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Biomedical subjects

M Claudon

Publications and source records attributed to M Claudon.

At least 37 records · Page 2Linked to original sources
PubMed2000

Renal arteries in patients at risk of renal arterial stenosis: multicenter evaluation of the echo-enhancer SH U 508A at color and spectral Doppler US. Levovist Renal Artery Stenosis Study Group.

PURPOSE: To assess SH U 508A in the diagnosis of suspected renal arterial stenosis by means of ultrasonography (US) and to confirm the safety of SH U 508A in a clinical setting. MATERIALS AND METHODS: A randomized crossover study was performed in 198 patients from 14 European centers who were referred for renal arterial angiography because they were suspected of having renal arterial stenosis. All patients underwent nonenhanced and SH U 508A-enhanced Doppler US of the renal arteries. Doppler criteria included measurement of renal arterial peak systolic velocity (threshold, 1.4-2.0 m/sec) in all centers and renoaortic ratio (threshold, 3.0-3.5) in nine. RESULTS: The number of examinations with successful results increased following enhanced Doppler US examination--160 (83.8%) compared with 122 (63.9%) with nonenhanced Doppler US (P = .001), including patients with obesity or renal dysfunction. Renal arterial stenosis (> or =50%) was detected at angiography in 72 patients. Results at enhanced Doppler US were in agreement with results at angiography more often than with results at nonenhanced Doppler US in the diagnosis or exclusion of renal arterial stenosis (P = .001). For patients examined with nonenhanced and enhanced Doppler US, sensitivity (80.0% and 83.7%, respectively) and specificity (80.8% and 83.6%, respectively) remained unchanged. There were no clinically important adverse events following use of SH U 508A. CONCLUSION: In patients suspected of having renal arterial stenosis, SH U 508A increased the number of diagnostic renal arterial Doppler studies.

Adult↗
PubMed2000

[Ultrasound contrast agents].

Ultrasound contrast agents are introducing a new vision to ultrasonography. The increase in the Doppler signal intensity improves difficult examinations. Technical failures in the study of transcranial, liver and renal vessel might be rescued with the injection of these new compounds. The introduction of specific image sequences such as harmonic imaging and pulse inversion imaging allows detection of parenchymal enhancement in liver and renal examinations. The injection of ultrasound contrast agents also provides dynamic quantitative information to develop functional imaging. However, it is mandatory to understand the interaction with the ultrasound beam in order to optimise their use and define the adequate ultrasound sequence.

Artifacts↗
PubMed2000

[Bladder candidosis after renal transplantation: contribution of ultrasonography].

Candidosis of the ureter and the bladder is an infrequent complication after renal transplantation. A case occurring early after kidney transplantation is reported in a patient presenting with candiduria. Ultrasound examination detected several fungal bezoars, presenting as a proliferating, avascular lesions, located within the ureter and the bladder. It allowed to demonstrate the rapid extension of lesions, in spite of a medical treatment, leading to a successful endoscopic removal of fungus balls.

Aged↗
PubMed2000

[Upper urinary tract MRI].

New MRI modalities today available allow exploration of many kidney diseases. Main developments have been made in the diagnosis of small tumors and tumoral extension of huge masses. The other important way of application is MR urography which perfectly show the dilated urinary tract in few seconds. Their potential application are for renal insufficiency, allergic reaction to iodine contrast media and in cases of contra indication to ionised radiations. It is a complementary sequence to assess the urinary tract in pelvic exploration. The evaluation of kidney function will be possible in the near future.

Contraindications↗
PubMed1999

Bilateral cystic lymphangioma of the adrenal gland.

We report the case of a 22-year-old woman with a large, bilateral lymphangiomatous cyst originating from the adrenal glands. Since she was having persistent pain and the diagnosis was uncertain, we did surgery.

Adrenal Gland Neoplasms↗
PubMed1999

Renal blood flow in pigs: changes depicted with contrast-enhanced harmonic US imaging during acute urinary obstruction.

PURPOSE: To evaluate contrast agent-enhanced harmonic ultrasonographic (US) imaging and Doppler hemodynamics during acute urinary obstruction. MATERIALS AND METHODS: In 12 piglets, the distal ureter was obstructed for 60 minutes, followed by intravenous injection of furosemide. In six piglets, ureteral pressure was further elevated to mean arterial pressure, and in six other piglets ureteral obstruction was released. Contrast-enhanced harmonic imaging was performed, and interlobar resistive index (RI) and renal blood flow were determined at baseline and during each experimental condition. A bolus injection curve was constructed by plotting mean pixel intensity versus time, and the area under this normalized curve was compared with renal blood flow values. RESULTS: Ureteral obstruction and high ureteral pressure reduced cortical renal blood flow to 88% and 66%, respectively, of baseline values. Administration of contrast agent resulted in marked homogeneous enhancement of the renal cortex. The area under the curve diminished during ureteral obstruction and correlated well with mean cortical blood flow. RI correlated well with renal perfusion pressure but poorly with changes in renal blood flow. CONCLUSION: Contrast-enhanced harmonic US imaging depicts changes in renal blood flow during acute obstruction. Interlobar RI is a good predictor of renal perfusion pressure but not of changes in renal blood flow.

Animals↗
PubMed1999

Depiction of renal perfusion defects with contrast-enhanced harmonic sonography in a porcine model.

OBJECTIVE: Our purpose was to test the feasibility and optimization of contrast-enhanced gray-scale harmonic sonography for the evaluation of focal renal perfusion defects in an animal model. SUBJECTS AND METHODS: We performed arteriography and contrast-enhanced harmonic sonography on six anesthetized piglets after embolization of each kidney with an autologous clot through the main renal artery. Harmonic images were obtained with continuous (30 Hz) and ECG-triggered acquisition. The two harmonic sonography strategies were compared with respect to the number and conspicuity of devascularized areas, and correlation was made with arteriographic findings. RESULTS: Contrast-enhanced harmonic sonography showed focal areas of absent or diminished vascularity that corresponded closely with perfusion defects seen on angiography. Enhancement ratios to perfused cortex were significantly higher than to devascularized cortex in both continuous (mean +/- SD, 469 +/- 5% versus 102 +/- 8%, p < .0005 by t test) and triggered (673 +/- 7% versus 198 +/- 7%, p < .0001) modes. Triggered acquisition increased the conspicuity of perfusion defects over that obtained with continuous imaging (p < .002 by t test). CONCLUSION: Contrast-enhanced harmonic sonography is an effective method of depicting focal renal perfusion defects. Triggered acquisition further improves lesion conspicuity.

Animals↗
PubMed1998

Lymphoproliferative disorders after renal transplantation: role of medical imaging.

Post-transplantation lymphoproliferative disorders (PTLD) are a complication of immunosuppressed transplant recipients, and their incidence is reported to be 20-120 times greater than the rate in the general population. After kidney transplantation, PTLD more likely arise within the renal transplant fossa. Radiological patterns of these forms are presented and discussed, according to a review of the literature, and illustrated by cases from our institution. Ultrasound plays an essential role in the early diagnosis of PTLD by detecting a urinary obstruction associated with adenopathy or an ill-defined mass not previously seen. However, in the case of an inconclusive US examination, CT or MRI should be performed to confirm the presence of a mass. Both techniques are useful in evaluating the extension of the process within the transplantation fossa; MRI seems more accurate and can be used for the follow-up, especially after reduction in immunosuppressive therapy without transplant removal.

Biopsy↗
PubMed1997

Identification of five new genes, closely related to the interleukin-1beta converting enzyme gene, that do not encode functional proteases.

Interleukin-1beta converting enzyme (ICE) was the first identified member of a growing family of cysteine proteases that now includes ten mammalian homologs. Within this large family, two functional proteins, denoted TX and TY share 60% amino-acid identity with ICE in the mature protein and, together with ICE, constitute the ICE subfamily. The present study describes the identification of five new gene sequences, denoted S1-S5, closely related to ICE and TX and belonging to this subfamily. Sequences were identified using genomic Southern-blot analysis of human DNA with probes corresponding to ICE and TX exon 6. Using PCR amplification and cloning, the complete exon-6 sequence of these new genes was identified; three exhibit around 90% identity with Ice within exon 6, whereas the two others share about 70% identity with Ice. Examination of open reading frames and of amino acids essential for ICE activity indicate that none of these genes encodes for a functional protease. In conclusion, extensive analysis of the genes closely related to Ice shows that the Ice subfamily is constituted of eight members. Three of them encode for functional proteases (ICE, TX and TY) whereas the remaining members probably correspond to pseudogenes.

Amino Acid Sequence↗
PubMed1997

Imaging of angiomyolipomas.

In this article we review renal angiomyolipomas (AMLs) from cases in the world literature and 60 cases from our own institution. We also analyze the role and the place of the various imaging techniques in the detection and diagnosis of AMLs. Discussion is focused on the natural history of this benign neoplasm as an isolated form or as a part of the tuberous sclerosis (TS) complex or as part of a third less certain group of multiple AML without stigmata of TS. We also consider the growth patterns and hemorrhagic risks of AML to help define an approach to the current management of this lesion.

Angiomyolipoma↗