emerging therapeutic approaches.

RECENT FINDINGS

Animal models demonstrate that FI begins shortly after tendon injury, progresses with muscle retraction and denervation, and is largely irreversible despite repair. Key cellular drivers include fibroadipogenic progenitor cells (FAPs), influenced by mechanical loading and inflammatory signaling pathways. Clinical studies show that FI is associated with advanced age, female sex, and full-thickness tears. Higher degrees of preoperative FI correlate with poorer functional outcomes and increased re-tear rates. Novel therapeutic targets, including pathways regulating FAP activity, TGF-β, and cell-based therapies, show promise in preclinical studies. Emerging strategies such as leukocyte-poor platelet-rich plasma (PRP) may mitigate FI progression in clinical settings. Fatty infiltration remains a significant barrier to successful rotator cuff repair and functional recovery. While surgical repair may slow FI progression, it is not consistently effective in reversing established muscle degeneration. Improved understanding of the molecular mechanisms driving FI has identified potential therapeutic targets, but their clinical applicability requires further validation. Future advances in regenerative medicine, including cell-based therapies and modulation of fibroadipogenic progenitors, offer hope for mitigating FI and improving long-term outcomes.

Advantages of 3-dimensional Measurements for Supraspinatus Intramuscular Fatty Evaluation in Patients With Medium to Massive Rotator Cuff Tears: Comparison With a Single Sagittal Slice

BACKGROUND

Fatty infiltration of the rotator cuff muscles is highly related to poor outcomes after rotator cuff tears. Fat fraction (FF) based on traditional 2-dimensional measurements (2D-FF) from a single sagittal Y-view slice cannot determine intramuscular FF in the rotator cuff muscles; the newly developed 3-dimensional method (3D-FF) is supposed to precede 2D measurements for intramuscular FF evaluation in accuracy and reliability.

PURPOSE

(1) To measure 3D-FF and (2) to compare 3D-FF and 2D-FF in terms of quantitative values and intra- and interobserver agreement.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

Six-point Dixon magnetic resonance imaging was performed in patients with full-thickness supraspinatus tears. 2D-FF was calculated on a single sagittal Y-view. Semiautomatic segmentation software (ITK-SNAP) was used to reconstruct 3D volumes of the supraspinatus muscle and fat. 3D-FF was obtained by dividing the fat volume by the total volume of the supraspinatus muscle. A paired t test was used to compare the individual differences between 2D-FF and 3D-FF results. Linear regression and Bland-Altman analyses were performed to determine the agreement between 2D-FF and 3D-FF. Intraclass correlation coefficients (ICCs) were calculated to determine intra- and interobserver agreement.

RESULTS

The 3D muscular and fatty models presented an inhomogeneous distribution of intramuscular fat in the supraspinatus, indicating the superiority of 3D-FF over 2D-FF in capturing all muscle morphologic information. 2D-FF was significantly higher than 3D-FF in the supraspinatus with large (19.5% ± 5.9% vs 16.2% ± 3.7%; P = .002) and massive (34.8% ± 13.3% vs 26.2% ± 9.4%; P < .001) rotator cuff tears. 2D-FF overestimated the FF compared with 3D-FF by >50% in 14.7% of all patients and by >15% in 67.6% of patients with large or massive RCTs. The discrepancy between 2D-FF and 3D-FF increased with increasing mean FF. The intra- and interobserver agreement of 3D-FF (ICCs, 0.89-0.99 and 0.89-0.95) was superior to that of 2D-FF (ICCs, 0.71-0.95 and 0.64-0.79).

CONCLUSION

3D-FF indicated an inhomogeneous distribution of intramuscular fat by capturing all muscle and fat morphologic information. In patients with large and massive rotator cuff tears, 2D-FF of the supraspinatus was significantly higher than 3D-FF. 3D-FF was more reliable than 2D-FF for estimating fatty infiltration in the supraspinatus, with better intra- and interobserver agreement.

Clinical Y-view versus 3-dimensional assessments of intramuscular fat in patients with full-thickness rotator cuff tears

RATIONALE AND OBJECTIVES

Recent evidence suggests an inhomogeneous distribution of intramuscular rotator cuff fat infiltration (FI) in a small sample of individuals with rotator cuff tears, yet clinically just a few slices at the scapular Y-view are used to evaluate FI in patients with rotator cuff tears. The purpose of this study was to determine if assessment of FI using the scapular Y-view is representative of the entire muscle in patients with full-thickness rotator cuff tears, and whether this varies by tear size.

MATERIALS AND METHODS

Patients (N = 25) diagnosed with full-thickness rotator cuff tear and confirmed with magnetic resonance imaging (MRI) were included. Fat-water sequences were used to objectively quantify mean FI (%) in the entire 3D muscle and the mean from 3 slices at the Y-view. Mixed-model 2 × 2 ANOVAs were used to assess for differences between methods, and if results vary by tear-size.

RESULTS

There were no statistically significant differences between mean amount of FI of the entire 3D muscle and mean Y-view in the supraspinatus or infraspinatus muscles (p > 0.05). Additionally, this did not differ across tear size groups (p > 0.05).

CONCLUSION

Results of this study suggest FI assessed in the Y-view is not different (mean difference < 1.0%) from FI of the entire 3D muscle in patients with full-thickness rotator cuff tears. Therefore, the clinical utility of evaluating rotator cuff intramuscular fat infiltration with the Y-view is further supported in patients with full-thickness rotator cuff tears across tear sizes.

Effects of aging and menopause on pancreatic fat fraction in healthy women population: A strobe-compliant article

Pancreatic fat fraction has been shown to increase in many pathological situations. However, pancreatic fat fraction and its physiological changes in healthy women are still unclear. The aim of this study is to investigate the effect of aging and menopause on pancreatic fat fraction in healthy female population.This was a cross-sectional study. A phantom of fat-water mixtures was established. One hundred sixty-seven healthy women (20-70 years) were recruited. Fat fraction was quantified with double-echo chemical shift magnetic resonance imaging with T1 and T2* correction. The association between measured and actual fat fractions was determined with Pearson correlation. Linear regression analysis was used to establish the calibration curve. Fat fractions were analyzed via analysis of variance.A significant positive linear correlation was revealed between the measured and actual fat fractions on the phantom (r = 0.991, P < .001). There was no significant difference in fat fractions among caput, corpus, and cauda of the pancreas. Pancreatic fat fraction remained constant during the age of 20 to 40 years (4.41 ± 0.79%) but significantly increased during the ages of 41 to 50 and 51 to 70 years (7.49 ± 1.10% and 9.43 ± 1.51%, respectively, P < .001). Moreover, pancreatic fat fractions of the healthy women aged 41 to 70 years were still significantly higher than these in the groups aged 20 to 40 years when postmenopausal healthy women were removed (P < .001). For volunteers aged 46 to 49 years, pancreatic fat fraction of the postmenopausal women was significantly increased compared with that of their premenopausal counterparts (P < .001).We found that an even distribution of pancreatic fat in healthy women, aging and menopause as 2 independent risk factors for pancreatic steatosis, a fatty infiltration in the pancreas beginning in the fifth decade in women.

Reliability of MR Quantification of Rotator Cuff Muscle Fatty Degeneration Using a 2-point Dixon Technique in Comparison with the Goutallier Classification: Validation Study by Multiple Readers

RATIONALE AND OBJECTIVES

Presurgical assessment of fatty degeneration is important in the management of patients with rotator cuff tears. The Goutallier classification is widely accepted as a qualitative scoring system, although it is highly observer-dependent and has poor reproducibility. The objective of this study was to quantify fatty degeneration of the supraspinatus muscle using a 2-point Dixon technique in patients with rotator cuff tears by multiple readers, and to evaluate the reproducibility compared to Goutallier classification.

MATERIALS AND METHODS

Two hundred patients with rotator cuff tears who underwent magnetic resonance imaging (MRI), including 2-point Dixon sequence at 3.0-T, were selected retrospectively. Qualitative and quantitative analyses of fatty degeneration were performed by two radiologists and three orthopedic surgeons independently. The fat quantification was performed by measuring signal intensity values of in phase (S(In)) and fat image (S(Fat)), and calculating fat fraction as S(Fat)/S(In). The reproducibility of MR quantification was analyzed by the intra- and interclass correlation coefficients and Bland-Altman plots.

RESULTS

The interobserver agreement of the Goutallier classification among five readers was moderate (k = 0.51), whereas the interclass correlation coefficient regarding fat fraction value quantified in 2-point Dixon sequence was excellent (0.893). The mean differences in fat fraction values from the individual segmentation results were from -0.072 to 0.081. Proposed fat fraction grading and Goutallier grading showed similar frequency and distribution in severity of rotator cuff tears.

CONCLUSIONS

Fat quantification in the rotator cuff muscles using a 2-point Dixon technique at 3.0-T MRI is highly reproducible and clinically feasible in comparison to the qualitative evaluation using Goutallier classification.

Systematic review of quantitative imaging biomarkers for neck and shoulder musculoskeletal disorders

Background

This study systematically summarizes quantitative imaging biomarker research in non-traumatic neck and shoulder musculoskeletal disorders (MSDs). There were two research questions: 1) Are there quantitative imaging biomarkers associated with the presence of neck and shoulder MSDs?, 2) Are there quantitative imaging biomarkers associated with the severity of neck and shoulder MSDs?

Methods

PubMed and SCOPUS were used for the literature search. One hundred and twenty-five studies met primary inclusion criteria. Data were extracted from 49 sufficient quality studies.

Results

Most of the 125 studies were cross-sectional and utilized convenience samples of patients as both cases and controls. Only half controlled for potential confounders via exclusion or in the analysis. Approximately one-third reported response rates. In sufficient quality articles, 82% demonstrated at least one statistically significant association between the MSD(s) and biomarker(s) studied. The literature synthesis suggested that neck muscle size may be decreased in neck pain, and trapezius myalgia and neck/shoulder pain may be associated with reduced vascularity in the trapezius and reduced trapezius oxygen saturation at rest and in response to upper extremity tasks. Reduced vascularity in the supraspinatus tendon may also be a feature in rotator cuff tears. Five of eight studies showed an association between a quantitative imaging marker and MSD severity.

Conclusions

Although research on quantitative imaging biomarkers is still in a nascent stage, some MSD biomarkers were identified. There are limitations in the articles examined, including possible selection bias and inattention to potentially confounding factors. Recommendations for future studies are provided.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-017-1694-y) contains supplementary material, which is available to authorized users.

Chemical shift MR imaging in the lumbar vertebra: the effect of field strength, scanner vendors and flip angles in repeatability of signal intensity index measurement

BACKGROUND

To evaluate the reproducibility of signal intensity index (SII) measurements with MRI systems from different vendors and with different field strengths, and to test the effectiveness of flip angle.

METHODS

Thirty-two healthy volunteers (mean age 35.3 ± 9.3 years) were enrolled in this ethics committee-approved study. Chemical shift MR imaging was performed on 1.5- and 3.0-T MR systems from three vendors. Two independent observers measured SII values in five lumbar segments. Inter- and intraobserver agreement was assessed using the interclass correlation coefficients (ICCs). Differences of mean SII values between different field strengths and MR vendors as well as flip angles were compared by using repeated-measures analysis of variance. Differences of mean SII values between different flip angles were also compared by using paired-sample t test.

RESULTS

Inter- and intra-observer correlation coefficients showed good agreement (all ICC > 0.75) when measuring SII values at different MR systems (ICCs ranging from 0.896 to 0.983) and flip angles (ICCs ranging from 0.824 to 0.983). There were no significant differences in mean SII values measured by different MR vendors with different field strengths (all p > 0.05 ranging from 0.337 to 0.824). The differences in the mean SII between the four different flip angles were statistically significant (all p < 0.05 ranging from < 0.001 to 0.004) except the group of flip angle 50° versus 70° (p = 0.116).

CONCLUSION

The SII measurement using chemical shift MR imaging may be comparable between different MR systems. Also high flip angles showed better stability to quantitate lumbar fat content.

Effect of Gd-DOTA on fat quantification in skeletal muscle using two-point Dixon technique - preliminary data

PURPOSE

To assess differences in fat signal fraction (FSF) in skeletal muscle as determined by two-point Dixon technique at 3T before and after application of intravenous gadoterate meglumide (Gd-DOTA).

MATERIALS AND METHODS

Eight patients (mean age, 50.8 years; range, 41-72 years) underwent clinical whole-body MRI at 3T for myopathic symptoms. Two-point Dixon technique based T1-weighted turbo spin-echo images were acquired before and after the administration of intravenous Gd-DOTA. On both image sets, the FSF was calculated in the gluteus medius, gluteus maximus, and quadriceps muscles bilaterally. Pre- and post-contrast FSF values were compared by linear regression, Bland-Altman plot as well as paired Student t-tests with Bonferroni correction.

RESULTS

The mean pre- and post-contrast FSF of included muscles were 28.7%±14.9% and 27.8%±15.1%, respectively. Linear regression indicated almost equivalent FSF estimation between pre- and post-contrast measurements (sum of squared residuals R(2), 0.92±0.04; slope, 0.97; X-intercept, -0.05; Y-intercept, +0.05). The Bland-Altman plot revealed a minimal systematical bias of the post-contrast FSF measurements of -0.87%. Paired Student t-tests did not reveal significant differences (overall p-value, 0.168).

CONCLUSION

Gd-DOTA does not significantly influence FSF quantification in skeletal muscle based on the two-point Dixon technique at 3T.

Quantification of Fatty Degeneration Within the Supraspinatus Muscle by Using a 2-Point Dixon Method on 3-T MRI

OBJECTIVE

The objective of this study was to quantify fatty degeneration of the supraspinatus muscle by using a 2-point Dixon technique on 3-T MRI and to evaluate the correlation of muscular atrophy and fat fraction values among different severities of rotator cuff tears across differing ages and sexes.

SUBJECTS AND METHODS

Patients with shoulder pain (n = 359) were evaluated by shoulder MRI on a 3-T unit, including a 2-point Dixon sequence for quantification of muscle atrophy and fatty degeneration within the supraspinatus muscle. Two board-certified musculoskeletal radiologists evaluated the degree of rotator cuff tears in three groups: full-thickness tear (n = 63), partial tear (n = 54), and no tear (n = 242). In quantitative analysis, we measured signal intensity values of in-phase images (SIn) and fat images (SFat) within the supraspinatus muscle, and the fat fraction was calculated as SFat/SIn. The Thomazeau occupation ratio was used as a quantitative index of muscular atrophy. Fat fraction and muscle atrophy were evaluated among these groups.

RESULTS

Fat fraction values were changed with the degree of rotator cuff tears and were (mean ± SD) 0.258 ± 0.123 among patients with full-thickness tears, 0.166 ± 0.067 among patients with partial tears, and 0.128 ± 0.061 among patients with no tears, with statistically significant differences (p < 0.001). The values were higher in female than in male patients in all groups. The Pearson correlation coefficient was 0.348 between age and fat fraction value, and 0.664 between muscular atrophy rate and fat fraction value.

CONCLUSION

An increase in supraspinatus fatty degeneration was statistically significantly correlated with severity of supraspinatus tears and moderately correlated with muscular atrophy. Fatty degeneration tends to progress more rapidly than muscular atrophy in female patients, with statistically significant sex differences.

Intraobserver and interobserver agreement of Goutallier classification applied to magnetic resonance images

BACKGROUND

Fatty infiltration of the muscle bellies is an important prognostic factor in rotator cuff tears. It was described initially in computed tomography examinations, and there is an ongoing debate about whether magnetic resonance (MR) is a reliable method for staging fatty infiltration. This study sought to determine intraobserver and interobserver agreement for Goutallier's classification of fatty infiltration of the rotator cuff as evaluated through MR imaging.

MATERIALS AND METHODS

Twenty MR examinations of the shoulder showing full-thickness tear of the supraspinatus tendon, with or without associated lesions, were evaluated by 3 radiologists with experience in musculoskeletal system imaging and 3 fellowship-trained shoulder surgeons. The evaluators classified the fatty infiltration of the supraspinatus muscle according to the guidelines proposed by Goutallier et al. After 8 weeks, they re-evaluated the examinations, without access to their previous reports. Weighted κ index values were determined for intraobserver and interobserver agreement analyses, and intraobserver agreement κ values are reported with 95% confidence intervals (CIs).

RESULTS

The mean intraobserver agreement was 0.832 among the orthopedists (CI > 95%) and 0.741 among the radiologists (CI > 95%). Interobserver agreement was 0.8214 (evaluation 1) and 0.7231 (evaluation 2) among the orthopedists (P < .0001) and 0.6627 (evaluation 1) and 0.6067 (evaluation 2) among the radiologists (P < .0001). Intraobserver agreement was not associated with length of experience or frequency of routine evaluations.

CONCLUSIONS

When it is applied to MR images of rotator cuff musculature, Goutallier's fatty infiltration staging rubric yielded highly significant intraobserver and interobserver agreement.

MR Quantification of the Fatty Fraction from T2*-corrected Dixon Fat/Water Separation Volume-interpolated Breathhold Examination (VIBE) in the Assessment of Muscle Atrophy in Rotator Cuff Tears

RATIONALE AND OBJECTIVES

To assess the usefulness of T2*-corrected fat fraction (FF) map from volume-interpolated breathhold examination (VIBE) magnetic resonance (MR) sequence in patients with the rotator cuff pathology.

MATERIALS AND METHODS

The phantom study was performed to validate the FF maps. Eighty-nine shoulder MR arthrographies were analyzed: (1) divided into three groups namely tendinopathy/normal tendons, partial-thickness tears, and full-thickness tears, and (2) occupation ratio (OR) was measured for muscular atrophy. Uncorrected and T2*-corrected FF maps were reconstructed from the VIBE images. The Pearson correlation test was used to correlate the FFs with ORs. The FF and the OR were compared between groups using the Student t test.

RESULTS

T2*-corrected FF maps could provide a higher correlation than uncorrected FF maps. There were significantly negative correlations between the ORs and the FFs (P < .01). In the normal and the partial-thickness tear group, the OR did not show a significant difference, although the FF maps showed a significant difference (P < .01).

CONCLUSIONS

This quantitative assessment of the T2*-corrected FF in the rotator cuff muscles was found to be reliable and correlated well with the ORs. The T2*-corrected FF maps could be used for more sophisticated assessments of the fat even in the partial-thickness tear.

Quantitative assessment of fat infiltration in the rotator cuff muscles using water-fat MRI

PURPOSE

To evaluate a chemical shift-based fat quantification technique in the rotator cuff muscles in comparison with the semiquantitative Goutallier fat infiltration classification (GC) and to assess their relationship with clinical parameters.

MATERIALS AND METHODS

The shoulders of 57 patients were imaged using a 3T MR scanner. The rotator cuff muscles were assessed for fat infiltration using GC by two radiologists and an orthopedic surgeon. Sequences included oblique-sagittal T1-, T2-, and proton density-weighted fast spin echo, and six-echo gradient echo. The iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) was used to measure fat fraction. Pain and range of motion of the shoulder were recorded.

RESULTS

Fat fraction values were significantly correlated with GC grades (P < 0.0001, κ >0.9) showing consistent increase with GC grades (grade = 0, 0%-5.59%; grade = 1, 1.1%-9.70%; grade = 2, 6.44%-14.86%; grade = 3, 15.25%-17.77%; grade = 4, 19.85%-29.63%). A significant correlation between fat infiltration of the subscapularis muscle quantified with IDEAL versus 1) deficit in internal rotation (Spearman Rank Correlation Coefficient [SRC] = 0.39, 95% confidence interval [CI] 0.13-0.60, P < 0.01) and 2) pain (SRC coefficient = 0.313, 95% CI 0.049-0.536, P = 0.02) was found but was not seen between the clinical parameters and GC grades. Additionally, only quantitative fat infiltration measures of the supraspinatus muscle were significantly correlated with a deficit in abduction (SRC coefficient = 0.45, 95% CI 0.20-0.60, P < 0.01).

CONCLUSION

An accurate and highly reproducible fat quantification in the rotator cuff muscles using water-fat magnetic resonance imaging (MRI) techniques is possible and significantly correlates with shoulder pain and range of motion.

Fatty degeneration of multifidus muscle in patients with chronic low back pain and in asymptomatic volunteers: quantification with chemical shift magnetic resonance imaging

OBJECTIVE

To evaluate and compare the fatty degeneration of multifidus muscles by chemical shift magnetic resonance imaging (MRI) in patients with chronic low back pain and in asymptomatic volunteers.

MATERIALS AND METHODS

Sixty-five patients with lumbar disc pathology were selected prospectively for this study. The control group consisted of 25 asymptomatic volunteers. The patients were grouped according to the fatty degeneration of multifidus muscles by a semiquantitative method (grade 0-4) on axial T2 weighted imaging. Chemical shift MRI was performed in the axial plane using a double-echo fast low-angle shot (FLASH) sequence. Fatty degeneration was calculated through signal intensity suppression rate (SISR) and signal intensity index (SII).

RESULTS

The semiquantitative grading of fatty degeneration of the multifidus muscle was 0 in 25 of 65 patients (patient group 0), 1 in 20 patients (patient group 1), 2 in 20 patients (patient group 2). Neither grade 3 nor grade 4 were detected in patient groups. For the control group, patient group 0, patient group 1, and patient group 2, median SISR values were 5.00, -9.00, -17.50, and -22.50 %, respectively. SII median values were -4.20 % for the control group, 7.00 % for patient group 0, 12.50 % for patient group 1, and 19.50 % for patient group 2. SISR values in the multifidus muscle calculated for the patient groups were significantly lower than those calculated for the control group. SII values in patients groups were significantly higher than in the control group.

CONCLUSIONS

Chemical shift MRI may be a useful method to quantitatively evaluate the fatty degeneration in multifidus muscle in patients with low back pain.

Severe atrophy and fatty degeneration of the infraspinatus muscle due to isolated infraspinatus tendon tear

Atrophy of both the supraspinatus and infraspinatus muscles is usually caused by chronic rotator cuff tear, but may also derive from suprascapular nerve entrapment at the spinoglenoid notch. Isolated infraspinatus muscle atrophy is uncommon, and typically associates with suprascapular nerve entrapment occurring distal to the spinoglenoid notch. However, isolated atrophy of the infraspinatus muscle due to insertional tear of the infraspinatus tendon may also occur. We present a case of a 43-year-old male with isolated infraspinatus muscle atrophy and fatty degeneration following an isolated full-thickness infraspinatus tendon tear at the insertion site on the humerus. While it is important to rule out other causes of infraspinatus muscle atrophy, such as concomitant rotator cuff tendon/muscle pathology or suprascapular nerve palsy, we present this case to increase awareness of this uncommon clinical presentation and the potential implications for treatment.