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Biomedical subjects

O Louis

Publications and source records attributed to O Louis.

42 records · Page 3Linked to original sources
PubMed1984

[Evaluation of left cardiac function in chronic obstructive bronchopneumopathy. Correlation of the radiographic analysis of the thorax and hemodynamic data].

Chest radiographs, taken in the standing position, were reviewed in 47 hospitalised patients with chronic obstructive respiratory failure; the review was done retrospectively and the radiographs were examined for signs of left ventricular failure. Only interstitial and alveolar oedema were considered, upper lobe blood diversion was commonly seen in patients, probably reflecting pulmonary hypertension independent of any re-distribution of left ventricular origin. Interstitial oedema was seen in 9 patients (19.2%) of whom only one reached a pulmonary capillary pressure of 25 mmHg, traditionally considered as a threshold of interstitial oedema. In 8 other patients, the pulmonary capillary pressure was either moderately elevated between 15 and 25 mmHg (3 cases) or strictly normal (5 cases). The discordance observed between the radiological data and haemodynamics very probably reflects (bearing in mind the descriptions in valvular and ischaemic heart disease) a greater sensitivity of the radiograph when compared to measurements of pulmonary capillary pressure at rest in cases of left ventricular failure "fruste". The greater sensitivity of radiological analysis in patients suffering from chronic airflow obstruction contrasts with the classical notion, according to which the radiological expression of definite left ventricular failure was frequently poor in this kind of patient by reason of a destruction of the vascular bed, which limited the development of pulmonary oedema.

Adult↗
PubMedDate not supplied

Fat fraction of lumbar bone marrow using in vivo proton nuclear magnetic resonance spectroscopy.

Localized proton spectra of the human lumbar vertebral body were recorded in vivo at 1.5 T, using the STEAM (stimulated echo acquisition mode) pulse sequence. Thirty-seven patients (18 men, 19 women) were examined, ranging in age from 21 to 68 years (mean = 40, SD = 13). The fat fraction of the bone marrow was calculated from the areas of the fat and water peaks in the spectrum. The results demonstrate that, in the course of aging, there is a systematic increase in measured fat percentage of about 7% per decade of age. No sex difference could be established on the basis of our results.

Adult↗
PubMedDate not supplied

Mineral content of vertebral trabecular bone: accuracy of dual energy quantitative computed tomography evaluated against neutron activation analysis and flame atomic absorption spectrometry.

The goal of this study was to evaluate the accuracy of preprocessing dual energy quantitative computed tomography (QCT) for assessment of trabecular bone mineral content (BMC) in lumbar vertebrae. The BMC of 49 lumbar vertebrae taken from 16 cadavers was measured using dual energy QCT with advanced software and hardware capabilities, including an automated definition of the trabecular region of interest (ROI). The midvertebral part of each vertebral body was embedded in a polyester resin and, subsequently, an experimental ROI was cut out using a scanjet image transmission procedure and a computer-assisted milling machine in order to mimic the ROI defined on QCT. After low temperature ashing, the experimental ROIs reduced to a bone powder were submitted to either nondestructive neutron activation analysis (n = 49) or to flame atomic absorption spectrometry (n = 45). BMC obtained with neutron activation analysis was closely related (r = 0.896) to that derived from atomic absorption spectrometry, taken as the gold standard, with, however, a slight overestimation. BMC values measured by QCT were highly correlated with those assessed using the two reference methods, all correlation coefficients being > 0.841. The standard errors of the estimate ranged 47.4-58.9 mg calcium hydroxyapatite in the regressions of BMC obtained with reference methods against BMC assessed by single energy QCT, 47.1-51.9 in the regressions involving dual energy QCT. We conclude that the trabecular BMC of lumbar vertebrae can be accurately measured by QCT and that the superiority in accuracy of dual energy is moderate, which is possible a characteristic of the preprocessing method.

Aged↗