Valérie Lacroix

Gradient-based delineation of the primary GTV on FDG-PET in non-small cell lung cancer: A comparison with threshold-based approaches, CT and surgical specimens.

PURPOSE The aim of this study was to validate a gradient-based segmentation method for GTV delineation on FDG-PET in NSCLC through surgical specimen, in comparison with threshold-based approaches and CT. MATERIALS AND METHODS Ten patients with stage I-II NSCLC were prospectively enrolled. Before lobectomy, all patients underwent contrast enhanced CT and gated FDG-PET. Next, the surgical specimen was removed, inflated with gelatin, frozen and sliced. The digitized slices were used to reconstruct the 3D macroscopic specimen. GTVs were manually delineated on the macroscopic specimen and on CT images. GTVs were automatically segmented on PET images using a gradient-based method, a source to background ratio method and fixed threshold values at 40% and 50% of SUV(max). All images were finally registered. Analyses of raw volumes and logarithmic differences between GTVs and GTV(macro) were performed on all patients and on a subgroup excluding the poorly defined tumors. A matching analysis between the different GTVs was also conducted using Dices similarity index. RESULTS Considering all patients, both lung and mediastinal windowed CT overestimated the macroscopy, while FDG-PET provided closer values. Among various PET segmentation methods, the gradient-based technique best estimated the true tumor volume. When analysis was restricted to well defined tumors without lung fibrosis or atelectasis, the mediastinal windowed CT accurately assessed the macroscopic specimen. Finally, the matching analysis did not reveal significant difference between the different imaging modalities. CONCLUSIONS FDG-PET improved the GTV definition in NSCLC including when the primary tumor was surrounded by modifications of the lung parenchyma. In this context, the gradient-based method outperformed the threshold-based ones in terms of accuracy and robustness. In other cases, the conventional mediastinal windowed CT remained appropriate.

Repair of Bicuspid Aortic Valves in Patients With Aortic Regurgitation

Background— Bicuspid aortic valve regurgitation can be caused by a defect in the valve itself or by dysfunction of one or more components of the aortic root complex. A successful repair thus requires correction of all aspects of the problem simultaneously. We review our experience addressing both the valve and the aortic root when correcting bicuspid valve regurgitation. Methods and Results— Between 1996 and 2004, we treated 68 patients for aortic regurgitation. Thirty patients had isolated aortic regurgitation, and 38 had an associated ascending aortic aneurysm. All patients were treated using a standardized and integrated surgical technique, which included resection of the median raphe or leaflet plication, subcommissural annuloplasty, reinforcement of the leaflet free edge, and sinotubular junction plication. In the 38 patients with proximal aortic dilatation, reimplantation or remodeling of the aortic root was performed. Immediate postoperative echocardiography showed grade ≤1 aortic regurgitation in all patients. Three patients nonetheless needed an early re-operation because of recurrent regurgitation. No hospital mortality was observed. At a mean follow-up of 34 months after surgery, all patients were in New York Heart Association (NYHA) class 1 or 2. Two patients needed a re-operation (23 and 92 months, respectively). Echocardiographic follow-up showed no progression of the regurgitation in 58 surviving patients. Four patients progressed to grade 2 regurgitation. Conclusion— Our data indicate that regurgitant bicuspid aortic valves, whether alone or in association with a proximal aortic dilatation, can be repaired successfully provided that both the valve and the aortic root problems are treated simultaneously.

Effects of Preoperative Aortic Insufficiency on Outcome After Aortic Valve–Sparing Surgery

Background— The presence of significant preoperative aortic insufficiency (AI) or the need for cusp repair has been suggested as a risk factor for poorer outcomes after aortic valve (AV)–sparing surgery. We analyzed the influence of these factors on the mid-term outcomes of AV surgery. Methods and Results— Between 1996 and 2008, 164 consecutive patients underwent elective AV-sparing surgery. Severe preoperative AI (grade ≥3+) was present in 93 patients (57%), and 54 (33%) had a bicuspid valve. Root repair was performed with either the reimplantation (74%) or the remodeling (26%) technique, and cusp repair was performed in 90 patients (55%). Mean clinical follow-up was 57 months. Hospital mortality was 0.6%. Cusp repair was required in 52% of the patients with preoperative AI ≤2+ and in 57% of those with AI ≥3+ (P=0.6). Cusp repair was required more frequently in bicuspid versus tricuspid valves (91% versus 38%, P<0.001). Overall survival at 8 years was 88±8%. Freedom from AV reoperation at 8 years was similar with preoperative AI ≤2+ versus preoperative AI ≥3+ (89±11% versus 90±7%, P=0.7) and with versus without cusp repair (84±17% versus 92±8%, P=0.5). Freedom from recurrent AI (grade ≥3+) at 5 years was also similar between groups (90±10% versus 89±8%, P=0.9, and 90±8% versus 89±9%, P=0.8, respectively). By multivariate analyses, predictors of recurrent AI ≥2+ were preoperative left ventricle end-diastolic diameter and AI >1+ on discharge echocardiography. Conclusions— With a systematic approach to cusp assessment and repair, AV-sparing surgery for root pathology has an acceptable mid-term outcome, irrespective of preoperative AI or need for cusp repair.

A numerical hemodynamic tool for predictive vascular surgery

We suggest a new approach to peripheral vascular bypass surgery planning based on solving the one-dimensional (1D) governing equations of blood flow in patient-specific models. The aim of the present paper is twofold. First, we present the coupled 1D-0D model based on a discontinuous Galerkin method in a comprehensive manner, such as it becomes accessible to a wider community than the one of mathematicians and engineers. Then we show how this model can be applied to predict hemodynamic parameters and help therefore clinicians to choose for the best surgical option bettering the hemodynamics of a bypass. After presenting some benchmark problems, we apply our model to a real-life clinical application, i.e. a femoro-popliteal bypass surgery. Our model shows good agreement with preoperative and intraoperative measurements of velocity and pressure and post-surgical reports.

The Athlete's Heart - Gender Aspects

Background— Bilateral internal thoracic arteries (BITA) demonstrated superiority over other grafts to the left coronary system in terms of patency and survival benefit. Several BITA configurations are proposed for left-sided myocardial revascularization, but the ideal BITA assemblage is still unidentified. Methods and Results— From 03/2003 to 08/2006, 1297 consecutive patients underwent isolated bypass surgery in our institution. 481 patients met the inclusion criteria for randomization, and 304 (64%) were randomized. Patients were allocated to BITA in situ grafting (n=147) or Y configuration (n=152) then evaluated for clinical, functional, and angiographic outcome after 6 months and 3 years. Patient telephone interviews were conducted every 3 months and a stress test performed twice yearly under the referring cardiologist’s supervision. Angiographic follow-up was performed 6 months after surgery. The primary and secondary end points were, respectively, major adverse cerebrocardiovascular events (MACCE) and the proportion of ITA grafts that were completely occluded at follow-up angiography. More arterial anastomoses were performed in patients randomized to the Y than the in situ configuration (3.2 versus 2.4; P<0.001). No significant difference between the 2 groups in terms of hospital mortality or morbidity was found. At follow-up, there was no significant difference in any MACCE rate between the 2 groups. 450 out of 464 anastomosis (97%) in the BITA Y group and 287 of 295 (97%) in the BITA in situ group were controlled patent (P=0.99). Conclusion— Excellent patency rates were achieved using both BITA configurations with no significant differences in terms of MACCE up to 19 months postoperatively, but longer-term results remain to be established.BACKGROUND: Bilateral internal thoracic arteries (BITA) demonstrated superiority over other grafts to the left coronary system in terms of patency and survival benefit. Several BITA configurations are proposed for left-sided myocardial revascularization, but the ideal BITA assemblage is still unidentified. METHODS AND RESULTS: From 03/2003 to 08/2006, 1297 consecutive patients underwent isolated bypass surgery in our institution. 481 patients met the inclusion criteria for randomization, and 304 (64%) were randomized. Patients were allocated to BITA in situ grafting (n=147) or Y configuration (n=152) then evaluated for clinical, functional, and angiographic outcome after 6 months and 3 years. Patient telephone interviews were conducted every 3 months and a stress test performed twice yearly under the referring cardiologists supervision. Angiographic follow-up was performed 6 months after surgery. The primary and secondary end points were, respectively, major adverse cerebrocardiovascular events (MACCE) and the proportion of ITA grafts that were completely occluded at follow-up angiography. More arterial anastomoses were performed in patients randomized to the Y than the in situ configuration (3.2 versus 2.4; P>0.001). No significant difference between the 2 groups in terms of hospital mortality or morbidity was found. At follow-up, there was no significant difference in any MACCE rate between the 2 groups. 450 out of 464 anastomosis (97%) in the BITA Y group and 287 of 295 (97%) in the BITA in situ group were controlled patent (P=0.99). CONCLUSIONS: Excellent patency rates were achieved using both BITA configurations with no significant differences in terms of MACCE up to 19 months postoperatively, but longer-term results remain to be established.

Endovascular treatment of an aneurysmal aberrant right subclavian artery

Purpose: To describe combined endovascular and surgical management of a complex aneurysmal aberrant right subclavian artery (RSA). Case Report: A 75-year-old obese man with severe chronic obstructive pulmonary disease was referred for treatment of a 6.8-cm aneurysm of an aberrant right subclavian artery. A stent-graft was deployed in the proximal part of the descending aorta to cover the origin of the dilated aberrant RSA, and then a venous carotid-subclavian bypass was made to restore blood flow in the right arm. In a second stage, the prevertebral segment of the aberrant RSA was embolized to avoid retrograde perfusion of the aneurysm. Conclusions: Combined endovascular and surgical treatment of an aneurysmal aberrant subclavian artery is feasible, safe, and effective. This less invasive approach could be the treatment of choice in high-risk patients.

Inlet boundary conditions for blood flow simulations in truncated arterial networks

In the context of patient-specific cardiovascular applications, hemodynamics models (going from 3D to 0D) are often limited to a part of the arterial tree. This restriction implies the set up of artificial interfaces with the remaining parts of the cardiovascular system. In particular, the inlet boundary condition is crucial: it supplies the impulsion to the system and receives the reflected backward waves created by the distal network. Some aspects of this boundary condition need to be properly defined such as the treatment of backward waves (reflected or absorbed) and the value of the imposed hemodynamic wave (total or forward component). Most authors prescribe as inlet boundary condition (BC) the total measured variable (pressure, velocity or flow rate) in a reflective way. We show that with this type of inlet boundary condition, the model does not produce physiological waveforms. We suggest instead to prescribe only the forward component of the prescribed variable in an absorbing way. In this way, the computed reflected waves superpose with the prescribed forward waves to produce the total wave at the inlet. In this work, different inlet boundary conditions are implemented and compared for a 1D blood flow model. We test our boundary conditions on a truncated arterial model presented in the literature as well as on a patient-specific lower-limb model of a femoral bypass. We show that with this new boundary condition, a much better fitting is observed on the shape and intensity of the simulated pressure and velocity waves.

Validation of a 1D patient-specific model of the arterial hemodynamics in bypassed lower-limbs: Simulations against in vivo measurements

The validation of a coupled 1D-0D model of the lower-limb arterial hemodynamics is presented. This study focuses on pathological subjects (6 patients, 72.7±11.1 years) suffering from atherosclerosis who underwent a femoro-popliteal bypass surgery. The 1D model comprises four vessels from the upper-leg, peripheral networks are modeled with three-element windkessels and in vivo velocity is prescribed at the inlet. The model is patient-specific: its parameters reflect the physiological condition of the subjects. In vivo data are acquired invasively during bypass surgery using B-mode ultrasonography and catheter. Simulations from the model compare well with measured velocity (u) and pressure (p) waveforms: average relative root-mean-square error between numerical and experimental waveforms are limited to εp=9.6%, εu=16.0%. The model is able to reproduce the intensity and shape of waveforms observed in different clinical cases. This work also details the introduction of blood leakages along the pathological arterial network, and the sensitivity of the model to its parameters. This study constitutes a first validation of a patient-specific numerical model of a pathological arterial network. It presents an efficient tool for engineers and clinicians to help them improve their understanding of the hemodynamics in diseased arteries.

Comparison of saphenous vein graft versus right gastroepiploic artery to revascularize the right coronary artery: A prospective randomized clinical, functional, and angiographic midterm evaluation

OBJECTIVE Despite its theoretic advantage over saphenous vein grafts, the right gastroepiploic artery graft has not been accepted as the ideal conduit to revascularize the right coronary artery. We therefore prospectively randomized these 2 grafts types to compare their clinical, functional, and angiographic evolution at 6 months and 3 years. METHODS From 2003 to 2006, 1397 consecutive patients underwent isolated revascularization at the University of Louvain Medical School. Of this group, 370 patients met the inclusion criteria for randomization and 66% of those were randomized. The right coronary artery was revascularized with saphenous vein grafts in 116 patients and with right gastroepiploic arteries in 122 patients. All patients underwent angiographic control 6 months postoperatively. The end points were major adverse cerebrocardiovascular events and proportion of grafts patent or functional at follow-up angiography. RESULTS There were no significant differences between the 2 groups in terms of hospital events. At follow-up there was no significant difference in major adverse cerebrocardiovascular events between the 2 groups. At the 6-month angiographic follow-up, 91% of the anastomoses in the right gastroepiploic artery group and 95% of the anastomoses in the saphenous vein graft group were controlled patent (P = .92). In nonoccluded right coronary arteries, the proportion of patent grafts was significantly lower and the proportion of nonfunctioning grafts was significantly higher in the right gastroepiploic artery group than in the saphenous vein graft group. CONCLUSION There were no significant patency or major adverse cerebrocardiovascular events rate differences between the 2 groups; however, the number of functional grafts was significantly higher in the saphenous vein graft group. Careful selection of the coronary target is mandatory to obtain good results in gastroepiploic artery grafting.

Endovascular treatment of acute aortic isthmic rupture: concerning midterm results.

BACKGROUND We evaluated midterm results of endovascular management of traumatic aortic isthmic ruptures. METHODS Between 2001 and 2008, 10 patients (seven males, mean age 38 years) underwent endovascular treatment of an acute aortic rupture. Eight procedures were emergent, with four cases of hemodynamic instability with Glasgow scores of 3, 5, and 7. Associated traumas were severe brain, liver, and pelvic bone injuries. All procedures were performed with transoesophageal echocardiography monitoring. We used two AneuRx and nine Medtronic Talent or Valiant stent grafts. RESULTS All patients survived their traumatic isthmic rupture. In nine patients, stent-graft deployment was successful. One patient experienced a distal migration needing a laparotomy and deployment of an additional new thoracic stent graft. The mean intensive care unit stay was 48 hr (range 24-168). The mean hospital stay was 11 days (range 8-43). All patients were controlled clinically and by contrast computed tomography (CT) according to the EUROSTAR protocol. There were no endoleaks, stent graft-related complications, or late deaths during a mean follow-up of 49 months. The control CT showed a lack of apposition of the proximal part of the stent graft at the inner curve of the aortic arch in three patients. CONCLUSION The midterm results of endovascular treatment of acute traumatic aortic isthmic rupture are encouraging and compare favorably to the surgical approach. Late follow-up is required to exclude possible stent-graft complications, especially in young patients with angulated aortic arches.