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Biomedical subjects

E Bellon

Publications and source records attributed to E Bellon.

At least 19 recordsLinked to original sources
PubMed2006

Videomanometry reveals clinically relevant parameters of swallowing in children.

OBJECTIVE: The aim of this pilot study is to demonstrate the technical and clinical feasibility of videomanometry to assess swallowing in infants and young children presenting with dysphagia. METHODS: We performed videomanometry using a combined solid state catheter and a perfused manometric sleeve assembly in eight patients (2-28 months) presenting at a tertiary care institution with symptoms of dysphagia. Solid state sensors were positioned at the inferior margin of the valleculae and the laryngeal entrance and the upper esophageal sphincter sleeve assembly was positioned across the upper esophageal sphincter. Manometric and radiological data were digitally recorded simultaneously using a manofluoromixer. Liquid bolus swallows were recorded in each patient and different geometric parameters of deglutition were measured. RESULTS: Placement and fixation of the catheter was well tolerated and no adverse effects occurred. The children easily swallowed test boluses as selected during clinical examination. Results indicate that pharyngeal contractility can be evaluated as well as relaxation of the upper esophageal sphincter during swallowing of wet boluses. CONCLUSIONS: Videomanometry in young children is feasible with the limited discomfort of the placement of the catheter. It is a promising technique that will allow more accurate assessment of pediatric oropharyngeal dysphagia.

Child, Preschool↗
PubMed2003

Electrical stimulation reveals complex neuronal input and activation patterns in single myenteric guinea pig ganglia.

The myenteric plexus plays a key role in the control of gastrointestinal motility. We used confocal calcium imaging to study responses to electrical train stimulation (ETS) of interganglionic fiber tracts in entire myenteric ganglia of the guinea pig small intestine. ETS induced calcium transients in a subset of neurons: 52.2% responded to oral ETS, 65.4% to aboral ETS, and 71.7% to simultaneous oral and aboral ETS. A total of 41.3% of the neurons displayed convergence of oral and aboral ETS-induced responses. Responses could be reversibly blocked with TTX (10(-)6 M), demonstrating involvement of neuronal conduction, and by removal of extracellular calcium. omega-Conotoxin (5 x 10(-7) M) blocked the majority of responses and reduced the amplitude of residual responses by 45%, indicating the involvement of N-type calcium channels. Staining for calbindin and calretinin did not reveal different response patterns in these immunohistochemically identified neurons. We conclude that, at least for ETS close to a ganglion, confocal calcium imaging reveals complex oral and aboral input to individual myenteric neurons rather than a polarization in spread of activity.

Animals↗
PubMed2003

Development of the orohypopharyngeal cavity in normal infants and young children.

OBJECTIVE: To study the growth of the oropharynx and hypopharynx in infants and young children by measuring the lengths of the segments between nasopharyngeal valve and tongue base, tongue base and arytenoids, and arytenoids and upper esophageal sphincter. These measurements will be used as references for developing manofluoroscopy to study deglutition in infants and young children. PATIENTS AND METHODS: Twenty-three children (14 boys, 9 girls) between birth and 4 years of age were prospectively studied. All children had near normal growth parameters and were free of medical illnesses or other major medical conditions that are known to influence the pharyngeal cavity. Lateral videofluoroscopy was used to assess the pharyngeal structures during breathing. All images were digitally recorded and analyzed using a computer program designed specifically for this study. RESULTS AND CONCLUSIONS: Statistically significant correlations were found between the age or height of the patient and the distance from velopharyngeal valve to tongue base and the distance from tongue base to arytenoids, showing a linear increase of the length of the oro- and hypopharynx with age and patient height. There was no significant difference in the pharyngeal distances between boys and girls. On the basis of these results, a linear regression comparison could be established to define the length of each pharyngeal segment for any age until 4 years and for the 50th percentile of height.

Age Factors↗
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↗
PubMed2002

Web-access to a central medical record to improve cooperation between hospital and referring physicians.

We set up Web-access to the central electronic medical record of the University Hospitals Leuven. Purpose was to enable external physicians to more actively participate in the care process as full members of the multidisciplinary treatment team. They get a view on the complete care process in the hospital, and can access results as these become available instead of being provided summary information post factum. This complements traditional electronic exchange between healthcare records. We report on technical setup and results from an extended pilot. We believe that this approach can enrich the discussion on how to provide the "global medical record".

Appointments and Schedules↗
PubMed2001

The relation of CT-determined tumor parameters and local and regional outcome of tonsillar cancer after definitive radiation treatment.

PURPOSE: To investigate the value of CT-derived tumor parameters as predictor of local and regional outcome of tonsillar squamous cell carcinoma treated by definitive radiation therapy. METHODS AND MATERIALS: The pretreatment CT studies of 112 patients with tonsillar squamous cell carcinoma were reviewed. After redigitizing the films, primary and nodal tumor volume was calculated with the summation-of-areas technique. The nodal CT aspect was graded using a 3-point scale (homogenous, inhomogeneous, and necrotic). Mean follow-up time was 33 months. Actuarial statistical analysis of local and regional outcome was done for each of the covariates; multivariate analysis was performed using Cox's proportional hazards model. RESULTS: In the actuarial analysis, CT-determined primary tumor volume was significantly correlated with local recurrence rate (p < 0.05) when all patients were considered, but primary tumor volume did not predict local control within the T2, T3, and T4 category. CT-determined nodal volume was significantly related to regional outcome (p < 0.01), but nodal density was not. Total tumor volume was not significantly related to locoregional outcome (p = 0.1). In the multivariate analysis, the T and N categories were the independent predictors of local and regional outcomes, respectively. CONCLUSION: Compared to other head-and-neck sites, primary and nodal tumor volume have only marginal predictive value regarding local and regional outcome after radiation therapy in tonsillar cancer.

Adult↗
PubMed2001

Interobserver variations in gross tumor volume delineation of brain tumors on computed tomography and impact of magnetic resonance imaging.

PURPOSE: (1) To assess the interobserver variability of brain tumor delineation on computed tomography (CT). (2) To assess the impact of the addition of magnetic resonance imaging (MRI) information. METHODS: Nine physicians were asked to delineate the gross tumor volume (GTV) of five patients with supratentorial inoperable brain tumors on CT scans and 2 weeks (or more) later on MRIs. The delineations were performed on a computer screen. During delineation on MRI, the registered CT images (without delineation) were displayed on the screen (MRI+CT). RESULTS: A high interobserver variability in GTV delineation on CT is found: the ratio of the largest to the smallest defined volumes varies for the five patients by factors of resp. 2.8, 1.8, 1.8, 1.9 and 1.7. The interobserver variability is as large on MRI+CT as on CT alone (ratio largest/smallest volume: 2.4, 1.7, 1.9, 2.7 and 1.5). Volumes delineated on MRI+CT (mean: 69.6 cm(3)) are larger than on CT alone (mean: 59.5 cm(3)). Residual volumes (volume delineated on one image modality but not on the other) are >0 for CT alone and for MRI+CT. CONCLUSIONS: A large interobserver variability in GTV delineation of brain tumors is demonstrated. The addition of MRI to CT does not reduce interobserver variability. GTVs delineated on MRI+CT are larger than on CT alone, but some volumes are delineated on CT and not on MRI. Therefore, a combination of the two image modalities is recommended for brain tumor delineation for treatment planning.

Brain Neoplasms↗
PubMed2001

Free cytosolic Ca2+ recordings from myenteric neurones in multilayer intestinal preparations.

The ability to simultaneously monitor different myenteric neurones in a multilayer preparation may enhance our understanding of the enteric nervous system. Longitudinal muscle myenteric plexus preparations were mounted in recording chambers with a coverslip base and loaded with Indo-1-AM. cytosolic Ca2+ concentration ([Ca2+]i); changes were recorded at room temperature with a confocal microscope. In addition to mechanical (pressure-ring) and pharmacological (nifedipine) reduction of muscle contractions, purpose-designed software was developed to reposition regions of interest and avoid artefacts. Confocal scanning permitted optical selection of single cell layers. High K+ depolarization, used to distinguish between excitable and nonexcitable cells, caused a synchronous [Ca2+]i rise in 84.3% of the ganglion cells. Acetylcholine, substance P and serotonin (all at 10(-5) mol L(-1)) induced transient [Ca2+]i changes in subpopulations of myenteric neurones (45.1%, 42.9 and 21.9%, respectively). In addition to immediate responses to agonists, delayed [Ca2+]i changes were also recorded, suggesting the presence of both directly activated and synaptically driven neurones. Functionally identified neurones and other cells in close apposition to the ganglia (interstitial cells of Cajal) could also be studied. This study demonstrates the potential of optical Ca2+ recordings to monitor spread of activity in myenteric neurones and to study their interaction with non-neuronal targets.

Acetylcholine↗
PubMed2000

Synaptic transmission induces transient Ca2+ concentration changes in cultured myenteric neurones.

The enteric nervous system controls most of the gastrointestinal functions. We applied confocal microscopy and the Ca2+ indicator Fluo-3 as an optical approach to study synaptic activation in cultures of myenteric neurones. The optical recording of [Ca2+]i (the intracellular Ca2+ concentration) was used to monitor activation, since [Ca2+]i is crucial in the coupling between neuronal excitation and the activation of several intracellular events. Extracellular fibre tract stimulation (2 s, 30 Hz) caused a transient [Ca2+]i rise in a subset of neurones (50%). These transients lasted for 5.2 s (n=36), with an average amplitude of 3.4 +/- 1.3 times the basal concentration. The removal of extracellular Ca2+ (n=15) or the application of 10-6 M tetrodotoxin (n=16) blocked this response. The N-type Ca2+-channel blocker omega-conotoxin (5 x 10 -7M) abolished the [Ca2+]i increase, while blockade of L-type and P/Q type Ca2+ channels had no effect. Single stimuli evoked a [Ca2+]i rise in the processes. omega-conotoxin-sensitive postsynaptic events required repetitive stimulation. Cholinergic blockade did not inhibit the [Ca2+]i rise in all neurones, suggesting that, besides acetylcholine, other neurotransmitters are involved. Optical imaging of [Ca2+]i can be used to study synaptic spread of activation in enteric neuronal circuits expressed in culture.

Action Potentials↗
PubMed1999

The contribution of magnetic resonance imaging to the three-dimensional treatment planning of localized prostate cancer.

PURPOSE: To investigate whether the use of transaxial and coronal MR imaging improves the ability to localize the apex of the prostate and the anterior part of the rectum compared to the use of transaxial CT alone, and whether the incorporation of MR could improve the coverage of the prostate by the radiotherapy field and change the volume of rectum irradiated. METHODS AND MATERIALS: Ten consecutive patients with localized prostate carcinoma underwent a CT and an axial and coronal MR scan in treatment position. The CT and MR images were mathematically aligned, and three observers were asked to contour independently the prostate and the rectum on CT and on MR. The interobserver variability of the prostatic apex location and of the delineation of the anterior rectal wall were assessed for each image modality. A dosimetry study was performed to evaluate the dose to the rectum when MR was used in addition to CT to localize the pelvic organs. RESULTS: The interobserver variation of the prostatic apex location was largest on CT ranging from 0.54 to 1.07 cm, and smallest on coronal MR ranging from 0.17 to 0.25 cm. The interobserver variation of the delineation of the anterior rectum on MR was small and constant along the whole length of the prostate (0.09+/-0.02 cm), while for CT it was comparable to that for the MR delineation at the base of the prostate, but it increased gradually towards the apex, where the variation reached 0.39 cm. The volume of MR rectum receiving more than 80% of the prescribed dose was on average reduced by 23.8+/-11.2% from the CT to the MR treatment plan. CONCLUSION: It can be concluded that the additional use of axial and coronal MR scans, in designing the treatment plan for localized prostate carcinoma, improves substantially the localization accuracy of the prostatic apex and the anterior aspect of the rectum, resulting in a better coverage of the prostate and a potential to reduce the volume of the rectum irradiated to a high dose.

Dose-Response Relationship, Radiation↗
PubMed1998

Laryngeal tumor volume measurements determined with CT: a study on intra- and interobserver variability.

PURPOSE: To investigate the intra- and interobserver variability of computed tomography-based volume measurements of laryngeal tumors. METHODS AND MATERIALS: The volume of 13 laryngeal tumors was repeatedly measured by five independent observers in four different sessions, using the summation-of-areas technique. Mean tumor volume and its standard deviation were calculated for each tumor. Statistical analysis was done with analysis of variance, Spearman rank correlation, and linear regression. RESULTS: Both the effect of the observers (p < 0.0001) and the effect of the session (p < 0.01) on tumor volume was statistically significant. Interobserver variability was the most important component of total variability (89.3%). A significant rank correlation was found between mean volume and standard deviation (p < 0.01); the relationship between mean tumor volume and standard deviation can be described using linear regression [standard deviation = 0.28 volume + 0.35 (R = 0.79)]. CONCLUSION: Total variability in the computed tomography-based measurement of laryngeal tumor volume can be reduced by having the measurements done by a single trained observer.

Analysis of Variance↗
PubMed1997

Evaluation of manual vs semi-automated delineation of liver lesions on CT images.

In this paper we compare a semi-automated delineation method with totally manual delineation for area quantification, with respect to efficiency, quality, and intra- and interobserver variability. Liver lesions on 28 CT images were delineated by three observers, twice using completely manual delineation and twice using a semi-automated method. Quantitative comparisons were performed with respect to delineated area and time required for the delineation tasks. Subjective comparisons were performed with respect to efficiency and perceived quality of the semi-automated method. The areas obtained using semi-automated delineation were significantly smaller (11 %) than those obtained using totally manual delineation. Intraobserver and interobserver variability with the semi-automated method were approximately three times lower than with manual delineation. Efficiency of the semi-automated method was subjectively rated favorable, although further improvements are possible. With respect to quality, the semi-automated method was ranked better than the manual method in 73 % of cases.

Humans↗
PubMed1997

Size quantification of liver metastases in patients undergoing cancer treatment: reproducibility of one-, two-, and three-dimensional measurements determined with spiral CT.

PURPOSE: To assess the reproducibility of one-, two-, and three-dimensional measurements of the size of liver metastases. MATERIALS AND METHODS: The sizes of 10 liver metastases were determined 200 times: Ten observers measured each lesion by using images obtained at two different CT studies and with five different measurement techniques (maximum diameter, product of diameters, area, volume, and product of three diameters). They repeated each measurement in a separate session. The influence of measurement technique and lesion type (size and morphologic appearance) on measurement reproducibility was assessed. RESULTS: Three-dimensional measurements proved to be as reproducible as one- and two-dimensional measurements. Measurement reproducibility was influenced mainly by the size (P < .0001) and morphologic appearance (P < .01) of the lesions. CONCLUSION: Three-dimensional size measurements obtained with spiral CT are reproducible and could therefore replace the two-dimensional measurements of tumor size currently obtained with follow-up CT studies.

Humans↗
PubMed1996

Integrating digital ICU viewing into the global working environment.

We illustrate that to benefit from the advantages of Picture Archiving and Communication Systems (PACS) for the Intensive Care Unit (ICU), the PACS must be strongly integrated within the overall working environment. This includes adaptation of the PACS toward specific working patterns and integrating it with the Hospital Information System (HIS). This is reflected in our prototype system in different ways. The user interface of the viewing station is centered around often used patterns in ICU viewing. Information about bed occupancy is retrieved from the HIS and exploited in the viewing station. A digital connection between the phosphorplate scanner and the HIS ensures that images are correctly related to other patient information and to previous images. Using minor adaptations to the existing HIS, PACS and HIS have been made to cooperate in integrated presentation of images and radiological reports, as a step towards a multi-media medical information system. We discuss the relation between PACS and the global information environment, emphasizing organizational issues rather than technological aspects.

Computer Systems↗
PubMed1995

Experimental teleradiology. Novel telematics services using image processing, hypermedia and remote cooperation to improve image-based medical decision making.

We illustrate the possible impact of information technology on digital radiology using two pilot projects. The first aimed to improve the transfer of radiological information and the interaction between radiologist and referring physician, using hypermedia documents and hypermedia electronic mail. During a 12-month evaluation period, approximately 100 hypermedia reports were generated and distributed to hepatologists and neurosurgeons. The second project aimed to improve planning of orthopaedic surgery, using an image processing service for three-dimensional visualization and a conferencing system to support active cooperation. Over two months, 12 routine cases were reconstructed in three dimensions and conferencing was carried out between surgeons and radiologists in hospitals 15 km apart. Initial results were encouraging. Telematics may be valuable in reconciling the growing need for multidisciplinary cooperation with the growing geographical and organizational separation of different experts. We conclude that to benefit from information technology, the focus should not be on a direct translation of traditional working methods, but rather on possibilities that were not available in the film-based environment.

Belgium↗
PubMed1995

Emergent treatment of pelvic fractures. Comparison of methods for stabilization.

The emergent care of an unstable pelvic ring disruption in the patient who is hemodynamically unstable includes rapid application of military antishock trousers or an external fixator in an attempt to control bleeding and hemodynamically stabilize the patient. However, use of the military antishock trousers is limited in that it restricts access to the abdomen and lower extremities. The external fixator is limited at many institutions by the need to apply it in the operating room. Two experimental devices have been developed to provide emergent pelvic fracture reduction and temporary stabilization in the trauma room, while maintaining access to the abdomen and lower extremities. This study compared the efficacy of pelvic fracture reduction and stabilization in a cadaveric model using an external fixator with the efficacy of 2 experimental devices, the pelvic stabilizer and the pelvic c-clamp. Based on their ability to restore pelvic volume and reduce pubic diastasis and their application time, the 3 devices performed similarly. Complications in applying each device were noted but were of less clinical significance for the external fixator. Surgeon practice on cadavera before clinical use will help ensure safe application of either experimental device in the trauma room.

Aged↗
PubMed1994

Combining fast response and low cost in an intensive care unit viewing station.

This paper describes a prototype viewing station for the Intensive Care Unit (ICU) that combines a low cost with a fast response for the primary viewing tasks. A single monitor is used together with the possibility to switch to another image on the same screen instantaneously. To reduce the time for image retrieval and display, the viewing station anticipates the need for particular images, and preloads these from the disk into the internal memory whenever the computer has some idle time. Preliminary experience suggests that the use of a single monitor is no fundamental limitation for this application. Most of the time, the system can anticipate which images will be required shortly. This has an important impact on the user efficiency.

Data Display↗