Atypical MRI Presentation of High-Grade Chondrosarcoma in the Proximal Femur.

Teaching Point: Although magnetic resonance imaging (MRI) plays a considerable role in the detection and differentiation of chondrosarcoma (e.g., by cortical breakthrough, peritumoral soft tissue edema, and extra-osseous extension), it is important to be aware of atypical features of common bone tumors.

Extramedullary Acute Myeloid Leukemia Tumor Presenting in the Radial Nerve.

Teaching Point: Extramedullary acute myeloid leukemia tumor belongs to the differential diagnosis when a tumor develops in a patient with a history of leukemia, and magnetic resonance imaging is of diagnostic value by demonstrating iso-intensity and hyperintensity compared to skeletal muscle respectively on T1- and T2-weighted images and homogeneous contrast enhancement.

Whole-body diffusion-weighted magnetic resonance imaging for the detection of bone metastases and their prognostic impact in metastatic renal cell carcinoma patients treated with angiogenesis inhibitors.

Background: Metastatic renal cell carcinoma (mRCC) patients with bone metastases (BM) are at high risk for skeletal related events and have a poorer outcome when treated with vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs). Computed tomography (CT) lacks sensitivity to detect BM in mRCC. We aimed to determine the added value of whole body diffusion-weighted magnetic resonance imaging (WB-DWI/MRI) to CT for the detection of BM in mRCC and to estimate the prognostic impact of the number of BM in mRCC patients treated with VEGFR-TKIs.Material and methods: We conducted a prospective study including consecutive mRCC patients treated with a first-line VEGFR-TKI in the metastatic setting. All patients underwent a pretreatment thoracic-abdominal-pelvic CT and WB-DWI/MRI. CT and WB-DWI/MRI were compared for the detection of BM. The number of detected BM was correlated with response rate (RR), progression-free survival (PFS) and overall survival (OS) after start of the VEGFR-TKI.Results: Ninety-two patients were included. BM were found in 55% of the patients by WB-DWI/MRI and in 43% of the patients by CT (p = .003). Mean number of BM discovered per patient was 6.8 by WB-DWI/MRI versus 1.9 by CT (p = .006). The cutoff of ≤5 versus >5 BM on WB-DWI/MRI had the highest discriminative power for all outcome measures. Patients with >5 BM had a lower RR (10% versus 42%), more frequently early progressive disease (43% versus 13%, p = .003), shorter PFS (4 versus 10 months, p = .006) and shorter OS (10 versus 35 months, p < .0001) compared to patients with ≤5 BM.Conclusion: WB-DWI/MRI detects significantly more BM in mRCC patients than CT, allowing better estimation of the prognostic impact of BM in mRCC patients treated with VEGFR-TKIs. The prognostic impact should now be validated in patients treated with immune checkpoint inhibitors.

Standardization of torsional CT measurements of the lower limbs with threshold values for corrective osteotomy.

INTRODUCTION: Re-establishing anatomic rotational alignment of shaft fractures of the lower extremities remains challenging. Clinical evaluation in combination with radiological measurements is important in pre- and post-surgical assessment. Based on computed tomography (CT), a range of reference values for femoral torsion (FT) and tibial torsion (TT) have historically been reported, which require standardization to optimize the significant intra- and inter-observer variability. The aims of this study were (re-)evaluation of the reference FT and TT angles, determination of the normal intra-individual side-to-side torsional differences to aid the surgical decision-making process for reoperation, and development of a novel 3D measurement method for FT. MATERIALS AND METHODS: In this retrospective study, we included 55 patients, without any known torsional deformities of the lower extremities. Two radiologists, independently, measured the rotational profile of the femora using the Hernandez and Weiner CT methods for FT, and the tibiae using the bimalleolar method for TT. The intra-individual side-to-side difference in paired femora and paired tibiae was determined. A 3D technique for FT assessment using InSpace® was designed. RESULTS: FT and TT demographic values were lower than previously reported, with mean FT values of 5.1°-8.8° and mean TT values of 25.5°-27.7°. Maximal side-to-side differences were 12°-13° for FT and 12° for TT. The Weiner method for FT was less variable than the Hernandez method. The new 3D method was equivocal to the conventional CT measurements. CONCLUSION: The results from this study showed that the maximal side-to-side tolerance in asymptomatic normal adult lower extremities is 12°-13° for FT and 12° for TT, which could be a useful threshold for surgeons as indication for revision surgery (e.g., derotational osteotomy). We developed a new 3D CT method for FT measurement which is similar to 2D and could be used in the future for virtual 3D planning.

Postoperative radiograph of the hip arthroplasty: what the radiologist should know.

This pictorial review aims to provide the radiologist with simple and systematic guidelines for the radiographic evaluation of a hip prosthesis. Currently, there is a plethora of commercially available arthroplasties, making postoperative analysis not always straightforward. Knowledge of the different types of hip arthroplasty and fixating techniques is a prerequisite for correct imaging interpretation. After identification of the type of arthroplasty, meticulous and systematic analysis of the following parameters on an anteroposterior standing pelvic radiograph should be undertaken: leg length, vertical and horizontal centre of rotation, lateral acetabular inclination, and femoral stem positioning. Additional orthogonal views may be useful to evaluate acetabular anteversion. Complications can be classified in three major groups: periprosthetic lucencies, sclerosis or bone proliferation, and component failure or fracture. Teaching Points • To give an overview of the different types of currently used hip arthroplasties. • To provide a simple framework for a systematic approach to postoperative radiographs. • To discuss radiographic findings of the most common complications.

Excruciating Low Back Pain After Strenuous Exertion: Beware of Lumbar Paraspinal Compartment Syndrome.

BACKGROUND: Low back pain is extremely common and usually a minor self-limiting condition. Rarely, however, it is a harbinger of serious medical illness. Paraspinal compartment syndrome is a rare condition, but its timely recognition is important to allow adequate treatment. CASE REPORT: A 16-year-old boy presented to the Emergency Department (ED) with severe low back pain, necessitating intravenous opioids. Laboratory results showed severe rhabdomyolysis. Magnetic resonance imaging of the lumbar spine showed diffuse edema and swelling in the paraspinal muscles. Aggressive fluid therapy was started but despite narcotic analgesia the pain persisted and creatine kinase (CK) levels increased. Compartment pressures of the erector spinae were found to be increased. The decision was made to proceed with bilateral paraspinal fasciotomies. Postoperatively, the patient noted immediate pain relief with rapid decrease of CK level. The patient is pain free and resumed running and swimming 3 months after admission in the ED. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although paraspinal compartment syndrome is a rare condition, its recognition is of paramount importance to allow adequate surgical treatment, preventing muscle necrosis. Although back pain most often has a benign course, a careful history and physical examination in patients presenting with low back pain allows determination of "red flags." Mandatory further diagnostic tests can identify underlying serious illness.

Weak associations between structural changes on MRI and symptoms, function and muscle strength in relation to knee osteoarthritis.

PURPOSE: To explore associations between MRI-defined structural abnormalities and clinical features related to knee osteoarthritis (OA). METHODS: Structural and clinical knee OA features were assessed in 87 women (45 with knee OA symptoms). Structural features were quantified by the Kellgren and Lawrence grade on radiography and by the Boston-Leeds Osteoarthritis Knee Score on MRI. Clinical features were assessed using the Knee Injury and Osteoarthritis Outcome Score, functional tests and muscle strength measurements. Associations were examined using regression analyses. RESULTS: Limited significant associations between structural and clinical features were found. An increased meniscal signal was associated with more pain/symptoms (P < 0.027). An anterior cruciate ligament tear was associated with poorer stair climbing test performance (P = 0.045). In a stepwise linear regression model, patellofemoral cartilage integrity and pain explained 28 % of the isometric quadriceps strength variability. The amount of cartilage lesions, loose bodies and pain explained 38 % of the isokinetic quadriceps strength variability. Synovitis/effusion and patellofemoral cartilage integrity combined with pain explained 34 % of the isometric hamstring strength variability. CONCLUSION: Although MRI-detected cartilage lesions, synovitis/effusion and loose bodies did explain part of the muscle strength variability, results suggest that MRI does not improve the link between joint degeneration and the clinical expression of knee OA. MRI contributes less than expected to the understanding of pain and function in knee OA and possibly offers little opportunity to develop structure-modifying treatments in knee OA that could influence the patient's pain and function. LEVEL OF EVIDENCE: Case series with no comparison groups, Level IV.

Effectiveness of initial treatment allocation based on expert opinion for prevention of rapid radiographic progression in daily practice of an early RA cohort.

OBJECTIVES: To evaluate expert treatment selection for early rheumatoid arthritis and to validate a prediction model for rapid radiographic progression (RRP) in daily practice. METHODS: Patients received initial combination therapy with steroids (ICTS) or disease-modifying antirheumatic drug monotherapy (IMT) after informal evaluation of prognostic factors, followed by a tight control strategy. Changes in Sharp/van der Heijde score (total Sharp score (TSS)) of >5 units over 1 year (=RRP) were documented. The mean change in TSS and proportion with RRP were compared between groups. Based on the 28 swollen joint count, rheumatoid factor titre and C reactive protein/erythrocyte sedimentation rate, patients were placed in the ASPIRE prediction matrix, yielding a RRP risk. Numbers needed to treat (NNT) intensively to avoid one RRP after 1 year were calculated. RESULTS: The mean change in TSS after 1 year and the proportion with RRP was lower in the ICTS group (n=37) than in the IMT group (n=43). The mean calculated risk of RRP was higher in patients with radiographic progression. The mean NNT intensively to prevent RRP was lower in the ICTS group than in the IMT group. The positive predictive value of NNT for RRP prevention was 12.6%, but the negative predictive value reached 100%. CONCLUSION: ICTS seems more effective in preventing RRP than IMT. The predictive matrix model could be helpful in preventing overtreatment in practice.

Radiofrequency ablation of spinal osteoid osteoma: clinical outcome.

STUDY DESIGN: A prospective study on 24 patients with spinal osteoid osteoma treated with radiofrequency ablation (RFA). OBJECTIVE: To determine if and when computed tomography (CT)-guided RFA is a safe and effective treatment for spinal osteoid osteomas. SUMMARY OF BACKGROUND DATA: Surgery has been considered the standard treatment for spinal osteoid osteomas. Surgery may cause spinal instability, infection, and nervous injury. We evaluated CT-guided RFA as an alternative treatment. METHODS: A total of 28 RFA procedures in 24 patients with spinal osteoid osteoma were performed, using a 5-mm noncooled electrode. Clinical symptoms and spinal deformity were evaluated before and after the procedure. Unsuccessful treatment was defined as the presence of residual or recurrent symptoms. The mean follow-up was 72 months (range: 9-142 months). RESULTS: Nineteen (79%) patients were successfully treated after 1 RFA, and all except one after repeat RFA. One patient with nerve root compression needed further surgery. No complications were observed. Spinal deformity persisted in 3 of 7 patients after successful RFA. CONCLUSION: CT-guided RFA is a safe and effective treatment for spinal osteoid osteoma. Surgery should be reserved for lesions causing nerve root compression.

The healing pattern of osteoid osteomas on computed tomography and magnetic resonance imaging after thermocoagulation.

OBJECTIVE: To compare the healing pattern of osteoid osteomas on computed tomography (CT) and magnetic resonance imaging (MRI) after successful and unsuccessful thermocoagulation. MATERIALS AND METHODS: Eighty-six patients were examined by CT and 18 patients by dynamic gadolinium-enhanced MRI before and after thermocoagulation for osteoid osteoma. Thermocoagulation was successful in 73% (63/86) and unsuccessful in 27% (23/86) of patients followed by CT. Thermocoagulation was successful in 72% (13/18) of patients followed by MRI. After treatment, the healing of the nidus on CT was evaluated using different healing patterns (complete ossification, minimal nidus rest, decreased size, unchanged size or thermonecrosis). On MRI the presence of reactive changes (joint effusion, "oedema-like" changes of bone marrow and soft tissue oedema) and the delay time (between arterial and nidus enhancement) were assessed and compared before and after thermocoagulation. RESULTS: Complete ossification or a minimal nidus rest was observed on CT in 58% (16/28) of treatment successes (with > 12 months follow-up), but not in treatment failures. "Oedema-like" changes of bone marrow and/or soft tissue oedema were seen on MR in all patients before thermocoagulation and in all treatment failures. However, residual "oedema-like" changes of bone marrow were also found in 69% (9/13) of treatment successes. An increased delay time was observed in 62% (8/13) of treatment successes and in 1/5 of treatment failures. CONCLUSION: Complete, or almost complete, ossification of the treated nidus on CT correlated with successful treatment. Absence of this ossification pattern, however, did not correlate with treatment failure. CT could not be used to identify the activity of the nidus following treatment. The value of MR parameters to assess residual activity of the nidus was limited in this study.

Osteoid osteoma: factors for increased risk of unsuccessful thermal coagulation.

PURPOSE: To retrospectively identify risk factors that may impede a favorable clinical outcome after thermocoagulation for osteoid osteoma. MATERIALS AND METHODS: Informed consent (permission for the procedure and permission to use patient data for analysis) was obtained from all patients who met study criteria, and institutional review board did not require approval. Analysis included age, sex, size and location of osteoid osteoma, presence of calcified nidus, number of needle positions used for coagulation, coagulation time, accuracy of needle position, learning curve of radiologist, and previous treatment in 95 consecutive patients with osteoid osteoma treated with thermocoagulation. With chi(2) analysis, Fisher exact test, or unpaired Student t test and logistic regression analysis, 23 unsuccessfully treated patients were compared with 72 successfully (pain-free) treated patients. RESULTS: Parameters associated with decreased risk for treatment failure were advanced age (mean age, 24 years in treatment success group vs 20 years in treatment failure group) and increased number of needle positions during thermocoagulation. Estimated odds ratios were, respectively, 0.93 (95% confidence interval: 0.88, 0.99) and 0.10 (95% confidence interval: 0.02, 0.41). Patients with a lesion of 10 mm or larger seemed at risk for treatment failure (odds ratio = 2.68), but the 95% confidence interval of 0.84 to 8.52 included the 1.00 value. Needle position was inaccurate in nine of 23 patients with treatment failure; only one needle position was used in eight of these nine patients. Lesion location, calcification, sex, coagulation time, radiologist's learning curve, and previous treatment were not risk factors. CONCLUSION: Multiple needle positions reduce the risk of treatment failure in all patients and should especially, but not exclusively, be used in large (> or =10-mm) lesions or lesions that are difficult to engage to reduce the risk for unsuccessful treatment.

Reliability and validity of lumbosacral spine radiograph reading by chiropractors, chiropractic radiologists, and medical radiologists.

STUDY DESIGN: A cross-sectional diagnostic study was conducted in two sessions. OBJECTIVE: To determine and compare the reliability and validity of contraindications to chiropractic treatment (infections, malignancies, inflammatory spondylitis, and spondylolysis-listhesis) detected by chiropractors, chiropractic radiologists, and medical radiologists on plain lumbosacral radiographs. SUMMARY OF BACKGROUND DATA: Plain radiography of the spine is an established part of chiropractic practice. Few studies have assessed the ability of chiropractors to read plain radiographs. METHODS: Five chiropractors, three chiropractic radiologists and five medical radiologists read a set of 300 blinded lumbosacral radiographs, 50 of which showed an abnormality (prevalence, 16.7%), in two sessions. The results were expressed in terms of reliability (percentage and kappa) and validity (sensitivity and specificity). RESULTS: The interobserver agreement in the first session showed generalized kappas of 0.44 for the chiropractors, 0.55 for the chiropractic radiologists, and 0.60 for the medical radiologists. The intraobserver agreement showed mean kappas of 0.58, 0.68, and 0.72, respectively. The difference between the chiropractic radiologists and medical radiologists was not significant. However, there was a difference between the chiropractors and the other professional groups. The mean sensitivity and specificity of the first round, respectively was 0.86 and 0.88 for the chiropractors, 0.90 and 0.84 for the chiropractic radiologists, and 0.84 and 0.92 for the medical radiologists. No differences in the sensitivities were found between the professional groups. The medical radiologists were more specific than the others. CONCLUSIONS: Small differences with little clinical relevance were found. All the professional groups could adequately detect contraindications to chiropractic treatment on radiographs. For this indication, there is no reason to restrict interpretation of radiographs to medical radiologists. Good professional relationships between the professions are recommended to facilitate interprofessional consultation in case of doubt by the chiropractors.

Osteoid osteoma: clinical results with thermocoagulation.

PURPOSE: To determine the clinical results in an unselected group of consecutive patients with osteoid osteoma treated with thermocoagulation. MATERIALS AND METHODS: In 97 consecutive patients with clinical and/or radiologic evidence of osteoid osteoma at any location, the clinical symptoms were assessed before and after thermocoagulation with computed tomographic guidance. A good response was defined as disappearance of symptoms that were manifested at presentation and attributed to osteoid osteoma. Clinical assessment was performed prior to discharge; within 2 weeks after the procedure; and at 3, 6, 12, and 24 months follow-up. After 24 months, a postal questionnaire was used for assessment. RESULTS: The mean clinical follow-up after the only or the last thermocoagulation session was 41 months (range, 5-81 months). Response was good after one session of thermocoagulation in 74 (76%) of 97 patients, and the 95% CI was 68% to 85%. Patients with persistent symptoms did well after repeated thermocoagulation (good response in 10 of 12 patients), but results of repeated thermocoagulation were poor in patients with recurrent symptoms (good response in five of 10). The overall success rate after one or two thermocoagulation procedures combined was 92% (89 of 97 patients), and the 95% CI was 86% to 97%. Complications were observed in two patients. CONCLUSION: Percutaneous thermocoagulation is a safe and effective method for treatment of osteoid osteoma at any location. Repeated thermocoagulation is successful in patients with persistent symptoms.

Ultrasound of the Elbow.

Ultrasound is ideally suited for the evaluation of soft tissue lesions of the elbow. The ultrasound study of the elbow is rapid, dynamic and cost-effective. This article presents a brief overview of scanning technique and illustrates some common pathologies.