Comparison of quality control methods for automated diffusion tensor imaging analysis pipelines

© 2019 Haddad et al. The processing of brain diffusion tensor imaging (DTI) data for large cohort studies requires fully automatic pipelines to perform quality control (QC) and artifact/outlier removal procedures on the raw DTI data prior to calculation of diffusion parameters. In this study, three automatic DTI processing pipelines, each complying with the general ENIGMA framework, were designed by uniquely combining multiple image processing software tools. Different QC procedures based on the RESTORE algorithm, the DTIPrep protocol, and a combination of both methods were compared using simulated ground truth and artifact containing DTI datasets modeling eddy current induced distortions, various levels of motion artifacts, and thermal noise. Variability was also examined in 20 DTI datasets acquired in subjects with vascular cognitive impairment (VCI) from the multi-site Ontario Neurodegenerative Disease Research Initiative (ONDRI). The mean fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were calculated in global brain grey matter (GM) and white matter (WM) regions. For the simulated DTI datasets, the measure used to evaluate the performance of the pipelines was the normalized difference between the mean DTI metrics measured in GM and WM regions and the corresponding ground truth DTI value. The performance of the proposed pipelines was very similar, particularly in FA measurements. However, the pipeline based on the RESTORE algorithm was the most accurate when analyzing the artifact containing DTI datasets. The pipeline that combined the DTIPrep protocol and the RESTORE algorithm produced the lowest standard deviation in FA measurements in normal appearing WM across subjects. We concluded that this pipeline was the most robust and is preferred for automated analysis of multisite brain DTI data

Simulating Haptic Feedback of Abdomen Organs on Laparoscopic Surgery Tools

Abstract: Minimally invasive surgeries (MIS) such as laparoscopic procedures are widely used for many types of abdomen surgeries because of its numerous advantages over open surgeries. They require very high levels of skills of surgeons acquired through experience. The best and the safest way of getting hands on experience is the computer simulation or virtual reality (VR). The VR surgical simulators have a great potential to revolutionize the training paradigm of surgical interns. The haptic feedback plays as equally as visual feedback to provide realistic environment to trainees. In this paper, we present a method incorporate hapitics on VR simulator. A software procedure is developed using the Libraries of Open Haptic Toolkit along with the Open GL graphic libraries to implement three basic haptic ranges: soft, mild(firm) and hard into organ models. The feedback of the expert surgeons in the field was obtained to model the organs rather than measuring mechanical properties of soft tissues due to practical limitations. A commercially available six Degrees of Freedom (DoF) position sensing and three DoF force feedback haptic device is used to implement the interface

Development of a PID based closed loop controller for shape memory alloy actuators

Shape Memory Alloy (SMA) spring actuator was designed and fabricated using commercially available NiTiNOL material by shape setting with the use of a special fixture. So, before applying the actuator to an application, a force characterization was conducted and force variation respect to uncontrolled temperature was analyzed. Due to the difference between force and temperature sensor's response time, a lag can occur between force and temperature measurements. Therefore, a more controlled technique was further implemented by developing a Proportional-Integral-Derivative (PID) based closed loop controller, together with a Graphical User Interface (GUI) which supports parameter control and sensor calibration. Finally, a force feedback controlling method also developed using the same PID technique for a force sensitive applications, where controlled forces need to be maintained by varying temperature of SMA accordingly.</p