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R Duvauferrier

Publications and source records attributed to R Duvauferrier.

At least 37 records · Page 2Linked to original sources
PubMed1999

Slice simulation from a model of the parenchymous vascularization to evaluate texture features: work in progress.

RATIONALE AND OBJECTIVES: To demonstrate the usefulness of a model of the parenchymous vascularization to evaluate texture analysis methods. METHODS: Slices with thickness varying from 1 to 4 mm were reformatted from a 3D vascular model corresponding to either normal tissue perfusion or local hypervascularization. Parameters of statistical methods were measured on 16128x128 regions of interest, and mean values and standard deviation were calculated. For each parameter, the performances (discrimination power and stability) were evaluated. RESULTS: Among 11 calculated statistical parameters, three (homogeneity, entropy, mean of gradients) were found to have a good discriminating power to differentiate normal perfusion from hypervascularization, but only the gradient mean was found to have a good stability with respect to the thickness. Five parameters (run percentage, run length distribution, long run emphasis, contrast, and gray level distribution) were found to have intermediate results. In the remaining three, curtosis and correlation was found to have little discrimination power, skewness none. CONCLUSION: This 3D vascular model, which allows the generation of various examples of vascular textures, is a powerful tool to assess the performance of texture analysis methods. This improves our knowledge of the methods and should contribute to their a priori choice when designing clinical studies.

Blood Vessels↗
PubMed1999

[Comparison of accreditation procedures, ISO 9000 certification procedures and total quality management. Personal experiences and application of quality assurance in a department of radiology and medical imaging].

Management of quality assurance protocols in a radiology department can be done by using several tools or models. Some are specific like accreditation manuals issued by some organizations, others like the ISO 9000 certification and the Total Quality management are more general and already well known by manufacturers. In order to implement a process of quality improvement, we have reviewed three models of quality assurance: evaluation in total quality based on the European model "EFQM", accreditation based on booklets from French cancer centers and Canadian radiology centers and, finally, accreditation based on the ISO 9002 certification model. Based on results of our comparative study, these three tools of quality management are not contradictory and may be complementary. However, they can be compared in terms of constraints they impose, of their historical background, of the criteria evaluated as well as the role of different teams. In conclusion, we suggest that directors of radiology department interested in implementing a quality assurance program first evaluate their department using the Canadian accreditation model issued in 1993 which is useful to become familiar with this new concept of quality. In a second step, a self assessment using the EFQM has to be done in collaboration with all members of the administration board in order to integrate all parameters and to share this protocol with all decision makers. The last step is to consolidate the organization of the quality assurance protocols by means of the ISO 9002 certification.

Accreditation↗
PubMed1999

[Web radiology servers: advices for users, their development and evaluation of the quality of sites].

Sites available on the Internet are constantly increasing and over 15,000 medical websites covering all medical sub-specialties are now available. Finding relevant information on the web may be time consuming and difficult. We suggest that new users begin by accessing servers where lists of available sites are grouped under headings such as medical sub-specialties. We will list a selection of useful radiological websites providing image databases, case reports, radiological anatomy and continuing medical education. While surfing on the web, an evaluation of the quality of the websites is necessary. We used the quality criteria proposed by Darmoni to rate the quality of ten websites. The overall quality was good, but the lack of help options and external links were the main pitfalls that we noted. All webmasters should pay attention to quality criteria and show the Darmoni criteria on their homepage. In order to evaluate which internet options should be developed, we evaluated our own website and submitted a questionnaire to our users. Clinical cases were the most requested feature, they could be used for continuing medical education.

Computer-Assisted Instruction↗
PubMed1999

[From accreditation to certification. Quality management in a radiology department].

The leaders of a radiology department started a quality process based on ISO 9001 certification and the total quality management program. The purpose of this work is to match the conformity of this quality system to ANAES recommendations. If the concordance is obvious, the advantages of using quality insurance to get an accreditation are important. In conclusion, a quality process is proposed, it includes a quality insurance manual of ISO 9001 norm, the total quality management in the first point of the norm and the ANAES recommendations spread over the 20 points of the norm.

Accreditation↗
PubMed1999

[Optimization of a teleradiology system between two geriatric hospitals and a radiology department of a CHU].

The routine use of a 64 kb/sec Numeris network requires that a compromise be reached between image quality and time required for image transfer. Our goal was to present our experience and describe our choices when reporting examinations for two geriatric hospitals located at a short distance from our radiology department. Different digitization parameters were tested (resolution, compression) for 10 plain films corresponding to the usual clinical situations: abdominal X ray, chest X ray, wrist, spine and pelvis X rays. A subjective analysis of the global quality and of the quality of a region of interest enlarged twelve times has been performed. After result analysis, our choices were: digitization using 75 or 150 DPI and systematic use of a reversible compression format. This system proved satisfactory for both clinicians and radiologists; since its implementation, 1,800 files have been reviewed.

Computer Communication Networks↗
PubMed1998

Lower limb angiography: a prospective study comparing carbon dioxide with iodinated contrast material in 30 patients.

OBJECTIVE: We prospectively compared patients' tolerance for and the usefulness of carbon dioxide (CO2) with iodinated contrast material in the study of lower limb arteries in 30 patients. SUBJECTS AND METHODS: We systematically performed digital subtraction angiography with electronic injection of CO2 (injection average, 330 ml) and digital subtraction angiography with iodinated contrast material in 30 patients (20 men and 10 women; mean age, 67.5 years) suffering from lower limb ischemia. Patients were monitored for vital signs and comfort. Four reviewers subjectively evaluated vessel visibility at five levels (pelvis, thigh, knee, calf, and ankle). We used the Student's t test to evaluate the tolerance and the global examination quality. The chi-square test was used to evaluate the stratified analysis of the observers and scores of the image quality according to the anatomic level studied. Bartlett's test of equality of variances was used to compare the variances between the readers. RESULTS: CO2 was less well tolerated (p < .01) than iodine was. Fifty-three percent of patients reported CO2 was equally well tolerated (53%), 40% reported more discomfort than with iodine, and 4% reported less discomfort than with iodine. Both techniques were equivalent for imaging of the iliac arteries, but CO2 performed poorly in the arteries below the knee (p << .001). CONCLUSION: CO2 angiography with electronic injection proved to be less comfortable than iodinated angiography. CO2 arteriography is equivalent to iodinated arteriography for imaging the iliac arteries but imaging performance progressively degrades in the more distal arteries of the legs.

Adult↗
PubMed1998

A virtual university Web system for a medical school.

This paper describes a Virtual Medical University Web Server. This project started in 1994 by the development of the French Radiology Server. The main objective of our Medical Virtual University is to offer not only an initial training (for students) but also the Continuing Professional Education (for practitioners). Our system is based on electronic textbooks, clinical cases (around 4000) and a medical knowledge base called A.D.M. ("Aide au Diagnostic Medical"). We have indexed all electronic textbooks and clinical cases according to the ADM base in order to facilitate the navigation on the system. This system base is supported by a relational database management system. The Virtual Medical University, available on the Web Internet, is presently in the process of external evaluations.

Computer-Assisted Instruction↗
PubMed1998

Computed tomography guided thoracic sympatholysis for palmar hyperhidrosis.

METHODS: Sixteen patients (mean age 26.3 years; range 18-38) with palmar hyperhidrosis underwent 29 sympatholyses after unsuccessful medical, and in 8 ionophoresis, treatments. Sympatholysis was performed under local anesthesia with computed tomographic guidance. After opacification of the injection site at T3 with Iopamiron 200, phenolization was performed with 10 ml 6% phenol. RESULTS: Good immediate results evaluated on the basis of venous dilatation, and dryness and warmth of the skin were obtained in 23 cases (80%). There were 6 immediately unsuccessful procedures in 4 patients. At 20 months, good results, assessed on the basis of objective criteria and subjective patient self-evaluation were obtained in 22 cases (75% including immediate failures). Computed tomography guided thoracic sympatholysis performed under local anesthesia is an effective treatment for palmar hyperhidrosis. Morbidity is low and hospital stay is short. CONCLUSIONS: Our findings suggest that thoracic sympatholysis should be indicated as the first intention procedure when surgery is required in patients with palmar hyperhidrosis.

Adolescent↗
PubMed1998

[The virtual university in medicine. Context, concepts, specifications, users' manual].

The widespread use of Web servers, with the emergence of interactive functions and the possibility of credit card payment via Internet, together with the requirement for continuing education and the subsequent need for a computer to link into the health care network have incited the development of a virtual university scheme on Internet. The Virtual University of Radiology is not only a computer-assisted teaching tool with a set of attractive features, but also a powerful engine allowing the organization, distribution and control of medical knowledge available in the www.server. The scheme provides patient access to general information, a secretary's office for enrollment and the Virtual University itself, with its library, image database, a forum for subspecialties and clinical case reports, an evaluation module and various guides and help tools for diagnosis, prescription and indexing. Currently the Virtual University of Radiology offers diagnostic imaging, but can also be used by other specialties and for general practice.

Computer-Assisted Instruction↗
PubMed1998

[Radiologic analysis of known-interval cancers after 2 years of organized mass screening for breast cancer in Ille-et-Vilaine].

The first thirty-two known interval breast cancers (appearing within the first or second year after a negative screen) occurring during a two-year breast screening round were reviewed and the radiograms analyzed. Five classes were established: true interval cancers (13/32 cases), radiologically occult cancers (2/32), cancers with no specific sign (7/32), false negative cancers (5/32) and unclassifiable cancers (5/32). In more than 50% of the cases, there was no abnormality on the initial radiographic test, although the literature reports that the rate of false-negatives in interval cancers is less than 20%. Standard classification (by at least 3 readers) is very important to provide a possible explanation of cancer development. Action should be initiated to reduce their number.

Adult↗
PubMed1997

Prospective randomized trial of chemoembolization versus intra-arterial injection of 131I-labeled-iodized oil in the treatment of hepatocellular carcinoma.

Intra-arterial injection of radioactive Lipiodol has shown promising results in patients with hepatocellular carcinoma (HCC) and portal obstruction. The aim of this prospective, randomized trial was to compare the efficacy and tolerance of 131I-labeled Lipiodol and chemoembolization for the treatment of patients with HCC. From September 1990 to September 1993, 142 patients (135 men, 7 women; age: 65 +/- 6.6 years) were randomly assigned to treatment groups and given either intra-arterial injections of 131I-labeled Lipiodol (60 mCi; 2.2 GBq) (n = 73) or chemoembolization (70 mg cisplatin) (n = 69). Subsequent injections were given at 2, 5, 8, 12, and 18 months. Tumor response was assessed on the basis of tumor size and serum alpha-fetoprotein levels. Patient tolerance was assessed clinically and angiographically. Survival rate was the main end-point. A total of 129 patients (65 in the 131I-labeled Lipiodol group and 64 in the chemoembolization group) were available for analysis; 13 were excluded, mainly because of portal vein thrombosis. The two groups were comparable. Actuarial survival curves were not significantly different between the two groups. Overall survival rates at 6 months, 1, 2, 3, and 4 years were 69%, 38%, 22%, 14%, and 10%, and 66%, 42%, 22%, 3%, and 0% in the 131I-labeled Lipiodol and chemoembolization groups, respectively. Reduction in tumor size was similar for the two groups, with complete response in 1 and 0 patients and partial response in 15 and 16 patients in the 131I-labeled Lipiodol and chemoembolization groups, respectively. Tolerance was significantly better in the 131I-labeled Lipiodol group both clinically (3 severe side effects vs. 29 in the chemoembolization group; P < .001) and angiographically (1 arterial thrombosis vs. 10 in the chemoembolization group; P < .01). In terms of patient survival and tumor response, radioactive 131I-labeled Lipiodol and chemoembolization were equally effective in the treatment of HCC, but tolerance to 131I-labeled Lipiodol was significantly better.

Aged↗
PubMed1997

A network of web multimedia medical information servers for a medical school and university hospital.

Modern medicine requires a rapid access to information including clinical data from medical records, bibliographic databases, knowledge bases and nomenclature databases. This is especially true for University Hospitals and Medical Schools for training as well as for fundamental and clinical research for diagnosis and therapeutic purposes. This implies the development of local, national and international cooperation which can be enhanced via the use and access to computer networks such as Internet. The development of professional cooperative networks goes with the development of the telecommunication and computer networks and our project is to make these new tools and technologies accessible to the medical students both during the teaching time in Medical School and during the training periods at the University Hospital. We have developed a local area network which communicates between the School of Medicine and the Hospital which takes advantage of the new Web client-server technology both internally (Intranet) and externally by access to the National Research Network (RENATER in France) connected to the Internet network. The address of our public web server is http:(/)/www.med.univ-rennesl.fr.

Artificial Intelligence↗
PubMed1997

Computer assisted medical diagnosis using the Web.

The ADM (Aide au diagnostic Medical) project was started 15 years ago and was the first telematic project for physicians in France using the MINITEL terminal. The knowledge base contains information on more than 10000 diseases from all pathological fields, using more than 100000 signs or symptoms. The ADM system has two main functionalities for physicians: consultation of diseases descriptions and list of diseases containing one or more symptoms. The ADM knowledge base is supported by a relational database management system (DBMS ORACLE) and we developed a Web interface using the Perl language to produce HTML pages for the web server. We will describe our experience on redesigning a large existing medical knowledge base for diffusion on the web Internet.

Artificial Intelligence↗
PubMed1997

[Evaluation of carboxy-angiography in the study of arteriopathy of the lower limbs].

PURPOSE: We prospectively compared the safety and the usefulness of CO2 with iodinated contrast material in the study of lower limb arteries. PATIENTS AND METHOD: The study included 30 patients (20 men, 10 women, mean age 67) suffering from lower limb ischemia: stage II (3), stage III (13), stage IV (9), Leriche syndrome (1), post-operative (4). We systemically performed an aortic injection (L3), via a 4F catheter, of (1) CO2-DSA (5 to 6 injections of 75 ml at a flow rate of 20 ml/s) and (2) DSA with iodine contrast material (100 ml at a flow rate of 8 ml/s). Patients were monitored for pain and vital signs. Four reviewers did a subjective evaluation of the vessel visibility at five levels (pelvis, thigh, knee, calf, ankle). RESULTS: No side effect was found. Concerning pain, the patients had the same sensation in 53%; pain was more disagreeable with CO2 in 40%, more disagreeable with iodine in 7%. Concerning vessel visualization, there was a good coherence between the readers and we found the same quality in 61%. CO2 was less informative in 35%, and more informative in 4%. Image quality decreased with fragmentation of the gas and remoteness of injection site. CONCLUSION: CO2 angiography, with electronic injection, is a safe alternative to conventional angiography with iodinated contrast material. The disagreeable sensations can be reduced with explanations given before injection and reducing flow rate. Image stacking software could imitate the side effects of fragmentation of the CO2 bubble. This method appears to be a good alternative for patients with severe renal impairment or allergic problems.

Adult↗
PubMed1997

[Value of automated medical indexing of an image database and a digital radiological library].

We indexed the contents of a radiology server on the web to facilitate access to research documents and to link reference texts to images contained in radiology databases. Indexation also allows case reports to be transformed with no supplementary work into formats compatible with computer-assisted training. Indexation was performed automatically by ADM-Index, the aim being to identify the medical concepts expressed within each medical text. Two types of texts were indexed: medical imaging reference books (Edicerf) and case reports with illustrations and captions (Iconocerf). These documents are now available on a web server with HTML format for Edicerf and on an Oracle database for Iconocerf. When the user consults a chapter of a book or a case report, the indexed terms are displayed in the heading; all reference texts and case reports containing the indexed terms can then be called up instantaneously. The user can express his search in natural language. Indexation follows the same process allowing instantaneous recall of all reference texts and case reports where the same concept appears in the diagnosis or clinical context. By using the context of the case reports as the search index, all case reports involving a common medical concept can be found. The context is interpreted as a question. When the user responds to this question, ADM-Index compares this response with the answer furnished by the reference texts and case reports. Correct or erroneous responses can thus be identified, converting the system into a computer-assisted training tool.

Abstracting and Indexing↗