A new platform for laparoscopic training and education.

A new platform for laparoscopic training and education is presented. Fundamental requirements about a flexible haptic interface, specter of training areas, skill assessment, educational content, and level of realism are presented and discussed. The new system, including a new and flexible haptic interface and a broad specter of training modules combined with the use of multimedia content, is described.

Ultrasound-based vessel wall tracking: an auto-correlation technique with RF center frequency estimation.

Vessel diameter is related to the distending blood pressure, and is used in estimations of vessel stiffness parameters. The vessel walls can be tracked by integrating wall velocities estimated by ultrasound (US) Doppler techniques. The purpose of this work was to evaluate the performance of the modified autocorrelation estimator when applied on vessel wall motion. As opposed to the conventional autocorrelation method that only estimates the mean Doppler frequency, the modified autocorrelation method estimates both the mean Doppler frequency and the radiofrequency (RF) center frequency. To make a systematic evaluation of the estimator, we performed computer simulations of vessel wall motion, where pulse bandwidth, signal-to-noise ratio (SNR), signal-to-reverberation ratio, packet size and sample volume were varied. As reference, we also analyzed the conventional autocorrelation method and the cross-correlation method with parabolic interpolation. Under the simulation conditions considered here, the modified autocorrelation method had the lowest bias and variance of the estimators. When integrating velocity estimates over several cardiac cycles, the resulting tissue displacement curves might drift. This drift is directly related to the magnitude of the estimator bias and variance. Hence, the modified autocorrelation method should be the preferred choice of method.

Quantification of left ventricular diastolic pressure-volume relations during routine cardiac catheterization by two-dimensional digital echo quantification and left ventricular micromanometer.

BACKGROUND: Currently there is no simple clinical method for quantifying the left ventricular (LV) diastolic pressure-volume relation. Echocardiographic-automated endocardial border detection, however, may be combined with LV micromanometer to construct LV pressure-volume loops. We investigated the feasibility of on-line display and sampling of LV pressure-volume loops by such an approach. For this purpose we used a new echocardiographic digital echo quantification (DEQ) method in combination with LV pressures on-line and in real-time. METHODS: Eighteen patients were screened by conventional echocardiography and DEQ. Ten of the patients with high quality images were included in the study. Left ventricular pressures and volumes were recorded simultaneously and were displayed on-line as pressure-volume loops. Changes in LV volume were induced by intravenous saline. Left ventricular chamber compliance was estimated as change in volume divided by change in pressure from minimum diastolic pressure to end-diastolic pressure (average LV chamber compliance). RESULTS: Left ventricular pressure-volume loops were displayed on-line during the examination. When compared with the Simpson's method, DEQ underestimated end-diastolic volume (EDV) by 35% and overestimated end-systolic volume (ESV) by 14%. Beat-to-beat variability for ESV and EDV were 7.4% +/- 0.8% and 7.2% +/- 0.7 %, respectively. Volume loading increased LV end-diastolic pressure (LVEDP) from 14.0 +/- 1.6 to 24.7 +/- 2.0 mm Hg (P <.05) and EDV from 79 +/- 10 to 85 +/- 11 mL (NS), and decreased LV chamber compliance from 4.0 +/- 0.7 to 2.0 +/- 0.3 mL/mm Hg (P <.05). CONCLUSION: The current study demonstrates that LV pressure-volume loops can be displayed and evaluated in real-time during routine cardiac catheterization. This may represent a clinically useful method for identifying patients with reduced chamber compliance. The underestimation of the volumes by DEQ compared with the Simpson's method suggests that further refinements should be performed to improve the endocardial border detection algorithm.

A tutorial platform suitable for surgical simulator training (SimMentor).

BACKGROUND: The introduction of simulators in surgical training entails the need to develop pedagogic platforms adapted to the potentials and limitations provided by the information technology. As a solution to the technical challenges in treating all possible interaction events and to obtain a suitable pedagogic approach, we have developed a pedagogic platform for surgical training, SimMentor. METHODS: In SimMentor the procedure to be practiced is divided into a number of natural phases. The trainee will practice on one phase at a time, however he can select the sequence of phases arbitrarily. A phase is taught by letting the trainee alternate freely between 2 modes: 1: A 3-dimensional animated guidance designed for learning the objectives and challenges in a procedure. 2: An interactive training session through the instrument manipulator device designed for training motoric responses based on visual and tactile responses produced by the simulator. The two modes are interfaced with the same virtual reality platform, thus SimMentor allows a seamless transition between the modes. RESULTS: We have developed a prototype simulator for robotic assisted endoscopic CABG (Coronary Artery Bypass Grafting) procedure by first focusing on the anastomosis part of the operation. Tissue, suture and instrument models have been developed and integrated with a simulated model of a beating heart comprises the elements in the simulator engine that is used in construction a training platform for learning different methods for performing a coronary anastomosis procedure. CONCLUSION: The platform is designed for integrating the following features: 1) practical approach to handle interactivity events with flexible-objects 3D simulators, 2) methods for quantitative evaluations of performance, 3) didactic presentations, 4) effective ways of producing diversity of clinical and pathological training scenarios.