T2 Black Synovitis in Musculoskeletal MRI: Disease Spectrum and Imaging Characteristics of Joint Diseases

The synovium may be affected by a wide spectrum of disorders, including inflammatory, infectious, degenerative, traumatic, hemorrhagic, and tumorous conditions. Magnetic resonance imaging (MRI) is a valuable imaging modality to characterize synovial disorders. Most abnormal lesions appear as areas of nonspecific high signal intensity on T2-weighted images (T2-WI) due to high water content or increased perfusion. However, T2 hypointensity can be attributed to blood components of varying ages, calcification, inorganic crystals, fibrosis, caseous necrosis and/or amyloid deposition. Hypointense lesions on T2-WI are infrequent and additional clinical and imaging characteristics can help to limit the list of differential diagnoses, which may include tenosynovial giant cell tumor, synovial chondromatosis, rheumatoid arthritis, tuberculous arthritis, chronic tophaceous gout, amyloid arthropathy, synovial hemangioma, lipoma arborescens and hemosiderotic synovitis. Recently, susceptibility weighted imaging has been developed and may contribute to more accurate diagnosis for deoxygenated blood and calcium. We review the MRI features of hypointense synovial lesions on MRI and emphasize the characteristic findings that suggest a correct diagnosis.

Non-Contact VITAL Signs Monitoring of a Patient Lying on Surgical Bed Using Beamforming FMCW Radar.

Respiration and heartrates are important information for surgery. When the vital signs of the patient lying prone are monitored using radar installed on the back of the surgical bed, the surgeon's movements reduce the accuracy of these monitored vital signs. This study proposes a method for enhancing the monitored vital sign accuracies of a patient lying on a surgical bed using a 60 GHz frequency modulated continuous wave (FMCW) radar system with beamforming. The vital sign accuracies were enhanced by applying a fast Fourier transform (FFT) for range and beamforming which suppress the noise generated at different ranges and angles from the patient's position. The experiment was performed for a patient lying on a surgical bed with or without surgeon. Comparing a continuous-wave (CW) Doppler radar, the FMCW radar with beamforming improved almost 22 dB of signal-to-interference and noise ratio (SINR) for vital signals. More than 90% accuracy of monitoring respiration and heartrates was achieved even though the surgeon was located next to the patient as an interferer. It was analyzed using a proposed vital signal model included in the radar IF equation.

A Systematic Approach to Diagnosing Arthritis Based on Radiological Imaging.

Radiology plays a key role in the diagnosis of arthritis. We herein suggest an algorithmic approach to diagnosing arthritis. First, the number of joint involvements is reviewed. Monoarticular arthritis includes septic arthritis, pigmented villonodular synovitis, and synovial chondromatosis. Second, polyarticular arthritis can be categorized by its characteristics: erosive, productive, and mixed. Erosive disease includes rheumatoid arthritis, hemophilia, and amyloidosis, while productive disease includes osteoarthritis and hemochromatosis. Third, mixed diseases are subcategorized by symmetricity. Ankylosing spondylitis and inflammatory bowel disease related arthritis affect joints symmetrically, while psoriatic arthritis, reactive arthritis, and crystalline arthropathy are asymmetric. Adjacent soft tissue density, periostitis, and bone density are ancillary findings that can be used as additional differential diagnostic clues. The final step in identifying the type of arthritis is to check whether the location is a site frequently affected by one particular disease over another. This systematic approach would be helpful for radiologists in diagnosing arthritis.

Diagnostic performance of electron-density dual-energy CT in detection of cervical disc herniation in comparison with standard gray-scale CT and virtual non-calcium images.

OBJECTIVES: To assess the diagnostic performance of dual-energy CT (DECT) with electron-density (ED) image reconstruction compared with standard CT (SC) and virtual non-calcium (VNCa) image CT reconstruction for detecting cervical disc herniation. METHODS: This cross-sectional study was approved by the IRB. We enrolled 64 patients (336 intervertebral discs from C2/3 to C7/T1; mean age, 55 years; 17 women and 47 men) who underwent DECT with spectral reconstruction and 3-T MRI within 2 weeks between January 2018 and June 2020. Four radiologists independently evaluated the first image set of randomized SC, VNCa, and ED images to detect cervical disc herniation. After 8 weeks, the readers re-evaluated the second and the last image sets with an 8-week interval. MRI evaluations performed by two other experienced served as the reference standard. Comparing diagnostic performance between each images set was evaluated by a generalized estimating equation. RESULTS: A total of 233 cervical disc herniations were noted on MRI. For detecting cervical disc herniation, electron-density images showed higher sensitivity (94% [219/233; 95% CI, 90-97] vs. 76% [177/233; 70-81] vs. 69% [160/233; 62-76]) (p < 0.001) and similar specificity (90% [93/103; 83-95] vs. 89% [92/103; 82-96] vs. 90% [93/103; 83-95]) (p > 0.05) as SC and VNCa images, respectively. Inter-reader agreement for cervical disc herniation calculated among the four readers was moderate for all image sets (κ = 0.558 for ED, κ = 0.422 for SC, and κ = 0.449 for VNCa). CONCLUSION: DECT with ED reconstruction can improve cervical disc herniation detection and diagnostic confidence compared with SC and VNCa images. KEY POINTS: • Intervertebral discs with high material density are well visualized on electron-density images obtained from dual-energy CT. • Electron-density images showed much higher sensitivity and diagnostic accuracy than standard CT and virtual non-calcium images for the detection of cervical disc herniation. • Electron-density images can have false-negative results, especially for disc herniation with high signal intensity on T2W images and can show pseudo-disc extrusion at the lower cervical spine.

Assessment of rapidly advancing bone age during puberty on elbow radiographs using a deep neural network model.

OBJECTIVES: Bone age is considered an indicator for the diagnosis of precocious or delayed puberty and a predictor of adult height. We aimed to evaluate the performance of a deep neural network model in assessing rapidly advancing bone age during puberty using elbow radiographs. METHODS: In all, 4437 anteroposterior and lateral pairs of elbow radiographs were obtained from pubertal individuals from two institutions to implement and validate a deep neural network model. The reference standard bone age was established by five trained researchers using the Sauvegrain method, a scoring system based on the shapes of the lateral condyle, trochlea, olecranon apophysis, and proximal radial epiphysis. A test set (n = 141) was obtained from an external institution. The differences between the assessment of the model and that of reviewers were compared. RESULTS: The mean absolute difference (MAD) in bone age estimation between the model and reviewers was 0.15 years on internal validation. In the test set, the MAD between the model and the five experts ranged from 0.19 to 0.30 years. Compared with the reference standard, the MAD was 0.22 years. Interobserver agreement was excellent among reviewers (ICC: 0.99) and between the model and the reviewers (ICC: 0.98). In the subpart analysis, the olecranon apophysis exhibited the highest accuracy (74.5%), followed by the trochlea (73.7%), lateral condyle (73.7%), and radial epiphysis (63.1%). CONCLUSIONS: Assessment of rapidly advancing bone age during puberty on elbow radiographs using our deep neural network model was similar to that of experts. KEY POINTS: • Bone age during puberty is particularly important for patients with scoliosis or limb-length discrepancy to determine the phase of the disease, which influences the timing and method of surgery. • The commonly used hand radiographs-based methods have limitations in assessing bone age during puberty due to the less prominent morphological changes of the hand and wrist bones in this period. • A deep neural network model trained with elbow radiographs exhibited similar performance to human experts on estimating rapidly advancing bone age during puberty.

Imaging appearance of post-arthroscopic radiocarpal chondrolysis: comparison with osteoarthritis associated with scapholunate dissociation.

BACKGROUND: Since the diagnosis of post-arthroscopic chondrolysis is very difficult, it can be underdiagnosed and confused with other diseases in clinical practice. PURPOSE: To propose imaging features of post-arthroscopic radiocarpal chondrolysis (PRCC) and to compare these with osteoarthritis associated with scapholunate dissociation which are the most common misdiagnoses of PRCC. MATERIAL AND METHODS: To identify missed diagnoses of PRCC, 994 magnetic resonance imaging scans performed in 910 patients were retrospectively reviewed. After the identification of 73 patients who exhibited significant radiocarpal cartilage loss, 11 were diagnosed with PRCC. Since scapholunate advanced collapse was the most common incorrect diagnosis of PRCC (4/11), the imaging findings were compared among the 11 patients with PRCC and 14 patients with osteoarthritis caused by scapholunate dissociation who were diagnosed in the same period. The following imaging features were evaluated: scapholunate dissociation; the center of disease and grade of radiocarpal joint destruction; characteristics of bone marrow edema; the presence of radial styloid and distal scaphoid osteophytes; and the extent of joint effusion and synovitis. RESULTS: The imaging diagnosis of PRCC was significantly differentiated from osteoarthritis associated with scapholunate dissociation based on occurrence at a younger age, bone marrow edema crossing the joint, center of disease in the proximal radioscaphoid joint, and absence of radial styloid and scaphoid osteophytes (P < 0.05). PRCC occasionally presented with arch-shape bone marrow edema based on the proximal carpal row. CONCLUSION: The diagnosis of PRCC can be aided if its characteristic imaging findings are differentiated from other disease entities in patients with a history of arthroscopy.

An intracortical chondromyxoid fibroma in the diaphysis of the metatarsal.

Chondromyxoid fibromas (CMFs) are rare, benign, primary tumors of bones, and occur in the metaphyses of the medullary canals of the long bones. The occurrence of intracortical CMFs is extremely rare. Very few cases of intracortical CMFs located in the long tubular bones have been reported to date. Moreover, even though the feet are the second most common site for CMF (after the knees), intracortical metatarsal CMF has not been reported previously, to our knowledge. We report an intracortical CMF occurring in the diaphysis of the metatarsal in a 17-year-old man. It showed the same imaging findings as usual intramedullary CMFs, except for its cortical location. The development and serial increase in this tumor over time are also demonstrated in this report. Additionally, we present a review of current literature on intracortical CMFs.

Intravoxel incoherent motion (IVIM) analysis of vertebral bone marrow changes after radiation exposure from diagnostic imaging and interventional procedures.

Background High cumulative radiation dose in cancer patients warrants systemic examination of possible changes in bone marrow. Purpose To assess retrospectively changes in vertebral bone marrow diffusion and perfusion using intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in hepatocellular carcinoma (HCC) patients after exposure to radiation from diagnostic imaging and interventional procedures. Material and Methods A total of 21 IVIM-DWI sets in 20 HCC patients, consisting of baseline and follow-up liver magnetic resonance imaging (MRI) with an interval less than 100 days, were reviewed after varying levels of radiation exposure from transarterial chemoembolization (TACE), multiphase liver CT, and abdominal radiography. IVIM parameters (apparent diffusion coefficient [ADC], true diffusion coefficient [D], pseudodiffusion coefficient [D*], and perfusion fraction [PF]) of vertebral bone marrow were analyzed for significant differences between baseline and follow-up MRI using Wilcoxon signed-rank test, and for correlations with cumulative effective dose, as well as time interval between last radiation exposure and follow-up MRI using Spearman's correlation. Results Compared to baseline MRI, ADC, D*, and PF significantly decreased on follow-up MRI (ADC: median [interquartile range], 0.405 × 103 mm2/s [0.364-0.477] versus 0.390 [0.348-0.461]; D*: 24.011 [18.141-29.584] versus 20.815 [15.022-28.347]; PF: 10.960% [8.828-12.985] versus 9.125 [8.606-12.803]) ( P < 0.05). There was no significant difference in D ( P = 0.807). Cumulative effective dose was moderately correlated with decrease in D* (r = 0.434). In addition, longer intervals between last exposure and follow-up MRI showed negative correlations with changes in D and ADC (r = -0.352 and -0.333, respectively). Conclusion Vertebral bone marrow diffusion and perfusion parameters were significantly changed after exposure to medical radiation.

Intramuscular granular cell tumor: emphasizing the stripe sign.

We present a case of an intramuscular granular cell tumor in the thigh manifesting a 'stripe sign' on magnetic resonance imaging (MRI). This MR finding may correspond with the entrapped muscle fibers within the tumor, which demonstrated parallel arrangement on histopathologic examination. In addition, other disease entities characterized by the presence of this sign such as proliferative myositis, heterotopic ossification, and muscular sarcoidosis will be reviewed.

Usefulness of Digital Tomosynthesis for the Detection of Airway Obstruction: A Case Report of Bronchial Carcinosarcoma.

Bronchial carcinosarcoma is a very rare malignant tumor that is composed of carcinomatous and sarcomatous elements. We describe the first case in which digital tomosynthesis was useful for the evaluation of airway obstruction by bronchial carcinosarcoma that was overlooked on initial chest radiography.

Quantitative analysis of lungs and airways with CT in subjects with the chronic obstructive pulmonary disease (COPD) candidate FAM13A gene: case control study for CT quantification in COPD risk gene.

OBJECTIVE: To investigate the relationship between a chronic obstructive pulmonary disease (COPD) candidate gene, based on a genomewide association study, and computed tomographic (CT) quantitative analysis; and to find a phenotype in the COPD candidate FAM13A gene. MATERIALS AND METHODS: This study was conducted in subclinical male smokers between 2 groups with matched age and smoking status; 162 subjects (mean age, 58 years) with risk (CTGA, n = 85) and reference (TCAG, n = 77) diplotypes replicated through genomewide association study underwent chest CT for quantitative analysis of lungs and airways. We analyzed the measures in both the risk and reference groups using a 2-sample t test. RESULTS: Subjects with the risk CTGA diplotype had significantly higher total lung volume and emphysema index than the reference TCAG diplotype (P = 0.04). Mean lung density was significantly lower (P < 0.05) in the risk group. However, in the analysis of airways, wall area, luminal area, wall and lumen area ratio, and mean lung density on expiratory and inspiratory phases, no significant differences between the 2 groups were seen. CONCLUSIONS: There is a strong relationship between CT quantitative analysis and the COPD candidate gene. Furthermore, the CTGA diplotype was associated with emphysema among the phenotypes of COPD.

Functional magnetic resonance cholangiography with Gd-EOB-DTPA: a study in healthy volunteers.

PURPOSE: To describe the patterns of bile distribution in the biliary tree, duodenum, jejunum, and stomach, and to determine the gallbladder ejection fraction (GBEF) by using functional magnetic resonance cholangiography (MRC) with gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) in healthy volunteers. MATERIALS AND METHODS: Forty subjects were included in this study. After conventional MRC, pre-fatty meal MRC (PRFM) was obtained at 30, 40, 50, and 60min after contrast agent injection. Then, post-fatty meal MRC (POFM) was obtained every 10min for 1h. We assessed the PRFM and POFM for opacification of contrast agent in the first- and second-order intrahepatic ducts (IHDs) and the common bile duct (CBD). Contrast agent opacification in the cystic duct was assessed, and the percentage volume of contrast agent filling in the gallbladder (GB) was calculated on PRFM. We calculated the GBEF and assessed the presence of contrast agent in the GB, duodenum, jejunum, and stomach. RESULTS: Thirty-six (90%) subjects showed grade 3 CBD opacification (visible contrast and well-defined bile duct border) on 60-min PRFM. Thirty-four (85%) subjects showed grade 3 first-order IHD opacification on 60-min PRFM. All (100%) subjects showed cystic duct opacification of contrast agent, and the average percentage volume of contrast agent filling in the GB was 68.81%±16.84% on 60-min PRFM. The GBEF at 30-min POFM was 35.00%±18.26%. Ten (25%) subjects had no contrast agent in the stomach and small bowel on all PRFMs. Twelve (30%) subjects had contrast medium in the stomach on PRFM and/or POFM. CONCLUSIONS: Functional MRC with Gd-EOB-DTPA can allow determining the distribution of bile in the biliary tree and small intestine, as well as the GBEF.

The sonographic "coffee bean" sign helps distinguish an axillary neurofibroma from a lymphadenopathy.

Axillary masses may represent various soft tissue tumors or lymphadenopathy. Neurofibromas are benign peripheral nerve sheath tumors and, while they are very uncommon, it is important to remember that neurogenic tumors arising from brachial plexus can develop in the axilla. We describe an axillary neurofibroma arising from the brachial plexus that presented with a "coffee bean sign" on sonography that distinguished it from axillary lymphadenopathy.

Long-term outcomes of arthroscopic debridement and thermal shrinkage for isolated partial intercarpal ligament tears.

A retrospective analysis was performed based on the medical records and imaging studies of 16 wrists (14 patients) with isolated partial intercarpal ligament tears (scapholunate ligament: 6 wrists, lunotriquetral ligament, 10 wrists) treated with arthroscopic debridement and thermal shrinkage. Three wrists had Geissler grade 1 tears and 13 wrists had grade 2 tears. Mean follow-up was 52.8 months. Overall pain visual analog scale scores improved significantly (P<.05) at rest and during activities of daily living and heavy manual work. Mean flexion-extension arc was 136.5°. Mean postoperative grip strength was 106 lb, which was significantly better than preoperative grip strength. Mean modified Mayo wrist score was 70 preoperatively and 94.7 postoperatively, a significant improvement. Overall functional outcomes according to the modified Mayo wrist score were rated as excellent in 13 wrists and good in 3. No patient had radiographic evidence of instability or arthritic changes. The scapholunate and lunotriquetral intervals in all patients were less than 3 mm on neutral and pronation grip radiographs. On lateral radiographs, no signs of intercalated segmental instability were seen, with a mean scapholunate angle of 55.3°. The results of this study suggest that arthroscopic debridement and thermal shrinkage provide symptomatic pain relief and prevention of intercarpal instability for a significant period of time in patients with partial intercarpal ligament tear.

Classification of Metastatic versus Non-Metastatic Axillary Nodes in Breast Cancer Patients: Value of Cortex-Hilum Area Ratio with Ultrasound.

PURPOSE: To investigate the significance of the cortex-hilum (CH) area ratio and longitudinal-transverse (LT) axis ratio and the blood flow pattern for diagnosis of metastatic axillary lymph nodes by ultrasound in breast cancer patients. METHODS: From October 2005 to July 2006, we prospectively evaluated axillary nodes with ultrasound in 205 consecutive patients who had category 4B, 4C or 5 breast lesions according to the Breast Imaging Reporting and Data System-Ultrasound (BI-RADS-Ultrasound®). Among the 205, there were 24 patients who had pathologic verification of breast cancer and axillary lymph node status. For a total of 80 axillary nodes we measured the areas of the cortex and hilum of lymph nodes and calculated the area ratio. We also measured the length of the longitudinal and transverse axis of the lymph nodes and calculated the length ratio. We evaluated the blood flow pattern on power Doppler imaging and classified each lymph node into a central or peripheral pattern. Diagnostic performance was analyzed according to positive criteria for lymph node metastasis (CH area ratio >2, LT axis ratio <2, peripheral type on power Doppler imaging). RESULTS: The sensitivity of the CH area ratio was superior to that of the LT axis ratio (94.1% vs. 82.3%, p=0.031) and to that of the blood flow pattern (94.1% vs. 29.4%, p=0.009). For specificity, all three evaluating parameters had high values (89.1-95.6%) and no significant differences were found (p=0.121). The CH area ratio had a better positive predictive value than the LT axis ratio (94.1% vs. 80.0%, p=0.030) and power Doppler imaging (94.1% vs. 66.6%, p=0.028). For the negative predictive value, the CH area ratio was superior to the LT axis ratio (95.6% vs. 86.6%, p=0.035) and the blood flow pattern (95.6% vs. 63.0%, p=0.027). CONCLUSION: We recommend the CH area ratio of an axillary lymph node on ultrasound as a quantitative indicator for the classification of lymph nodes. The CH area ratio can improve diagnostic performance when compared with the LT axis ratio or blood flow pattern.

Biliary reflux detection in anomalous union of the pancreatico-biliary duct patients.

AIM: To demonstrate the imaging findings of biliopancreatic and pancreatico-biliary reflux in patients with anomalous union of the pancreatico-biliary duct (AUPBD) on gadoxetic acid-enhanced functional magnetic resonance cholangiography (fMRC). METHODS: This study included six consecutive patients (two men and four women; mean age 47.5 years) with AUPBD. All subjects underwent endoscopic retrograde cholangiopancreatography (ERCP); one subject also underwent bile sampling of the common bile duct (CBD) to measure the amylase level because his gadoxetic acid-enhanced fMRC images showed evidence of pancreatico-biliary reflux of pancreatic secretions. Of the five patients with choledochal cysts, four underwent pylorus-preserving pancreaticoduodenectomy. RESULTS: The five cases of choledochal cysts were classified as Todani classification I. In three of the six patients with AUPBD, injected contrast media reached the distal CBD and pancreatic duct on delay images, suggesting biliopancreatic reflux. In two of these six patients, a band-like filling defect was noted in the CBD on pre-fatty meal images, which decreased in size on delayed post-fatty meal images, suggesting pancreatico-biliary reflux of pancreatic secretions, and the bile sampled from the CBD in one patient had an amylase level of 113,000 IU/L. In one of the six patients with AUPBD, contrast media did not reach the distal CBD due to multiple CBD stones. CONCLUSION: Gadoxetic acid-enhanced fMRC successfully demonstrated biliopancreatic reflux of bile and pancreatico-biliary reflux of pancreatic secretions in patients with AUPBD with and without choledochal cysts.

Analysis of adjacent fracture after percutaneous vertebroplasty: does intradiscal cement leakage really increase the risk of adjacent vertebral fracture?

OBJECTIVE: The purpose of this study was to evaluate the incidence and risk factors associated with adjacent vertebral fracture after percutaneous vertebroplasty (PVP) to treat osteoporotic vertebral compression fractures. We also investigated the effect of intradiscal cement leakage on adjacent vertebral fracture formation after PVP. MATERIALS AND METHODS: From January 2003 to March 2009, 188 patients (163 women, 25 men; mean age, 70.9 years; range, 42-92 years) who underwent 214 PVP sessions at 351 levels for osteoporotic vertebral compression fractures were retrospectively enrolled in this study. The effect of intradiscal cement leakage on new adjacent vertebral fracture formation after PVP was evaluated. Possible other risk factors were also analyzed using univariate and multivariate methods. The risk factors included age, gender, mean bone mineral density (BMD), the vertebral level treated, presence of an intravertebral cleft or cyst before treatment, kyphosis angle, wedge angle, and the injected cement volumes. RESULTS: During the follow-up periods, new adjacent vertebral fractures developed in 36 (10.3%) of 351 treated levels. For 91 (25.9%) levels, intradiscal cement leakage was detected on procedural fluoroscopic radiographs. There was no statistically significant association between intradiscal cement leakage and new adjacent vertebral compression fracture (p = 0.789). Among the other risk factors, only the vertebral levels treated, especially the thoracolumbar junction, showed a significant relationship to new adjacent vertebral fractures (univariate analysis, p = 0.037; multivariate analysis, p = 0.043). CONCLUSIONS: Intradiscal cement leakage does not seem to be related to subsequent adjacent vertebral compression fracture in patients who underwent PVP for treatment of an osteoporotic compression fracture. The thoracolumbar location of the initial compression fracture is the only factor correlated with an adjacent vertebral fracture after PVP.

Imaging findings of femoroacetabular impingement syndrome: focusing on mixed-type impingement.

The aim of our study was to analyze the imaging findings of femoroacetabular impingement (FAI). Eight consecutive patients [age range, 19-46 years (mean, 28.6 years); M/F ratio=7:1] who underwent operation for FAI were analyzed. We analyzed bump, acetabular retroversion and protrusion, and osteoarthritis in the radiographs. In MR arthrography, we analyzed alpha-angle, anterolateral labral tear, cartilage abnormality, herniation pit, paralabral cyst, subchondral cyst, and marrow edema. We correlated the imaging findings with operative findings. In the radiographs, all eight patients showed bump and osteoarthritis (Kellgren-Lawrence score II-IV), and five (62.5%) patients showed acetabular retroversion. In MR arthrography, anterolateral labral tear and mild cartilage abnormality (Outerbridge grade I and II) were seen in all eight patients; increased alpha-angle was seen in six cases (75%). Anterolateral labral tear, bump, and mild cartilage abnormality were seen in all eight patients during operation. According to the above findings, we divided the patients into three cam-type and five mixed-type FAI. In the five mixed-type FAI, both bump and acetabular retroversion were seen. The mixed-type FAI is the most prevalent type in our study. The main imaging findings of mixed-type FAI were acetabular retroversion, bump, and early osteoarthritis in radiographs, and anterolateral labral tear, cartilage abnormality, and increased alpha-angle in MR arthrography.

Supraspinatus tendon tears: comparison of 3D US and MR arthrography with surgical correlation.

OBJECTIVE: The objective of the study was to compare the diagnostic reliability of 3D US with MR arthrography in diagnosing supraspinatus tendon tears, with arthroscopic findings used as the standard. MATERIALS AND METHODS: In a prospective study 50 patients who later underwent arthroscopic surgery of the rotator cuff were examined pre-operatively by 3D US with MR arthrography. The presence or absence of a full- or partial-thickness supraspinatus tendon tear and the tear size as demonstrated by each imaging and arthroscopy was recorded. The tear size was divided into three grades: small (<1 cm), medium (1-3 cm), and large (>3 cm). RESULTS: The arthroscopic diagnosis was a full-thickness tear in 40 patients, partial-thickness tears in 5, and intact supraspinatus tendon in 5. 3D US correctly diagnosed 35 out of 40 full-thickness tears and MR arthrography 39 out of 40 full-thickness tears. Regarding partial-thickness tears, 3D US underestimated 2 cases as no tear and overestimated 1 case as a full-thickness tear. MR arthrography underestimated 1 case as a partial-thickness tear and overestimated 2 cases as full-thickness and partial-thickness tears respectively. 3D US and MR arthrography yield a sensitivity for full-thickness tears of 87.5% and 97.5% with specificity of 90.0% and 90.0%. Based on the grading system, 3D US measurements correctly predicted the tear size of 23 (65.7%) of the 35 full-thickness tears and MR arthrography 30 (75.0%) of the 39 full-thickness tears. CONCLUSION: Three-dimensional ultrasound seems to be a promising imaging modality comparable to MR arthrography for the assessment of the supraspinatus tendon tears.