The conditions in which the image intensity of vessels transporting laminar flow is attenuated in black‐blood MR angiography (BB‐MRA) with turbo spin‐echo (TSE) and conventional spin‐echo (CSE) pulse sequences are investigated experimentally with a flow phantom, studied theoretically by means of a Bloch equation‐voxel sensitivity function (VSF) formalism, and computer modeled. The experiments studied the effects of: a) flow velocity, b) imaging axes orientation relative to the flow direction, and c) phase encoding order of the TSE train. The formulated Bloch equation‐VSF theory describes flow effects in two‐dimensional (2D)‐ and 3D‐Fourier transform magnetic resonance imaging. In this theoretical framework, the main attenuation mechanism instrumental to BB‐MRA, i.e., transverse magnetization dephasing caused by flow in the presence of the imaging gradients, is described in terms of flow‐induced distortions of the individual voxel sensitivity functions. The computer simulations predict that the intraluminal homogeneity and extent of flow‐induced image intensity attenuation increase as a function of decreasing vessel diameter, in support of the superior image quality achieved with TSE‐based BB‐MRA in the brain. Magn Reson Med 41:575–590, 1999. © 1999 Wiley‐Liss, Inc.

Background: The adverse consequences of HIV and related comorbidities on the central nervous system remain prevalent in the era of combination antiretroviral therapy. Metabolic syndrome (MetS) is a common comorbidity in HIV and has been linked to increased neurocognitive impairment in the general population. We investigated the association between MetS and neurocognition among persons living with HIV (PLHIV). Methods: Participants included 109 PLHIV and 92 HIV-uninfected adults (HIV2) from the Multi-dimensional Successful Aging cohort study at the University of California San Diego (age: M = 50.8, SD = 8.0). Participants completed neuromedical, psychiatric, and neurocognitive assessments. Based on a comprehensive neurocognitive battery, we examined global neurocognitive deficits (based on the entire battery) and neurocognitive deficits in 7 domains (verbal fluency, learning, recall, executive function, working memory, speed of information processing, and fine motor skills). MetS was determined via the standard criteria by the National Cholesterol Education Program's Adult Treatment Panel-III. Covariates examined included demographics and psychiatric comorbidities (and HIV disease characteristics among PLHIV). Results: MetS had an independent significant effect on global neurocognitive deficits among PLHIV (P = 0.03) but not among their HIV2 counterparts (P = 0.93). Among PLHIV, MetS was most strongly associated with the neurocognitive domains of learning, fine motor skills, and executive function. Diabetes and elevated triglycerides were the MetS components most strongly linked with increased global neurocognitive deficits in PLHIV. Conclusions: The present findings underscore the need for early identification of PLHIV at risk for MetS and the implementation of preventive and treatment approaches to lessen the development of MetS and neurocognitive impairment among PLHIV.

The aim of this study was to examine the frequency spectrum of arterial pulses in 17 patients with acute, uncomplicated myocardial infarction. Recordings of right radial pulses were taken from these patients immediately after their arrival at the emergency room. This information was considered as baseline data and was monitored at the same time each day for up to 7 days. These serial recordings of radial pulses were then analyzed together with recordings from 3 control groups of patients not suffering from myocardial infarction. These included subjects who underwent coronary arteriography (n=24), coronary angioplasty (n=18), and mitral valvuloplasty (n=13). The

The conditions in which the image intensity of vessels transporting laminar flow is attenuated in black-blood MR angiography (BB-MRA) with turbo spin-echo (TSE) and conventional spin-echo (CSE) pulse sequences are investigated experimentally with a flow phantom, studied theoretically by means of a Bloch equation-voxel sensitivity function (VSF) formalism, and computer modeled. The experiments studied the effects of: a) flow velocity, b) imaging axes orientation relative to the flow direction , and c) phase encoding order of the TSE train. The formulated Bloch equation-VSF theory describes flow effects in two-dimensional (2D)-and 3D-Fourier transform magnetic resonance imaging. In this theoretical framework, the main attenuation mechanism instrumental to BB-MRA, i.e., transverse magnetiza-tion dephasing caused by flow in the presence of the imaging gradients, is described in terms of flow-induced distortions of the individual voxel sensitivity functions. The computer simulations predict that the intraluminal homogeneity and extent of flow-induced image intensity attenuation increase as a function of decreasing vessel diameter, in support of the superior image quality achieved with TSE-based BB-MRA in the brain. Magn Reson Med 41:575-590, 1999. 1999 Wiley-Liss, Inc.