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Biomedical subjects

G Marchal

Publications and source records attributed to G Marchal.

At least 19 recordsLinked to original sources
PubMed2006

Additional value of PET-CT in the staging of lung cancer: comparison with CT alone, PET alone and visual correlation of PET and CT.

Integrated positron emission tomography (PET) and computed tomography (CT) is a new imaging modality offering anatomic and metabolic information. The purpose was to evaluate retrospectively the accuracy of integrated PET-CT in the staging of a suggestive lung lesion, comparing this with the accuracy of CT alone, PET alone and visually correlated PET-CT. Fifty patients undergoing integrated PET-CT for staging of a suggestive lung lesion were studied. Their tumor, node, metastasis (TNM) statuses were determined with CT, PET, visually correlated PET-CT and integrated PET-CT. These TNM stages were compared with the surgical TNM status. Integrated PET-CT was the most accurate imaging technique in the assessment of the TNM status. Integrated PET-CT predicted correctly the T status, N status, M status and TNM status in, respectively, 86%, 80%, 98%, 70% versus 68%, 66%,88%, 46% with CT, 46%, 70%, 96%, 30% with PET and 72%, 68%, 96%, 54% with visually correlated PET-CT. T status and N status were overstaged, respectively, in 8% and 16% with integrated PET-CT, in 20% and 28% with CT, in 16% and 20% with PET, in 12% and 20% with visually correlated PET-CT and understaged in 6% and 4% with integrated PET-CT, versus 12% and 6% with CT, 38% and 10% with PET and 12% with visually correlated PET-CT. Integrated PET-CT improves the staging of lung cancer through a better anatomic localization and characterization of lesions and is superior to CT alone and PET alone. If this technique is not available, visual correlation of PET and CT can be a valuable alternative.

Adult↗
PubMed2006

Evaluation of the diagnostic value of a computed radiography system by comparison of digital hard copy images with screen-film mammography: results of a prospective clinical trial.

The purpose of the study was to determine prospectively the diagnostic value of a computed radiography (CR) system by comparing mammographic hard copy images with screen-film mammography (SFM). A series of 100 patients, who came for diagnostic investigation, underwent two-view SFM (Lorad M-IV Platinum) and digital mammography with a CR system (AGFA CR system). The images were obtained by double exposure, i.e. same view without removing compression of the corresponding breast. The CR images were processed with dedicated processing for mammography. Six radiologists read sets of SFM and CR images. The primary efficacy parameter was the overall diagnostic value. The secondary efficacy parameters were lesion conspicuity and lesion details (for masses and micro-calcifications), tissue visibility at chest wall and at skin line, axillary details, overall density and sharpness impression and the overall noise impression. These parameters were scored by a 7-point scoring system. "CR non-inferior to SFM" was concluded if the lower confidence interval bound exceeded 80%. The confidence interval for the overall diagnostic value was between 96.4% and 100%. Pooled analysis of the ten features for image quality comparison demonstrated for all but one feature (lesion details of the calcifications) CR non-inferiority to SFM.

Adult↗
PubMed2006

Characteristics of dosemeter types for skin dose measurements in practice.

A growing number of papers report deterministic effects in the skin of patients who have undergone interventional radiological procedures. Dose measurements, and especially skin dose measurements, are therefore increasingly important. Methods and acceptable dosemeters are, however, not clearly defined. This paper is the result of a literature overview with regard to assessing the entrance skin dose during radiological examinations by putting a dosemeter on the patient's skin. The relevant intrinsic characteristics, as well as some examples of clinical use of the different detector types, are presented. In this respect, thermoluminescence, scintillation, semiconductor and film dosemeters are discussed and compared with respect to their practical use.

Film Dosimetry↗
PubMed2006

Towards a proposition of a diagnostic (dose) reference level for mammographic acquisitions in breast screening measurements in Belgium.

A diagnostic reference level (DRL) is a dose level for a typical X-ray examination of a group of patients with standard body sizes and for broadly defined types of equipment. These levels are expected not to be exceeded for standard procedures when good and normal practice regarding diagnostic and technical performance is applied. In this paper, we have calculated DRLs for screening mammography in Belgium. The 95th percentile of the mean average glandular dose is 2.46 mGy. The DRL based on polymethyl methacrylate (PMMA) measurements was 2.08 mGy. Correlation coefficient (R) between doses from patient studies and phantom studies was 0.90, with an average underestimation of the phantom measurements of 15% for systems that use only Mo/Mo anode/filter. For the centres that use other anode/filters, there is not enough scientific evidence that a single phantom measurement of a standard PMMA block is representative for the patient dose.

Belgium↗
PubMed2006

Image quality measurements and metrics in full field digital mammography: an overview.

This paper gives an overview of test procedures developed to assess the performance of full field digital mammography systems. We make a distinction between tests of the individual components of the imaging chain and global system tests. Most tests are not yet fully standardised. Where possible, we illustrate the test methodologies on a selenium flat-panel system.

Contrast Media↗
PubMed2006

Radiation dose vs. image quality for low-dose CT protocols of the head for maxillofacial surgery and oral implant planning.

The goal of this study was to determine the acquisition parameters for a low-dose multi-slice CT protocol and to compare the effective dose and the image quality of this low-dose protocol with the image quality of a clinical multi-slice CT protocol, routinely used for visualisation of the head. The low-dose protocol was derived from a clinical multi-slice CT protocol by lowering mA s and kV and increasing the pitch. The low-dose protocol yielded a dose reduction from 1.5 to 0.18 mSv for a multi-slice CT scan of the whole head, whereas noise in the low-dose CT images was increased. For bone segmentation, noise could be reduced by use of a non-linear edge preserving smoothing filter. Tests on ESP and skull phantom indicated that the accuracy of the measurements on low-dose CT is acceptable for image-based planning of maxillofacial and oral implant surgery, reducing the dose by a factor of 8.

Humans↗
PubMed2005

In vivo efficiency of targeted norfloxacin against persistent, isoniazid-insensitive, Mycobacterium bovis BCG present in the physiologically hypoxic mouse liver.

Persistence of Mycobacterium tuberculosis is a hypoxia-inducible state in which the bacteria are phenotypically insensitive to currently available antituberculous drugs. In humans, persistent M. tuberculosis is found in granulomatous lesions, either inside macrophages or in necrotic tissue, where the partial oxygen pressure (pO(2)) is very low. Persistent bacteria can remain silent for decades before overt tuberculosis develops. Due to insensitivity to classical drugs, M. tuberculosis persistence prevents rapid and definitive clearance of bacteria. Consequently, therapeutic molecules are required that are both active against persistent bacilli and able to reach their intramacrophagic location. In contrast to its native form, norfloxacin is active in vivo against Mycobacterium bovis BCG present in the lungs when temporarily linked to a macromolecular carrier targeted to macrophages. To study the efficiency of this macromolecular prodrug targeted to persistent mycobacteria confined inside macrophages, we established a short-term in vivo model based on the physiological pO(2) differences between lungs, spleen and liver. Whereas lungs and spleen are well oxygenated, the liver has a low pO(2) due to its portal irrigation. Therefore, studying mycobacteria in the liver yields information about in vivo persistent bacilli exposed to low pO(2). To our knowledge, no similar short-term in vivo model has been published to date. Using this model, we demonstrated the insensitivity to isoniazid of M. bovis BCG present in hypoxic sites, and showed that norfloxacin given as a mannosylated macrophage-targeted prodrug was able to kill these isoniazid-insensitive mycobacteria. This demonstrates that intracellular persistent mycobacteria are amenable to antibiotic treatment.

Animals↗
PubMed2004

Tuberculosis in HIV-infected patients: a comprehensive review.

The incidence of tuberculosis (TB) is currently increasing in HIV-infected patients living in Africa and Asia, where TB endemicity is high, reflecting the susceptibility of this group of patients to mycobacteria belonging to the TB group. In this population, extension of multiple resistance to anti-tuberculous drugs is also a matter of anxiety. HIV-induced immunosuppression modifies the clinical presentation of TB, resulting in atypical signs and symptoms, and more frequent extrapulmonary dissemination. The treatment of TB is also more difficult to manage in HIV-infected patients, particularly with regard to pharmacological interactions secondary to inhibition or induction of cytochrome P450 enzymes by protease inhibitors with rifampicin or rifabutin, respectively. Finally, immune restoration induced by highly active anti-retroviral therapy (HAART) in developed countries may be responsible for a paradoxical worsening of TB manifestations.

AIDS-Related Opportunistic Infections↗
PubMed2003

Size and geometry of hepatic radiofrequency lesions.

AIM: To report and compare the size and geometry of hepatic radiofrequency (RF) lesions using the currently available commercial devices. METHODS: A literature search was carried out for the period from January 1st 1990 to June 15th 2003. The commercial suppliers were asked to provide all available data. For each electrode and protocol, size and geometry of single-cycle thermal lesions were registered. RESULTS: No information at all on size and geometry of the inducible lesions was available for 17 of the 28 current commercial electrodes. Many descriptions of RF lesions are limited to the mean transverse diameter. With normal blood flow, diameter of lesions is often smaller than suggested by the length of the electrode tip or the diameter of the deployed prongs. Lesions are rarely perfect spheres but either ellipses or flattened spheres. Distortion of the RF lesion by nearby blood vessels is very common. Fusion of thermal zones between prongs of expandable electrodes can be incomplete. Blood flow interruption using a Pringle maneuver yields larger lesions that are less distorted and more complete. CONCLUSIONS: There is insufficient experimental data for many electrodes that are currently used in patients. RF companies should provide these data before releasing electrodes for use. For those electrodes for which data exist, coagulation lesions are often smaller, less spherical, less complete and less regular than generally presumed. Accurate knowledge of size and geometry of RF lesions is crucial to prevent local recurrence.

Animals↗
PubMed2003

Extended freeze-dried Mycobacterium bovis Bacillus Calmette-Guérin induces the release of interleukin-12 but not tumour necrosis factor-alpha by alveolar macrophages, both in vitro and in vivo.

BACKGROUND: Airway hyper-responsiveness (AHR), chronic airway inflammation and predominance of the T helper type-2 (Th2; IL-4, IL-5, IL-13) over the Th1 (IL-2, IFN-gamma) immune response are hallmarks of asthma. Alveolar macrophages (AM) are the most numerous cells in the airway lumen, where they represent the first immune cell population encountered by inhaled antigens. AM act as antigen-presenting cells (APC) and they release various soluble mediators and enzymes. AM thus play a prominent role in the modulation of the local immunity in airways. In allergic airways, AM have been implicated in the pathogenesis of inflammation by promoting the Th2 versus the Th1 cytokine patterns. OBJECTIVES: Infections with attenuated bacteria or challenges with bacterial products may involve AM. Such stimuli have been shown to potentially restore the Th1/Th2 balance in asthmatic airways, but they also induce the release of inflammatory mediators. We investigated the response of AM when stimulated by two preparations of non-proliferating Bacillus Calmette-Guérin (BCG). METHODS: We evaluated the cytokine production by AM from BP2 and C57BL/6 mice when cultured with heat-killed (HK) and extended freeze-dried (EFD) BCG. We then investigated in vivo the release of soluble factors in the airway lumen of mice after instillation of these BCG preparations. Finally, we studied the profile of cytokine transcripts in the lung of mice pre-treated with BCG and then challenged with ovalbumin (OVA). RESULTS: HK BCG induced the production of both TNF-alpha and IL-12, and did not prevent high levels of Th2 cytokine transcripts. In contrast, EFD BCG induced a response dominated by the production of IL-12, with no later over-expression of Th2 cytokine transcripts. CONCLUSION: Our results show that EFD BCG induce the release of the Th1-promoting cytokine IL-12 by AM, without the deleterious effects of HK BCG. These data suggest that EFD BCG may be considered as a potential novel treatment to restore the Th1/Th2 imbalance in asthma.

Adjuvants, Immunologic↗
PubMed2002

Patient acceptance for CT colonography: what is the real issue?

The aim of this study was to evaluate the discomfort associated with CT colonography compared with colonoscopy and bowel purgation cleansing, and to evaluate patient preference between CT colonography and colonoscopy. In a total of 124 patients, scheduled for multidetector virtual CT colonography and diagnostic colonoscopy, patient acceptance and future preference were assessed during the different steps of the procedure (colon preparation, CT examination, and conventional colonoscopy). Patients who described contradictory findings between the degree of discomfort and their preference regarding follow-up examinations were retrospectively reinterviewed regarding the reason for this discrepancy. Colonoscopy was graded slightly more uncomfortable than virtual CT colonography, but the preparation was clearly the most uncomfortable part of the procedure. Concerning their preference regarding follow-up examinations, 71% of the patients preferred virtual CT colonography, 24% preferred colonoscopy, and 5% had no preference. Twenty-eight percent of the patients preferred virtual CT colonography despite that they thought it was equally or even more uncomfortable than colonoscopy. This was mainly due to the faster procedure (17 patients), the lower physical challenge (14 patients), and the lack of sedation (12 patients) of virtual CT colonography. Factors other than the discomfort related to the examinations play an important role in the patient's preference for virtual CT colonography, namely the faster procedure, the lower physical challenge, and the lack of sedation. Since the preparation plays a major decisive factor in the patient acceptance of virtual CT colonography, more attention should be given to fecal tagging.

Adult↗
PubMed2002

Complications of radiofrequency coagulation of liver tumours.

BACKGROUND: Radiofrequency coagulation (RFC) is being promoted as a novel technique with a low morbidity rate in the treatment of liver tumours. The purpose of this study was to assess critically the complication rates of RFC in centres with both large and limited initial experience, and to establish causes and possible means of prevention and treatment. METHODS: This is an exhaustive review of the world literature (articles and abstracts) up to 31 December 2001; 82 independent reports of RFC of liver tumours were analysed. RESULTS: In total, 3670 patients were treated with percutaneous, laparoscopic or open RFC. The mortality rate was 0.5 per cent. Complications occurred in 8.9 per cent: abdominal bleeding in 1.6 per cent, abdominal infection in 1.1 per cent, biliary tract damage in 1.0 per cent, liver failure in 0.8 per cent, pulmonary complications in 0.8 per cent, dispersive pad skin burn in 0.6 per cent, hepatic vascular damage in 0.6 per cent, visceral damage in 0.5 per cent, cardiac complications in 0.4 per cent, myoglobinaemia or myoglobinuria in 0.2 per cent, renal failure in 0.1 per cent, tumour seeding in 0.2 per cent, coagulopathy in 0.2 per cent, and hormonal complications in 0.1 per cent. The complication rate was 7.2, 9.5, 9.9 and 31.8 per cent after a percutaneous, laparoscopic, simple open and combined open approach respectively. The mortality rate was 0.5, 0, 0 and 4.5 per cent respectively. CONCLUSION: The morbidity and mortality of RFC, while low, is higher than previously assumed. With adequate knowledge, many complications are preventable.

Carcinoma, Hepatocellular↗
PubMed2002

Development of mixed Th1/Th2 type immune response and protection against Mycobacterium tuberculosis after rectal or subcutaneous immunization of newborn and adult mice with Mycobacterium bovis BCG.

Cell-mediated immunity plays a key role in containing the growth of Mycobacterium tuberculosis in the host. The induction of an antibody response or a mixed cell-mediated and humoral response is frequently associated with tuberculosis disease or a decrease in the ability to control M. tuberculosis load. We recently reported the induction of similar immune responses and protection by rectal, subcutaneous (SC) or intradermal administration of Mycobacterium bovis BCG in adult mice, guinea pigs and macaques. The rectal immunization, which did not induce the side-effects associated with parenteral routes (axillary adenitis) and which could be used to reduce the risks of viral transmission associated with unsafe injections in the developing world, was analysed and compared in newborn and adult BALB/c mice. The rectal and SC immunization induced, in mice immunized as newborns or as adults, a mixed T helper 1/T helper 2 (Th1/Th2) immune response; however, particularly in adult mice, after SC administration of BCG, the level of Th2 immune response is significantly higher than it is by the rectal route. Six months after immunization with BCG, rectal and SC delivery induced similar levels of protective immunity against a virulent challenge with M. tuberculosis strain (H37Rv) in mice immunized as adults, but the rectal BCG delivery triggered stronger protection than the SC delivery if mice were immunized as newborns.

Administration, Rectal↗
PubMed2002

[Preliminary study on isoniazid-epiroprim combination in a tuberculosis murine model].

The purpose of this study regarding isoniazid-epiroprim's association applied to antituberculosis chemotherapy, carried through murine model, initiated into Institut Pasteur of Côte d'Ivoire and worked out at Institut Pasteur of Paris was to evaluate the epiroprim's effect alone and associated with isoniazid on Mycobacterium tuberculosis. Sixteen mouses (lineage C57Bl/6) were inoculated by venous way with 10(5) viable bacillus (strain H37Rv) suspended in 500 microliters sterile physiological aqueous solution and were shared out into 4 sets. Fifteen days later the sets have been submitted or not to a daily treatment by gavage during three weeks (epiroprim, isoniazid, isoniazid plus epiroprim). The mouses were euthanasied, spleen and lung were removed from each animal. The titres of determined bacillus into those organs prove that isoniazid and epiroprim associated seem more efficacious than the isoniazid monotherapy for mouses pulmonary tuberculosis. Bacillus obtained are sensitive to isoniazid.

Animals↗
PubMed2002

Integrating images into a central medical information system.

Of the information items that must be easily available to the different actors involved in the care process, radiological images are not the least important. While until recently it was not feasible to include these into the medical information system, this situation has changed. Still, emphasis in PACS (Picture Archiving and Communication Systems) is primarily on the technological aspects. In this paper, in contrast, we stress the importance of integration of images into the overall workflow and into the overall medical record. We do so using illustrations from the PACS project of the University Hospitals Leuven. We briefly indicate that tight integration at the user interface level is needed, and that this requires more than standardized communication between subsystems.

Computer Systems↗