MR imaging signs of shoulder adhesive capsulitis: analysis of potential differentials and improved diagnostic criteria.

OBJECTIVE: To evaluate the prevalence of shoulder adhesive capsulitis (AC) signs on MR studies of patients with various common shoulder conditions. METHODS: MR images of 316 patients were retrospectively evaluated. Patients were divided into three groups: controls (66 patients), clinical AC (63 patients), and study group (187 patients). The final diagnosis of AC was reached clinically. The study group was composed of patients with focal and massive rotator cuff tears, active hydroxyapatite deposition disease, fractures around the shoulder, and post-surgery. The following AC signs were evaluated: inferior glenohumeral ligament (IGHL) thickening; coracohumeral ligament (CHL) thickening; and hyperintensity of the inferior glenohumeral ligament, which was graded in four classes. RESULTS: The IGHL signal intensity was statistically higher in patients with fractures than in controls (P = 0.008). There was no statistically significant difference in IGHL signal between the AC group and patients with massive rotator cuff tears and active hydroxyapatite deposition disease (P > 0.1). IGHL thickness in patients with fractures, massive rotator ruptures, and active hydroxyapatite deposition disease was significantly higher compared to controls (P < 0.02) and significantly lower compared to the AC group (P < 0.0001). Based on these findings, a grading system for fibro-inflammatory capsular changes is proposed. CONCLUSION: MR AC signs are frequent in patients with shoulder conditions other than AC; however, in these patients, capsular changes are less prominent than in patients with clinical AC.

Zero echo time MRI in shoulder MRI protocols for the diagnosis of rotator cuff calcific tendinopathy improves identification of calcific deposits compared to conventional MR sequences but remains sub-optimal compared to radiographs.

OBJECTIVE: To compare the diagnostic performance of standard MRI and standard MRI + ZTE images for the detection of rotator cuff calcific tendinopathy (RCCT) and to describe the artifacts encountered with ZTE images, using computed radiography (CR) as a reference. METHODS: In a retrospective study, patients with suspicion of rotator cuff tendinopathy who underwent standard MRI + ZTE images after radiography were enrolled between June 2021 and June 2022. Images were independently analyzed for calcific deposit presence and ZTE images artifacts, by two radiologists. Diagnostic performance was calculated individually with MRI + CR as the reference standard. RESULTS: A total of 46 RCCT subjects (27 women; mean age, 55.3 years ± 12.4) and 51 control subjects (27 men; mean age, 45.5 ± 12.9) were evaluated. For both readers, there was an increase in the sensitivity for the identification of calcific deposits of MRI + ZTE compared to MRI (77% (95% CI: 64.5-86.8) and 75.4% (95% CI: 62.7-85.5) versus 57.4% (95% IC: 44.1-70) and 47.5% (95% IC: 34.6-60.7), for R1 and R2, respectively). Specificity was quite similar for both readers and both imaging techniques and ranged from 96.6% (95% IC: 93.3-98.5) to 98.7% (95% IC: 96.3-99.7). Hyperintense joint fluid (62.8% of patients), long head of the biceps tendon (in 60.8%), and subacromial bursa (in 27.8%) on ZTE were considered artifactual. CONCLUSION: The addition of ZTE images to a standard MRI protocol improved MRI diagnostic performance of RCCT, but with a suboptimal detection rate and a relatively high frequency of artifactual soft tissue signal hyperintensity. KEY POINTS: • Adding ZTE images to standard shoulder MRI improves the MR-based detection of rotator cuff calcific tendinopathy, but half of the calcification unseen with standard MRI remained unseen with ZTE MRI. On ZTE images, joint fluid and long head biceps tendon were hyperintense in about 60% of the shoulders, as well as the subacromial bursa in about 30%, without calcific deposit on conventional radiographs. • The detection rate of calcific deposits using ZTE images was dependent on the disease phase. In the calcific stage, it reached 100% in this study but remained at a maximum of 80.7% in the resorptive phase.

Computed Tomography Bone Imaging: Pushing the Boundaries in Clinical Practice.

Bone microarchitecture has several clinical implications over and above estimating bone strength. Computed tomography (CT) analysis mainly uses high-resolution peripheral quantitative CT and micro-CT, research imaging techniques, most often limited to peripheral skeleton assessment. Ultra-high-resolution (UHR) CT and photon-counting detector CT, two commercially available techniques, provide images that can approach the spatial resolution of the trabeculae, bringing bone microarchitecture analysis into clinical practice and improving depiction of bone vascularization, tumor matrix, and cortical and periosteal bone. This review presents bone microarchitecture anatomy, principles of analysis, reference measurements, and an update on the performance and potential clinical applications of these new CT techniques. We also share our clinical experience and technical considerations using an UHR-CT device.

Solitary bone tumor imaging reporting and data system (BTI-RADS): initial assessment of a systematic imaging evaluation and comprehensive reporting method.

OBJECTIVES: Identify the most pertinent imaging features for solitary bone tumor characterization using a multimodality approach and propose a systematic evaluation system. METHODS: Data from a prospective trial, including 230 participants with histologically confirmed bone tumors, typical "do not touch" lesions, and stable chondral lesions, were retrospectively evaluated. Clinical data, CT, and MR imaging features were analyzed by a musculoskeletal radiologist blinded to the diagnosis using a structured report. The benign-malignant distribution of lesions bearing each image feature evaluated was compared to the benign-malignant distribution in the study sample. Benign and malignant indicators were identified. Two additional readers with different expertise levels independently evaluated the study sample. RESULTS: The sample included 140 men and 90 women (mean age 40.7 ± 18.3 years). The global benign-malignant distribution was 67-33%. Seven imaging features reached the criteria for benign indicators with a mean frequency of benignancy of 94%. Six minor malignant indicators were identified with a mean frequency of malignancy of 60.5%. Finally, three major malignant indicators were identified (Lodwick-Madewell grade III, aggressive periosteal reaction, and suspected metastatic disease) with a mean frequency of malignancy of 82.4%. A bone tumor imaging reporting and data system (BTI-RADS) was proposed. The reproducibility of the BTI-RADS was considered fair (kappa = 0.67) with a mean frequency of malignancy in classes I, II, III, and IV of 0%, 2.2%, 20.1%, and 71%, respectively. CONCLUSION: BTI-RADS is an evidence-based systematic approach to solitary bone tumor characterization with a fair reproducibility, allowing lesion stratification in classes of increasing malignancy frequency. TRIAL REGISTRATION: Clinical trial number NCT02895633 . KEY POINTS: • The most pertinent CT and MRI criteria allowing bone tumor characterization were defined and presented. • Lodwick-Madewell grade III, aggressive periosteal reaction, and suspected metastatic disease should be considered major malignant indicators associated with a frequency of malignancy over 75%. • The proposed evidence-based multimodality reporting system stratifies solitary bone tumors in classes with increasing frequencies of malignancy.

Evaluation of Dorsal Subluxation of the Scaphoid in Patients With Scapholunate Ligament Tears: A 4D CT Study.

OBJECTIVE. The purpose of this study was to evaluate the variation of the posterior radioscaphoid (RS) angle in patients with and without scapholunate ligament (SLL) tears during wrist radioulnar deviation. SUBJECTS AND METHODS. Seventy-three patients with clinically suspected scapholunate instability were prospectively evaluated with 4D CT and CT arthrography from February 2015 to April 2018. The posterior RS angle is formed between the articular surface of the scaphoid fossa of the radius and the most posterior point of the scaphoid in the sagittal plane. Two independent radiologists calculated this angle during radioulnar deviation. Posterior RS angles were correlated with the SLL status and the presence of a scapholunate diastasis on conventional stress radiographs. RESULTS. Readers 1 and 2 found mean posterior RS angles of 99° and 98°, respectively, in patients without and 107° and 111°, respectively, in patients with a scapholunate diastasis. The posterior RS angle amplitude varied 7.6-9.3° in the subgroups studied. The reproducibility of posterior RS angle measurement was considered good (intraclass correlation coefficient, 0.73). Mean posterior RS angles increased 6-10% and 12-14% when patients with an intact SLL were compared with those with partial tears and full tears, respectively (p < 0.001). These values also increased 8-13% when patients with diastasis were compared with those without (p < 0.0001). A dynamic acquisition was not necessary to assess this angle, with neutral posterior RS angles yielding a sensitivity of 64% and 72% and specificity of 79% and 94% for the diagnosis of SLL tears by readers 1 and 2, respectively. CONCLUSION. Posterior RS angle tended to increase with the severity of SLL tears and with the presence of scapholunate instability and yielded high sensitivity and specificity for the detection of SLL tears.

The Impact of Dose Reduction in Quantitative Kinematic CT of Ankle Joints Using a Full Model-Based Iterative Reconstruction Algorithm: A Cadaveric Study.

OBJECTIVE: The objective of our study was to evaluate the quality and reproducibility of semiautomatic measurements of the ankle in low-dose kinematic CT studies using a full model-based iterative reconstruction (MBIR). MATERIALS AND METHODS: Kinematic CT was performed in five cadaveric ankles at three acquisition dose levels: standard dose (1020 mGy × cm), low dose (10% of the standard dose), and ultra-low-dose (1.5% of the standard dose). All images were reconstructed using a full MBIR algorithm. Two semiautomatic measurements (one distance and one angle) were performed by two readers. Registration error was evaluated. The bone aspect on CT and presence of metallic implants were considered in the analysis. The influence of dose on the measurements obtained, reproducibility, and image quality was assessed. RESULTS: With the standard- and low-dose protocols, registration quality was good (registration error, 0.65-4.72%), measurements were similar (p = 0.9), and reproducibility was excellent (intraclass correlation coefficient [ICC] = 0.881). With the ultra-low-dose protocol, the registration quality was poor, yielding measurements significantly different from the other protocols (p < 0.001) and poor reproducibility (ICC = 0.39). In a specimen with normal bone and no metal implant, the registration error was low (0.61-1.01%), measurements were similar (p > 0.5), and reproducibility was excellent (ICC, 0.885-0.996) for the three dose levels tested. CONCLUSION: Full MBIR allows reliable and reproducible measurements in ankle kinematic CT with a low-dose protocol, but an ultra-low-dose protocol may lead to unreliable results.

Diffusion-weighted magnetic resonance imaging for the initial characterization of non-fatty soft tissue tumors: correlation between T2 signal intensity and ADC values.

OBJECTIVE: To evaluate the performance of quantitative diffusion-weighted imaging (DWI) correlated with T2 signal in differentiating non-fatty benign from malignant tumors. MATERIAL AND METHODS: A total of 76 patients with a histologically confirmed non-fatty soft tissue tumors (46 benign and 30 malignant) were prospectively included in this ethics committee approved study. All patients signed an informed consent and underwent MRI with DWI with two b values (0 and 600). ADC values from the solid components of these tumors were obtained and were correlated with the lesion's signal intensity on T2-weighted fat-saturated sequences. ADC values were obtained from adjacent normal muscle to allow calculation of tumor/muscle ADC ratios. RESULTS: There were 58 hyperintense and 18 iso or hypointense lesions. All hypointense lesions were benign. The mean ADC values for benign and malignant tumors were 1.47 ± 0.54 × 10(-3) and 1.17 ± 0.38 × 10(-3) mm(2)/s respectively (p < 0.005). The mean ADC ratio in benign iso or hypointense tumors was significantly lower than that of hyperintense ones (0.76 ± 0.21 versus 1.58 ± 0.82 - p < 0.0001). An ADC ratio lower than 0.915 was highly specific for malignancy (96.4 %), whereas an ADC ratio higher than 1.32 was highly sensitive for benign lesions (90 %). CONCLUSION: ADC analysis can be useful in the initial characterization of T2 hyperintense non-fatty soft tissue masses, although this technique alone is not likely to change patient management.

Analysis of the position of the branches of the ulnar nerve in Guyon's canal using high-resolution MRI in positions adopted by cyclists.

PURPOSE: To study variations in the anatomical relationships of the branches of the ulnar nerve in Guyon's canal relative to the hamulus of hamate (HH) in a grip encountered among cyclists. MATERIALS AND METHODS: Forty-seven wrist examinations were performed on a 3-T MRI (soft antenna, 16 channels) in propeller sequence in the plane perpendicular to the carpus in 28 healthy volunteers in three cycling positions (neutral, hyperextension and ulnar deviation). The positions and distance between the superficial (SB) and deep (DB) branches of the ulnar nerve with respect to the HH were determined on the section passing through the HH. RESULTS: The mean distances between the SB (d s) and DP (d p) and HH were 2.4 and 0.6 mm, respectively. The d s in hyperextension and ulnar deviation were 2.2 mm (P = 0.3) and 3 mm (P = 0.07), respectively. The d p in hyperextension and ulnar deviation were 0.3 mm (P = 0.02) and 0.5 mm (P = 0.15), respectively. Hyperextended, 60 % of SB and 40 % of DB were close to the HH, and 26 % of DB came directly in contact with it. In ulnar deviation, 30 % of SB and 29 % of DB approached HH, and 47 % of DB were in contact with it. CONCLUSION: This study shows that SB and DB positions of the ulnar nerve vary with respect to the HH depending on the position of the wrist, and such differences may promote Guyon's canal syndrome in cyclists.

Impact of ROI Positioning and Lesion Morphology on Apparent Diffusion Coefficient Analysis for the Differentiation Between Benign and Malignant Nonfatty Soft-Tissue Lesions.

OBJECTIVE: The objective of our study was to assess the impact of two methods of apparent diffusion coefficient (ADC) selection on the diagnostic performance of DWI in the characterization of nonfatty soft-tissue masses. SUBJECTS AND METHODS: Sixty-five histologically confirmed soft-tissue tumors imaged from November 2009 through October 2012 were evaluated. The minimal ADC (ADCmin) and average ADC (ADCavg) values for each tumor were obtained using two ROI-positioning methods: manual and semiautomatic. Two readers correlated the findings to lesion histology and morphology on conventional MRI sequences. RESULTS: The ADCmin values obtained using the manual method presented a better sensitivity with a similar specificity when compared with the ADCmin values obtained using the semiautomatic method (manual vs semiautomatic: 75-83% and 59-63% vs 58-67% and 63% and 63%, respectively). The interobserver agreement for the ADCmin values was similar between the ADC selection methods (intraclass correlation coefficient = 0.81 and 0.87 for manual and semiautomatic methods, respectively). In the subgroup of solid lesions, the ADCavg values obtained using the manual method offered a better sensitivity for benign-malignant differentiation (60-81% vs 60% and 60% for ADCavg and ADCmin, respectively). CONCLUSION: The ADCmin values obtained with manual ROI positioning offered the best diagnostic performance for tumor characterization. The semiautomatic method yielded similar specificity values. For solid masses, the ADCavg values were better correlated with tumor histology than the ADCmin values.

In vivo depiction of cortical bone vascularization with ultra-high resolution-CT and deep learning algorithm reconstruction using osteoid osteoma as a model.

PURPOSE: The purpose of this study was to evaluate the ability to depict in vivo bone vascularization using ultra-high-resolution (UHR) computed tomography (CT) with deep learning reconstruction (DLR) and hybrid iterative reconstruction algorithm, compared to simulated conventional CT, using osteoid osteoma as a model. MATERIALS AND METHODS: Patients with histopathologically proven cortical osteoid osteoma who underwent UHR-CT between October 2019 and October 2022 were retrospectively included. Images were acquired with a 1024 × 1024 matrix and reconstructed with DLR and hybrid iterative reconstruction algorithm. To simulate conventional CT, images with a 512 × 512 matrix were also reconstructed. Two radiologists (R1, R2) independently evaluated the number of blood vessels entering the nidus and crossing the bone cortex, as well as vessel identification and image quality with a 5-point scale. Standard deviation (SD) of attenuation in the adjacent muscle and that of air were used as image noise and recorded. RESULTS: Thirteen patients with 13 osteoid osteomas were included. There were 11 men and two women with a mean age of 21.8 ± 9.1 (SD) years. For both readers, UHR-CT with DLR depicted more nidus vessels (11.5 ± 4.3 [SD] (R1) and 11.9 ± 4.6 [SD] (R2)) and cortical vessels (4 ± 3.8 [SD] and 4.3 ± 4.1 [SD], respectively) than UHR-CT with hybrid iterative reconstruction (10.5 ± 4.3 [SD] and 10.4 ± 4.6 [SD], and 4.1 ± 3.8 [SD] and 4.3 ± 3.8 [SD], respectively) and simulated conventional CT (5.3 ± 2.2 [SD] and 6.4 ± 2.5 [SD], 2 ± 1.2 [SD] and 2.4 ± 1.6 [SD], respectively) (P < 0.05). UHR-CT with DLR provided less image noise than simulated conventional CT and UHR-CT with hybrid iterative reconstruction (P < 0.05). UHR-CT with DLR received the greatest score and simulated conventional CT the lowest score for vessel identification and image quality. CONCLUSION: UHR-CT with DLR shows less noise than UHR-CT with hybrid iterative reconstruction and significantly improves cortical bone vascularization depiction compared to simulated conventional CT.

Post-processing of quantitative 4D-CT for initial evaluation of scapholunate Instability: Assessment of simplified approaches to data analysis.

OBJECTIVES: To evaluate the diagnostic performance of simplified post-processing approaches for quantitative wrist 4D-CT in the assessment of scapholunate instability (SLI). METHODS: A prospective monocentric case-control study included 60 patients with suspected post-traumatic scapholunate ligament (SLL) tears and persistent pain. Of these, 40 patients exhibited SLL tears, subdivided into two groups of 20 each: one group with completely torn ligaments and the other with partially torn ligaments. The remaining 20 patients, whose SLLs were intact, served as controls. 4D-CT and CT arthrography were performed, and post-processed by two readers using three approaches: the standard method with full data assessment and dedicated software, partial data assessment with post-processing software (bone locking), and partial data assessment without post-processing software (no bone locking). The scapholunate gap (SLG) parameter was measured in millimeters to evaluate scapholunate diastasis during radioulnar deviation (RUD). The scapholunate ligament status on CT arthrography was considered the gold standard. RESULTS: The SLG-derived parameters (range, mean, and maximal values) were significantly increased in patients with both intact and torn scapholunate ligaments across all post-processing approaches (P values ranging from 0.001 to 0.004). SLG range was the best parameter for diagnosing SLL tears, with ROC AUC values ranging from 0.7 to 0.88 across the three post-processing methods. The interobserver reproducibility was better with the alternative approaches (ICC values 0.93-0.96) compared to the standard approach (ICC values 0.65-0.72). Additionally, post-processing time was shorter with the alternative approaches, especially when specific software was not used (reduced from 10 to three minutes). CONCLUSION: Simpler approaches to wrist 4D-CT data analysis yielded acceptable diagnostic performances and improved interobserver reproducibility compared to the standard approach.

Ultra-high-resolution CT of the temporal bone: Comparison between deep learning reconstruction and hybrid and model-based iterative reconstruction.

PURPOSE: The purpose of this study was to evaluate the ability of ultra-high-resolution computed tomography (UHR-CT) to assess stapes and chorda tympani nerve anatomy using a deep learning (DLR), a model-based, and a hybrid iterative reconstruction algorithm compared to simulated conventional CT. MATERIALS AND METHODS: CT acquisitions were performed with a Mercury 4.0 phantom. Images were acquired with a 1024 × 1024 matrix and a 0.25 mm slice thickness and reconstructed using DLR, model-based, and hybrid iterative reconstruction algorithms. To simulate conventional CT, images were also reconstructed with a 512 × 512 matrix and a 0.5 mm slice thickness. Spatial resolution, noise power spectrum, and objective high-contrast detectability were compared. Three radiologists evaluated the clinical acceptability of these algorithms by assessing the thickness and image quality of the stapes footplate and superstructure elements, as well as the image quality of the chorda tympani nerve bony and tympanic segments using a 5-point confidence scale on 13 temporal bone CT examinations reconstructed with the four algorithms. RESULTS: UHR-CT provided higher spatial resolution than simulated conventional CT at the penalty of higher noise. DLR and model-based iterative reconstruction provided better noise reduction than hybrid iterative reconstruction, and DLR had the highest detectability index, regardless of the dose level. All stapedial structure thicknesses were thinner using UHR-CT by comparison with conventional simulated CT (P < 0.009). DLR showed the best visualization scores compared to the other reconstruction algorithms (P < 0.032). CONCLUSION: UHR-CT with DLR results in less noise than UHR-CT with hybrid iterative reconstruction and significantly improves stapes and tympanic chorda tympani nerve depiction compared to simulated conventional CT and UHR-CT with iterative reconstruction.

CT in non-traumatic acute abdominal emergencies: Comparison of unenhanced acquisitions and single-energy iodine mapping for the characterization of bowel wall enhancement.

Objectives: To evaluate the benefit of unenhanced CT and single energy iodine mapping (SIM) to conventional contrast-enhanced CT for bowel wall enhancement characterization in an acute abdomen setting. Methods: CT images from 45 patients with a suspected acute abdomen who underwent abdominopelvic CT from April 2018 to June 2018 were analyzed retrospectively by two independent radiologists. These patients had been referred by emergency department physicians in a context of acute abdominal pain and had a confirmed etiological diagnosis. Three image sets were evaluated separately (portal phase images alone; portal phase images and unenhanced images, portal phase images, and single energy iodine maps). Diagnostic accuracy and confidence were assessed. Quantitative analysis of bowel wall enhancement was also performed. Results: The number of correct diagnoses increased by 8% and 12% with unenhanced images and 6% and 13% with SIM for readers 1 and 2, respectively, compared to the portal phase only. There was an improvement in the confidence of the etiological diagnosis with the number of certain diagnoses increasing from 23% to 100%, which was statistically significant for reader 2 and of borderline significance for reader 1 (P = 0.002 and 0.052, respectively) when unenhanced phase and SIM were added. The inter-rater agreement improved when unenhanced and portal phase images were associated, compared to portal phase images alone (kappa = 0.652 [ICC=0.482-0.822] and 0.42 [ICC=0.241-0.607] respectively). Conclusion: SIM and unenhanced images improve the reproducibility and the diagnostic confidence to diagnose ischemic and inflammatory/infectious bowel wall thickening compared to portal phase images alone. Summary sentence: The analysis of unenhanced and SIM images in association with portal phase images improves the reproducibility and the radiologist's confidence in the etiological diagnosis of acute non-traumatic bowel wall thickening in adults.

Ultrasound assessment of the lateral collateral ligamentous complex of the elbow: imaging aspects in cadavers and normal volunteers.

OBJECTIVE: The Lateral Collateral Ligamentous complex (LCL) is an important stabiliser of the elbow. It has a Y-shaped structure with three components. In this study, we sought to describe the ultrasound aspect of the individual components of this ligamentous complex and to evaluate the performance of ultrasound in both cadavers and in normal subjects. METHODS: Ten cadaveric elbow specimens underwent high-frequency ultrasound. Two specimens were sliced and two were dissected for anatomical correlation. Ten elbows of normal subjects were also evaluated by ultrasound. The findings were compared. RESULTS: The three components of the LCL could be visualised in all specimens and normal subjects with the exception of the proximal portion of one specimen. In 80% of the specimens and 100% of the healthy volunteers the proximal portion of the LCL could be separated from the extensor tendons. CONCLUSION: High-resolution ultrasound can assess all components of the LCL of the elbow and can distinguish them from surrounding structures.

MR Imaging Biomarkers for Clinical Impairment and Disease Progression in Patients with Shoulder Adhesive Capsulitis: A Prospective Study.

BACKGROUND: MRI diagnostic criteria of shoulder adhesive capsulitis (AC) are nowadays widely used, but there is little information available on the association between MRI findings and clinical impairment. PURPOSE: To determine the correlation of MRI findings with the Constant-Murley Score (CMS), pain duration and symptoms at the one-year follow-up in AC patients. MATERIALS AND METHODS: This monocentric prospective study included 132 patients with a clinical diagnosis of shoulder AC who underwent shoulder MRI. Mean patient age was 54.1 ± 9.3 years, and there were 55 men and 77 women. A radiologist examined all patients and completed the CMS just prior to MRI. Pain duration was assessed along with the signal intensity and measured the maximal thickness of the inferior glenohumeral ligament (IGHL) by two radiologists. Medical record analysis was performed in a sub-group of 49 patients to assess prognosis approximately one year after the MRI examination. Linear regression analysis with the Pearson test and the Fisher exact test were used to determine the association between MRI findings and clinical impairment. RESULTS: There was a significant difference in mean pain duration score (3.8 ± 1.2 versus 3.2 ± 0.9 and 3.8 ± 1.2 versus 3.2 ± 0.9, respectively, for readers 1 and 2) and in mean mobility scores (15.7 ± 8 points versus 19.6 ± 10.1 points and 15.8 ± 8.2 points versus 19.4 ± 10 points, respectively, for readers 1 and 2) in patients with a high IGHL signal compared to those with a low IGHL signal (p < 0.05). IGHL was thicker in patients with clinical improvement at one-year follow-up compared to those presenting clinical stability or worsening (p < 0.05). CONCLUSIONS: In patients with shoulder AC, the degree of signal intensity at the IGHL was inversely related to shoulder pain duration and range of motion, and a thickened IGHL indicated a favorable outcome at one-year follow-up.