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Biomedical subjects

A Cotten

Publications and source records attributed to A Cotten.

At least 19 recordsLinked to original sources
PubMed2002

Computed tomography image analysis of the calcaneus in male osteoporosis.

The present study aimed to characterize bone microarchitecture assessed by computed tomography (CT) at the calcaneus in male subjects suffering from osteoporosis. Seventy-nine subjects were assessed (45 with osteoporosis and 34 control subjects matched for age). Osteoporosis was defined according to the World Health Organization classification either at the lumbar spine or at the femoral neck. Thirty-three subjects (73%) had a past history of low-energy fracture mainly represented by vertebral fractures (24/33). Nine axial sections (1 mm in width and 2 mm apart) were selected for each subject. Bone microarchitecture analysis was performed using structural (binary and skeletonized images but also skeletonization from gray levels) and fractal analyses. Bone densitometry by dual-energy X-ray absorptiometry (DXA) at the calcaneus was also performed in 73 cases. Bone mineral density (BMD) was decreased in osteoporotic patients compared with controls both at the lumbar spine and hip and also at the calcaneus (p<0.01). Also 14 microarchitectural features among 25 measured were significantly different between the two groups (p<0.01). The odds ratio for fracture per 1 control group standard deviation decrease were also significant for 13 structural features but also for BMD at the calcaneus. The odds ratios after adjustment for BMD at the calcaneus were significant for the following features (p<0.05): number of valleys, 2.8 (1.2-6.9); trabecular partition, 3.3 (1.3-7.9); apparent trabecular spacing, 1.8 (1.0-3.1); trabecular bone pattern factor, 2.2 (1.1-4.3); Euler number, 3.0 (1.1-8.7); node-to-terminus strut count, 3.3 (1.4-7.8); terminus-to-terminus strut count, 2.9 (1.2-6.9); and fractal dimension, 3.7 (1.5-9.7). Few and weak correlations were found between BMD at the calcaneus measured with DXA and features obtained from CT, suggesting that these two methods give different information about bone status. In conclusion, male osteoporosis is a disease characterized by decreased bone mass but also by microarchitectural deterioration of bone tissue which is partly independent of BMD.

Absorptiometry, Photon↗
PubMed2002

[Imaging of lipoma and liposarcoma].

The aim of this paper is to describe the two most frequent lipomatous soft tissue tumors, lipoma and liposarcoma, and to highlight the radiologic features allowing their differentiation.

Diagnosis, Differential↗
PubMed2002

[Imaging of the lumbar spine].

The role of conventional radiographs in the evaluation of the lumbar spine remains unchanged. The respective place of CT and MRI in the evaluation of lumbar spine disorders has not significantly changed in spite of technical advances. However, their diagnostic capabilities have improved.

Adult↗
PubMed2001

Image-guided endoscopic spine surgery: Part I. A feasibility study.

STUDY DESIGN: A feasibility study was performed to determine the efficacy of computer assistance in endoscopic spine surgery. OBJECTIVES: To assess a new method for computer assistance based on image guidance during thoracoscopic or any endoscopic spine procedure. To evaluate the reproducibility, the sensitivity and the reliability of the technique first in vitro and second in clinical use. SUMMARY OF BACKGROUND DATA: The computer-based, image-guided surgery is now a routine tool used in open spine surgery. Exposure of the anatomy of the vertebra is needed for registration. This methodology is inapplicable in endoscopic approach. Fluoroscopic-based navigation combines the technology of image-guided surgery and C-arm fluoroscopy. The navigation is based on the fluoroscopic images acquired before surgery. This technology is applicable to endoscopic surgery but the navigation is based on fluoroscopic image. The computed tomography images are not exploited. There are no published data on a technique that allows image-guided surgery based on computed tomography and magnetic resonance imaging. METHOD: A laboratory study was performed on a thoracic human spine. One vertebra was marked on the right lateral side of the body with five titanium marks. A percutaneous reference frame was specifically designed to be placed in the pedicle of the same marked vertebrae. The reference frame acted as a 3D localizer and a registration tool. The spine model was scanned including the reference frame. A standard Stealth station treatment guidance platform (Medtronic, Sofamor Danek, Memphis, TN) was used for simulation. The registration was obtained using the reference frame. Twenty navigation procedure trials were done and the error was recorded based on the distance between the anatomical point and the corresponding virtual one. RESULTS: Registration was always possible using the stealth station and a standard spine navigational software (spine 3, Medtronic Sofamor Danek, Memphis, TN). The mean error after registration given by the computer was 0.96 mm. The mean error recorded during the navigation simulation was 1.6 mm. CONCLUSIONS: This technique allows the possibility of computed tomography and magnetic resonance imaging-based, image-guided endoscopic surgery. It is probable that in the near future, as image fusion technology improves, the fluoronavigation based on fluoroscopic images would enable to navigate on multimodal images. Otherwise the technique described in this article is the only reproducible one that allows computed-tomography-based computer assistance during endoscopic procedures.

Endoscopy↗
PubMed2001

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 degrees (2-18 degrees) and 2 others had an anteversion of 3 degrees. 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 degrees, so that we recommend that CT measurements made without allowing for the position of the pelvis should be interpreted with caution.

Adult↗
PubMed2001

Lumbar spinal ganglia enhancement after gadolinium chelate administration: a radio-histological correlation.

The aim of the present study was to assess the frequency of enhancement of lumbar spinal ganglia after Gadolinium chelate injection in patients without radiculopathy, and to correlate the enhancement with histology. This study is based on the analysis of MR lumbar examinations conducted on 18 patients without radicular symptoms, or previous surgery of the lumbar spine, or disease of the nervous system. The patients were imaged with a 1.5 T unit. Sagittal images were first obtained with a T1-weighted turbo spin-echo. Axial and sagittal images were then obtained with a T1-weighted turbo spin-echo, fat-saturated sequence after Gadolinium intravenous injection from the T12/L1 to the L5/S1 level. All 180 spinal ganglia demonstrated an important and homogeneous enhancement after Gadolinium injection. Four spinal ganglia obtained by dissection from four different fresh cadavers were studied by light microscopy to determine the potential relationship between contrast enhancement and presence and topography of vessels within the spinal ganglia. Vessels were particularly abundant at the peripheral zone of the spinal ganglia. The post-contrast enhancement of the spinal ganglia after Gadolinium administration has to be known and may be explained by the microvasculature pattern.

Adult↗
PubMed2001

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.

Arthroplasty↗
PubMed2001

Giant cystic Schmorl's nodes: imaging findings in six patients.

OBJECTIVE: We describe the imaging findings of an unusual type of Schmorl's node appearing as giant cystlike lesion of the vertebral bodies. CONCLUSION: Giant cystic Schmorl's nodes are unusual entities; their radiologic appearance differs dramatically from the classic description and is diagnostically challenging. However, the appearance of these nodes on conventional radiographs and especially on MR images is characteristic. Knowledge of this entity would help to eliminate unnecessary invasive diagnostic or therapeutic procedures.

Adolescent↗
PubMed2001

[Osteoid osteoma of the radial bicipital tuberosity: report of 2 cases].

We report two cases of osteoid osteoma located in the bicipital tuberosity of the radius. This unusual localization illustrates the clinical polymorphism frequently observed in osteoid osteomas of the elbow and consequently the tendency to late diagnosis. Resistant contraction of the brachial biceps, in forearm pronation, suggests the need for complementary exams, particularly computed tomography. Surgical resection via anterior access can control pain and prevent recurrence.

Adult↗
PubMed2000

Radio-anatomic demonstration of the vertebral lumbar venous plexuses: an MRI experimental study.

The aim of this study was to provide a basis of knowledge of the anatomy of the venous plexuses in the lumbar spine both in anatomical slices and in MR images in order to help the analysis of these structures in MR images of living subjects. Four fresh cadaveric lumbar spines were studied after the injection of coloured gelatin mixed with gadolinium. The specimens were injected by an intraosseous technique. Axial and sagittal fat-saturated T1-weighted MR images were performed on the specimens. Thereafter, specimens were frozen and cut into 5-mm thick slices, three in the axial plane and one in the sagittal plane. All the components of the internal and external venous plexuses were identified on the MR images in correlation with the corresponding anatomic sections. The MR anatomy of the venous system of the lumbar spine is important as it has been implicated in many pathophysiological mechanisms and as it may also cause pitfalls in MR imaging.

Cadaver↗
PubMed2000

Comparison of double-contrast CT arthrography image quality with nonionic contrast agents: isotonic dimeric iodixanol 270 mg I/mL and monomeric iohexol 300 mg I/mL.

RATIONALE AND OBJECTIVES: The authors evaluated the image quality on delayed CT arthrography images with the use of the nonionic dimeric contrast agent, iodixanol 270 mg I/mL, compared with iohexol 300 mg I/mL. METHODS: A total of 132 patients with shoulder pain were included in a randomized, parallel, double-blind study. Sixty seven patients received iodixanol and 65 patients received iohexol. Patients underwent two CT-arthrography examinations: the first was performed 20 to 30 minutes after contrast injection and the second, 50 to 70 minutes after contrast injection. Data from 31 patients were excluded from the efficacy analysis. The overall quality of CT arthrography images was graded into four categories: excellent, good, moderate, and bad. RESULTS: The overall quality of delayed CT arthrography images was significantly better in the iodixanol group (P = 0.001, alpha = 0.05). On the first CT examination, image quality was good or excellent in 88% of the cases in the iodixanol group and in 96.1% in the iohexol group. The results on the delayed CT arthrography examination indicated that image quality was good or excellent in 88% of the cases when iodixanol was used and in 63.5% when iohexol was used. CONCLUSIONS: The overall quality of delayed images was significantly better with iodixanol than with iohexol.

Adult↗
PubMed2000

In vivo comparison between computed tomography and magnetic resonance image analysis of the distal radius in the assessment of osteoporosis.

In a prospective case-control cross-sectional study, we investigated the usefulness of both computed tomography (CT) and magnetic resonance (MR) image analysis of the distal radius for distinguishing a small sample of fractured osteoporotic women from control women regardless of bone mineral density. The study population included 12 subjects who were divided into two groups according to their bone status. The first group consisted of six women with at least one vertebral fracture occurring in the absence of high-energy trauma, and the second group consisted of six women without disease affecting bone mass or bone metabolism. Cross-sectional and coronal slices were obtained from both CT and MR systems. For CT images, the slice thickness was 1000 jim and the plane resolution was approx 200 jim x 200 jim. MR images were obtained from a 1.5-T imager with a two-dimensional spin-echo Ti-weighted sequence leading to a slice thickness of 2000 jim and a plane resolution of 195 jim x 195 jim. Bone texture analysis was performed using fractal and structural methods leading to the measurement of 23 features. Most of the structural variables derived from histomorphometric parameters and were measured after segmentation from a binary or a skeletonized image. Bone densitometry was measured by dual-energy X-ray absorptiometry both at the lumbar spine and the nondominant femoral neck. On cross-sectional slices, 12 variables, mainly obtained from structural analysis, were significantly different between the two groups for CT images (p < 0.05) against two variables only for MR images (p < 0.05). The number of variables statistically different between the two groups was significantly higher for CT images compared with MR images (p = 0.003). In the same way, odds ratios for fracture per 1 control group standard deviation decrease were significant for 10 variables on CT images, whereas, in contrast, none of the variables measured on MRI images led to significant odds ratios. The results obtained for the two methods on coronal slices were poorer without a difference between either CT or MR images in terms of discrimination between fracture and nonfracture subjects. In conclusion, this study suggests that bone texture analysis obtained from CT compared with MRI offers a best discrimination between controls and osteoporotic patients, probably the result to the spatial resolution. which is better for CT than for MR images.

Absorptiometry, Photon↗
PubMed2000

Does high-resolution computed tomography image analysis of the distal radius provide information independent of bone mass?

This study aimed to investigate the usefulness of computed tomography (CT) image analysis of the distal radius for comparing two groups of postmenopausal women matched for age and bone mineral density at both the lumbar spine and femoral neck. The first one consisted of 16 women with at least one vertebral fracture and the second consisted also of 16 women without disease affecting bone mass or bone metabolism. Eight slices were selected in each patient: four consecutive coronal slices and four consecutive axial slices. Bone texture analysis was performed using structural methods leading to the measurement of 24 features. Most of the structural variables derived from histomorphometric parameters and were measured after segmentation from a binary or a skeletonized image. Nine variables were significantly different between the two groups on axial slices: valley number, valley surface area, apparent bone volume/tissue volume (BV/TV), apparent trabecular separation, apparent trabecular number, trabecular bone pattern factor, trabecular skeletal length, node count, and node-to-node strut count. Also four variables were significantly different between osteoporotic women and controls on coronal slices: apparent BV/TV, trabecular partition, node-to-node strut count, and terminus-to-terminus strut count. In conclusion this study suggests that bone texture analysis could yield additional data on bone mass for explaining bone strength and therefore could be used for improving the prediction of fracture risk.

Absorptiometry, Photon↗
PubMed2000

MR imaging of the knee at 0.2 and 1.5 T: correlation with surgery.

OBJECTIVE: The purpose of this study was to compare the diagnostic efficacy of low- and high-field-strength MR imagers in the diagnosis of anterior cruciate ligament tears and meniscus tears. SUBJECTS AND METHODS: In 219 patients with suspected internal derangement of the knee, MR imaging at 0.2 and 1.5 T was performed with similar sequences. Only patients with surgically confirmed diagnosis (n = 90) were included in the statistical analysis. Radiologists were unaware of diagnosis and field strength. Sensitivity, specificity, diagnostic accuracy, and inter- and intraobserver variability were determined. RESULTS: There was excellent correlation between the field strengths in accuracy, sensitivity, and specificity for anterior cruciate ligament and meniscus tears. Accuracy for medial meniscus, lateral meniscus, and anterior cruciate ligament tears was 91-93%, 88-90%, and 93-96%, respectively, at 0.2 T and 91-94%, 91-93%, and 97-98%, respectively, at 1.5 T. Inter- and intraobserver variability values showed excellent correlation (kappa > 0.8). CONCLUSION: The level of diagnostic accuracy in anterior cruciate ligament tears and meniscus tears is comparable for low- and high-field-strength MR imagers.

Adolescent↗
PubMed2000

Thoracic outlet: anatomic correlation with MR imaging.

OBJECTIVE: The purpose of this report is to describe the normal MR anatomy of the thoracic outlet and its modification after postural maneuvers using an anatomic-MR imaging correlation. CONCLUSION: MR imaging appears to be a useful technique to study the thoracic outlet and its contents because of its excellent soft-tissue depiction and its multiplanar capabilities. T1-weighted images obtained in the sagittal plane clearly depicted the different compartments of the cervicothoracic-brachial junction. Hyperabduction maneuvers may have potential applications in the assessment of the thoracic outlet syndrome by showing the location of compression.

Aged↗
PubMed2000

[Cortical septic osteitis: two cases].

Cortical septic osteitis is defined as a predominant or exclusive infection of the cortex which may lead to diagnosis pitfalls. With the two cases presented here, principal radiological features allowing a correct diagnosis are recalled.

Adult↗