Biomedical subjects

Michel Nonent

Publications and source records attributed to Michel Nonent.

10 recordsLinked to original sources

PubMed2006

Multi-slice computer tomography of left ventricular function with automated analysis software in comparison with conventional ventriculography.

PURPOSE: To evaluate the accuracy of left ventricular volumetric and functional parameters from multi-slice computed tomography using automated analysis software, and to correlate results with those of invasive left ventriculography. MATERIALS AND METHODS: In 145 consecutive patients (mean age, 61 years+/-12) known or suspected to have coronary artery disease, a 16-channel multi-slice computed tomography (Philips Mx8000 IDT 16) was performed using a standard technique. Using short-axis secondary multi-slice computed tomography reformations, we determined end-diastolic and end-systolic left ventricular volumes and ejection fraction with a commercially available analysis software capable of automated contour detection. Conventional left ventriculography was performed according to standard techniques within the following 24 h. Bland-Altman analysis was performed to calculate the limits of agreement and systematic errors between multi-slice computed tomography and conventional left ventriculography. RESULTS: As determined by computer tomography, mean end-systolic (53+/-29 mL) left ventricular volumes had an acceptable correlation with conventional ventriculography (67+/-50 mL; r=0.74; p<0.001) and mean end-diastolic (119+/-33 mL) left ventricular volumes a poor correlation with conventional ventriculography measurements (154+/-69 mL; r=0.41). Left ventricular ejection fraction (57%+/-14 versus 55%+/-14 for conventional ventriculography; r=0.79) showed a very good correlation (p<0.001). Bland-Altman analysis showed acceptable limits of agreement (+/-9.2% for ejection fraction) without systematic errors. CONCLUSION: The use of a multi-slice computed tomography with an automatic calculation software has a good correlation with conventional ventriculography findings and could accurately assess left ventricular function, but should not be used for ventricular volumes, because of biased estimations.

Cineradiography↗

PubMed2006

Abdominal and iliac arterial stenoses: comparative double-blinded randomized study of diagnostic accuracy of 3D MR angiography with gadodiamide or gadopentetate dimeglumine.

PURPOSE: To prospectively evaluate accuracy of gadolinium-enhanced three-dimensional (3D) magnetic resonance (MR) angiography with gadodiamide and gadopentetate dimeglumine (0.1 mmol/kg), with intraarterial DSA as reference standard, for imaging abdominal and iliac arterial stenoses. MATERIALS AND METHODS: The study was approved by all institutional review boards; informed consent was obtained from each subject before procedures. Two hundred forty-seven subjects were included; 240 received either contrast agent and were available for safety analysis; 222 were available for accuracy analysis. Enhanced 3D MR angiography and DSA were performed; image data were evaluated in a double-blinded randomized study. Stenoses were classified as not relevant (<50% stenosis) or relevant (> or =50%). For detection of main stenosis, accuracy with enhanced 3D MR angiography compared with that with DSA was determined. RESULTS: The difference in accuracy for imaging with gadodiamide and gadopentetate was 3.6%. Noninferiority was inferred because the lower bound of the exact two-sided 95% confidence interval was -10.1 and was above the noninferiority margin (-15%). Accuracy for detection of the main stenosis was low, 56.4% for gadodiamide and 52.8% for gadopentetate group. Subgroup analysis with exclusion of inferior mesenteric artery and internal iliac arteries and the most false-positive stenosis classifications yielded better results: 76.6% and 71.6%, respectively. Sensitivity, specificity, and negative and positive predictive values did not differ substantially between study groups. In the main analysis, values were 44%, 96%, 35%, and 97% for gadodiamide and 44%, 83%, 30%, and 90% for gadopentetate, respectively. In the subgroup analysis, values were 66%, 95%, 61%, and 96% for gadodiamide and 63%, 86%, 58%, and 88% for gadopentetate, respectively. CONCLUSION: Noninferiority of gadodiamide versus gadopentetate was verified based on the primary end point, which was accuracy for detection of the main stenosis with enhanced 3D MR angiography compared with DSA.

Abdomen↗

PubMed2006

Swallowing, arterial pulsation, and breathing induce motion artifacts in carotid artery MRI.

PURPOSE: To identify and quantify the potential sources of motion in carotid artery imaging. MATERIALS AND METHODS: Two healthy volunteers and 12 patients (20-75 years old) with atherosclerotic disease were scanned on a Philips Intera 1.5T system. A single-shot balanced-fast field echo (bFFE) sequence was used to acquire real-time axial views of the carotid artery wall (three images per second). A three-step acquisition protocol was performed to analyze the three types of motion (arterial pulsation, breathing, and swallowing) separately. The isocenter carotid artery motion amplitude in either the x or y direction was measured. Radial variation in the carotid lumen between the systolic and diastolic phases was analyzed. Motion frequency was reported for each patient. RESULTS: Significant motion related to arterial pulsation (amplitude = 0.27-0.93 mm, mean = 0.6, SD = 0.19), breathing (amplitude = 0.5-3.6 mm, mean = 1.56, SD = 0.99)), and swallowing (amplitude = 1.4-9.2 mm, mean = 4.7, SD = 2.4) were visualized. CONCLUSION: Pulsation, breathing, and swallowing are sources of significant motion in the carotid artery wall. Such motion should be considered in the future to improve carotid artery image quality.

Adult↗

PubMed2005

Management of suspected venous thromboembolism: the impact of a multifaceted intervention.

OBJECTIVE: To achieve a common strategy in the event of a suspected venous thromboembolism. DESIGN: A multifaceted intervention, combining an audit strategy and implementation of local guidelines: phase 1, the first step, consisted of a 6-month audit to identify dysfunction; during phase 2, intervention, local guidelines were formulated by a working group and then implemented; phase 3 consisted of a re-audit over a 6-month period following the intervention. SETTING: A tertiary hospital, France. PARTICIPANTS: 419 patients with suspected venous thromboembolism in phase 1; 287 patients with suspected pulmonary embolism in phase 3. RESULTS: First phase: a dysfunction was observed in three of five criteria under study: (i) the diagnostic procedure lasted more than 48 hours in 114 patients (27.2%); (ii) no anticoagulant therapy at the time of suspicion in 116 patients (27.7%); (iii) an inconclusive lung scan without further testing in the event of a suspected pulmonary embolism in 40 patients (14%); the intervention phase was thus restricted to the management of suspected pulmonary embolism; similar results were found during the phase 3 re-audit. CONCLUSION: No improvement in the diagnostic work-up in the event of a suspected pulmonary embolism was observed following this multifaceted intervention.

Adolescent↗

PubMed2004

Concordance rate differences of 3 noninvasive imaging techniques to measure carotid stenosis in clinical routine practice: results of the CARMEDAS multicenter study.

BACKGROUND AND PURPOSE: To replace digital subtraction angiography (DSA) in carotid stenosis evaluation, noninvasive imaging techniques have to reach a high concordance rate. Our purpose is to compare the concordance rates of contrast-enhanced MR angiography (CEMRA) and CT angiography (CTA) with Doppler ultrasound (DUS) in clinical routine practice. METHODS: We evaluated prospectively with DUS, CEMRA, and CTA 150 patients suspected of carotid stenosis. The overall concordance rates of the 3 techniques were calculated for symptomatic stenosis > or =50% and > or =70%, for asymptomatic stenosis > or =60%, and for occlusion. For the carotid arteries treated by surgery (n=97), the results of each method and combined techniques were recorded, and misclassification rates were evaluated from surgical reports. RESULTS: The overall concordance rates of DUS-CEMRA, DUS-CTA, and CEMRA-CTA were not statistically different. However, the concordance rate of DUS-CEMRA (92.53%) was significantly higher than that for DUS-CTA (79.10%) in the surgical asymptomatic stenosis group (P=0.0258). CTA considered alone would misclassify the stenosis in a significant number of cases (11 of 64) in the surgical asymptomatic group compared with CEMRA (3 of 67) and DUS (1 of 66) (P=0.0186 versus MRA, P=0.0020 versus DUS). CONCLUSIONS: With the techniques as utilized in our study, the overall concordance rates of combined noninvasive methods are similar for measuring carotid stenosis in clinical routine practice, but in asymptomatic carotid stenosis, the decision making for surgery is significantly altered if DUS and CTA are considered in place of DUS and CEMRA.

Aged↗

PubMed2003

[Diagnosis of postoperative venous thromboembolism].

UNLABELLED: AN IMPORTANT SUBJECT: The thromboembolic disease still prevails in the context of surgery, despite the progression in prophylaxis. Particular attention must be paid to the possibility of delayed events, often occurring within the three months following a surgical procedure. Although many general studies, assessing supplementary examination or diagnostic strategies are available, the proportion of patients concerned by a post-operative context varies. IN PRACTICE: The Doppler is the diagnostic examination of choice in the case of suspected deep vein thrombosis, but it is not recommended in a strategy of screening for asymptomatic thrombosis in surgery. A suspected embolism can be confirmed or eliminated using noninvasive examinations, but it requires that invasive tests be performed more often than in a medical context. The indication for a helical computed tomography, presently more readily available than a pulmonary angiography, would appear legitimate, so long as a Doppler of the lower limbs is systematically associated. RESERVATIONS IN THE POST-OPERATIVE PERIOD: The results of this strategy, most satisfactory in the majority of patients, do not appear as interesting post-operatively. The studies targeting the management of suspected post-operative pulmonary embolism are rare and warrant further encouragement.

Adult↗

PubMed2003

Limited uterine artery embolization with tris-acryl gelatin microspheres for uterine fibroids.

PURPOSE: To evaluate the midterm results of limited embolization of the uterine arteries in the management of symptomatic uterine fibroids and to evaluate the efficacy and safety of limited uterine artery embolization (UAE) with use of calibrated tris-acryl gelatin microspheres in the management of symptomatic uterine fibroids. MATERIALS AND METHODS: Twenty women (mean age, 43 years) with symptomatic uterine fibroids underwent bilateral embolization of the uterine arteries with use of calibrated microspheres. Devascularization of the fibroids was achieved and the main uterine artery was left patent in all women. Embolization was offered as an alternative to surgery in all women who had been treated unsuccessfully with medical therapy. RESULTS: All procedures were technically successful. Microspheres 700-900 micro m in diameter were used in 14 women (70%). After a mean follow-up duration of 30.2 months (range, 24-48 mo), all women reported improvement in their symptoms, with 85% reporting complete resolution of menorrhagia at the most recent follow-up. One woman with multiple fibroids required a second embolization procedure because of persisting symptoms at 6 months. She is currently symptom-free after 48 months. In two women with submucosal fibroids, expulsion of necrotic fibroids occurred 2 and 7 months after the procedure, respectively. All women resumed normal menstruation after the procedure. One woman had a successful full-term pregnancy after embolization. CONCLUSION: Early experience with UAE with use of calibrated tris-acryl gelatin microspheres indicates that it is safe and efficacious in controlling menorrhagia.

Adult↗

PubMed2003

Transthoracic sonography of the lung and pleura in view of a suspected pulmonary embolism: a pilot study.

OBJECTIVE: To evaluate the diagnostic performance of transthoracic sonography of the lung in view of an acute suspicion of pulmonary embolism. METHODS: The diagnosis of pulmonary embolism was made within 48 hours of admission with the use of a validated strategy that combined a lung scan, lower limb sonography, helical computed tomography, and pulmonary angiography in 74 consecutive patients. All patients had a 3-month follow-up. Transthoracic sonography of the lung and pleura was performed in a blinded fashion by investigators unaware of the diagnostic process. It was interpreted as suggestive or not suggestive of pulmonary embolism on the basis of previously published descriptions. The results were kept apart from the patient files until the end of the study. RESULTS: Pulmonary embolism was confirmed in 31 (42%) of the 74 patients. None of the patients classified as pulmonary embolism-negative had a thromboembolic event during the 3-month follow-up. The diagnostic performance of transthoracic sonography was as follows: sensitivity, 71% (95% confidence interval, 52%-85%); specificity, 77% (95% confidence interval, 61%-88%); positive predictive value, 69% (95% confidence interval, 50%-83%); and negative predictive value, 79% (95% confidence interval, 63%-89%). The finding of an isolated pleural infarction was significantly more frequent in pulmonary embolism-positive patients compared with pulmonary embolism-negative patients (P = .0001). CONCLUSIONS: The results from this study suggest that transthoracic sonography of the lung does not fulfill satisfactory performance criteria in view of a clinical suspicion of pulmonary embolism.

Aged↗

PubMed2002

Diagnostic strategy for patients with suspected pulmonary embolism: a prospective multicentre outcome study.

BACKGROUND: We designed a prospective multicentre outcome study to evaluate a diagnostic strategy based on clinical probability, spiral CT, and venous compression ultrasonography of the legs in patients with suspected pulmonary embolism (PE). The main aim was to assess the safety of withholding anticoagulant treatment in patients with low or intermediate clinical probability of PE and negative findings on spiral CT and ultrasonography. METHODS: 1041 consecutive inpatients and outpatients with suspected PE were included. Patients with negative spiral CT and ultrasonography and clinically assessed as having a low or intermediate clinical probability were left untreated. Those with high clinical probability underwent lung scanning, pulmonary angiography, or both. All patients were followed up for 3 months. FINDINGS: PE was diagnosed in 360 (34.6%) patients; 55 had positive ultrasonography despite negative spiral CT. Of 601 patients with negative spiral CT and ultrasonography, 76 were clinically assessed as having a high probability of PE; lung scanning or angiography showed PE in four (5.3% [95% CI 1.5-13.1]). The remaining 525 patients were assessed as having low or intermediate clinical probability, and 507 of them were not treated. Of these patients, nine experienced venous thromboembolism during follow-up (1.8% [0.8-3.3]). The diagnostic strategy proved inconclusive in 95 (9.1%) patients, and pulmonary angiography was done in 74 (7.1%). INTERPRETATION: Withholding of anticoagulant therapy is safe when the clinical probability of PE is assessed as low or intermediate and spiral CT and ultrasonography are negative.

Adult↗

PubMed2002

High prevalence of asymptomatic deep vein thrombosis on admission in a medical unit among elderly patients.

The prevention of venous thromboembolism in medical patients remains questioned. All consecutive outpatients admitted in our medical unit were considered for inclusion in this study which aimed to estimate the prevalence of asymptomatic venous thrombosis on admission and the incidence during hospital stay. Exclusion criteria were: age <18 years, suspicion of venous thromboembolism, stay <4 days, ongoing anticoagulant therapy. Venous compression ultrasonography of the lower limbs was performed within 48 h. 234 patients were included. The prevalence of asymptomatic deep vein thrombosis on admission and the incidence during hospital follow-up were respectively 5.5% (95% confidence interval, 3.1 to 9.5%) and 2.6 per 1,000 person-days (95% confidence interval, 0.0 to 5.2). The prevalence and the incidence reached respectively 17.8% (95% confidence interval, 8.5 to 32.6%) and 6.0 per 1,000 person-days (95% confidence interval, 0.0 to 12.7) among patients over 80 years. A high prevalence of asymptomatic deep vein thrombosis on admission was suggested particularly among elderly medical patients.

Age Factors↗