Bayesian and influence function-based empirical likelihoods for inference of sensitivity in diagnostic tests.

In medical diagnostic studies, a diagnostic test can be evaluated based on its sensitivity under a desired specificity. Existing methods for inference on sensitivity include normal approximation-based approaches and empirical likelihood (EL)-based approaches. These methods generally have poor performance when the specificity is high, and some require choosing smoothing parameters.

Relative efficiency of using summary versus individual data in random-effects meta-analysis.

Meta-analysis is a statistical methodology for combining information from diverse sources so that a more reliable and efficient conclusion can be reached. It can be conducted by either synthesizing study-level summary statistics or drawing inference from an overarching model for individual participant data (IPD) if available. The latter is often viewed as the "gold standard.

Early detection and staging of chronic liver diseases with a protein MRI contrast agent.

Early diagnosis and noninvasive detection of liver fibrosis and its heterogeneity remain as major unmet medical needs for stopping further disease progression toward severe clinical consequences. Here we report a collagen type I targeting protein-based contrast agent (ProCA32.collagen1) with strong collagen I affinity.

Transfer Functions of a Spinal Cord Stimulation System in Mixed Media and Homogeneous Media for Estimation of RF Heating during MRI Scans.

There is a risk for patients with spinal cord stimulation (SCS) implants that MRI-RF induced heating may cause harm to spinal cord (SC) or spinal nerves. The ISO/TS 10974 Clause 8, Tier 3 based evaluation of RF heating has been commonly used for active implantable manufactures through regulatory body world-wide. Generating TFs for the lead and SCS system is an essential component in Tier 3.

Investigation of Key Variables Impacting ICM Sensing Using Computer Simulations.

The insertable cardiac monitors (ICMs) used for diagnosing and managing abnormal heart activities can falsely detect heart rhythms due to respiration, device rotation/orientation, device position, device flipping, and body mass that alter the amplitudes and morphologies. The objective of this paper is to investigate the effects of these key variables on ICM sensing by using computer simulations and virtual human family. We observed in these simulations that sensing amplitudes can vary greatly depending on device flipping, orientation/rotation, and migration; change significantly due to respiration effect; and are most sensitive to it when body mass is large.

Mechanisms of Dorsal Root Ganglion Stimulation in Pain Suppression: A Computational Modeling Analysis.

Objective: The mechanisms of dorsal root ganglion (DRG) stimulation for chronic pain remain unclear. The objective of this work was to explore the neurophysiological effects of DRG stimulation using computational modeling.

Methods: Electrical fields produced during DRG stimulation were calculated with finite element models, and were coupled to a validated biophysical model of a C-type primary sensory neuron.

THE SCREENING AND RANKING ALGORITHM FOR CHANGE-POINTS DETECTION IN MULTIPLE SAMPLES.

The chromosome copy number variation (CNV) is the deviation of genomic regions from their normal copy number states, which may associate with many human diseases. Current genetic studies usually collect hundreds to thousands of samples to study the association between CNV and diseases. CNVs can be called by detecting the change-points in mean for sequences of array-based intensity measurements.

Modeling the impact of spinal cord stimulation paddle lead position on impedance, stimulation threshold, and activation region.

The effectiveness of spinal cord stimulation (SCS) for chronic pain treatment depends on selection of appropriate stimulation settings, which can be especially challenging following posture change or SCS lead migration. The objective of this work was to investigate the feasibility of using SCS lead impedance for determining the location of a SCS lead and for detecting lead migration, as well as the impact of axial movement and rotation of the St. Jude Medical PENTA™ paddle in the dorsal-ventral or medial-lateral directions on dorsal column (DC) stimulation thresholds and neural activation regions.

Computational modeling analysis of a spinal cord stimulation paddle lead reveals broad, gapless dermatomal coverage.

Spinal cord stimulation (SCS) is an effective therapy for treating chronic pain. The St. Jude Medical PENTA(TM) paddle lead features a 4 × 5 contact array for achieving broad, selective coverage of dorsal column (DC) fibers.

Modeling dermatome selectivity of single-and multiple-current source spinal cord stimulation systems.

A recently published computational modeling study of spinal cord stimulation (SCS) predicted that a multiple current source (MCS) system could generate a greater number of central points of stimulation in the dorsal column (DC) than a single current source (1 CS) system. However, the clinical relevance of this finding has not been established. The objective of this work was to compare the dermatomal zone selectivity of MCS and 1 CS systems.

Modified screening and ranking algorithm for copy number variation detection.

Motivation: Copy number variation (CNV) is a type of structural variation, usually defined as genomic segments that are 1 kb or larger, which present variable copy numbers when compared with a reference genome. The screening and ranking algorithm (SaRa) was recently proposed as an efficient approach for multiple change-points detection, which can be applied to CNV detection. However, some practical issues arise from application of SaRa to single nucleotide polymorphism data.

A Bayesian hierarchical model of nontraumatic lower-extremity amputation rates.

A Bayesian hierarchical generalized linear model is used to estimate the risk of lower-extremity amputations (LEA) among diabetes patients from different counties in the state of Missouri. The model includes fixed age effects, fixed gender effect, random geographic effects, and spatial correlations between neighboring counties. The computation is done by Gibbs sampling using OPENBUGS.

Estimation of the optimal VV delay by an IEGM-based method in cardiac resynchronization therapy.

Determination of the optimal interventricular (VV) delay in cardiac resynchronization therapy currently relies on costly, time-consuming echocardiographic (ECHO) methods. This study evaluated the performance of a new intracardiac electrogram (IEGM)-based VV method compared to the aortic velocity time integral (AVTI) method of VV delay optimization. The study included two patient groups.