Dual-energy CT in vertebral compression fractures: performance of visual and quantitative analysis for bone marrow edema demonstration with comparison to MRI.

OBJECTIVE: To prospectively evaluate the performance of virtual non-calcium (VNC) dual-energy CT (DECT) images for the demonstration of trauma-related abnormal marrow attenuation in collapsed and non-collapsed vertebral compression fractures (VCF) with MRI as a reference standard. MATERIALS AND METHODS: Twenty patients presenting with non-tumoral VCF were consecutively and prospectively included in this IRB-approved study, and underwent MRI and DECT of the spine. MR examination served as a reference standard. Two independent readers visually evaluated all vertebrae for abnormal marrow attenuation ("CT edema") on VNC DECT images; specificity, sensitivity, predictive values, intra and inter-observer agreements were calculated. A last reader performed a quantitative evaluation of CT numbers; cut-off values were calculated using ROC analysis. RESULTS: In the visual analysis, VNC DECT images had an overall sensitivity of 84%, specificity of 97%, and accuracy of 95%, intra- and inter-observer agreements ranged from k = 0.74 to k = 0.90. CT numbers were significantly different between vertebrae with edema on MR and those without (p < 0.0001). Cut-off values provided sensitivity of 85% (77%) and specificity of 82% (74%) for "CT edema" on thoracic (lumbar) vertebrae. CONCLUSIONS: VNC DECT images allowed an accurate demonstration of trauma-related abnormal attenuation in VCF, revealing the acute nature of the fracture, on both visual and quantitative evaluation.

Rapid osteolysis of the femoral neck: consequence of an insufficiency fracture of the hip?

PURPOSE: To describe the imaging and clinical features of rapid osteolysis of the femoral neck in an attempt to better understand this uncommon pathology. MATERIALS AND METHODS: We retrospectively reviewed the files of 11 patients (six women and five men) aged 53-78 years diagnosed with rapid osteolysis of the femoral neck. Available imaging studies included radiographs, CT, MRI, and bone scintigraphy. Histopathological evaluations were available for seven cases. RESULTS: All patients presented with complaints of hip pain, six of whom had acute symptoms, while the rest had progressive symptoms and impairment. All but one case were found to have bone deposition in adjacent hip muscles. CT confirmed bone deposition in adjacent tissues and true osteolysis of the femoral neck with relative sparing of the articular surfaces. Bone scintigraphy and MRI were useful to exclude underlying neoplastic disease. CONCLUSIONS: Rapid osteolysis of the femoral neck tends to occur in patients with underlying comorbidities leading to bone fragility and may actually represent a peculiar form of spontaneous insufficiency fracture. Recognition of its imaging features and clinical risk factors may help distinguish this process from other more concerning disorders such as infection or neoplasm.

Cone-beam computed tomography arthrography: an innovative modality for the evaluation of wrist ligament and cartilage injuries.

PURPOSE: Cone-beam computed tomography (CBCT) has become an important modality in dento-facial imaging but remains poorly used in the exploration of the musculoskeletal system. The purpose of this study was to prospectively evaluate the performance and radiation exposure of CBCT arthrography in the evaluation of ligament and cartilage injuries in cadaveric wrists, with gross pathology findings as the standard of reference. MATERIALS AND METHODS: Conventional arthrography was performed under fluoroscopic guidance on 10 cadaveric wrists, followed by MDCT acquisition and CBCT acquisition. CBCT arthrography and MDCT arthrography images were independently analyzed by two musculoskeletal radiologists working independently and then in consensus. The following items were observed: scapholunate and lunotriquetral ligaments, triangular fibrocartilage complex (TFCC) (tear, integrity), and proximal carpal row cartilage (chondral tears). Wrists were dissected and served as the standard of reference for comparisons. Interobserver agreement, sensitivity, specificity, and accuracy were determined. Radiation dose (CTDI) of both modalities was recorded. RESULTS: CBCT arthrography provides equivalent results to MDCT arthrography in the evaluation of ligaments and cartilage with sensitivity and specificity between 82 and 100%, and interobserver agreement between 0.83 and 0.97. However, radiation dose was significantly lower (p < 0.05) for CBCT arthrography than for MDCT arthrography with a mean CTDI of 2.1 mGy (range 1.7-2.2) versus a mean of 15.1 mGy (range 14.7-16.1). CONCLUSION: CBCT arthrography appears to be an innovative alternative to MDCT arthrography of the wrist as it allows an accurate and low radiation dose evaluation of ligaments and cartilage.

Intercostal myositis ossificans misdiagnosed as osteosarcoma in a 10-year-old child.

Myositis ossificans (MO) is a rare benign cause of heterotopic bone formation within soft tissue. It most commonly affects adolescents and young adults, typically in the limbs and following trauma. Very few cases have been reported in children. We report here a case of nontraumatic MO occurring in a 10-year-old girl with an uncommon location in the 5th right intercostal space; it was initially misdiagnosed and treated as osteosarcoma. Imaging findings including plain radiographs, CT, MRI, bone scintigraphy and PET-CT are described. This case highlights the central role played by imaging in diagnosis, thus avoiding biopsy that can erroneously suggest osteosarcoma as the diagnosis, as occurred in this case.

Navigated non-image-based positioning of the acetabulum during total hip replacement.

We tested the hypothesis that the non-image-based navigation system used in our department was able to measure accurately the 3D positioning of the acetabular cup of a total hip replacement (THR) and to increase the accuracy of its implantation during THR. We studied 50 consecutive navigated implantations of a THR and compared the intra-operative measurement of the cup by the navigation system to the post-operative measurement by computed tomography (CT) scan. The mean difference between the navigated and CT scan measurements for cup inclination was 2 degrees . The mean difference between the navigated and CT-scan measurements for cup flexion was 4 degrees . These differences were significant but considered to be clinically irrelevant in most cases. A total of 73% of the cases were within the safe zone defined prior to the study. The non-image-based system used allows a precise orientation of the cup during THR.

Anterior approach for knee arthrography: tolerance evaluation and comparison of two routes.

PURPOSE: To prospectively evaluate patient tolerance and technical success of the anterior knee puncture approach for arthrography by using two different routes. MATERIALS AND METHODS: The study had Strasbourg University Hospital review board approval. Informed consent was obtained from all patients (and from their parents, if patients were minors). In 159 patients (89 male and 70 female; age range, 14-82 years; mean age, 44.3 years +/- 16 [standard deviation]) referred for computed tomographic (CT) arthrography, anterior puncture of the knee was performed by using an anterolateral (n = 73) or anterior paramedian (n = 86) route. For each patient, body mass index, absolute pain on a visual analog scale, relative pain (compared with anticipatory pain), and history of previous knee arthrography were recorded. A score reflecting the technical success of the procedure was established by using a five-point scale. Factors influencing tolerance and technical success were analyzed with Pearson correlation coefficients. Student t and chi2 tests were used to compare the two routes. RESULTS: The anterior approach for knee arthrography was well tolerated (mean visual analog scale score, 12.9 +/- 16.4) and technically successful (mean technical success score, 1.36 +/- 0.84) in most cases. Absolute pain was not influenced by age, sex, or body mass index and was only weakly correlated (r = 0.33) with the technical success score. The technical success score weakly correlated (r = 0.23) with the body mass index. A slight but significant reduction in absolute (P < .05) and relative (P < .01) pain was observed for the anterolateral route compared with the anterior paramedian route, while no significant differences (P > .05) were found for other parameters, including the technical success score. CONCLUSION: The anterior approach for knee arthrography is technically successful and well tolerated, particularly when an anterolateral route is used.

Multidetector CT arthrography of the wrist joint: how to do it.

With its exquisite spatial resolution, multidetector computed tomographic (CT) arthrography of the wrist is a valuable tool for the diagnosis and evaluation of a wide spectrum of articular disorders. Traumatic tears of the interosseous ligaments can be classified as complete or incomplete and as partial- or full-thickness tears at multidetector CT arthrography and can also be differentiated from asymptomatic degenerative lesions. In addition, tears of the triangular fibrocartilage complex can be differentiated according to their location. A tailored contrast material injection technique and multiplanar reformation are recommended for optimal assessment of these structures. Multidetector CT arthrography is also remarkably effective in demonstrating cartilage and bone abnormalities, many of which cannot be depicted with other imaging techniques. The chief limitation of multidetector CT arthrography lies in the evaluation of soft-tissue abnormalities, which may benefit from the addition of other imaging techniques such as ultrasonography or magnetic resonance imaging. A basic knowledge of the relevant anatomy, pathophysiologic features, and imaging technique is mandatory for obtaining high-yield diagnostic information concerning the wrist joint. (c) RSNA, 2008.

Wrist ligament tears: evaluation of MRI and combined MDCT and MR arthrography.

OBJECTIVE: The purpose of this study was to evaluate the performance of MRI and a combination of MDCT arthrography and MR arthrography in the diagnosis of tears and cartilage abnormalities of the wrist ligaments. SUBJECTS AND METHODS: The feasibility of combining MDCT arthrography and MR arthrography and performing them with an optimized contrast solution was evaluated in vitro and in vivo. Forty-five consecutively enrolled subjects with suspected wrist ligament tears underwent MRI and a combined MDCT and MR arthrographic procedure. Two observers reviewed the images for evidence of tears and cartilage abnormalities of the scapholunate and lunotriquetral ligaments and triangular fibrocartilaginous complex. Interobserver agreement was determined with kappa statistics, and the diagnostic accuracy of each technique was calculated. RESULTS: A 1:1 solution of 2.5 mmol/L tetraazacyclododecanetetraacetic acid (DOTA)-gadolinium and 300 mg I/mL iopamidol provided adequate contrast enhancement for both in vitro and in vivo MDCT arthrographic and MR arthrographic images. Interobserver agreement was substantial for MRI (kappa = 0.61) and MR arthrography (kappa = 0.71) and almost perfect for MDCT arthrography (kappa = 0.93). The sensitivity and specificity of MRI, MDCT arthrography, and MR arthrography for tears of the scapholunate ligament were 59% and 70%, 95% and 96%, and 68% and 87% for the first observer and 77% and 83%, 95% and 100%, and 77% and 87% for the second observer. For tears of the lunotriquetral ligament, these values were 30% and 94%, 100% and 94%, and 60% and 97% for the first observer and 50% and 97%, 90% and 100%, and 50% and 94% for the second observer. The three techniques appeared equivalent for complete tears of the scapholunate and lunotriquetral ligaments, but partial tears were significantly better visualized with MDCT arthrography. The sensitivity and specificity of MRI, MDCT arthrography, and MR arthrography for triangular fibrocartilaginous complex tears were 27% and 100%, 100% and 100%, and 82% and 100% for the first observer and 45% and 100%, 100% and 100%, and 82% and 100% for the second observer. For cartilage abnormalities, these values were 30% and 100%, 100% and 100%, and 30% and 100% for the first observer and 10% and 100%, 100% and 100%, and 40% and 100% for the second observer. CONCLUSION: MDCT arthrography appears more accurate than MRI and MR arthrography, particularly for discerning partial tears of the scapholunate and lunotriquetral ligaments that do not necessitate surgical therapy.

Percutaneous Laser Photocoagulation of Osteoid Osteomas.

Osteoid osteoma is a painful benign bone tumor. The curative treatment of this tumor consists of complete surgical or percutaneous excision of the nidus with immediate and dramatic relief of symptoms. Interstitial laser photocoagulation (ILP) is a low-invasive percutaneous technique of thermal destruction (coagulation) of deep-seated tumors elsewhere in the body, using low-power laser energy. The aim of ILP is the local destruction of osteoid osteoma without bone weakening. Twenty-two patients with osteoid osteoma were treated with percutaneous ILP of the nidus under computed tomography guidance. The laser energy was provided by a high-power semiconductor diode laser (805 nm) with a 400-&mgr;m optical fiber. Complete pain relief was obtained in 21 patients. Percutaneous ILP of osteoid osteoma seems to be a promising, simple, precise, and minimally invasive technique as an alternative to traditional surgical and percutaneous ablations.

MDCT arthrography or MR arthrography for imaging the wrist joint?

Imaging of the wrist joint has been radically modified over the last decade, particularly since multidetector computed tomography (MDCT) arthrography and magnetic resonance (MR) arthrography have become widely available. These two modalities allow a confident assessment of ligament tears and potential diagnosis of associated abnormalities of cartilage, bone, and soft tissues. The interosseous scapholunate and lunotriquetral ligaments and the triangular fibrocartilage complex (TFCC) are the most important structures to consider. Precise analysis of their different lesions, including recognition of degenerative tears, is essential for guiding the treatment. After a brief overview of the different injuries of interosseous ligaments and cartilage, this article thoroughly exposes the technical aspects of wrist MDCT arthrography and MR arthrography, reviews their results, and discusses their performances in light of recent literature. Finally, we propose an imaging strategy to decide between MDCT arthrography and MR arthrography depending on the clinical query. Other imaging modalities are not forgotten in this strategy. The evaluation of ligamentous and TFCC pathology must always begin with conventional radiographs. Cineradiography, ultrasound, and standard MRI are also useful in selected cases.

Should plain X-rays be routinely performed after blunt knee trauma? A prospective analysis.

BACKGROUND: We tested the hypothesis that it was possible to decrease the number of performed x-rays after a knee trauma without delayed fracture diagnosis by using the Ottawa knee rules. METHODS: Patients had routine x-rays of the injured knee during the first stage of the study and selective x-rays during the second stage. All patients were followed up to 6 months after the trauma. RESULTS: 138 patients were included in the first stage; 57 had negative Ottawa criteria: no fracture was observed; following the Ottawa rules, 41% of the x-rays could have been avoided. 178 patients were included in the second stage; 63 patients had negative Ottawa criteria: no fracture was diagnosed during the whole follow-up; 35% of the x-rays have been avoided. CONCLUSIONS: Ottawa rules allowed decreasing the number of x-rays performed after a knee trauma by 35% with a sensitivity for a knee fracture detection of 100%.