Single slice MR image estimation of 3D supraspinatus intramuscular fatty infiltration in older adults: relevance for clinical practice and research.

OBJECTIVE: (1) To compare older adults stratified by supraspinatus tendon tear status (STT status)-no tear (Intact), partial-thickness (PT) tear, full-thickness (FT) tear-by 3D Dixon fat fraction (3D-FF); 2D fat fraction (2D-FF); and 2D Goutallier grade (2D-GG) at the Y-shaped view, and 1.4 cm and 2.8 cm medial to the Y-shaped view. Stratified by STT status to determine (2) correlation of 3D-FF with 2D-FF and 2D-GG and (3) inter-rater reliability at and medial to the Y-shaped view. MATERIALS AND METHODS: Forty-five volunteers ≥ 60 years recruited prospectively received shoulder MRI. 3D-FF and 2D-FF were measured on 6-point-Dixon MRI by three trainees. Goutallier grade was assessed on T1-weighted MRI by three fellowship-trained diagnostic radiologists. Descriptive, reliability, and correlation analyses were performed. RESULTS: Groups showed no difference in age. The FT group showed higher (p < 0.05) mean 3D-FF (14.09% ± 10.99%), mean 2D-FF (1.4 cm medial to Y-shaped view, 14.91% ± 12.11%; 2.8 cm medial to Y-shaped view, 13.32% ± 9.48%), and mean 2D-GG (Y-shaped view, 1.71 ± 0.78; 1.4 cm medial to Y-shaped view, 1.71 ± 0.69; 2.8 cm medial to Y-shaped view, 1.71 ± 0.72), relative to Intact/PT groups. 3D-FF showed strong correlation with 2D-FF among all groups/all analyses (rho, 0.80-0.98; p < 0.001). 3D-FF showed strong correlation with 2D-GG for all FT group analyses (rho, 0.85-0.91; p < 0.05). 3D-FF showed moderate-to-strong correlation considering all Intact/PT group analyses (rho, 0.51-0.79; p < 0.50). Dixon fat fraction showed excellent reliability for all groups (≥ 0.884, intraclass correlation coefficient). Goutallier grade showed excellent reliability for FT group (0.771, weighted Fleiss's kappa) but poor (0.294) and fair (0.502) for Intact and PT groups, respectively. CONCLUSION: Single slice MR image estimation of 3D supraspinatus intramuscular fatty infiltration has merit for continued use in clinical populations requiring potential rotator-cuff-repair surgery. However, Dixon fat fraction should be prioritized for use in research over Goutallier grade due to superior reliability.

Estimating 3D supraspinatus intramuscular fatty infiltration in older adults: a pilot study.

BACKGROUND: A recent report suggests that semi-quantitative two-dimensional Goutallier grade (2D-GG) correlates poorly with quantitative three-dimensional Dixon fat fraction (3D-Dixon-FF) on magnetic resonance imaging (MRI). PURPOSE: To determine whether the finding of poor correlation of supraspinatus 3D-Dixon-FF with 2D-GG is reproducible, and to determine the strength of the correlation of 3D-Dixon-FF with quantitative 2D Dixon fat fraction (2D-Dixon-FF). MATERIAL AND METHODS: Ten adults aged ≥60 years were recruited prospectively received shoulder MRI. 2D-Dixon-FF and 3D-Dixon-FF were measured on 6-point Dixon fat fraction maps. 2D-GG was rated on T1-weighted images. RESULTS: The mean age of participants was 70.7 ± 3.7 years. The mean 3D-Dixon-FF was 8.3% ± 5.7%; the mean 2D-Dixon-FF was 7.3% ± 4.4%; and the mean 2D-GG was 0.9 ± 0.7. There was a strong correlation for 3D-Dixon-FF with 2D-Dixon-FF (rho = 0.90; P < 0.001) and with 2D-GG (rho = 0.73; P = 0.017). Excellent inter-observer reliability was found for Dixon fat fraction (intraclass correlation coefficient = 0.946), which was good for Goutallier grade (weighted kappa = 0.634). CONCLUSION: Supraspinatus 3D-Dixon-FF had a strong correlation with 2D-Dixon-FF and 2D-GG in our study population.

Extra-capsular floating fat at the extremity: a review.

Extra-capsular floating fat may present in a variety of non-articular locations at the extremity. Manifestation of floating fat or fat-fluid level(s) outside of a joint is a marker of trauma or infection. Recognizing radiologic sign(s) of extra-capsular floating fat can aid radiologists to provide an informed differential diagnosis and facilitate clinical care. This review discusses the etiology, mechanisms, and imaging appearance of extracapsular floating fat in specific anatomic and non-anatomic locations at the extremity.

Gluteal muscle fatty infiltration, fall risk, and mobility limitation in older women with urinary incontinence: a pilot study.

OBJECTIVE: Gluteal muscle quality influences risk of falling and mobility limitation. We sought (1) to compare gluteal muscle fatty infiltration (FI) between groups of older women with urinary incontinence (UI) at risk for falling (at-risk group) and not at risk for falling (not-at-risk group), and (2) to determine correlation of gluteal FI with Timed Up and Go (TUG) and Short Physical Performance Battery (SPPB) performance. MATERIALS AND METHODS: Prospective pilot study of gluteal FI on pelvis MRI for 19 women with UI, aged ≥ 70 years. A musculoskeletal radiologist selected axial T1-weighted MR images; then, two blinded medical student research assistants analyzed gluteal FI by quantitative fuzzy C-means segmentation. TUG and SPPB tests were performed. TUG ≥ 12 s defined participants as at risk for falling. Descriptive, correlation, and reliability analyses were performed. RESULTS: Mean age, 76.3 ± 4.8 years; no difference for age or body mass index (BMI) between the at-risk (n = 5) versus not-at-risk (n = 14) groups. SPPB score (p = 0.013) was lower for the at-risk group (6.4 ± 3.1) than for the not-at-risk group (10.2 ± 1.9). Fuzzy C-means FI-%-estimate differed between the at-risk group and the not-at-risk group for bilateral gluteus medius/minimus (33.2% ± 15.6% versus 19.5% ± 4.1%, p = 0.037) and bilateral gluteus maximus (33.6% ± 15.6% versus 19.7% ± 6.9%, p = 0.047). Fuzzy C-means FI-%-estimate for bilateral gluteus maximus had significant (p < 0.050) moderate correlation with age (rho = - 0.64), BMI (rho = 0.65), and TUG performance (rho = 0.52). Fuzzy C-means FI-%-estimates showed excellent inter-observer and intra-observer reliability (intraclass correlation coefficient, ≥ 0.892). CONCLUSION: Older women with UI at risk for falling have greater levels of gluteal FI and mobility limitation as compared to those not at risk for falling.

Reliability of supraspinatus intramuscular fatty infiltration estimates on T1-weighted MRI in potential candidates for rotator cuff repair surgery: full-thickness tear versus high-grade partial-thickness tear.

OBJECTIVE: Patients with supraspinatus high-grade partial-thickness tear or full-thickness tear are potential candidates for rotator cuff repair surgery. We sought (1) to compare supraspinatus intramuscular fatty infiltration between these groups by Goutallier grade, fuzzy C-means and an orthopaedic surgeon visible percentage estimate, (2) and to determine the reliability of each method. MATERIALS AND METHODS: We performed a retrospective cross-sectional study of supraspinatus intramuscular fatty infiltration on T1-weighted MR images for 93 shoulders with either supraspinatus partial-thickness tear > 50% tendon thickness or full-thickness tear by Goutallier grade, fuzzy C-means and an orthopaedic surgeon visible percentage estimate, by two observers for each method. Descriptive statistics were performed to compare groups. Inter- and intra-observer reliability was determined. Correlative analysis among the three methods was performed. RESULTS: Significant differences of mean supraspinatus intramuscular fatty infiltration were present when comparing supraspinatus high-grade partial-thickness tear versus full-thickness tears by Goutallier grade (p = 0.004), fuzzy C-means (p = 0.002) and orthopaedic surgeon visible percentage estimate (p = 0.001). There was no significant difference for age (55.0 ± 11.1 years versus 56.1 ± 9.6 years) or sex (35.4% male versus 47.8% male) for supraspinatus high-grade partial-thickness tear and full-thickness tear, respectively. A significant difference existed among the subgroup of full-thickness tears stratified by tear size by all three methods (p < 0.020). Inter- and intra-observer reliability was Goutallier grade 0.590 and 0.624, fuzzy C-means 0.768 and 0.925 and orthopaedic surgeon visible percentage estimate 0.858 and 0.686, respectively. For shoulders with mean Goutallier grade ≥ 2.0, inter-observer reliability was 0.878 and 0.802 for fuzzy C-means and orthopaedic surgeon visible percentage estimate, respectively. A strong correlation was present among the three methods of supraspinatus FI analysis (rho ≥ 0.72). CONCLUSION: Supraspinatus full-thickness tears have higher amounts of intramuscular fatty infiltration compared to high-grade partial-thickness tear. Quantitative fuzzy C-means shows excellent inter-observer reliability for estimating supraspinatus intramuscular fat. Experienced orthopaedic surgeons' semi-quantitative estimation of supraspinatus visible intramuscular fat may offer improved reliability as compared to semi-quantitative Goutallier grade.

Mimickers of Hill-Sachs Lesions [Formula: see text].

The purpose of this article is to describe the imaging appearance, etiology, clinical features, and treatment of rare presentations of common bone and joint diseases known to mimic Hill-Sachs lesions. Knowledge of uncommonly encountered manifestations of ankylosing spondylitis, rheumatoid arthritis, septic joint, hyperparathyroidism, hydroxyapatite deposition disease, malignant bone tumors, and benign bone cysts which mimic traumatic Hill-Sachs lesions is important for radiologists to guide the clinical care of patients who present with shoulder symptoms.

Association of Patient Self-Reported Shoulder Scores to Quantitative and Semiquantitative MRI Measures of Rotator Cuff Intramuscular Fatty Infiltration: A Pilot Study.

OBJECTIVE. The purpose of this study was to determine the relationship of supraspinatus fat fraction and Goutallier grade to the American Shoulder and Elbow Surgeons (ASES) score in cohorts of older adults with painful full-thickness supraspinatus tendon (SST) tear and control subjects. SUBJECTS AND METHODS. Seventeen control subjects and 15 study participants with painful full-thickness SST tear were prospectively recruited (mean age ± SD, 63.0 ± 10.1 years and 62.6 ± 9.0 years, respectively). Study participants received shoulder MRI and completed ASES questionnaires at one time. Goutallier grade was assessed on T1-weighted MRI. Fat fraction was measured on 6-point Dixon MRI. Body mass index (BMI) was determined. Descriptive, correlation, reliability, and regression analyses were performed. RESULTS. The control and painful full-thickness SST tear cohorts differed in mean supraspinatus fat fraction (3.3% ± 1.4% and 7.3 ± 5.9%, respectively; p = 0.024) and Goutallier grade (0.4 ± 0.5 and 0.9 ± 0.7, respectively; p = 0.022). Fat fraction (p = 0.014) and Goutallier grade (p = 0.017) showed a significant inverse association with ASES score only in the SST tear cohort. The association of BMI to ASES score was significant only in the control group (p = 0.036). The correlation between BMI and fat fraction were different for the two groups (control cohort, r = 0.676 and p = 0.003; SST tear cohort, r = 0.124 and p = 0.687). Fat fraction showed strong interobserver reliability (intraclass correlation coefficient, 0.903); Goutallier grade showed poor interobserver reliability (κ = 0.178). CONCLUSION. The association of ASES score and supraspinatus fat fraction or Goutallier grade differs between patients with painful full-thickness SST tear and control subjects without symptoms. Although fat fraction shows strong reliability, Goutallier grade should be regarded cautiously because of suboptimal reproducibility. Our results also suggest that painful full-thickness SST tear alters the correlation between supraspinatus fat fraction and BMI as compared with control subjects.

Quantification of shoulder muscle intramuscular fatty infiltration on T1-weighted MRI: a viable alternative to the Goutallier classification system.

BACKGROUND: Quantification of rotator cuff intramuscular fatty infiltration is important for clinical decision-making in patients with rotator cuff tear. The semi-quantitative Goutallier classification system is the most commonly used method, but has limited reliability. Therefore, we sought to test a freely available fuzzy C-means segmentation software program for reliability of the quantification of shoulder intramuscular fatty infiltration on T1-weighted MR images and for correlation with fat fraction by six-point Dixon MRI. MATERIALS AND METHODS: We performed a prospective cross-sectional study to measure visible intramuscular fat area percentage on oblique sagittal T1 MR images by fuzzy C-means segmentation and fat fraction maps by six-point Dixon MRI for 42 shoulder muscles. Intra- and inter-observer reliability were determined. Correlative analysis for fuzzy C-means and six-point Dixon intramuscular fatty infiltration measures was also performed. RESULTS: We found that inter-observer reliability for the quantification of visible intramuscular fat area percentage by fuzzy C-means segmentation and fat fraction by six-point Dixon MRI was 0.947 and 0.951 respectively. The intra-observer reliability for the quantification of visible intramuscular fat area percentage by fuzzy C-means segmentation and fat fraction by six-point Dixon MRI was 0.871 and 0.979 respectively. We found a strong correlation between fuzzy C-means segmentation and six-point Dixon techniques; r = 0.850, p < 0.001 by individual muscle; and r = 0.977, p < 0.002 by study subject. CONCLUSION: Quantification of intramuscular fatty infiltration by fuzzy C-means segmentation on T1-weighted sequences demonstrates excellent reliability and strong correlation with fat fraction by six-point Dixon MRI. Quantitative fuzzy C-means segmentation is a viable alternative to the semi-quantitative Goutallier classification system.

Hook of the Hamate: The Spectrum of Often Missed Pathologic Findings.

OBJECTIVE: The purposes of this article are to review hook of the hamate anatomy, describe the imaging features of the spectrum of pathologic conditions, and discuss the pearls and pitfalls of imaging for clinical decision making for pathologic entities affecting the hook of the hamate. CONCLUSION: Knowledge of the anatomy, imaging appearance, and clinical management of hook of the hamate abnormalities is important for radiologists in guiding the care of patients with ulnar-sided wrist symptoms.

Case 229: Burn-related Global Ankylosis of Interphalangeal Joints with Associated Acroosteolysis.

History A 50-year-old woman presented with a 6-month history of polyarthralgia involving the left and right hands, wrists, elbows, ankles, and knees. Her pain was not associated with morning stiffness but did worsen over the course of the day. She denied experiencing fevers, chills, or mouth ulcers. She did not report paresthesias or blue discoloration of her fingers when they were exposed to cold. Her family history was remarkable for an aunt who died of systemic lupus erythematosus and for a brother with arthritis. Her medical history was remarkable for vitamin D deficiency, hypertension, and rehabilitation for burns. At clinical examination, she had mild tenderness to palpation of her joints, without associated erythema, swelling, or crepitus. Healed skin grafts were also noted. Blood chemistry tests revealed a rheumatoid factor of 8.5 IU/mL (normal range, 0-13.9 IU/mL), an erythrocyte sedimentation rate of 2 mm/hr (normal range, 0-40 mm/hr), and a C-reactive protein value of 0.4 mg/L (3.8 nmol/L) (normal range, 0-4.9 mg/L [0-46.7 nmol/L]). Antinuclear antibodies test results were negative. Radiography of the right and left hands was performed.

Can MDCT Unmask Instability in Binder-Stabilized Pelvic Ring Disruptions?

OBJECTIVE: Pelvic binders may hinder radiologic assessment of pelvic instability after trauma, and avulsive injuries can potentially unmask instability in this setting. We compare the performance of MDCT for the detection of pelvic disruptions in patients with binders to a matched cohort without binders, and we assess the utility of avulsive injuries as signs of pelvic instability. MATERIALS AND METHODS: MDCT examinations of 56 patients with binders were compared with MDCT examinations of 54 patients without binders. Tile grading by an experienced orthopedic surgeon was used as the reference standard (A, stable; B, rotationally unstable; C, rotationally and vertically unstable). Two radiologists performed blinded reviews of CT studies in two reading sessions (sessions 1 and 2). In session 1, Tile grade was predicted on the basis of established signs of instability, including pubic symphysis and sacroiliac (SI) joint widening. In session 2, readers could change the Tile grade when avulsive injuries were seen. Diagnostic performance for predicting rotational instability and vertical instability was assessed. RESULTS: In the binder group, AUCs under the ROC curves for rotational instability increased from fair (0.73-0.77) to good (0.82-0.89) when avulsive signs were considered. In the control group, AUCs were good in both sessions. AUCs for vertical instability were fair with binders in both sessions. Agreement with the reference standard increased from fair (0.30-0.32) to moderate (0.46-0.54) when avulsive signs were considered in the binder group but were in the moderate range for both sessions in the control group. Combined evaluation for inferolateral sacral fractures, ischial spine fractures, and rectus abdominis avulsions resulted in optimal discrimination of rotational instability. CONCLUSION: Evaluation for avulsive signs improves MDCT sensitivity for the detection of rotational instability but not vertical instability in patients with binders.

Scapular Fractures: What Radiologists Need to Know.

OBJECTIVE: The purpose of this article are to review scapular anatomy and function, describe imaging features of traumatic scapular injury, and discuss the role of diagnostic imaging in clinical decision making after shoulder trauma. CONCLUSION: Knowledge of scapular anatomy, function, injury patterns, imaging appearance, and clinical management is important for the radiologist to the care of patients who present with acute shoulder trauma.

Voriconazole-related periostitis presenting on magnetic resonance imaging.

Painful periostitis is a complication of long-term antifungal therapy with voriconazole. A high clinical suspicion coupled with imaging and laboratory assessment is useful to establish the diagnosis. Prompt discontinuance of voriconazole typically results in the resolution of symptoms and signs. This report describes the presentation of voriconazole-related periostitis on magnetic resonance imaging.

Arthroplasty-Related Pseudotumor of the Scapula: Case Report and Review of the Literature.

Arthroplasty-related pseudotumors are nonneoplastic and noninfectious inflammatory masses that are typically associated with adverse reaction to metal debris. Pseudotumors most commonly occur in the setting of metal-on-metal joint replacements at the hip. However, the presentation of pseudotumor at the shoulder is exceedingly rare. In this article, we reported a case of arthroplasty-related pseudotumor of the scapula. Clinical history, radiologic signs, and tissue analysis are described. Knowledge of this rare diagnosis will support clinical decision making for teams of radiologists, pathologists, oncologists, and orthopaedic surgeons who provide care for patients presenting with suspicious shoulder masses.

Shoulder Dysfunction and Mobility Limitation in Aging.

Mobility limitation is common among older populations and is a major burden to public health. While lower extremity dysfunction is a known contributor, the influence of shoulder dysfunction on mobility is less well understood. Shoulder pain and rotator cuff tear are common causes of shoulder dysfunction, and both ailments are highly prevalent in older adults. This article discusses shoulder pain and rotator cuff tear as contributors to shoulder dysfunction and describes the association of shoulder dysfunction with mobility limitation in older adults.

Association of Shoulder Dysfunction with Mobility Limitation Among Older Adults in the Baltimore Longitudinal Study of Aging.

Association between lower extremity dysfunction and mobility limitation in older adults is well-established; whereas, the impact of upper extremity dysfunction on mobility remains unclear. Since lower extremity dysfunction does not explain all mechanisms that contribute to mobility limitation, more holistic hypotheses that explain reduced mobility in older populations are needed. The shoulders facilitate dynamic stability for ambulation, but the impact of shoulder dysfunction on mobility is poorly understood. This study examined the cross-sectional association of restricted shoulder elevation and external rotation range of motion (ROM) with poor lower extremity function and walking endurance capacity among 613 older adults aged 60 years and older in the Baltimore Longitudinal Study of Aging. Results showed that persons with abnormal shoulder elevation or external rotation ROM were 2.5 to 4.5 times more likely to perform poorly on the expanded Short Physical Performance Battery (p < .050) and the fast-paced 400 m walk test (p < .050), relative to participants with normal shoulder ROM. These findings provide nascent preliminary evidence that shoulder dysfunction is associated with mobility limitation and suggest that future studies are needed to clarify its impact on mobility and to develop novel interventions to improve prevention or mitigation of age-related declines in mobility.