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Biomedical subjects

J F Lebas

Publications and source records attributed to J F Lebas.

At least 37 records · Page 2Linked to original sources
PubMed1988

[Nuclear magnetic resonance imaging in gynecology. An evaluation of its current applications].

The authors present a research carried out by the Universities of Essen, Tubingen (RFA) and Grenoble, France, on the use of magnetic resonance imaging (M.R.I.) in gynaecology. After clarifying our knowledge of the normal anatomy of the pelvis and of the tissular characteristics of MRI the principal indications are discussed and set out. The investigation is shown to be particularly valuable in working out the aetiology, the volume and the spread of a pelvic mass whether it is benign or malignant when it is important to be exact in finding the origin of the tumour. This research has been illustrated by analysing 35 case histories including 28 malignant tumours. A second study was carried out on 30 cases of cancer of the cervix. In this field MRI is the only test that can be carried out before therapy to give a tridimensional assessment of the size of the tumour and whether it has spread into the parametrium. The visual impressions obtained by MRI illustrate each chapter: of the gynaecological anatomy, of the pathology, in cancers of the cervix, in pelvic masses and particularly in ovarian tumours.

Female↗
PubMed1988

[Contribution of oculography and magnetic resonance imaging to the clinico-topographic correlates in ischemic vascular disorders of the brainstem].

6 patients with brainstem infarction and oculomotor signs were studied. One case was consistent with a mesencephalic infarct (internuclear ophthalmoplegia); 4 cases were consistent with a protuberantial infarct (3 cases of "one and a half" syndrome and one case of pontine reticular syndrome associated with a palsy of the root of the VIth nerve. One case was a laterobulbar syndrome. These 6 patients were studied with CT scan and magnetic resonance imaging (MRI CGR Magniscan 5000 with supraconductor magnet of 0.5 Tesla) with T2 weighted images (TR = 2000 ms, TE = 60; 120 ms) in joined section of 9 or 6 mm thickness. The MRI findings were in each case consistent with an infarction. The clinico-topographic correlations are compared with the oculographic findings.

Brain Ischemia↗
PubMed1988

[Magnetic resonance imaging in menisco-ligamentous lesions. Comparison with arthroscopy. Apropos of 37 cases].

Results of magnetic resonance imaging of 37 cases of lesions of meniscus and ligaments of knee are reported and compared with arthroscopy findings. Use of MRI appears to be an excellent non-invasive diagnostic method, with current major indications in acute knee injuries and for evaluation of chronic laxity. It also allows guidance of surgical procedures. In the future, MRI should replace the more aggressive arthrography, this with a relatively short examination time, since sagittal section imaging in TI permits detection of the majority of lesions.

Acute Disease↗
PubMed1987

[Magnetic resonance imaging in dissection of the aorta].

In order to evaluate the usefulness of this new exploratory method in dissection of the aorta, 13 patients (10 men and 3 women, mean age 58 +/- 14 years) were examined by means of an 0.5 Tesla Magniscan 5000 nuclear magnetic resonance machine. Fifteen examinations were performed: 5 in patients with actual aortic dissection (type A 4 including one acute, type B1), 5 in patients previously operated upon for type A dissection and 5 for suspected acute aortic dissection unconfirmed by other examinations. Magnetic resonance imaging (MRI), synchronized with electrocardiography, was carried out using spin-echo techniques with 1 to 3 echoes and multiple contiguous sections along several planes. In the 5 patients with actual dissection the 2 channels separating the membrane could be demonstrated, thus providing a firm diagnosis (MRI proved superior to angiography in 2/5 patients). All 5 patients could be classified as either type A or type B. Extension to the cervical vessels was observed in 3 cases and the portal of entry was seen in one case, but the origin of the coronary arteries was never visualized. In the 5 patients previously operated upon MRI provided detailed analysis of the prosthesis of the supra-coronary ascending aorta implanted in all cases, of the aorta proximal and distal to that segment and of the periaortic mediastinum. By studying the signal from the false channel distal to the prosthesis information was obtained as to the presence in it (2 patients) or absence of circulating blood.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Straight azygos continuation of the inferior vena cava. Apropos of 3 cases using an NMR study].

Three patients with straight azygos vein continuation of inferior vena cava (IVC) were studied by nuclear magnetic resonance (NMR) imaging. In all three cases the diagnosis had been established previously by ultrasound and/or computed tomography imaging, but NMR images provided better anatomical precision of the venous anomaly : visualization of the total trajectory of the major azygos vein, the caliber of which can exceed that of aorta, and absence of retrohepatic segment of IVC but presence of a short supradiaphragmatic segment towards which converge the suprahepatic veins; anastomotic etwork between IVC and major azygos vein contributing to ensure continuity of venous drainage superior to its renal segment. The advantages of NMR are described and the precise diagnostic role of this new method of imaging in the diagnosis of this type of anomaly discussed.

Adult↗
PubMed1986

[Magnetic resonance imaging in multiple sclerosis. Sensitivity and correlation with the clinical picture].

The aim of imaging the brain in Multiple Sclerosis (MS) is to prove the dissemination of lesions, so critical for the diagnosis and so difficult to ascertain clinically. Our study included 21 patients with clinically definite (12) and probable (9) MS. A 21 patients underwent a neurological standard examination, a double-dose delayed CT scan and a Magnetic Resonance Imaging with a superconducting 0.5 Tesla magnet. Jointed slices were performed with a T2-weighted Spin-Echo sequence (TE 60, 120; TR 2000 msec). MRI detected 640 lesions in 20 patients while CT scan detected only 24 lesions in 9 patients. Technical limiting factors are discussed. Abnormalities in MRI were high-intense spots, blotches and streaks, located predominantly in the periventricular area. Capping lesions were common around the ventricular horns. "Plaques" were visualized in the posterior fossa. For each patient, the total surface of the lesions was calculated and was found to be related with the presence of lesions and with the cortical atrophy on CT scan. A correlation between the surface of lesions calculated by MRI and the disability scale was found especially in the group of patients with clinically proven cerebral lesions, while patients with predominantly spinal forms had a significantly lower surface of lesions. This finding could yield a new quantitative evaluation of the MS pathologic process which could be used to assess therapeutic efficacy.

Adult↗
PubMed1984

Analysis of brain metabolism changes induced by acute potassium cyanide intoxication by 31P NMR in vivo using chronically implanted surface coils.

Chronic implantation of surface coils on the skull has been developed to record 31P NMR spectra of the brain in unanesthetized rats. Intraperitoneal sublethal potassium cyanide doses induce strong and reversible changes in high-energy phosphate compounds in the brain, similar in part to those induced by ischemia. These effects are dose-dependent as far as phosphocreatine, inorganic orthophosphates and pH are concerned; ATP does not seem to be altered by KCN doses ranging from 3 to 5 mg/kg but starts decreasing at a dose of 6 mg/kg. The fraction of Mg2+ complexed ATP which could be estimated as about 90% was not affected by KCN intoxication. For high doses (6 mg/kg) a new peak, appearing on the upfield side of the inorganic phosphate peak, may correspond to an acidic compartment, the significance of which is discussed.

Adenosine Triphosphate↗
PubMed1982

[The value of tomodensitometry in the diagnosis of dermoid cysts. Apropos of 5 cases].

Results of computed tomography before operation in 5 cases of dermoid cysts (mediastinal: 3; retroperitoneal: 1; ovarian: 1) are employed to assess the contribution of this technique, and to define its place in relation to other diagnostic radiological procedures (straight radiographs and ultrasonography). The CT scan enables three morphological types to be distinguished, and also supplies very precise data on the extension, limits, and relationships of the tumor. The effective place of this examination in the diagnosis of dermoid cysts depends upon two factors: data obtained from the straight radiograph and the initial site of the lesion. When the former supplies specific information, the only role of the CT scan and ultrasonography is to determine the precise extent of the tumor pre-operatively, the CT scan being superior to ultrasonography for this purpose. When straight radiographs do not reveal characteristic signs, the diagnostic assistance of the scanner appears to be irreplaceable, even in those abdominal or pelvic regions where ultrasonography is best conducted.

Adult↗
PubMed1981

[Oesophageal cancer extension. Diagnostic contribution and effects on therapy of computed tomography. Report on 40 cases (author's transl)].

Based on a homogeneous series of 40 cases of thoracic or abdominal oesophageal cancer, of which 23 had been confirmed by operation, the authors analyse the contribution of the CT scan to the diagnosis of the extension of the cancer, and evaluate the effects on therapy of this technique. Computed tomography supplies much more precise and complete details of possible cancer extension than any other pre-operative investigation. Conducted after radiological and endoscopic examination of the oesophagus, it supplies rapid, perfectly readable, irreplaceable information on local, regional, and metastatic spread of the cancer. This only slightly aggressive examination enables evaluation of the size of the tumour and its direct relationships, effective exploration of the mediastinal and coeliac glands regions, and detection of possible pleural, pulmonary, or hepatic metastases. Its role in the decision to operate is a considerable one: true assessment of of local, regional, or metastatic extension assists the surgeon in his choice of either curative or palliative therapy. Better still, it enables a route of approach to be decided as a function of data concerning possible extension, as well as the best surgical tactic. As a support for radiotherapy or chemotherapy for this type of cancer, computed tomography greatly assists follow-up supervision.

Esophageal Neoplasms↗
PubMed1980

[Fatty masses in the mediastinum. A report on 21 cases including 16 after computer tomography investigations (author's transl)].

The authors use this term to describe collections of fatty material in the tissues, circumscribed or not, which may cause permanent deformity of the mediastinum. This definition may not be based upon histological examinations but it is perfectly appropriate following the recent use of computer tomography (CAT) investigations. The authors base their comments on the study of 21 cases divisible into two groups of unequal size: in 5 cases, studied without using CAT, diagnosis was made during operation; in the 16 other cases it was made by CAT. The masses may be circumscribed or not, but mixed forms have been observed. Among the circumscribed masses. Those in the right cardiophrenic region appear to be the frequent and are observed mainly in women: a retrocardiac location implies than an associated hiatus hernia must be searched for; the mediastinoparietal reduplicated form being rarely seen. The spreading types are noted mainly in men and occur usually in the superior or median part of the mediastinum. These masses can be demonstrated and diagnosis simplified by the use of CAT, as it is a truly specific radiological examination which eliminates the use of tomography, pneumomediastinum, and angiography as diagnostic procedures. Surgical operation is no longer practiced for diagnostic purposes and can be avoided in very many cases.

Adult↗
PubMed1979

Impedance rheoplethysmography. The role of estimation of vasodilatory activity.

The activity of a number of vasodilatory drugs was studied, with the help of impedance rheoplethysmography, on the vascular bed of the hind limb of anaesthetized rabbits. The vasodilators under study induce changes in rheoplethysmogram to a more or less important degree. The results were compared with those obtained with electromagnetic flowmetry. This method seems to be useful in the study of vasodilators because it allows to measure their effects and the duration thereof in a non-aggressive way. This method using flowmetry, allows to study in an analytical way those substances' effects on artery, vein and also capillary.

Animals↗