Imaging evaluation of developmental hip dysplasia in the young adult.

OBJECTIVE: The purpose of this article is to review the clinical and imaging features as well as the potential complications of hip dysplasia in the young adult. Hip dysplasia is an important cause of secondary osteoarthrosis, which accounts for a significant proportion of patients requiring total hip arthroplasty. The radiographic diagnosis of mild hip dysplasia in the young adult may be subtle and is primarily based on the detection of deficient coverage of the femoral head by the acetabulum. CONCLUSION: Cross-sectional imaging, including CT and MRI, afford improved detection and characterization by providing morphologic information about acetabular deficiency. MRI also allows evaluation of potential associated injuries to the articular cartilage, the labrum, and the ligamentum teres. Familiarity with the radiographic and cross-sectional imaging findings of mild hip dysplasia in the young adult may allow a timely diagnosis and implementation of treatment strategies, which may prevent or delay the development of early osteoarthritis.

Diagnostic accuracy of MRI in the measurement of glenoid bone loss.

OBJECTIVE: The purpose of this study is to assess the accuracy of MRI quantification of glenoid bone loss and to compare the diagnostic accuracy of MRI to CT in the measurement of glenoid bone loss. MATERIALS AND METHODS: MRI, CT, and 3D CT examinations of 18 cadaveric glenoids were obtained after the creation of defects along the anterior and anteroinferior glenoid. The defects were measured by three readers separately and blindly using the circle method. These measurements were compared with measurements made on digital photographic images of the cadaveric glenoids. Paired sample Student t tests were used to compare the imaging modalities. Concordance correlation coefficients were also calculated to measure interobserver agreement. RESULTS: Our data show that MRI could be used to accurately measure glenoid bone loss with a small margin of error (mean, 3.44%; range, 2.06-5.94%) in estimated percentage loss. MRI accuracy was similar to that of both CT and 3D CT for glenoid loss measurements in our study for the readers familiar with the circle method, with 1.3% as the maximum expected difference in accuracy of the percentage bone loss between the different modalities (95% confidence). CONCLUSION: Glenoid bone loss can be accurately measured on MRI using the circle method. The MRI quantification of glenoid bone loss compares favorably to measurements obtained using 3D CT and CT. The accuracy of the measurements correlates with the level of training, and a learning curve is expected before mastering this technique.

Fovea alta on MR images: is it a marker of hip dysplasia in young adults?

OBJECTIVE: The objective of our study was to investigate the association between high fovea capitis (fovea alta) and hip dysplasia in young adults. MATERIALS AND METHODS: In a retrospective study, blinded observers reviewed 82 pelvic radiographic and hip MRI studies of three groups of patients: those with developmental dysplasia of the hip (DDH) (center-edge angle, ≤20°), those with borderline DDH (center-edge angle, 21°-25°), and control patients (center-edge angle, >25°). The center-edge angle and coxa valga (femoral neck-shaft angle, >135°) were assessed on pelvic radiographs, and fovea alta was assessed on MR images (delta angle, ≤10°). The Mann-Whitney and Fisher exact tests were used to correlate fovea alta with DDH and with coxa valga, respectively. Interobserver agreement for center-edge and delta angles and the diagnostic performance of fovea alta as a marker of DDH were calculated. RESULTS: Thirty-one patients with DDH, 23 with borderline DDH, and 28 without DDH were included. Excellent interobserver agreement was found for center-edge angle (concordance correlation coefficient, 0.94) and for delta angle (concordance correlation coefficient, 0.91). Fovea alta had a significant association with DDH (p<0.001) but no association with coxa valga (p>0.57). A significant difference (p<0.001) was found between patients with DDH (3.4°) and those without DDH (21.7°) with respect to mean delta angle measurements. Fovea alta had 69.4% sensitivity, 82.1% specificity, 67.2% positive predictive value, 81.0% negative predictive value, and 75.6% overall accuracy as an indicator of DDH. CONCLUSION: Fovea alta shows promise as a strong MRI marker of DDH.

Pattern recognition of benign nodules at ultrasound of the thyroid: which nodules can be left alone?

OBJECTIVE: The purpose of this study was to evaluate morphologic features predictive of benign thyroid nodules. MATERIALS AND METHODS: From a registry of the records of 1,232 fine-needle aspiration biopsies performed jointly by the cytology and radiology departments at a single institution between 2005 and 2007, the cases of 650 patients were identified for whom both a pathology report and ultrasound images were available. From the alphabetized list generated, the first 500 nodules were reviewed. We analyzed the accuracy of individual sonographic features and of 10 discrete recognizable morphologic patterns in the prediction of benign histologic findings. RESULTS: We found that grouping of thyroid nodules into reproducible patterns of morphology, or pattern recognition, rather than analysis of individual sonographic features, was extremely accurate in the identification of benign nodules. Four specific patterns were identified: spongiform configuration, cyst with colloid clot, giraffe pattern, and diffuse hyperechogenicity, which had a 100% specificity for benignity. In our series, identification of nodules with one of these four patterns could have obviated more than 60% of thyroid biopsies. CONCLUSION: Recognition of specific morphologic patterns is an accurate method of identifying benign thyroid nodules that do not require cytologic evaluation. Use of this approach may substantially decrease the number of unnecessary biopsy procedures.

Variable sac behavior after endovascular repair of abdominal aortic aneurysm: analysis of core laboratory data.

OBJECTIVES: The behavior of the aneurysm sac after endovascular grafting has been the subject of significant speculation. The importance of sac behavior is manifested by the correlation between aneurysm size or size change and risk for rupture, and potentially further extrapolated to define the need for secondary intervention. This study was undertaken to define graft-specific differences and the effect of endoleak on sac remodeling. METHODS: Core laboratory data were obtained for three US Phase II clinical trials. Patients were included if they met anatomic inclusion criteria and underwent placement of the latest version of a bifurcated endovascular prosthesis. Unsupported Dacron (Ancure), supported Dacron (Zenith), and expanded polytetrafluoroethylene (Excluder) grafts were evaluated. Digitized images were electronically assessed for aneurysm size (area, maximum, minimum diameter) with National Institutes of Health Image software. Two blinded reviewers analyzed each radiographic study to ensure accurate image selection and establish the presence or absence of endoleak. A third reviewer adjudicated discrepancies. chi(2) analysis and mixed nonlinear modeling were used to analyze the results. RESULTS: Of 1506 patients evaluated, 723 (227 Ancure, 343 Excluder, 153 Zenith) met inclusion criteria for the study. Mean follow-up was 23.2 months (Ancure, 31.3 months; Excluder, 19.6 months; Zenith, 19.3 months). The incidence of any endoleak was 39.1% (Ancure, 58.1%; Excluder, 34.7%; Zenith, 20.9%; P <.001). Type of prosthesis, presence or absence of endoleak, and baseline size were determinants of rate of aneurysm shrinkage. Reduction in sac size was greatest with the Zenith graft, followed by the Ancure and Excluder grafts. Presence of endoleak had a moderating effect on rate of sac shrinkage with the Zenith and Ancure grafts; however, sac size increased in the presence of endoleak with the Excluder graft. Finally, baseline size was positively correlated with rate of aneurysm shrinkage. CONCLUSIONS: The behavior of the aneurysm sac depends on the type of prosthesis, presence or absence of endoleak, and baseline size of the sac. Differential sac behavior must be considered when determining the need for secondary interventions, timing follow-up studies, and assessing success or failure of endovascular repair.