Biomedical subjects

Pierre E Dupont

Publications and source records attributed to Pierre E Dupont.

3 recordsLinked to original sources

PubMed2006

Producing diffuse ultrasound reflections from medical instruments using a quadratic residue diffuser.

Simultaneous visualization of tissue and surgical instruments is necessary during ultrasound-guided medical procedures. Standard minimally invasive instruments are typically metallic and act as strong specular scatterers. As a result, such instruments saturate the image or disappear according to the angle of incidence, obscuring nearby tissue and making it difficult to determine the instrument's precise location. The objective of this study was to produce diffusive reflections from the surface of surgical instruments for improved visualization in ultrasound. A surface profile based on a 2D quadratic residue diffuser (QRD) was employed, which has been demonstrated to reduce specular reflection in other acoustic applications. The backscattered echo amplitude from the diffusive surface at various angles of insonation was measured and compared to that from unmodified metal surfaces and heart tissue surfaces. The QRD resulted in an 8 dB reduction of the specular signal. Furthermore, the dynamic range for angles up to 75 degrees was less than 20 dB for the QRD and more than 65 dB for a flat surface. The QRD surface produces two beneficial results for the simultaneous imaging of instruments and tissue. First, the conspicuity of diffusive surfaces in ultrasound images is markedly improved in comparison with unmodified metal surfaces. Secondly, the echo amplitude of diffusive metal surfaces differs in mean and standard deviation from that of tissue facilitating image enhancement and segmentation.

Acoustics↗

PubMed2003

Application of robotics in congenital cardiac surgery.

Over the past 5 years, robotic systems that combine advanced endoscopic imaging with computer-enhanced instrument control have been used for both coronary revascularization and intracardiac procedures in adults. In addition, endoscope positioning systems and articulated instruments with a robotic wrist mechanism have further expanded the potential applications for robotics in cardiac surgery. In pediatric cardiac surgery, potential applications can be divided into simple scope manipulation versus the use of 3-dimensional imaging and a robotic wrist for dissection and reconstruction. A voice-controlled robotic arm for scope manipulation can facilitate current pediatric thoracoscopic procedures such as ligation of patent ductus arteriosus and division of vascular rings. By using an advanced imaging system along with a robotic wrist, more complex extracardiac and even intracardiac procedures can be performed in children. Examples include coarctation repair, septal defect repair, and mitral or tricuspid valvuloplasty. Furthermore, with adequate intracardiac imaging, a robot-assisted off-pump approach to intracardiac pathology is conceivable. New real-time 3-dimensional echocardiography now offers sufficient resolution to enable such procedures, while the addition of instrument tracking, haptic feedback, and novel tissue fixation devices can facilitate safe and reliable intracardiac repair without extracorporeal circulation.

Cardiac Surgical Procedures↗

PubMed2003

Real-time three-dimensional ultrasound for guiding surgical tasks.

OBJECTIVE: As a stand-alone imaging modality, two-dimensional (2D) ultrasound (US) can only guide basic interventional tasks due to the limited spatial orientation information contained in these images. High-resolution real-time three-dimensional (3D) US can potentially overcome this limitation, thereby expanding the applications for US-guided procedures to include intracardiac surgery and fetal surgery, while potentially improving results of solid organ interventions such as image-guided breast, liver or prostate procedures. The following study examines the benefits of real-time 3D US for performing both basic and complex image-guided surgical tasks. MATERIALS AND METHODS: Seven surgical trainees performed three tasks in an acoustic testing tank simulating an image-guided surgical environment using 2D US, biplanar 2D US, and 3D US for guidance. Surgeon-controlled US imaging was also tested. The evaluation tasks were (1) bead-in-hole navigation; (2) bead-to-bead navigation; and (3) clip fixation. Performance measures included completion time, tool tip trajectory, and error rates, with endoscope-guided performance serving as a gold-standard reference measure for each subject. RESULTS: Compared to 2D US guidance, completion times decreased significantly with 3D US for both bead-in-hole navigation (50%, p = 0.046) and bead-to-bead navigation (77%, p = 0.009). Furthermore, tool-tip tracking for bead-to-bead navigation demonstrated improved navigational accuracy using 3D US versus 2D US (46%, p = 0.040). Biplanar 2D imaging and surgeon-controlled 2D US did not significantly improve performance as compared to conventional 2D US. In real-time 3D mode, surgeon-controlled imaging and changes in 3D image presentation made by adjusting the perspective of the 3D image did not diminish performance. For clip fixation, completion times proved excessive with 2D US guidance (> 240 s). However, with real-time 3D US imaging, completion times and error rates were comparable to endoscope-guided performance. CONCLUSIONS: Real-time 3D US can guide basic surgical tasks more efficiently and accurately than 2D US imaging. Real-time 3D US can also guide more complex surgical tasks which may prove useful for procedures where optical imaging is suboptimal, as in fetal surgery or intracardiac interventions.

Humans↗