Computer Methods and Programs in Biomedicine

Editorial Board

2010-03-01

A framework for automatic construction of 3D PDM from segmented volumetric neuroradiological data sets

Yili Fu, Wenpeng Gao, Yongfei Xiao, Jimin Liu — 2010-03-01

Abstract: 3D point distribution model (PDM) of subcortical structures can be applied in medical image analysis by providing priori-knowledge. However, accurate shape representation and point correspondence are still challenging for building 3D PDM. This paper presents a novel framework for the automated construction of 3D PDMs from a set of segmented volumetric images. First, a template shape is generated according to the spatial overlap. Then the corresponding landmarks among shapes are automatically identified by a novel hierarchical global-to-local approach, which combines iterative closest point based global registration and active surface model based local deformation to transform the template shape to all other shapes. Finally, a 3D PDM is constructed. Experiment results on four subcortical structures show that the proposed method is able to construct 3D PDMs with a high quality in compactness, generalization and specificity, and more efficient and effective than the state-of-art methods such as MDL and SPHARM.

A simulation model of insulin saturation and glucose balance for glycemic control in ICU patients

2010-03-01

Abstract: Consistent tight blood sugar control in critically ill patients has proven elusive. Properly accounting for the saturation of insulin action and reducing the need for frequent measurements are important aspects in intensive insulin therapy. This paper presents a composite metabolic model, ‘Glucosafe’, that integrates models and parameters from normal physiology and accounts for the reduced rate of glucose gut absorption and saturation of insulin action in patients with reduced insulin sensitivity. Particularly, two different sites of reduced insulin sensitivity, before and after the non-linearity of insulin action, are explored with this model. These approaches are assessed based on the model’s accuracy in retrospectively predicting blood glucose measurements of 10 randomly chosen, hyperglycemic intensive care patients. For each patient, median absolute percent error is <25% for prediction times min and modelling reduced insulin sensitivity after the non-linearity, compared to <29% for modelling reduced insulin sensitivity before the non-linearity. Scaling the insulin effect (after the non-linearity) is a suitable assumption in this model structure. These results are preliminary and subject to further and more extensive validation of the model’s capability to predict the longer term (>2h) blood glucose excursion in critically ill patients.

A semi-automatic algorithm for measurement of basement membrane thickness in kidneys in electron microscopy images

Hai-Shan Wu, Steven Dikman, Joan Gil — 2010-03-01

Abstract: In this paper, we present a semi-automatic algorithm for measurement of the glomerular basement membrane thickness in electron microscopy kidney images. A string of sparsely spaced points are manually inputted along the central line of the basement membrane (lamina densa) to be measured. The gaps between successive input points are lineally interpolated. A nonlinear mapping is applied to straighten the curved central line. Two distance functions of edges to the central line are constructed. The smooth envelope lines are obtained by repetitive applications of a linear low-pass filtering followed by a comparing and selecting process. The boundaries of the glomerular basement membrane are obtained from the inverse mapping of the envelope functions. The average basement membrane thickness is estimated as the ratio of the basement membrane area to the length of the central line.

Development of subject-specific and statistical shape models of the knee using an efficient segmentation and mesh-morphing approach

Mark A. Baldwin, Joseph E. Langenderfer, Paul J. Rullkoetter, Peter J. Laz — 2010-03-01

Abstract: Subject-specific finite element models developed from imaging data provide functional representation of anatomical structures and have been used to evaluate healthy and pathologic knee mechanics. The creation of subject-specific models is a time-consuming process when considering manual segmentation and hexahedral (hex) meshing of the articular surfaces to ensure accurate contact assessment. Previous studies have emphasized automated mesh mapping to bone geometry from computed tomography (CT) scans, but have not considered cartilage and soft tissue structures. Statistical shape modeling has been proposed as an alternative approach to develop a population of subject models, but still requires manual segmentation and registration of a training set. Accordingly, the aim of the current study was to develop an efficient, integrated mesh-morphing-based segmentation approach to create hex meshes of subject-specific geometries from scan data, to apply the approach to natural femoral, tibial, and patellar cartilage from magnetic resonance (MR) images, and to demonstrate the creation of a statistical shape model of the knee characterizing the modes of variation using principal component analysis. The platform was demonstrated on MR scans from 10 knees and enabled hex mesh generation of the knee articular structures in approximately 1.5h per subject. In a subset of geometries, average root mean square geometric differences were 0.54mm for all structures and in quasi-static analyses over a range of flexion angles, differences in predicted peak contact pressures were less than 5.3% between the semi-automated and manually generated models. The integrated segmentation, mesh-morphing approach was employed in the efficient development of subject-specific models and a statistical shape model, where populations of subject-specific models have application to implant design evaluation or surgical planning.

Towards noise immune detection of fetal QRS complexes

M. Kotas, J. Jezewski, A. Matonia, T. Kupka — 2010-03-01

Abstract: The noninvasive fetal electrocardiography is a source of more precise information on the fetal heart activity than the measurements based on Doppler ultrasound signals. However, the clinical diagnostic applications of this technique are limited by difficulty with successful detection of small amplitude fetal QRS complexes. In this study, we investigate the influence of different stages of fetal signals processing on the detection performance. The main propositions of the paper are: application of normalized matched filtering to fetal QRS complexes enhancement and a new approach to the final detection of the complexes. Compared to the classical detectors, the proposed new one allows a significant increase of the detection performance for signals of very different quality.

Reducing blanking artifact in electrically evoked compound action potentials

Isaac Alvarez, Angel de la Torre, Manuel Sainz, Cristina Roldán — 2010-03-01

Abstract: The main source of distortion in the recording of the electrically evoked compound action potentials is the stimulus artifact. The popular hardware blanking technique tends to reduce this artifact, but generates a blanking artifact as a consequence of the transient state in the amplifier. In this paper we propose two techniques to deal with the blanking artifact. The proposed techniques are combined with conventional and generalized alternating stimulation in order to reduce both stimulus and blanking artifacts in the recording of the evoked potentials. A comparison over 126 evoked potential recordings reveals that the proposed blanking artifact reduction methods improve the quality of electrically evoked compound action potential recordings.

Saturn: A software application of tensor utilities for research in neuroimaging

Rubén Cárdenes, Emma Muñoz-Moreno, Antonio Tristan-Vega, Marcos Martin-Fernandez — 2010-03-01

Abstract: We present an advanced software tool designed for visualization and quantitative analysis of Diffusion Tensor Imaging (DTI) called Saturn. The software is specially developed to help clinicians and researchers in neuroimaging, and includes a complete set of visualization capabilities to browse and analyze efficiently DTI data, making this application a powerful tool also for diagnosis purposes. The software includes a robust quantification method for DTI data, using an atlas-based method to automatically obtain equivalent anatomical fiber bundles and regions of interest among different DTI data sets. Consequently, a set of measurements is also implemented to perform robust group studies among subjects affected by neurological disorders and control groups in order to look for significant differences. Finally, a comparison study with five similar DTI applications is presented, showing the advantages offered by this tool.

A guideline-based decision support for pharmacological treatment can improve the quality of hyperlipidemia management

Chiehfeng Chen, Kung Chen, Chien-Yeh Hsu, Wen-Ta Chiu, Yu-Chuan (Jack) Li — 2010-03-01

Abstract: Introduction: The Institute of Medicine has identified both Computerized Physician Order Entry (CPOE) and Electronic Prescription (EP) as key in reducing medication errors and improving safety. Many computerized clinical decision support systems (CDSSs) improve practitioner performance. However, the development of CDSSs involves a long cycle time that makes it difficult to apply in a wider scope.Methods: In this study, we integrated the hyperlipidemia treatment guideline ATP III (Adult Treatment Panel III) in a CPOE of a medical center. The first 200 consecutive patients followed up more than 1 year were recorded for analysis.Results: Our study revealed that 130 (65%) patients reached the LDL-C (low density lipoprotein-cholesterol) goal in 1 year. For those who with CDSS finished, 74% reached the LDL-C goal. For those who with CDSS exited, 57% reached the LDL-C goal. The odds ratio is 2.1 (1.2, 3.8) (p=0.022), which means for those who with CDSS finished can have 2 times of chance to reach the LDL-C goal. The mean of days to attain the LDL-C goal level after initiation of antihyperlipidemia therapy was 175±98 days. 11,806 prescribing records from 8023 patients were collected for analyzing the reasons of prematurely exiting the CDSS. The most frequent reason for exiting the system is “too busy to use”.Conclusion: We conclude that a CPOE with CDSS integrated may let more hyperlipidemia patients reach the LDL-C goal. However, data also showed the total prescribing time may increase. The results of a preliminary evaluation are presented to illustrate that the CDSSs can improve the quality of hyperlipidemia management.

Development and implementation of a national telehealth project for long-term care: A preliminary study

2010-03-01

Abstract: The aging population is a global phenomenon. The skyrocketing costs of healthcare and the shortage of healthcare providers will soon become a crucial issue all over the world. Taiwan's government executed the Taiwan's Telehealth Pilot Project (TTPP) from July 1, 2008 to December 31, 2008, using healthcare information technology to tackle these problems. The system has three different models, the home-care, the community-care, and the residential-care model to assist the elderly in the pursuit of better healthcare and improved quality of life. The results revealed both the home-care and community-care models facilitated timely medical responses if the enrolled patients had emergent conditions. In the home-care model, the hospital readmission rate was reduced from 8.19% to 3.17%, and the hospital visit rate was decreased from 2.95% to 2.90%. In community-care model, the medication nonadherence rate was reduced from 38.20% to 9.20%. In the residential-care model, reduced rates of readmission to the hospital, nosocomial infection and the adverse drug event were found. Telehealth enabled the aged with chronic illnesses to live independently and helped the institutionalized elderly get acute care more efficiently without increased manpower of healthcare organization.