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Background: People living with HIV have an increased risk of cardiovascular disease (CVD). Although coronary endothelial function (CEF) is an early direct indicator of CVD, only a few studies have been able to interrogate CEF directly. Most studies have examined vascular endothelial function through indirect assessment of brachial flow‐mediated dilatation (FMD). However, peripheral arteries are significantly larger and manifest atherogenesis differently from the coronary arteries, and so produce conflicting results. Additionally, none of these studies focused on young adults who acquired HIV perinatally or in early childhood. Objective: The present study investigates CEF in a unique population of young adults with lifelong HIV using direct magnetic resonance imaging (MRI) of coronary FMD (corFMD) with an in‐house developed MRI‐integrated isometric handgrip exercise system with continuous feedback and monitoring mechanisms (fmIHE). Methods: Young adults who acquired HIV perinatally or in early childhood (n = 23) and group‐matched healthy participants (n = 12) completed corFMD‐MRI with fmIHE. CorFMD was measured as the coronary cross‐sectional area response to the fmIHE. Results: In univariable and multivariable regression analysis, HIV status was a significant risk modifier. CD8+ T‐cell count and smoking pack‐years and their interaction with HIV status were independently associated with impaired coronary artery response to fmIHE. In people living with HIV, corFMD was significantly inversely correlated with CD8+ T‐cells and smoking pack‐years. In a multivariable regression analysis adjusted for age and body mass index, CD8+ T‐cells and smoking and their interaction with HIV status remained significant independent predictors of coronary endothelial dysfunction. Discussion: In this unique population of young adults, HIV status was a significant risk modifier, and immune activation and smoking were associated with decreased CEF, directly measured from the coronary vascular response to fmIHE. Conclusions: Management of CVD risk factors such as smoking and developing strategies that target immune activation in people living with HIV are warranted. [ABSTRACT FROM AUTHOR]

Cardiovascular stress test imaging assists in the diagnosis and monitoring of cardiovascular disease. The procedure can be carried out in a magnetic resonance (MR) scanner using pharmacological agents that mimic the effects of natural exercise. In order to provide real time indication of ischemia, thereby assisting in diagnosis and helping to assure patient safety, it is desirable to have real time monitoring of the myocardial regional function. This paper presents an algorithm for the real time myocardium region-of-interest reconstruction and myocardial strain computation using data acquired from a real time pulse sequence that has been previously reported. The chirp Fourier transform is used for efficient computation, enabling a real-time continuous strain map at a rate of 25 frames/s. Coupled with a real time data path from the scanner to a laptop computer, this algorithm enables real time continuous monitoring of cardiac strain and is targeted for use in the early detection and quantification of ischemia during MR stress tests. Index Terms--Cardiac motion, FastHARP (HARP-MRI), harmonic phase (HARP), magnetic resonance (MR) tagging, myocardial strain, real-time imaging.

This paper presents a novel approach for speckle reduction and coherence enhancement of ultrasound images based on nonlinear coherent diffusion (NCD) model. The proposed NCD model combines three different models. According to speckle extent and image anisotropy, the NCD model changes progressively from isotropic diffusion through anisotropic coherent diffusion to, finally, mean curvature motion. This structure maximally low-pass filters those parts of the image that correspond to fully developed speckle, while substantially preserving information associated with resolved-object structures. The proposed implementation algorithm utilizes an efficient discretization scheme that allows for real-time implementation on commercial systems. The theory and implementation of the new technique are presented and verified using phantom and clinical ultrasound images. In addition, the results from previous techniques are compared with the new method to demonstrate its performance. Index Terms--Coherence enhancement, nonlinear anisotropic diffusion, speckle reduction, ultrasound imaging.