Biomedical subjects

F Esteve

Publications and source records attributed to F Esteve.

9 recordsLinked to original sources

PubMed2002

Cerebral blood volume mapping by MR imaging in the initial evaluation of brain tumors.

PURPOSE: To assess the contribution of magnetic resonance (MR) cerebral blood volume (CBV) mapping in the initial evaluation of brain tumors. METHODS: 63 patients presenting a brain tumor underwent dynamic susceptibility-contrast MR imaging before surgery or biopsy: 28 high grade gliomas, 8 low grade gliomas, 2 pilocytic astrocytomas, 4 lymphomas, 12 metastases, 9 meningiomas. The CBV maps were obtained for each patient and the relative CBV (rCBV) in different areas was calculated using the ratio between the CBV in the pathological area (CBVp) and in the contralateral normal tissue(CBVn). The maximum rCBV (rCBVmax) for each tumor was determined and the mean values of rCBVmax in each group of tumors were compared using an unpaired Student t test (p=0.05). RESULTS: The rCBVmax for high grade gliomas (mean +/- SD: 2.6 +/- 1,2) was statistically different from low grade gliomas (0.9 +/- 0.4) (p<0.001), lymphomas (0.7 +/- 0.2) (p=0.002), meningiomas (9.1 +/- 4.4) (p<0.001) and kidney metastases (8.9 +/- 2.1) (p<0.001). The two pilocytic astrocytomas had a much lower rCBVmax than high grade gliomas. No statistically significant difference was found between high grade gliomas and lung metastases (2.4 +/- 0.9) (p=0.72). CONCLUSION: CBV mapping provides additional information on the vascularity of the lesions, which is not available with conventional MR imaging. It might be useful for differentiating certain lesions showing contrast enhancement, mainly high grade gliomas from kidney metastases, meningiomas, lymphomas or pilocytic astrocytomas.

Blood Volume↗

PubMed2001

A direct, automated, immuno-turbidimetric assay of free protein S antigen in plasma.

A new, fully automated, one-step, immuno-turbidimetric assay of free protein S (fPS) in plasma (STA Liatest Free Protein S; Diagnostica Stago, Asnières, France) has been developed for STA analysers. This technique combines the advantages of a direct assay of fPS using two monoclonal antibodies, which specifically recognize fPS but not protein S (PS)-C4b-binding protein complexes, and the advantages of automation. The assay has good analytical performances, with intra- and inter-assay variation coefficients below 5% for normal values, and slightly higher for abnormal values. In a comparison study with a one-step enzyme-linked immunosorbent assay for fPS (Asserachrom Free Protein S; Diagnostica Stago), a correlation coefficient of 0.93 with a regression line close to 1 was found between the two techniques (n = 166 normal or PS-deficient plasma samples collected from healthy subjects and individuals with a personal or family history of thrombosis). This new technique is specific, reproducible, easy to perform, and provides a useful tool in the diagnosis of PS deficiency.

Adolescent↗

PubMed2000

[Severe digoxin poisoning. The successful use of the classic treatment].

In our environment, the use of Fab antibodies for digoxin intoxication is often difficult due to the low availability of this drug in most centers. We present a case of massive digoxin intoxication that was successfully managed with the classic treatment. Later, we discuss the need to individualize the management of this kind of intoxications in order to reduce, when possible, sanitary costs.

Acute Disease↗

PubMed1999

Medialization laryngoplasty.

Medialization laryngoplasty was performed in 25 patients between 1993 and 1997. The underlying pathology resulting in glottal incompetence was vocal cord paralysis in 22 patients and vocal cord bowing in 3 patients. Two types of implants were used: self-carved Proplast in 19 patients and prefabricated hydroxyapatite prostheses in 6 patients. Preoperative and postoperative results were compared in terms of dysphagia, vocal quality as graded by three experienced voice specialists, and computer measurements of the glottal gap. All patients showed improvement both subjectively and on the objective measurements used. Swallowing returned to normal in all patients who had isolated recurrent laryngeal nerve paralysis. The voice improved in all patients but was rarely judged as entirely normal.

Adult↗

PubMed1999

The use of a semi-customized phantom for verification of conformal plans.

We have developed a technique for inverse treatment planning of prostate therapy designed to improve the degree of conformation between the dose distribution and the target volume. We compared the inverse plan with a "standard" four-field box technique as well as a four-field technique using oblique fields ("cross technique"). We validated the dosimetry of the inverse plan using Fricke gel solution in phantom specifically designed for this purpose. The phantom is a Plexiglas tank with a cross section, which approximates the dimensions of the pelvis. Anatomical data from computed tomography (CT) images of a patient were used to simulate organs in our phantom. This allows us to calculate dose distributions with the external geometry of the phantom and internal anatomy of the patient. Dose-volume histograms (DVHs) for the three different plans were calculated. The phantom containing the Fricke gel was irradiated according to the inverse plan. Magnetic resonance (MR) images was used to determine the dose distribution delivered to the phantom. We observe, on DVHs, that the inverse plan significantly reduces the dose to the rectum and the bladder but slightly increases the inhomogeneity inside the target volume. Correlation is good between isodoses on MR images and calculated isodoses. We conclude that inverse planning software can greatly improve the conformal degree of treatment to the prostate. This technique could be applied to other complex anatomic sites at which dose to organs at risk is a limiting factor and increased dose to the target volume is indicated. Our phantom and the Fricke gel solution are convenient to carry out validation of conformal treatments.

Humans↗

PubMed1998

[Robotics in neurosurgery: current status and future prospects].

Neurosurgery is in essence a field of application development for robots, based on multimodal image guidance. Specific motorized tools have already been developed and routinely applied in stereotaxy to position a probe holder or in conventional neurosurgery to hold a microscope oriented towards a given target. The potentialities of these approaches have triggered industrial developments which are now commercially available. These systems use databases, primarily coming from multimodal numerical images from X-ray radiology to magnetic resonance imaging. These spatially encoded data are transferred through digital networks to workstations where images can be processed and surgical procedures are pre-planned, then transferred to the robotic systems to which they are connected. We have been using a stereotaxic robot since 1989 and a microscope robot since 1995 in various surgical routine procedures. The future of these applications rely mainly on the technical progress in informatics, about image recognition to adapt the pre-planning to the actual surgical situation, to correct brain shifts (for instance), about image fusion, integrated knowledge such as brain atlases, as well as virtual reality. The future developments, covering surgical procedure, research and teaching, are sure to be far beyond our wildest expectations.

Forecasting↗

PubMed1997

[The robotization of neurosurgery: state of the art and future outlook].

Neurosurgery is by excellence a field of application for robots, based on multimodal image guidance. Specific motorized tools have been already developed and routinely applied in stereotaxy to position a probe holder or in conventional neurosurgery to hold a microscope oriented towards a given target. The potentialities of these approaches have triggered industrial developments currently commercially available. These systems use data bases, primarily coming from multimodal numerical images from X-ray radiology to magnetic resonance imaging. These spatially encoded data are transferred through digital networks to workstations where images can be processed and surgical procedures are preplanned, then transferred to the robotic systems to which they are connected. We have been using a stereotactic robot since 1989 and a microscope robot since 1995 in various surgical routine procedures. The future of these applications mainly rely on the technical progress in informatics, about image recognition to adapt the preplanning to the actual surgical situation, to correct brain shifts for instance, about image fusion, integrated knowledge such such as brain atlases, as well as virtual reality. The future developments, covering surgical procedure, research and teaching, will sure be far beyond our wildest expectations.

Forecasting↗

PubMed1995

[Dynamic characterization of the growth of brain tumors based on image sequences of nuclear magnetic resonance].

The evolution of a high grade glioblastoma of a patient undergoing radio-therapy has been analysed by considering a mathematical model which simulates the brain tumour growth within a two-dimensional domain defined by the brain and ventricles geometry. This simulated behaviour was compared with morphological data obtained from successive nuclear magnetic resonance scans of the patient. The model parameters include the proliferation rate and the diffusion coefficient of the tumour cells as well as their sensitivity to the irradiation. They were estimated using optimisation techniques to minimise the distance between simulated tumour area and scan data from different brain sections. The relevance of this quantitative estimation for the prognosis and for the consideration of additional parameters in the pre and post therapeutic evaluation of glioma is discussed.

Brain↗

PubMed1995

[A new X-ray source for medical imaging and radiotherapy research: synchrotron radiation].

Whether for diagnosis or therapeutic purposes, X-rays have many applications in medicine. Synchrotron Radiation sources open new perspectives. This has already been the case for a number of years in molecular and cellular biology where the scope of absorption and diffraction work has been greatly extended. This could also be the case for medical imaging and radiotherapy where the characteristics of the beam (collimation, stability, flux) allow new approaches in the energy range of radiological X-rays, namely between 30 keV and 100 keV. Such a source exists today in Grenoble, with the European Synchrotron Radiation Facility (ESRF). The opening of a beamline dedicated to medical research for whole European scientific community is planned for the end of 1996. This beamline, coupled with the "microbeam" beamlines, will cover medical imaging (angiography, tomodensitometry, microtomography, X-ray microscopy) as well as radiotherapy.

Animals↗