Biomedical subjects
Publications and source records attributed to A Maubon.
Static and dynamic MRI of the female pelvic floor is a new application of this technology. The capability of MRI to assess cavities and muscles on the same exploration is an important improvement. The authors describe successively: MRI is nowadays a decisive tool in the preoperative work-up of pelvic floor dysfunctions.
A positive diagnosis of benign ovarian tumor indicates a laparoscopic approach or a conservative treatment. Benign ovarian tumors are often easy to recognize with non ionizing modalities such as US and MRI. The most common benign ovarian tumors are: mature teratomas including dermoid cysts, tumors in the fibro-thecal group including fibromas and thecomas, benign serous and mucinous tumors (cystadenomas). Apart from ovarian tumors, endometriomas are more commonly extra ovarian, but may involve the ovarian stroma.
MRI assessment of pelvic floor dysfunction is still fairly recent. It is a fast expanding field, owing to its safety and simplicity when compared to other imaging modalities. The possibility of direct dynamic imaging is a decisive input, and it can be coupled to a clinical examination at the magnet. The most widely used sequences are T2 weighted fast TSE or fast gradient echo, in the sagittal and frontal planes. Dynamic MRI of the pelvic floor allows pre-operative staging of prolapse, detection of hidden prolapses and assessment of muscle trophicity. Post-operatively it allows assessment of surgical results and failures or recurrences.
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PURPOSE: In an attempt to determine the visceral risk secondary to a direct percutaneous puncture of the upper renal calix, the anatomic relations of the upper pole of the kidney were studied by magnetic resonance imaging. METHODS: Examination was performed on 25 normal volunteers placed successively in the right and left prone oblique position. The kidney axis and minimal distances from the cutaneous plane at the level of the upper and lower poles were measured. Axial and tangential simulated percutaneous approaches to the upper renal calix were compared in term of risk of damage to the pulmonary, splenic, and hepatic parenchyma. RESULTS: The transversal anteversion angle was statistically comparable for right and left kidneys, but the sagittal anteversion angle was significantly higher for right kidneys (p = 0.05). The minimal distance from the cutaneous plane was statistically comparable for the upper and lower poles. The lower pole was significantly deeper for left than right kidneys (p = 0.01). The visceral risk was statistically comparable for left and right kidneys and was significantly higher in case of an approach in the axis of the upper renal calix or through the 10th intercostal space compared to a puncture via the l1th space (p = 0.0001). CONCLUSION: A percutaneous puncture of the upper pole of the kidney above the 11th rib increases the risk of visceral damage. Preoperative evaluation, with the aid of CT scan or MRI, of the risk of pulmonary, splenic, or hepatic injury could be carried out in these cases.
Regarding a original observation of the Deimons-Meigs syndrome, the authors have derived, from a review of the literature, the main clinicals and etiopathogenics characteristics, and tried to discuss the terms and conditions of a therapeutic treatment appropriate to such a situation.
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PURPOSE: To assess, quantitatively and qualitatively, the diagnostic value of a segmented EPI T1W sequence compared to T1W and T2W TSE sequences. MATERIAL AND METHODS: A prospective analysis of abdominal and pelvic MRI examinations of 70 patients (44 women, 26 men, mean age of 61 years), was performed on a 0.5 T supraconductive magnet with 15 mT/m gradients. The sequences were randomized and compared in a blinded fashion by 3 independent reviewers: TSE T1W (TR/TE = 500/12 ms, NSA = 6, turbo factor 5, 3:49 min), EPI T1W (TR/TE = 500/30 ms, NSA = 6, EPI factor = 7, 2:13 min) and UTSE T2W (TR/TE = 1600-2500/100, NSA = 6, turbo factor = 31, 2:20 min). RESULTS: Quantitatively, no significant difference was found between T1W sequences for signal to noise ratio. The EPI T1W sequence had lower signal but stronger enhancement after gadolinium injection. Qualitatively, EPI T1W had significantly less flow artefacts (p < 0.001, wilcoxon test), and more chemical shift artifact (p < 0.01). For lesion detection, differences were not statistically significant between T1W sequences or between paired T1W and T2W sequences (sensitivity and specificity 84 and 86% for TSE T1W 76 and 86% for EPI T1W, 78 and 79% for UTSE T2W, 90 and 65% for TSE T1W-UTSE T2W, 88 and 65% for EPI T1W-UTSE T2W). Kappa concordance test (0.686) and Mac Nemar symmetry test (3.55) were high between T1W sequences. CONCLUSION: The segmented EPI T1W sequence used had equivalent results compared to the TSE T1W sequence, it allows a 40% reduction in acquisition time and this without difference in the diagnostic performances of the reviewers.
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We report on a patient presenting with rapidly progressive painless paraplegia, amyotrophy and fasciculations masquerading as motoneuron disease. There were no bowel or bladder involvement but the patient noted mild paresthesia on the external part of the right foot and hypertrophy of the right calve was present. While lumbar CT Scan was normal, MRI showed a large cyst of the conus. Analysis of the cyst concluded to a benign cyst of the conus. Paraplegia resolved after surgery and after one year, no relapse was observed so that an hidden ependymoma appeared unlikely.
Ovarian vein syndrome is classically described on the right side. Patients present with lumbar pain or renal colics due to a compression of the ureter between the external iliac artery and a dilated ovarian vein. We report an unusual case of left ovarian vein syndrome between a dilated ovarian vein and the psoas muscle, with a similar clinical presentation.
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Magnetic resonance imaging (MRI) is particularly well suited to pelvic explorations. Normal uterine zonal anatomy and its variations within the menstrual cycle are well codified. MRI is the best preoperative imaging modality for the localization of fibroids. MRI allows a good approach to tissue characterization in benign ovarian tumors and a precise loco-regional assessment in malignant tumors. It could eventually replace the surgical second look after therapy. In prostate cancer, MRI is the most accurate imaging modality to assess capsular invasion.
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