Anne Cotten

Variations of pelvic anteversion in the lying and standing positions: analysis of 24 control subjects and implications for CT measurement of position of a prosthetic cup.

The position of the acetabular implant plays a dominant role in the displacement of a total hip prosthesis. CT allows precise measurement of the position of the cup, but the influence of pelvic rotation on this measurement is unknown. The aim of this study was to determine, in a group of healthy subjects, whether a pelvic equilibrium exists specific to each individual, and whether this is constant over time on the one hand and between the standing and lying positions on the other. The study concerned 15 men and 9 women with a mean age of 31 years. Each subject had strictly lateral radiographs of the pelvis, lying and standing, repeated at two different times. Pelvic version was measured in these radiographs. Each individual had a pelvic position constant over time, both in the lying and standing positions, However, there were important variations of the position of the pelvis during passage from the lying to the standing position 22 patients had retroversion of the pelvis by a mean of 7° (2-18°) and 2 others had an anteversion of 3°. These major variations of the pelvic position between the standing and lying positions explain why CT studies made in the lying position do not allow for the anteversion of the cup in the standing position, which is close to the dynamic situation during which displacement may occur. Thus, an excessive anteversion of the cup may be masked when the scan is made in the lying position, since in this position the anteversion of the pelvis leads to retroversion of the cup. The error may reach 20°, so that we recommend that CT measurements made without allowing for the position of the pelvis should be interpreted with caution.

Acetabular labrum: MRI in asymptomatic volunteers.

PURPOSE The purpose of this study was to describe the MR appearance of the acetabular labrum in asymptomatic hips on high resolution MRI. METHOD Fifty-two hips in 46 asymptomatic volunteers with an age range of 15-85 years were evaluated with coronal and axial T1-weighted and T2-weighted sequences. The shape, margin, size, and signal intensity of the acetabular labrum were analyzed. RESULTS The labrum was absent in its anterosuperior aspect in five hips (10%). Intralabral regions of intermediate of high signal intensity were detected in 30 hips (58%) imaged with T1-weighted and proton density-weighted sequences. Intralabral linear hyperintense foci reaching the articular surface and consistent with a labral tear were detected in four labra on T2-weighted images. Intralabral microcysts were seen in three labra. CONCLUSION The MR appearance of the hip labrum is varied in asymptomatic volunteers. Intralabral increased signal intensity and absent anterosuperior labra are especially frequent and may represent asymptomatic lesions or normal variations.

Pigmented villonodular synovitis of the hip: review of radiographic features in 58 patients

Clinical and radiographic findings were retrospectively reviewed in a multicentric survey of 58 patients with histologically proven pigmented villonodular synovitis (PVNS) of the hip. The most common clinical features were mechanical pain (47 cases) and limitation of joint motion (47 cases). On plain films, a classic form with large and multiple lucencies was found in 36 cases, followed by an osteoarthritis-like form (9 cases), an arthritis-like form (8 cases), normal radiographic appearance (3 cases), osteonecrosis of the femoral head (one case) and joint destruction with acetabular protrusion (one case). Bilateral involvement of the hips was probable in two patients. In contrast to the knee, the hip showed a high prevalence of bony lesions and joint space narrowing. Although an uncommon disease, PVNS of the hip has to be considered when arthritis is associated with uncharacteristic clinical or radiographic findings.

Diffusion tensor imaging and fibre tracking in cervical spondylotic myelopathy

ObjectivesTo (1) obtain microstructural parameters (Fractional Anisotropy: FA, Mean Diffusivity: MD) of the cervical spinal cord in patients suffering from cervical spondylotic myelopathy (CSM) using tractography, (2) to compare DTI parameters with the clinical assessment of these patients (3) and with information issued from conventional sequences.MethodsDTI was performed on 20 symptomatic patients with cervical spondylotic myelopathy, matched with 15 volunteers. FA and MD were calculated from tractography images at the C2-C3 level and compressed level in patients and at the C2-C3 and C4-C7 in controls. Patients were clinically evaluated using a self-administered questionnaire.ResultsThe FA values of patients were significantly lower at the compressed level than the FA of volunteers at the C4-C7 level. A significant positive correlation between FA at the compressed level and clinical assessment was demonstrated. Increased signal intensity on T2-weighted images did not correlate either with FA or MD values, or with any of the clinical scores.ConclusionFA values were significantly correlated with some of the patients’ clinical scores. High signal intensity of the spinal cord on T2 was not correlated either with the DTI parameters or with the clinical assessment, suggesting that FA is more sensitive than T2 imaging.

End plate marrow changes in the asymptomatic lumbosacral spine: frequency, distribution and correlation with age and degenerative changes.

PurposeTo investigate the frequency and distribution of end plate marrow signal intensity changes in an asymptomatic population and to correlate these findings with patient age and degenerative findings in the spine.Materials and methodsMR imaging studies of the lumbosacral (LS) spine in 59 asymptomatic subjects were retrospectively reviewed by 2 musculoskeletal radiologists to determine the presence and location of fat-like and edema-like marrow signal changes about the end plates of the L1-2 through L5-S1 levels. The presence of degenerative changes in the spine was recorded as was patient age. Descriptive statistics were utilized to determine the frequency and associations of end plate findings and degenerative changes in the spine. Interobserver variability was determined by a kappa score. Binomial probability was used to predict the prevalence of the end plate changes in a similar subject population. The Fisher exact test was performed to determine statistical significance of the relationship of end plate changes with degenerative changes in the spine, superior versus inferior location about the disc and age of the patient population.ResultsFocal fat-like signal intensity adjacent to the vertebral end-plate was noted in 15 out of 59 subjects by both readers, and involved 38 and 36 out of 590 end plates by readers 1 and 2, respectively. Focal edema-like signal intensity adjacent to the vertebral end plate was noted in 8 out of 59 subjects by both readers and involved 11 and 10 out of 590 end plates by readers 1 and 2, respectively. Either fat or edema signal intensity occurred most often at the anterior (p<.05) aspects of the mid-lumbar spine and was seen in an older sub-population of the study (p<.05).ConclusionEnd plate marrow signal intensity changes are present in the lumbar spine of some asymptomatic subjects with a characteristic location along the spine and in vertebral end plates.

Early Rheumatoid Arthritis: A Review of MRI and Sonographic Findings

OBJECTIVE The introduction of anti-tumor necrosis factor alpha agents has opened new prospects in therapeutic management of patients with early rheumatoid arthritis, thereby creating new demands on radiologists to identify patients with aggressive disease at an early stage. As a result, imaging techniques such as MRI and sonography have developed during the past few years. CONCLUSION This article illustrates the imaging findings that may be encountered with these techniques in patients with early rheumatoid arthritis.

Synovial haemangioma of the knee: a frequently misdiagnosed lesion

ObjectiveThe objective of this study was to assess the contribution of magnetic resonance (MR) imaging in the diagnosis and surgical planning of five cases of synovial haemangioma of the knee.Patients and MethodsThe clinical, radiological and arthroscopic features of five pathologically proven synovial haemangiomas of the knee were retrospectively reviewed.ResultsA diagnostic delay, on average of 8 years, had occurred in four of the cases. Plain films were unremarkable, except for one case with arthropathy mimicking haemophilia, Arteriography, performed in three patients, was normal in one. CT, performed in three patients, showed the lesion, but the extent of the latter was better demonstrated with MR imaging. Synovial haemangiomas had a high signal intensity on T2-weighted images, without any extensive mass effect. Fibrofatty septa within the lesion were observed in three cases and muscular and/or fatty invasion in two. Arthroscopy allowed diagnosis of the lesion in two cases, but showed only non-specific synovitis in another two.ConclusionThis study emphasizes the valuable contribution of MR imaging in the diagnosis and surgical planning of synovial haemangiomas.

Tractography of lumbar nerve roots: initial results

ObjectivesThe aims of this preliminary study were to demonstrate the feasibility of in vivo diffusion tensor imaging (DTI) and fibre tracking (FT) of the lumbar nerve roots, and to assess potential differences in the DTI parameters of the lumbar nerves between healthy volunteers and patients suffering from disc herniation.MethodsNineteen patients with unilateral sciatica related to posterolateral or foraminal disc herniation and 19 healthy volunteers were enrolled in this study. DTI with tractography of the L5 or S1 nerves was performed. Mean fractional anisotropy (FA) and mean diffusivity (MD) values were calculated from tractography images.ResultsFA and MD values could be obtained from DTI-FT images in all controls and patients. The mean FA value of the compressed lumbar nerve roots was significantly lower than the FA of the contralateral nerve roots (p = 0.0001) and of the nerve roots of volunteers (p = 0.0001). MD was significantly higher in compressed nerve roots than in the contralateral nerve root (p = 0.0002) and in the nerve roots of volunteers (p = 0.04).ConclusionDTI with tractography of the lumbar nerves is possible. Significant changes in diffusion parameters were found in the compressed lumbar nerves.

Should percutaneous vertebroplasty be used to treat osteoporotic fractures? An update.

Acrylic cement vertebroplasty is being increasingly used to treat osteoporotic vertebral compression fractures (VCFs), although no controlled studies supporting this trend have been published. Vertebroplasty remains controversial as a treatment for osteoporotic fractures because it is a local response to a systemic disease and because the pain caused by osteoporotic fractures usually subsides within a few days or weeks. Current data suggest that pain severity may decrease by half, on average, in 90-100% of patients. Although vertebroplasty is usually well tolerated, serious neurological complications have been reported in a few patients. The most common adverse event is nerve root pain, usually caused by leakage of the cement into the intervertebral foramen. Whether vertebroplasty is followed by an increased risk of osteoporotic fractures in the adjacent vertebras remains unclear. Resorbable cements are being developed and may provide better results than the acrylic cements used today. At present, acrylic cement vertebroplasty to treat osteoporotic VCFs is appropriate in only a minority of patients selected carefully by a multidisciplinary team including a rheumatologist.

Image Analysis of the Distal Radius Trabecular Network Using Computed Tomography

Abstract: Bone texture analysis might provide information about bone structure in a noninvasive manner. In a prospective case–control cross-sectional study we investigated the value of computed tomography (CT) image analysis of the distal radius in the assessment of osteoporosis. Twenty patients suffering from postmenopausal osteoporosis were studied and compared with 21 age-matched controls. Eight slices were selected in each patient: four consecutive coronal slices and four consecutive cross-sectional slices. Bone texture analysis was performed using statistical, fractal and structural methods leading to the measurement of 32 features. Structural variables derived from histomorphometric parameters were measured after segmentation from a binary or a skeletonized image. Bone mineral density was measured by dual-energy X-ray absorptiometry both at the lumbar spine and the femoral neck. Eight of the 9 statistical features were significantly different in osteoporotic women as compared with controls (coronal slices, p < 0.05). Seven structural variables were statistically different between the two groups on coronal slices (p < 0.05): valley surface area, bone volume/tissue volume, trabecular partition, Euler’s number, trabecular bone pattern factor, node-to-node strut count and terminus-to-terminus strut count. The most significant results on coronal slices (p < 0.01) concerned 4 structural features: trabecular partition, Euler’s number, trabecular bone pattern factor and terminus-to-terminus strut count. Three features were statistically different (p < 0.01) between the two groups on cross-sectional slices (skeletonization from gray levels). A few features yielded by texture analysis were correlated with both lumbar spine and femoral neck bone mineral density, but the level of these correlations was weak (r < 0.5). In conclusion, CT image analysis of the distal radius is a useful tool for characterizing bone texture alterations in osteoporotic women. These findings are in keeping with microarchitectural osteoporosis-related changes diagnosed on bone biopsies.