Recommendations for the Management of Incidental Musculoskeletal Findings on MRI and CT.

The Canadian Association of Radiologists (CAR) Incidental Findings Working Group consists of both academic subspeciality and general radiologists tasked with either adapting American College of Radiology (ACR) guidelines to meet the needs of Canadian radiologists or authoring new guidelines where appropriate. In this case, entirely new guidelines to deal with incidental musculoskeletal findings that may be encountered on thoracoabdominal computed tomography or magnetic resonance imaging were drafted, focussing on which findings should prompt recommendations for further workup. These recommendations discuss how to deal with incidental marrow changes, focal bone lesions, abnormalities of the pubic symphysis and sacroiliac joints, fatty soft tissue masses, manifestations of renal osteodystrophy and finally discuss opportunistic osteoporosis evaluation.

Breast cancer and bone metastases: the association of axial skeleton MRI findings with skeletal-related events and survival.

The purpose of this study was to determine if bone metastasis characteristics on axial skeleton MRI are associated with either skeletal-related events (SREs) or survival in breast cancer patients. A retrospective review was performed on 247 breast cancer patients with bone metastases identified on axial skeleton MRI. MRI studies were reviewed for metastases T1 signal, signal uniformity, complete vertebral metastatic marrow replacement, metastases quantity, and distribution. Odds ratio (OR) and hazard ratios (HR) were calculated, with 95 % confidence intervals (95 % CI), to determine association with either future SREs or survival. At the time of analysis, 174 (70 %) patients had developed SREs and 176 (71 %) patients were dead. Features of skeletal metastases associated with SREs included the presence of complete metastatic marrow replacement within any vertebra; OR 2.363 (95 % CI 1.240-4.504, P = 0.0090), and more widely distributed metastases; OR 1.239 (95 % CI 1.070-1.435, P = 0.0040). Features associated with shorter survival included the presence of complete metastatic marrow replacement within any vertebra; HR 1.500 (95 % CI 1.105-2.036, P = 0.0093), and more widely distributed metastases; HR 1.141 (95 % CI 1.047-1.243, P = 0.0027). Metastases T1 signal, signal uniformity, and surprisingly quantity were not associated with SREs or survival. Axial skeleton MRI was able to identify characteristics predictive of future SREs and survival. These characteristics could be used for risk stratification for future trials if prospectively validated.

CT of preoperative and postoperative acetabular fractures revisited.

OBJECTIVE: We compared preoperative and postoperative computed tomography (CT) versus radiographic imaging in the evaluation of acetabular fractures (AFs). METHODS: Fifty-four patients who underwent imaging for AFs were retrospectively evaluated. Postoperative reduction quality was assessed on radiographs and CT scan by 2 observers. Rate of reintervention was noted. Radiation exposure from CT was calculated. RESULTS: After reduction, 24 patients had significant findings on postoperative CT. Five patients required reintervention, all of whom had significant postoperative CT findings and complex fractures. Notably, only 1 of the 5 patients had an indication for reintervention based on radiographs alone.The average dose for preoperative/postoperative CT study was 11.5/12.3 mSv, respectively, with a cumulative average dose of 23.8 mSv. CONCLUSIONS: Although reoperation rate is low after fixation of AFs, CT is required to identify those requiring reintervention. However, postoperative CT should be used judicially, only in patients presenting with complex acetabular fractures.

Progressive neurolymphomatosis with cutaneous disease: response in a patient with mycosis fungoides.

Peripheral neurolymphomatosis is a rare manifestation of advanced lymphoproliferative disorders. It is often associated with B cell lymphomas and rarely with cutaneous T cell lymphomas, such as mycosis fungoides and Sézary syndrome. In this case report, we present a 78-year-old male with a long-standing history of mycosis fungoides. The patient initially presented with chronic peripheral neuropathy in an ulnar nerve distribution. After an unsuccessful ulnar nerve transposition, the ulnar nerve was re-explored and a mass consistent with diffuse lymphomatous infiltration was diagnosed. Magnetic resonance (MR) imaging of the left brachial plexus and later of the sacral plexus demonstrated diffuse thickening and peripheral nodularity in keeping with neurolymphomatosis. The patient's clinical course rapidly deteriorated thereafter and the patient succumbed to his disease. Although uncommon, neurolymphomatosis may be considered in patients with chronic peripheral neuropathy and an underlying history of a lymphoproliferative disorder. US and MR may serve as helpful non-invasive adjuncts in making the diagnosis and identifying sites for biopsy.

Magnetic resonance imaging of muscle disease: a pattern-based approach.

Magnetic resonance imaging (MRI) is a powerful tool to assess the severity, distribution, and progression of muscle injury and disease. However, a muscle's response to a pathological insult is limited to only a few patterns on MRI, and findings can be nonspecific. A pattern-based approach is therefore essential to correctly interpret MR studies of abnormal muscle. In this article we review the anatomy, function, and normal MRI appearance of skeletal muscle. We present a classification scheme that categorizes abnormal MR appearances of muscle into 4 main pattern descriptors: (1) distribution; (2) change in size and shape; (3) T1 signal; and (4) T2 signal. Each category is further subdivided into the various patterns seen on MRI. Such an approach allows one to systematically assess abnormal findings on muscle MRI studies and ascertain clues to the diagnosis or differential diagnosis, particularly when findings are correlated with the clinical context.

MR and CT arthrography of the knee.

MR and CT arthrography are important imaging modalities for the assessment of the knee in certain situations. Indications for MR arthrography of the knee include assessment of the postoperative meniscus, the presence of chondral and osteochondral lesions, and the presence of intra-articular bodies. The major indication for CT arthrography is evaluating suspected internal derangement in patients who are unable to undergo MRI. In addition to reviewing the established clinical indications for MR and CT arthrography of the knee, the commonly used techniques, normal variants that can simulate disease, and the most commonly found pathologies that can be diagnosed with these modalities are discussed. Potential indications that are not currently well established in the literature including the evaluation of anterior cruciate ligament injury and autologous chondrocyte implants are examined. Where appropriate, the literature on controversial topics or diagnoses is reviewed. The use of conventional imaging versus CT and MR arthrography is also compared.

Evidence-based guideline recommendations on treatment strategies for localized Ewing's sarcoma of bone following neo-adjuvant chemotherapy.

OBJECTIVES: (1) To provide recommendations regarding the choice of surgery, radiation therapy (RT), or the combination of surgery plus RT in patients with localized Ewing's sarcoma of bone following neoadjuvant chemotherapy. (2) To determine the appropriate surgical planning imaging (pre-chemotherapy magnetic resonance imaging [MRI] or post-chemotherapy MRI) to identify optimal resection margins in patients with localized Ewing's sarcoma who undergo surgery following neoadjuvant chemotherapy. METHODS: MEDLINE, EMBASE, the Cochrane Library (1999 to February 2015), main guideline websites, and relevant annual meeting abstracts (2012 to January 2015) were searched. Internal and external reviews were conducted. RECOMMENDATIONS: 1. Recommendation (1) - In patients with localized Ewing's sarcoma of bone following neoadjuvant chemotherapy: (a) Surgery alone or RT alone are two reasonable treatment options; the combination of surgery plus RT is not recommended as an initial treatment option. (b) The local treatment for an individual patient should be decided by a multidisciplinary tumour board together with the patient after consideration of the following: (1) patient characteristics (e.g., age, tumour location, tumour size, response to neoadjuvant chemotherapy, and existing comorbidities), (2) the potential benefit weighed against the potential complications from surgery and/or toxicities associated with RT, and (3) patient preferences. 2. Recommendation (2) - In patients with localized Ewing's sarcoma who will undergo surgery: (a) Both pre-chemotherapy and post-chemotherapy MRI scans should be taken into consideration for surgical planning. In certain anatomic locations with good chemotherapy response, the post-chemotherapy MRI may be the appropriate imaging modality to plan surgical resection margins.

A systematic review of optimal treatment strategies for localized Ewing's sarcoma of bone after neo-adjuvant chemotherapy.

OBJECTIVE: To perform a systematic review to investigate the optimal treatment strategy among the options of surgery alone, radiotherapy (RT) alone, and the combination of RT plus surgery in the management of localized Ewing's sarcoma of bone following neo-adjuvant chemotherapy. METHODS: MEDLINE and EMBASE (1999 to February 2015), the Cochrane Library, and relevant conferences were searched. RESULTS: Two systematic reviews and eight full texts met the pre-planned study selection criteria. When RT was compared with surgery, a meta-analysis combining two papers showed that surgery resulted in a higher event-free survival (EFS) than RT in any location (HR = 1.50, 95% CI 1.12-2.00; p = 0.007). However another paper did not find a statistically significant difference in patients with pelvic disease, and no papers identified a significant difference in overall survival. When surgery plus RT was compared with surgery alone, a meta-analysis did not demonstrate a statistically significant difference for EFS between the two groups (HR = 1.21, 95% CI 0.90-1.63). Both surgical morbidities and radiation toxicities were reported. CONCLUSIONS: The existing evidence is based on very low aggregate quality as assessed by the GRADE approach. In patients with localized Ewing's sarcoma, either surgery alone (if complete surgical excision with clear margin can be achieved) or RT alone may be a reasonable treatment option. The optimal local treatment for an individual patient should be decided through consideration of patient characteristics, the potential benefit and harm of the treatment options, and patient preference.

Discordant response to chemotherapy between lymphadenopathy and bone lesions on gallium-67 scanning in Hodgkin's disease.

A 33-year-old woman with a diagnosis of Hodgkin's disease had a prechemotherapy whole-body Ga-67 scan to document gallium avidity of lesions and to assess response to therapy. A posttherapy scan showed a discordant response with complete resolution of lymphadenopathy and persistence of bone lesions. Radiographic evaluation of the left humerus, radius, and ulna demonstrated typical fibrous dysplasia as a cause for persistence of Ga-67 activity and shoulder activity probably representing arthropathy. She was in remission 3 years later although she fell and fractured the humerus through the bony lesion, and biopsy at the time of internal fixation confirmed fibrous dysplasia.

Differentiation of lipoma from liposarcoma on MRI using texture and shape analysis.

RATIONALE AND OBJECTIVES: To determine if differentiation of lipoma from liposarcoma on magnetic resonance imaging can be improved using computer-assisted diagnosis (CAD). MATERIALS AND METHODS: Forty-four histologically proven lipomatous tumors (24 lipomas and 20 liposarcomas) were studied retrospectively. Studies were performed at 1.5T and included T1-weighted, T2-weighted, T2-fat-suppressed, short inversion time inversion recovery, and contrast-enhanced sequences. Two experienced musculoskeletal radiologists blindly and independently noted their degree of confidence in malignancy using all available images/sequences for each patient. For CAD, tumors were segmented in three dimensions using T1-weighted images. Gray-level co-occurrence and run-length matrix textural features, as well as morphological features, were extracted from each tumor volume. Combinations of shape and textural features were used to train multiple, linear discriminant analysis classifiers. We assessed sensitivity, specificity, and accuracy of each classifier for delineating lipoma from liposarcoma using 10-fold cross-validation. Diagnostic accuracy of the two radiologists was determined using contingency tables. Interreader agreement was evaluated by Cohen kappa. RESULTS: Using optimum-threshold criteria, CAD produced superior values (sensitivity, specificity, and accuracy are 85%, 96%, and 91%, respectively) compared to radiologist A (75%, 83%, and 80%) and radiologist B (80%, 75%, and 77%). Interreader agreement between radiologists was substantial (kappa [95% confidence interval]=0.69 [0.48-0.90]). CONCLUSIONS: CAD may help radiologists distinguish lipoma from liposarcoma.

Hibernoma--a case series with multimodality imaging and pathologic correlation.

Hibernoma is an uncommon, benign tumor of brown fat origin. The distribution of this tumor originally was described as following the location of persistent brown fat within the subcutaneous tissue of the thorax (especially the periscapular and interscapular regions), neck, axilla, shoulder, and retroperitoneum. Recently, hibernoma was described as being most common in the thigh.

Prevalence of cam-type femoroacetabular impingement morphology in asymptomatic volunteers.

BACKGROUND: Femoroacetabular impingement is a cause of hip pain in adults and is a possible precursor of osteoarthritis, with the cam type of impingement being the most common. The purpose of this study was to determine the prevalence of cam-type morphology of the hip in asymptomatic patients. METHODS: Two hundred asymptomatic volunteers with no prior hip surgery or childhood hip problems underwent magnetic resonance imaging targeted to both hips. The subjects were examined at the time of magnetic resonance imaging for internal rotation of the hips at 90° of hip flexion and for a positive impingement sign. The contour of the femoral head-neck junction was quantified with use of the alpha angle. A value of >50.5° was considered positive for cam morphology. Measurements were performed independently by two musculoskeletal radiologists. RESULTS: The mean age of the individuals was 29.4 years (range, 21.4 to 50.6 years); 79% were white, and 55.5% were women. The mean alpha angle anteriorly at the three o'clock position was 40.9° ± 7.0° on the right and 40.6° ± 7.1° on the left, whereas the mean alpha angle anterosuperiorly at the 1:30 position was 50.2° ± 8.0° on the right and 50.1° ± 8.3° on the left. Fourteen percent of the volunteers had at least one hip with cam morphology: 10.5% had an elevated alpha angle on either the right or the left side, and 3.5% had the deformity in both hips. Seventy-nine percent (twenty-two) of twenty-eight individuals who had an elevated alpha angle were men, and 21% (six) were women. Individuals with an elevated alpha angle on at least one side tended to be male (p < 0.001), with 24.7% (twenty-two) of eighty-nine men having cam morphology compared with only 5.4% (six) of 111 women. CONCLUSIONS: The prevalence of cam-type femoroacetabular impingement deformity is higher in men as well as in individuals with decreased internal rotation. Defining what represents a normal head-neck contour is important for establishing treatment strategies in patients presenting with prearthritic hip pain.