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Biomedical subjects

J F Paul

Publications and source records attributed to J F Paul.

31 records · Page 2Linked to original sources
PubMed1999

Electron beam CT features of the pulmonary artery in Takayasu's arteritis.

OBJECTIVE: Pulmonary artery involvement in Takayasu's arteritis is suggestive of the disease. Our aim was to use electron beam CT to study pulmonary artery changes in patients with Takayasu's arteritis. CONCLUSION: Diffuse wall thickening and dilatation or stenosis were significantly more frequent on CT in patients with Takayasu's arteritis than in the control subjects. Knowledge of these findings may be of value when assessing pulmonary artery involvement and thus may be helpful for the diagnosis of Takayasu's arteritis.

Adult↗
PubMed1999

Interobserver variability in the interpretation of renal digital subtraction angiography.

OBJECTIVE: Our purpose was to analyze interobserver variability in the interpretation of renal digital subtraction angiography and to describe the main factors associated with observer discrepancies. MATERIALS AND METHODS: Forty-nine cases of unilateral atheromatous renal artery stenosis of more than 60% were quantified first by local investigators in a multicenter study and then by five other radiologists. Differences between radiologists for the minimum diameter (Dmin), the reference diameter (Dref), and the percentage of stenosis of the renal arteries were analyzed. Interpretations by the local investigators were then compared with the gold standard, defined as the mean for the five radiologists. RESULTS: The average SD for estimation of all renal artery stenoses by all radiologists was 7% for stenosis percentage, 0.5 mm for Dmin, and 0.7 mm for Dref. Main discrepancies occurred more frequently in cases of weakly opacified renal artery stenosis and poststenotic dilatation. The observations of local investigators disagreed by more than two SDs (14%) with the gold standard for 11 of 49 cases (22%). CONCLUSION: The accuracy of digital subtraction angiography in renal artery interpretations is poor because of variations in evaluating both Dmin and Dref. Precise and reproducible methods for quantification of renal artery stenosis are required.

Adult↗
PubMed1997

[Diagnostic approach of pulmonary embolism by spiral angioscanner].

Spiral volumetric computerized tomography (CT) allows the exploration of the whole chest during a single contrast injection and breath-hold. For the diagnosis of central pulmonary embolisms, the sensibility is between 78 and 98% and the specificity between 86 and 94% depending on the direct visualization of the endoluminal defect. Detection of intercurrent parenchymal pathologies or of non-obstructive arterial thrombi explain some false positive or inconclusive results of the ventilation-perfusion scintigraphy. Sub-segmental thrombi are less easily detected and sensibility for both central and sub-segmental embolisms is only 63%, explaining some rare false negatives of the CT on isolated sub-segmental embolisms. Chronic thrombi are outlying and contiguous with the arterial wall. They are associated with arterial stenosis, cut-off and loops and an oligemic mosaic pattern of the parenchyma. CT allows pre-operative staging before surgical recanalization and the intra-venous injection does not interfere with the arterial pressure. CT is a non-invasive, reliable and easily available technique which clearly plays an important role in the diagnosis of pulmonary embolism.

Angiography↗
PubMed1997

Automatic stenosis detection and quantification in renal arteriography.

Visual assessment of the degree of renal artery stenosis on renal arteriography has a large inter- and intraobserver variability. This degree is usually estimated by the ratio between the most narrowed portion of the artery and the reference diameter. The latter is a priori unknown information and thus operator dependent. The objective of the present work was to test the performances of a computer system that was designed to analyze and quantify lesions on 2D renal arteriograms. The main hypothesis was to consider that the most frequent diameter computed along the artery was a good candidate to approximate the reference diameter. Forty nine patient images were collected from the EMMA randomized trial, a multicenter study comparing two treatment strategies in unilateral atheromatous renal artery stenosis of at least 60%. For each image, the degree of stenosis was evaluated by five independent experts and the mean value was used to represent the gold standard for the computer system. The system is based on a fuzzy automaton and performs a syntactic analysis of the arterial segment providing automatic and reproducible quantification of lesions. Both the radiologist caring for the patient and the system were compared to the gold standard. Compared to individual radiologists, the computer system gave a more precise estimation of percent stenosis and did not over or under estimate the severity of the lesion.

Fuzzy Logic↗
PubMed1997

[Detection of renal artery stenoses by MRI with surface reconstruction. Value in patients with chronic renal failure].

Forty-three patients with renal artery stenoses were examined with time of flight MR angiography using maximum intensity projection and surface shaded rendering, and with digital substraction angiography. Sensitivity and specificity were 0.83 and 0.78 for main and secondary arteries, 0.87 and 0.84 for main arteries. In azotemic patients, the positive predictive value was estimated at 40%-70% and the negative predictive value at 95%-98%, while the prevalence of renal artery stenoses varied from 10% to 30%. These results validate MRI for the detection of renal artery stenoses in this population. Surface shaded display was more accurate than maximum intensity projection to reconstruct time of flight sequences and to grade renal artery stenoses.

Adult↗
PubMed1993

Description and representation of segmented renal arteries from angiograms.

This paper presents the first prototype of a system that uses syntactic techniques to describe normal and abnormal aspects of segmented renal arteries from angiographic images. The system is one part of a full understanding system devoted to the interpretation of angiograms. Its purpose is to provide symbolic descriptions of lesions that can further contribute to an accurate diagnosis from the image. The prototype consists of a modular system that takes artery outlines as input and provides a structural description of the artery as output in the framework of a precise quantification scheme. Each module yields heuristic parameters that influence the resulting description. The system is intended to be a tool to study independently the role of these different parameters in the inter and intra observer variability.

Humans↗
PubMed1992

[Treatment of venous thrombosis with low molecular weight heparin and fluindione].

Thirty-one consecutive patients with deep vein thrombosis were treated with Fraxiparine, a low molecular weight heparin, and fluindione, an oral anticoagulant prescribed at an early stage. Despite the weight/biological effectiveness ratio, the dose of Fraxiparine had to be adjusted in 46 percent of the patients to remain within the therapeutic range selected (0.5 to 1 antiXa/ml units). The early administration of fluindione reduced the duration of heparin therapy to 5.75 days. Using a prescription guide on days 2 and 4 might improve the safety of the fluindione induction.

Adult↗
PubMedDate not supplied

Follow-up electron beam CT for the management of early phase Takayasu arteritis.

PURPOSE: The purpose of this work was to assess typical findings of Takayasu arteritis on serial CT examinations following therapy. METHOD: Serial CT studies were performed on 16 patients with early phase Takayasu arteritis. Mural or luminal changes of the aorta on successive CT scans were compared with clinical data. RESULTS: Vascular lesions progressed during follow-up in 6 of 16 patients. In one patient, progression of lesions was symptomatic. In the other five of six patients with worsening lesions, vascular progression occurred without new clinical symptoms and was first identified on CT scans. One of these five had dilatation of the ascending aorta and required aortic repair. Four others had progression of stenotic vascular lesions leading to changes in medical treatment only or in combination with either surgery or angioplasty. For two of them, CT examinations showed decreased mural lesions after changes in medical treatment. CONCLUSION: CT examinations performed in treated patients with Takayasu arteritis demonstrate either regression, stabilization, or progression of vascular lesions. Serial CT examinations may thus be useful for evaluating response to treatment.

Adult↗