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F Verhaegen

Publications and source records attributed to F Verhaegen.

48 records · Page 3Linked to original sources
PubMed1996

[X-ray computed tomographic tests in the diagnosis and treatment of amebic liver abscesses].

PURPOSE: The aim of this study was to evaluate the CT findings of amebic liver abscesses and its usefulness for treatment. METHODS: CT was performed in 51 patients with proved amebic liver abscess. CT studies were made before and after contrast injection. RESULTS: Among the 98 abscesses, 66% occurred in the right lobe. 66% of the patients presented a solitary abscess. The diameters were found between 2 cms to 15 cms. The mean was 7 cms. An enhancing wall was present in 84%; the margins were festooned in 75%, smooth in the other cases; internal septations were noted in 57%. High density material within the abscess, before injection of contrast was seen in 50%. 30% of patients had focal intra-hepatic biliary dilatation, 27% right pleural effusion, 23% peri-hepatic fluid collection. One hepatic-colic fistula and one hepato-pulmonary fistula were not suspected on U.S. examination. Percutaneous aspiration was done in 31% of the patients, when the diameter of the abscesses were more than 10 cms or when they were seen in the left lobe or when fever or pain did not disappear after treatment. CONCLUSION: CT scan may be helpful in diagnosis of amebic liver abscess at an early stage or later when a complication is suspected. CT scan can also help to indicate and safely perform a percutaneous therapeutic aspiration.

Adolescent↗
PubMed1996

[X-ray computed tomographic and radiographic aspects of thoracic actinomycosis].

UNLABELLED: The aim of this study was to evaluate chest radiographs and computed tomography (CT) in patients with thoracic actinomycosis. MATERIAL AND METHOD: Chest radiographs and CT scans of 9 patients with proved thoracic actinomycosis were reviewed. CT scans were performed after intravenous contrast administration. RESULTS: Airspace consolidation was present in the upper lobes in 6 patients and in the lower lobes in 3. Cavitations not apparent on the radiographs were seen on CT s in 2 cases. Mediastinal lymphadenopathies were seen on CT s in 2 cases, in one the infection extended through the mediastinal pleura into the mediastinum. Pleural thickening adjacent to the airspace consolidation was identified in 6 cases. Chest wall invasion occurred in 4 cases with a wavy periostal reaction involving ribs adjacent to the site of parenchymal involvement in 3 cases. Extension into the abdomen through the diaphragm was seen in one case. DISCUSSION: In humans, actinomycosis involves the thorax in 15% of the cases. Thoracic and pulmonary parenchymal involvement is usually secondary to aspiration of colonized material from the oropharynx in patients with poor oral hygiene. There is a basilar predominance of the disease, but some studies have reported apical predominance. The pulmonary infection leads to an airspace consolidation mainly in the lung periphery. The infection may extend across fissures and through the pleura. Chest wall and bone invasion are not uncommon. A wavy periosteal reaction involving ribs is said to be highly suggestive of pulmonary actinomycosis. CONCLUSION: Thoracic actinomycosis is characterized by airspace consolidation with adjacent pleural thickening. Chest wall invasion with a wavy periosteal reaction is highly suggestive.

Actinomycosis↗
PubMed1995

[The double band sign: pleural tuberculosis in x-ray computed tomography].

We described on computed tomography, two cases of pleural tuberculosis with parietal pleural enhancement and thickening associated with another external high density line. We called this parietal pleural and extra pleural change, the "double band sign". After study of the regional anatomy, we think that this external line is the endothoracic fascia.

Humans↗
PubMed1995

Monte Carlo study of electron spectra and dose from backscattered radiation in the vicinity of media interfaces for monoenergetic photons of 50-1250 keV.

In the present paper electron fluence spectra and backscatter dose factors for monoenergetic photons (50, 100, 250 and 1250 keV) are presented. The influence of the atomic number of the backscatter materials glass, bone, steel and titanium is studied. For all radiations increases in dose were found in the immediate vicinity of the interface in a region extending over a distance determined by the photon energy. In a thin layer extending several tens of micrometers from the interface, a large increase in dose was found for 50 and 100 keV photons. The largest backscatter dose factor (3.5) was found for 50 keV photons and a steel interface. This large effect was found to be due largely to backscattered photoelectrons. K-shell fluorescent photons from titanium and steel were also included but were found to have almost no effect on backscatter dose factors or electron spectra. With both K-shell fluorescence and sampling of the photoelectron angular distribution switched off, much smaller backscatter factors were obtained. Beyond the thin region near the interface where the dose is increased, significant dose depressions were found for photons of these energies in a region extending several centimeters from the interface. The effect was maximum for 50 keV photons, for which dose depressions of about 35% for steel and titanium and 15% for glass and bone were obtained. For 250 and 1250 keV photons a more modest dose enhancement was found close to the interface (40-50%) but extending over a larger region (e.g. 5 mm for 1250 keV photons). Small differences in radiation quality nearer to the interface were found as expressed by track-averaged and dose-averaged restricted linear energy transfer, LET100,T and LET100,D, with a maximum effect for the 100 keV photons. For this radiation quality a decrease of 50% in LET100,T was found close to the interface.

Dose-Response Relationship, Radiation↗
PubMed1994

Scoring of radiation-induced micronuclei in cytokinesis-blocked human lymphocytes by automated image analysis.

The micronucleus assay in human lymphocytes is, at present, frequently used to assess chromosomal damage caused by ionizing radiation or mutagens. Manual scoring of micronuclei (MN) by trained personnel is very time-consuming, tiring work, and the results depend on subjective interpretation of scoring criteria. More objective scoring can be accomplished only if the test can be automated. Furthermore, an automated system allows scoring of large numbers of cells, thereby increasing the statistical significance of the results. This is of special importance for screening programs for low doses of chromosome-damaging agents. In this paper, the first results of our effort to automate the micronucleus assay with an image-analysis system are represented. The method we used is described in detail, and the results are compared to those of other groups. Our system is able to detect 88% of the binucleated lymphocytes on the slides. The procedure consists of a fully automated localization of binucleated cells and counting of the MN within these cells, followed by a simple and fast manual operation in which the false positives are removed. Preliminary measurements for blood samples irradiated with a dose of 1 Gy X-rays indicate that the automated system can find 89% +/- 12% of the micronuclei within the binucleated cells compared to a manual screening.

Algorithms↗
PubMed1994

Micronuclei induced by fast neutrons versus 60Co gamma-rays in human peripheral blood lymphocytes.

Here we compared the effectiveness of neutrons ( = 5.5 MeV) versus 60Co gamma-rays in producing micronuclei (MN) in human lymphocytes. To obtain dose-response data, blood samples of six donors were irradiated with doses ranging from 0.1 to 5 Gy for gamma-rays and 0.1-3 Gy for neutrons. A linear dependence of MN yield with dose was found for fast neutrons while for gamma-rays a nonlinear dependence existed. For both radiation qualities no significant interindividual differences were found. Derived relative biological effectiveness values decreased with increasing dose. The MN frequency distributions were overdispersed with respect to the Poisson distribution, with neutrons showing higher dispersion values than with gamma-rays. To compare the repair kinetics of both radiation qualities split-dose experiments were performed. A dose of 4 Gy gamma-rays (3 Gy neutrons) was delivered either as a single exposure or in two equal fractions separated by time intervals ranging from 30 min to 10 h (30 min to 7 h for neutrons). The data showed for gamma-rays a significant decline (30% +/- 10%) in MN yield with interfraction time due to repair of DNA damage. This repair is a continuous process starting almost immediately after the first of the two doses and lasting 3-5 h. For fast neutrons no decline was observed indicating irreparable damage.

Cells, Cultured↗
PubMed1994

The in vitro cytokinesis-block micronucleus assay: a detailed description of an improved slide preparation technique for the automated detection of micronuclei in human lymphocytes.

An improved slide preparation technique is described for the automated detection of micronuclei in binucleate cytokinesis-blocked human lymphocytes. This automated system (Discovery Image Analyser, Becton-Dickinson Image Cytometry Systems, Leiden, The Netherlands) searches for the pattern of two touching nuclei in binucleate cells instead of the edges of the cytoplasm. For this purpose several ratios of the fixative mixture, methanol/acetic acid, were checked. After fixation with a ratio of 25:1, touching nuclei were obtained in almost 100% of the binucleate cells. A hydrolysis treatment with 5 N HCl before staining with Romanowsky-Giemsa resulted in binucleate cells with dark-stained nuclei and micronuclei and a vaguely stained cytoplasm. The high visual contrast between cytoplasm and nuclear material obtained by this staining procedure makes an accurate automated detection of micronuclei feasible. Additionally, a 64 h culture time resulted in an optimal yield of binucleate cells. The results of manual micronucleus scoring on slides prepared with the 'manual protocol' and with the 'automation protocol' indicate no significant differences between both sets of data supporting the validity of the automation protocol.

Cell Division↗
PubMed1994

Sensitivity of micronucleus induction in human lymphocytes to low-LET radiation qualities: RBE and correlation of RBE and LET.

To use the micronucleus (MN) assay as a biological dosimeter, it is essential that the dose response to different radiation qualities is known. In this paper we present dose-response curves for MN induction by X rays (14, 50 and 350 kVp) and 60Co gamma rays. The dose responses for 14 kVp compared to 50 kVp and for 350 kVp compared to 60Co were found to differ significantly, whereas no significant difference could be demonstrated between 50 kVp and 350 kVp. Calculated RBE values with respect to 60Co gamma rays increase strongly with decreasing dose. The high RBE value (2.7) obtained for 14 kVp X rays in the low-dose region is of importance for radiological protection in clinical practice. A good linear correlation was found between the biological damage expressed by the RBE values for MN induction and the calculated physical parameter LET100,T expressing the energy deposition pattern in the medium. This correlation points to the fact that secondary phenomena involved in MN formation (repair, coagulation) do not differ greatly for the X-ray qualities used in this work. It can be concluded that MN induction in human lymphocytes can be used as a sensitive biological dosimeter for radiation damage by X rays and gamma rays.

Adult↗
PubMed1994

Dose conversion factors and linear energy transfer for irradiation of thin blood layers with low-energy X rays.

For irradiation of thin samples of biological material with low-energy X rays, conversion of measured air kerma, free in air to average absorbed dose to the sample is necessary. In the present paper, conversion factors from measured air kerma to average absorbed dose in thin blood samples are given for four low-energy X-ray qualities (14-50 kVp). These factors were obtained by Monte Carlo simulation of a practical sample holder. Data for different thicknesses of the blood and backing layer are presented. The conversion factors are found to depend strongly on the thicknesses of the blood layer and backing layer. In radiobiological work, knowledge of linear energy transfer (LET) values for the radiation quality used is often required. Track-averaged LET values for low-energy X rays are presented in this work. It is concluded that the thickness of the sample does not influence the LET value appreciably, indicating that for all radiobiological purposes this value can be regarded as a constant throughout the sample. Furthermore, the large difference between the LET value for a 50 kV spectrum found in this work and the value given in ICRU Report 16 is pointed out.

Blood↗
PubMedDate not supplied

High resolution chest CT in tuberculosis: evolutive patterns and signs of activity.

PURPOSE: The purpose of our study was to determine evolutive patterns and signs of active tuberculosis on high resolution CT (HRCT) scans. METHOD: We followed up over 15 months 27 patients with postprimary pulmonary tuberculosis that was proven bacteriologically. CT scans were performed before, during, and after 6 months of anti-tuberculosis treatment. Both 10-mm-thick sections and 1.5-mm-thick HRCT scans were performed. RESULTS: Ground-glass pattern was noticed 26 times, 9 times after 2 month treatment and only 2 times after 6 month treatment. Among these two patients, one did not undergo his treatment properly and the other one had an additional bacterial infection. Centrilobular nodules (n = 17) and poorly marginated nodules (n = 21) were present only before treatment. Reticular pattern (intralobular and septal thickening), interstitial nodules, and fibrosis were seen both before and after treatment. Ground-glass pattern, poorly marginated nodules, and infiltrates as well as centrilobular nodules were related to an active infection. CONCLUSION: This HRCT may be helpful to demonstrate activity in patients suspected of having tuberculosis and to assess antituberculous treatment efficiency.

Adolescent↗
PubMedDate not supplied

[Epidemic of pulmonary histoplasmosis after visiting a cave in New Caledonia].

We report an epidemic of acute pulmonary histoplasmosis which occurred in February 1994 among a group of 24 persons after they had once or twice visited a cave in New Caledonia. This study describes the physical and laboratory findings, which lead to the diagnosis of histoplasmosis. Each test was evaluated. All members of the group had a physical examination, early and late serological tests, pulmonary X-rays (including CT) and some had mycological examination of bronchoalveolar washes. Mycological investigations were made on samples collected from the cave. Histoplasmic skin testing was not possible. We defined a case as a person who visited the cave in January 1994, had evocative radiological features and at least four symptoms among the following: weakness, fever, headache, arthralgia, thoracic pains, dyspnea, cough and nausea. Of the 24 exposed persons, 7 cases were considered as severe, 8 cases as moderate, and 6 cases as mild, for a total of 21 cases and an attack rate of 87.5%. There was no progression towards disseminated histoplasmosis and no recorded death. The incubation period lasted from 5 to 17 days. The symptoms were divided into three groups. In the first group, the symptoms of fever, headache and arthralgia were common and nonspecific. In the second group, the symptoms of chest pain, cough, and dyspnea which often occurred later, were less common and more specific. In the third group, the symptoms of vomiting, diarrhea and dizziness were less common. The chest X-ray showed abnormalities in 100% of the cases, and in 11 of the 21 cases the characteristic finding was a miliary.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗