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The combined use of shoulder arthrography with MR and CT imaging offers distinct advantages over conventional nonarthrographic imaging techniques. The improved contrast and joint distension afforded by direct arthrography optimize evaluation of various intra-articular structures and help to define subtle abnormalities and distinguish normal variants from true shoulder pathology. In this article, we review the rationale and basic approaches to shoulder arthrography as well as the imaging appearance of the normal shoulder, anatomical variants, and pathology highlighted by this technique. [ABSTRACT FROM AUTHOR]

We present an uncommon imaging feature with fluid fat tracking within the tendon sheath of the flexor hallucis longus (FHL) after traumatic injury to the ankle joint. We propose a coined medical term "lipidus migrans" to define the presence of floating fat in a tendon sheath. This is due to lipohemarthrosis from intra-articular fracture of the ankle with leakage of fluid fat into the tendon sheath. Communication between the FHL tendon sheath and ankle joint can occur in up to 25% of patients. Radiologists should be aware of the presence of lipidus migrans as a potential posttraumatic complication after intra-articular ankle fracture and that fat in the tendon sheath may mimic fracture fragments or even a tendon sheath tumor.

Anterior cruciate ligament (ACL) tears are common injuries that if left untreated can result in chronic instability, cartilage damage, meniscal tears, and ligamentous injuries, eventually leading to early osteoarthritis. ACL reconstruction surgeries are therefore increasingly being performed. Despite the fact that most patients achieve excellent postoperative results, patients can present with recurrent instability and pain. These patients often undergo imaging with radiographs, magnetic resonance imaging, and/or computed tomography. An understanding of the imaging appearance of the normal ACL reconstruction and common causes of failure is therefore essential for the interpreting radiologist. This article reviews surgical techniques for ACL reconstruction, highlighting recent technical advances, the normal imaging appearance after ACL reconstruction, etiologies for reconstruction failure, and the diagnosis of these with the aid of imaging., Competing Interests: Disclosure The authors report no conflicts of interest in this work., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Purpose: To assess the MRI features of growth plate injury at the base of the coracoid process., Materials and Methods: Subjects were identified through retrospective search of our department imaging database and teaching files and the teaching files of two outside academic institutions. The coracoid base growth plate was examined with attention to widening, irregularity, abnormal signal intensity of the growth plate, and the presence of adjacent soft tissue edema. The apposing coracoid and scapular bony surfaces were examined for signal intensity and morphology., Results: Shoulder MRIs in eight patients with coracoid base growth plate disturbances were retrospectively reviewed (7 males, 1 female, mean age 15 years). Growth plate injury manifested as widening, irregularity and increased signal, apposing bony marrow edema and hypertrophy, and surrounding soft tissue edema. Five subjects were athletes (football, archery, basketball, swimming, rugby), two had a history of neuromuscular disorders, and one subject presented after a fall. Clinical indications included: rule out labral tear (n = 3), rule out rotator cuff tear or fracture after fall (n = 1), nonspecific pain (n = 1), shoulder subluxation, rule out glenoid pathology (n = 1, patient with underlying neuromuscular disorder), muscular dystrophy with shoulder pain (n = 1), and impingement (n = 1). Coracoid growth plate injury was not suspected clinically in any of the patients., Conclusion: Awareness of the imaging appearance of coracoid base growth plate injury can aid in a more accurate diagnosis of shoulder MRI studies in young pediatric athletes. While uncommon, coracoid growth plate injury should be considered when assessing children with shoulder symptomatology.

Objectives: To evaluate the ability of different MRI sequences to detect chondrocalcinosis within knee cartilage and menisci, and to analyze the association with joint degeneration., Methods: Subjects with radiographic knee chondrocalcinosis (n = 90, age 67.7 ± 7.3 years, 50 women) were selected from the Osteoarthritis Initiative and matched to controls without radiographic chondrocalcinosis (n = 90). Visualization of calcium-containing crystals (CaC) was compared between 3D T1-weighted gradient-echo (T1GE), 3D dual echo steady-state (DESS), 2D intermediate-weighted (IW), and proton density (PD)-weighted fast spin-echo (FSE) sequences obtained with 3T MRI and correlated with a semiquantitative CaC score obtained from radiographs. Structural abnormalities were assessed using Whole-Organ MRI Score (WORMS) and logistic regression models were used to compare cartilage compartments with and without CaC., Results: Correlations between CaC counts of MRI sequences and degree of radiographic calcifications were highest for GE (r T1GE  = 0.73, P < 0.001; r DESS  = 0.68, P < 0.001) compared to other sequences (P > 0.05). Meniscus WORMS was significantly higher in subjects with chondrocalcinosis compared to controls (P = 0.005). Cartilage defects were significantly more frequent in compartments with CaC than without (patella: P = 0.006; lateral tibia: P < 0.001; lateral femur condyle: P = 0.017)., Conclusions: Gradient-echo sequences were most useful for the detection of chondrocalcinosis and presence of CaC was associated with higher prevalence of cartilage and meniscal damage., Key Points: • Magnetic resonance imaging is useful for assessing burden of calcium-containing crystals (CaC). • Gradient-echo sequences are superior to fast spin echo sequences for CaC imaging. • Presence of CaC is associated with meniscus and cartilage degradation.

We present the case of a 46-year-old woman with no significant past medical history who developed left mid-thigh pain and fullness. Imaging demonstrated a mineralized soft-tissue mass, which increased in size during a year of monitoring, but retained a circumscribed appearance. The mass was located in the medial soft tissues of the thigh, separate from the bone on imaging studies, and this finding was confirmed during excision. The mass showed gross and microscopic features of an aneurysmal bone cyst. This diagnosis was supported by cytogenetic analysis revealing a t(17;17)(p13;q21) translocation corresponding to the USP6 and COL1A1 loci. Soft-tissue aneurysmal bone cyst is a rare entity, with fewer than 25 reports in the literature. Limited cytogenetic information about these tumors is available. To our knowledge, the USP6 and COL1A1 rearrangement has only previously been described in a pediatric soft-tissue aneurysmal bone cyst. We also discuss the differential diagnosis of ossifying soft-tissue lesions.

Magnetic resonance imaging (MRI) evaluation of the postoperative shoulder presents technical and diagnostic challenges related to imaging artifacts from hardware and micrometallic shavings, postsurgical scarring, and morphological alterations. Improved visualization of postoperative shoulder anatomy and pathology can be obtained with the use of metal artifact reduction techniques as well as MR arthrography. In this article we review the MR techniques that are designed to address these technical and diagnostic challenges, and we discuss the definitions and indications, normal MRI appearance, and complications of routine surgical procedures for treatment of injuries to the rotator cuff, labral ligamentous complex, and biceps tendon., (© 2014 Wiley Periodicals, Inc.)

Background: Subscapularis tendon avulsions of the lesser tuberosity are relatively rare and often missed acutely and their characteristic appearance is frequently not recognized or is misinterpreted for an osteochondroma or a neoplastic process., Questions/purposes: This report reviews our experience with six adolescents who had subscapularis tendon avulsions of the lesser tuberosity., Methods: Six male adolescents (12-15 years) presented with shoulder pain following history of trauma during amateur sport. Clinical notes including range of motion, strength tests, and pain assessment were reviewed along with imaging studies pre- and post treatment. Treatment consisted of either surgical or conservative measures., Results: Two of the six patients had a large avulsion that simulated an exostosis of the proximal humerus that was misdiagnosed as an osteochondroma at two different outside institutions. All six cases were diagnosed with subscapularis tendon avulsion of the lesser tuberosity following clinical and imaging evaluation at our institution. Five of the patients underwent surgical repair and fixation of the tendon and the lesser tuberosity with suture anchors. One patient was treated conservatively. All patients had a good outcome with recovery of full shoulder strength and motion upon follow-up., Conclusion: Clinicians should have a high index of suspicion of lesser tuberosity avulsions in adolescents who present with loss of internal rotation and anterior shoulder pain following traumatic injuries. In addition, an osseous fragment or exostosis along the inferomedial humeral head should suggest a subscapularis tendon avulsion and also should not be confused with an osteochondroma or a neoplastic process.

Objective: The purpose of this article is to review frequently encountered pitfalls as they pertain to normal and variant anatomy of the shoulder, including the rotator cuff and rotator cable, blood vessels, glenoid labrum, and the glenohumeral ligaments., Conclusion: MRI is the preferred method for evaluating internal derangement of the shoulder. Radiologists interpreting MR images should have a detailed understanding of pertinent anatomy and knowledge of common and uncommon pitfalls to avoid during image interpretation.

Objective: The purpose of this article is to review frequently encountered pitfalls as they pertain to the biceps tendon, bursae and cysts around the shoulder, incidental findings, postsurgical findings, and frequently encountered imaging artifacts., Conclusion: Imaging pitfalls in and around the shoulder are not limited to normal anatomy and anatomic variants. Radiologists must be cognizant of the vast variability of structures in the shoulder and of the incidental and postsurgical findings and artifacts affecting them.

Object: Extraspinal sciatica can present unique challenges in clinical diagnosis and management. In this study, the authors evaluated qualitative and quantitative patterns of sciatica-related pathology at the ischial tuberosity on MR neurography (MRN) studies performed for chronic extraspinal sciatica., Methods: Lumbosacral MRN studies obtained in 14 patients at the University of California, San Francisco between 2007 and 2011 were retrospectively reviewed. The patients had been referred by neurosurgeons or neurologists for chronic unilateral sciatica (≥ 3 months), and the MRN reports described asymmetrical increased T2 signal within the sciatic nerve at the level of the ischial tuberosity. MRN studies were also performed prospectively in 6 healthy volunteers. Sciatic nerve T2 signal intensity (SI) and cross-sectional area at the ischial tuberosity were calculated and compared between the 2 sides in all 20 subjects. The same measurements were also performed at the sciatic notch as an internal reference. Adjacent musculoskeletal pathology was compared between the 2 sides in all subjects., Results: Seven of the 9 patients for whom detailed histories were available had a specific history of injury or trauma near the proximal hamstring preceding the onset of sciatica. Eight of the 14 patients also demonstrated soft-tissue abnormalities adjacent to the proximal hamstring origin. The remaining 6 had normal muscles, tendons, and marrow in the region of the ischial tuberosity. There was a significant difference in sciatic nerve SI and size between the symptomatic and asymptomatic sides at the level of the ischial tuberosity, with a mean adjusted SI of 1.38 compared with 1.00 (p < 0.001) and a mean cross-sectional nerve area of 0.66 versus 0.54 cm(2) (p = 0.002). The control group demonstrated symmetrical adjusted SI and sciatic nerve size., Conclusions: This study suggests that chronic sciatic neuropathy can be seen at the ischial tuberosity in the setting of prior proximal hamstring tendon injury or adjacent soft-tissue abnormalities. Because hamstring tendon injury as a cause of chronic sciatica remains a diagnosis of exclusion, this distinct category of patients has not been described in the radiographic literature and merits special attention from clinicians and radiologists in the management of extraspinal sciatica. Magnetic resonance neurography is useful for evaluating chronic sciatic neuropathy both qualitatively and quantitatively, particularly in patients for whom electromyography and traditional MRI studies are unrevealing.

The Society of Radiologists in Ultrasound convened a panel of specialists from a variety of medical disciplines to reach a consensus about the recommended imaging evaluation of painful shoulders with clinically suspected rotator cuff disease. The panel met in Chicago, Ill, on October 18 and 19, 2011, and created this consensus statement regarding the roles of radiography, ultrasonography (US), computed tomography (CT), CT arthrography, magnetic resonance (MR) imaging, and MR arthrography. The consensus panel consisted of two co-moderators, a facilitator, a statistician and health care economist, and 10 physicians who have specialty expertise in shoulder pain evaluation and/or treatment. Of the 13 physicians on the panel, nine were radiologists who were chosen to represent a broad range of skill sets in diagnostic imaging, different practice types (private and academic), and different geographical regions of the United States. Five of the radiologists routinely performed musculoskeletal US as part of their practice and four did not. There was also one representative from each of the following clinical specialties: rheumatology, physical medicine and rehabilitation, orthopedic surgery, and nonoperative sports medicine. The goal of this conference was to construct several algorithms with which to guide the imaging evaluation of suspected rotator cuff disease in patients with a native rotator cuff, patients with a repaired rotator cuff, and patients who have undergone shoulder replacement. The panel hopes that these recommendations will lead to greater uniformity in rotator cuff imaging and more cost-effective care for patients suspected of having rotator cuff abnormality., (© RSNA, 2013.)

Cystic lesions are common around the knee and are often encountered as an incidental finding on routine magnetic resonance imaging examinations. The clinical presentation of cysts and other fluid collections is variable, depending on their size, location, and relationship to adjacent anatomic structures. This article reviews the anatomy, etiology, clinical presentation, and imaging features of commonly occurring cystic lesions around the knee and discusses some of the potential pitfalls that may be encountered in clinical practice., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objectives: Our goals were to quantify the reduction of the magic angle effect using short-tau inversion recovery (STIR) imaging and to determine the value of adding an axial STIR sequence to the magnetic resonance imaging ankle protocol., Materials and Methods: Axial STIR sequences were used to measure normal tendon T1 and to estimate signal loss due to the inversion recovery preparation of our clinical protocol. In addition, 102 ankles were imaged with axial fat-suppressed intermediate-weighted fast spin echo and STIR sequences. Two radiologists analyzed the tendons for signal intensity, size, abnormalities, and magic angle effect. The diagnostic value and image quality of the two sequences were compared., Results: We calculated a 50% reduction of signal intensity in healthy tendons on the STIR sequence at TI = 170 ms compared with TI = 0 ms, explaining the decrease in the magic angle effect. Using the STIR sequence, our study demonstrated significantly lower signal intensity within the tendons, more precise tendon size, and a lower magic angle effect compared with the standard intermediate-weighted FSE sequence (p < 0.001). Diagnostic classification of tendon abnormalities using the STIR sequences showed higher sensitivity (82.35% vs. 75.27%) and better agreement with a reference standard than the intermediate-weighted sequences, and superior image quality (p < 0.01)., Conclusions: Axial STIR sequences reduce magic angle effects and improve visualization of ankle tendon pathology.

Purpose: To determine if the measurement of the glenoid surface by computed tomography (CT) with curved multiplanar reconstructions (cMPR) in a cadaveric model is an accurate and reproducible technique., Methods: Ten dried cadaveric glenoid specimens were used. Two glenoids were subsequently modified mechanically to induce a bony Bankart lesion. Three skilled musculoskeletal radiologists performed cMPR on computed tomographic images of the glenoids; one of the radiologists repeated the same measurements after 3 months. Two of the 3 operators used the traditional "flat" MPR method as a control. An optical scanning system using a high-precision laser (CAM2 Laser Line Probe, Faro Technologies, Lake Mary, FL) was used as a reference. From the data obtained, an evaluation was performed for variability, degree of interoperator and intraoperator agreement, and degree of agreement between the laser and CT methods. Statistical analysis was performed with PASW-SPSS, version 18 (IBM, Armonk, NY) and R, version 2.12 statistical package., Results: The average difference between the 2 sets of cMPR measurements was approximately 1%, and maximum and minimum values were between 6.02% and -0.29%. The flat MPR method showed mean differences of 16% when compared with laser scanning, and maximum and minimum values were 31% and 8%, respectively. The interoperator variability for the "curved" method was limited and showed a coefficient of variation ranging from 0.78% to 2.82%. The Cronbach alpha coefficient for this set of measurements was alpha = 0.995. There was little intraoperator variability with the coefficient of variation between 0% and 2% and an intraclass correlation coefficient of 0.989., Conclusions: The use of cMPR computed tomographic imaging of the glenoid in a cadaveric model was found to be significantly more accurate than conventional MPR (flat MPR). Moreover, cMPR CT is a reproducible technique providing reliable information despite the relevant variable anatomy of the glenoid surface. This technique could reasonably also be used in a clinical setting as a more accurate noninvasive method. CLINICAL OF RELEVANCE: This technique could also reasonably be used in a clinical setting as a more accurate noninvasive method., (Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Thromboangiitis obliterans (Buerger's disease) is a rare, non-atherosclerotic, segmental, inflammatory vasculitis that most commonly involves small and medium-sized arteries, veins and nerves of the extremities and affects tobacco smokers between the ages of 25 and 45 years. The manifestations of Buerger's disease can be extremely variable and, therefore, awareness of the condition is important for both general and musculoskeletal radiologists. This paper presents the radiological appearance of the sequelae of Buerger's disease involving the upper and lower limbs., (Copyright © 2012 The Royal College of Radiologists. All rights reserved.)

Introduction: Early diagnosis of ulnar neuropathy at the elbow is important. Magnetic resonance neurography (MRN) images peripheral nerves. We evaluated the usefulness of elbow MRN in diagnosing ulnar neuropathy at the elbow., Methods: The MR neurograms of 21 patients with ulnar neuropathy were reviewed retrospectively. MRN was performed prospectively on 10 normal volunteers. The MR neurograms included axial T1 and axial T2 fat-saturated and/or axial STIR sequences. The sensitivity and specificity of MRN in detecting ulnar neuropathy were determined., Results: The mean ulnar nerve size in the symptomatic and normal groups was 0.12 and 0.06 cm(2) (P < 0.001). The mean relative signal intensity in the symptomatic and normal groups was 2.7 and 1.4 (P < 0.01). When using a size of 0.08 cm(2), sensitivity was 95% and specificity was 80%., Discussion: Ulnar nerve size and signal intensity were greater in patients with ulnar neuropathy. MRN is a useful test in evaluating ulnar neuropathy at the elbow.

Low back pain has a negative impact on the economy and society. Intervertebral disk degeneration is linked to the occurrence of low back pain. MRI provides three-dimensional morphologic and biochemical information regarding the status of the disk. This article reviews new and evolving MRI disk-imaging techniques, including grading, relaxation-time measurements, diffusion, and contrast perfusion. In addition, high-resolution magic-angle spinning methods to correlate in vitro disk degeneration (with pain, etc) and in vivo spectroscopic results are discussed. With the potential for morphologic and biochemical characterization of the intervertebral disk, MRI shows promise as a tool to quantitatively assess disk health., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Magnetic resonance imaging (MRI) is very sensitive for the detection of marrow abnormalities. Bone marrow edema on MRI has been defined as an area of low signal intensity on T1-weighted images, associated with intermediate or high signal intensity findings on T2-weighted images. The bone marrow edema pattern is a nonspecific finding with multiple etiologies. The knee is a common place for bone marrow signal abnormalities to appear on MRI. Besides contusions and fractures from acute trauma, there are a variety of other causes of the bone marrow edema pattern. It is important for the interpreter of the study to be aware of the different etiologies responsible for producing these changes and to be able to narrow the differential diagnosis without mistaking such a pattern for acute trauma or infiltrative tumor. This article concentrates on those entities that produce a bone marrow edema pattern not related to acute trauma including red marrow proliferation, stress, osteochondral lesions, osteonecrosis, bone marrow edema syndrome, arthropathy, infection, Paget's disease, and marrow replacement disorders., (© Thieme Medical Publishers.)

We report a 57-year-old man with a complete tear of his iliopsoas tendon at the distal myotendinous junction, a near complete tear of the iliopsoas tendon at the lesser trochanter of the femur, and a high-grade tear of his gluteus minimus tendon at the greater trochanter of the femur after being struck by a stun gun in the proximal left thigh. The stun gun discharge resulted in a forced contraction of the left hip flexor muscles, which resulted in pain, weakness and difficulty with active hip flexion. Three months after the being struck with the stun gun, the patient underwent magnetic resonance imaging (MRI) of the left hip. MRI of the left hip revealed a complete tear of the left iliopsoas tendon from the lesser trochanter with 4 cm of proximal retraction and a high-grade strain of the gluteus minimus tendon at the greater trochanter. The distal iliopsoas myotendinous junction and lesser trochanter tendon insertion were surgically repaired. This case illustrates that a stun gun can cause acute rupture of the iliopsoas tendon and tear of the gluteus minimus tendon, which is well visualized on MRI.

Objective: The purpose of this study was to determine the incidence and severity of arthrographic pain after intraarticular injection of a gadolinium mixture diluted in normal saline for direct MR arthrography., Subjects and Methods: From March 2009 until January 2010, 155 consecutive patients underwent direct MR arthrography; 20 patients were lost to follow-up. Patients were contacted by telephone between 3 and 7 days after joint injection. Using an 11-point numeric pain rating scale, patients were asked to report if they had experienced joint pain that was different or more intense than their preinjection baseline, the severity of pain, the duration of pain, time to onset of pain, and eventual resolution of pain., Results: The incidence of postarthrographic pain was 66% (89/135), with an average intensity of pain of 4.8 ± 2.4 (range, 1-10). Postarthrographic pain lasted an average of 44.4 ± 30.5 hours (range, 6-168 hours). The time to onset of pain after joint injection was on average 16.6 ± 13.1 hours (range, 4-72 hours). There was no significant difference regarding the severity or incidence of postarthrographic pain between groups on the basis of patient age (p = 0.20 and 0.26), patient sex (p = 0.20 and 0.86), contrast mixture contents (p = 0.83 and 0.49), or joint injected (p = 0.51 and 0.47). No patients experienced any other serious side effects., Conclusion: Sixty-six percent of patients who undergo direct MR arthrography will experience a fairly severe delayed onset of pain that completely resolves over the course of several days.

Magnetic resonance arthrography is widely used throughout the world for joint imaging. It extends the capabilities of conventional MR imaging because contrast solution distends the joint capsule, outlines intraarticular structures, and extends into soft tissue tears and defects. MR arthrography exploits the natural advantages gained from a joint effusion and can be performed on any joint.

This paper discusses the main types of MRI pseudotumors in and around the shoulder region. Some unusual types of pseudotumor will also be mentioned. Suggestions on how to improve awareness and diagnosis are also given.

The most unstable joint in the body, the glenohumeral joint is subject to many insults including microinstability, subluxation and dislocation. During the last two decades, MRI has allowed for direct visualization of many of the lesions related to instability, aiding in diagnosis as well as therapeutic planning and follow-up. This article reviews the use of MRI for shoulder instability and describes the different types of lesions associated with this disorder. Topics include technical considerations, the use of MR arthrography, normal anatomy and variants, labral and glenohumeral ligament pathology, and osseous lesions related to instability.

Purpose: In this invited review, the main subtypes of commoner bone tumors will be reviewed. Background and general concepts on pathology and surgery will be given with magnetic resonance imaging features of bone tumors. TEXT: The main malignant bone tumors being: osteogenic sarcoma, Ewings sarcoma, and chondrosarcoma are reviewed. Malignant intra-articular tumors are mentioned. The differential diagnoses including tumor mimickers are also reviewed., Conclusion: Magnetic resonance imaging allows for basic anatomical review and characterization of tumor type for diagnosis, therapy monitoring, and preoperative planning. A team approach to tumor imaging and treatment is optimal.

Objective: Skiing and hiking outside the boundaries remains an attractive wilderness activity despite the danger of avalanches. Avalanches occur on a relatively frequent basis and may be devastating. Musculoskeletal radiologists should be acquainted with these injuries., Design and Patients: Fourteen avalanche victims (11 men and 3 women; age range 17-59 years, mean age 37.4 years) were air transported to a high-grade trauma centre over a period of 2 years., Results: Radiographs, CT and MR images were prospectively evaluated by two observers in consensus. Musculoskeletal findings (61%) were more frequent than extraskeletal findings (39%). Fractures were most commonly seen (36.6%), involving the spine (14.6%) more frequently than the extremities (9.8%). Blunt abdominal and thoracic trauma were the most frequent extraskeletal findings., Conclusion: A wide spectrum of injuries can be found in avalanche victims, ranging from extremity fractures to massive polytrauma. Asphyxia remains the main cause of death along with hypoxic brain injury and hypothermia.

Objective: The purpose of this study was to review the diagnosis on MRI and radiography of 24 renal transplant recipients with hip pain suspicious for avascular necrosis and to investigate whether there is an association between kidney transplant patients with end-stage renal disease and symptomatic gluteus minimus and medius tendon abnormality., Conclusion: Symptomatic gluteus minimus and medius tendon lesions and abnormalities can occur in renal allograft recipients. The MRI findings of this entity allow an alternative diagnosis in this patient population.

Objective: The objectives of our study were to evaluate whether MRI findings of the sacroiliac joints are able to distinguish between active and inactive disease in patients with established ankylosing spondylitis and to determine whether these findings correlate with markers of clinical activity, disease duration, severity, and degree of radiographic damage., Materials and Methods: Eighteen patients with symptomatic moderate to severe ankylosing spondylitis were evaluated. MRI of the sacroiliac joint (1.5 T) was performed using fat-saturated T2-weighted, T1-weighted, STIR, and fat-saturated contrast-enhanced T1-weighted sequences. The sacroiliac joints were evaluated by two radiologists for enhancement, subchondral bone marrow edema, erosions, and subchondral fatty marrow infiltration. Findings on MRI were analyzed for correlation with multiple clinical characteristics and measures of disease activity, including radiographic scoring., Results: In 17 patients, MRI showed abnormal findings of the sacroiliac joint. Ten patients showed active disease on MRI as measured by abnormal enhancement and subchondral bone marrow edema. Disease activity detected using MRI correlated in a positive fashion with only C-reactive protein (CRP) level. There was no correlation with the other measures of disease activity or with disease duration. In 14 patients, fatty subchondral bone marrow was detected on MRI. These changes were seen in patients with active and chronic disease and correlated with higher radiographic scores but not with disease duration or markers of disease activity., Conclusion: Contrast-enhanced MRI of the sacroiliac joint is sensitive in depicting sacroiliitis in patients with established ankylosing spondylitis. Subchondral edema and enhancement correlate with high CRP levels. Subchondral fatty bone marrow changes were seen in both active and chronic sacroiliitis and are correlated with higher radiographic scores; these changes may be a marker of more advanced disease.

Objective: The purpose of our study was to determine if preoperative MRI can differentiate between occult ganglion and synovitis in the chronic painful wrist., Conclusion: MRI is accurate in preoperatively distinguishing between ganglion and synovitis in the setting of chronic dorsal wrist pain. Four main criteria were useful: margin, shape, internal structure, and enhancement after administration of contrast material, with shape and internal structure being most helpful.

Objective: To assess the rate of cartilage loss, the change in bone marrow edema pattern and internal joint derangement at 1.5-T MRI in patients with knee osteoarthritis and to correlate these findings with the clinical Western Ontario and McMaster University Osteoarthitis (WOMAC) score., Methods: Forty subjects (mean age 57.7+/-15 years; 16 females and 24 males) were recruited: 6 healthy volunteers (OA0), 17 patients with mild osteoarthritis (OA1) and 17 with severe osteoarthritis (OA2) based on the Kellgren-Lawrence scale. MR scans, radiographs and WOMAC scores were obtained at baseline, first follow-up (1.4+/-0.67 years; n=40) and second follow-up (2.4+/-0.4 years; n=26). Cartilage morphology, bone marrow edema (BME), meniscal and ligamentous pathology were assessed on MR images and quantified by two radiologists in consensus., Results: Full-thickness cartilage lesions were observed in 12/17 OA2 at baseline, in 13/17 at the first follow-up and in 7/10 at the second follow-up. Cartilage loss was found in eight patients at the first follow-up and five at the second follow-up. BME was observed in 23/40 patients at baseline, in 22/40 at the first follow-up and in 12/26 at the second follow-up. Changes in BME were visualized in 19/22 and 4/13 patients at the first and second follow-up, respectively. Changes in WOMAC scores over time did not correlate significantly with the amount of cartilage loss and the change in BME (P>0.05)., Conclusion: MRI is well suited to monitor the progression of OA in the longitudinal follow-up since it shows cartilage defects, BME and internal joint derangement, pathologies that are not visualized by radiographs. The lack of significant correlation between MRI findings and clinical findings is not unexpected, has been previously described and may in part be due to the fact that patients get more accustomed to their pain as the knee progressively degenerates.

Objective: The objective of this study was to determine the MRI characteristics of Merkel cell carcinoma, with an emphasis on histologic correlation., Materials and Methods: The demographic information about 15 patients from our institution and their MRI examinations were retrospectively reviewed by three musculoskeletal radiologists by consensus for lesion location and intrinsic characteristics. The study group was composed of three women and 12 men who ranged in age from 48 to 87 years, with a mean age of 75 years. Histology results of resected specimens were reviewed in all cases and were correlated with imaging., Results: MRI showed skin thickening, subcutaneous reticular stranding (n = 9, 60%); multiple anatomically aligned subcutaneous soft-tissue masses, representing lymphatic tumor nodules (n = 5, 33%); lymph node enlargement with fine, compressed, retained fatty tissue (n = 5, 33%); nodal necrosis (n = 1); and perifascial and intramuscular metastases (n = 2). Histology confirmed the lymphatic nature of the soft-tissue Merkel cell tumors., Conclusion: Patients with Merkel cell tumors may present at imaging with subcutaneous lymphatic reticular stranding, multiple subcutaneous masses, and lymph node metastases. Often there is massive lymph node enlargement with fine, compressed, retained fatty tissue.

Objective: The objective of our study was to determine the imaging appearances of a pseudotumor of the upper limb, latissimus dorsi tendinosis and tear, in five patients and to correlate those imaging findings with clinical history and histopathology., Conclusion: Tears or reactive tendinosis of the latissimus dorsi tendon at its insertion on the proximal humerus may present as a pseudotumor. Awareness of the imaging findings may allow accurate diagnosis and conservative management.