Cerebral Blood Flow in HIV/AIDS and Drug Abuse Detected by CASL MRI

描述（由申请人提供）：有大量证据表明药物使用/滥用（DA）和艾滋病毒/艾滋病对中枢神经系统造成损害。然而，这些研究中的大多数假设是这些因素对中枢神经系统的直接影响导致了认知的改变。这项探索性研究的目的是评估一种不同的机制，即血管功能的改变至少部分介导了DA和HIV/AIDS对认知的影响。如果整体假设是正确的，这意味着许多与DA和HIV/AIDS相关的CNS变化是继发于血管变化，这可能解释了为什么这些条件对认知有协同作用，并为DA和HIV/AIDS的认知变化的治疗和预防提供了尚未被典型利用的途径。为了评估中枢神经系统的改变至少部分负责DA和HIV/AIDS的认知变化的假设，我们将利用磁共振成像的一种新技术-动脉自旋标记。该技术允许在不使用造影剂或电离辐射的情况下测量和绘制区域脑血流量（rCBF）。此外，通过在扫描过程中挑战受试者呼吸二氧化碳，可以测量急性血管对高碳酸血症的反应。本探索性研究的目的是让我们获得必要的数据，以开展更大规模、多中心的血管完整性、DA、HIV/AIDS和中枢神经系统结构和功能完整性之间关系的研究。在使用这些最先进的方法来测量“急性”（即高碳酸血症）和“慢性”（即静息）rCBF作为跟踪疾病和调查HAD和相关疾病的潜在病理生理学的生物标志物之前，有必要建立一些关于技术稳定性和有效性的基本信息。本研究的目的是评估艾滋病毒/艾滋病患者伴用药和不伴用药的rCBF。具体来说，我们将确定rCBF在24周研究期间的稳定程度，并使用rCBF的O15 -水正电子发射断层扫描（PET）测量来确定MRI技术的标准有效性。患有艾滋病毒/艾滋病的人可能有思考困难。吸毒的人也可能有思维障碍。艾滋病毒/艾滋病患者或吸毒者的血液循环（血管）也可能有问题，这也是事实。这可能意味着没有足够的血液进入大脑，或者当大脑需要更多血液时，大脑中的血管没有正确反应。使用一种叫做磁共振成像的技术来测量大脑中的血流量是可能的，这种技术可以拍摄出血液在大脑不同部位流动的速度。这项探索性研究的目的是开始使用这项新技术来研究艾滋病毒/艾滋病患者和药物滥用者大脑中的血液流动。我们感兴趣的是，他们血液循环的变化是否可能是他们思维能力变化的部分原因。

DESCRIPTION (provided by applicant): There is a host of evidence showing CNS damage from drug use/abuse (DA) and HIV/AIDS. However, the majority of these studies assume that it is the direct effects of these factors on the CNS that result in altered cognition. The purpose of this exploratory study is to evaluate a different mechanism - namely, that alterations in vascular function are at least partial mediators of the effects of DA and HIV/AIDS on cognition. If the overall hypothesis is correct, that means that many of the CNS changes associated with DA and HIV/AIDS are secondary to vascular changes, and this might explain why there are synergistic effects between these conditions on cognition, and would suggest pathways for the treatment and prevention of cognitive changes in DA and HIV/AIDS that have not been typically exploited. In order to evaluate the hypothesis that alterations in CNS vasculature are at least partially responsible for the cognitive changes in DA and HIV/AIDS, we will take advantage of a novel technique available through magnetic resonance imaging - Arterial Spin Labelling. This technique allows for the measurement and mapping of regional cerebral blood flow (rCBF) without the use of contrast agents or ionizing radiation. In addition, by challenging the subject to breathe CO2 during the scan, it is possible to measure the acute vascular response to hypercapnia. The purpose of this exploratory study is to allow us to obtain the data necessary to develop a larger scale, multi-center study of the association between vascular integrity, DA, HIV/AIDS and CNS structural and functional integrity. Before using these state-of-the-art methods for measuring both "acute" (i.e., hypercapnic) and "chronic" (i.e., resting) rCBF as biomarkers for tracking disease and for investigating the underlying pathophysiology of HAD and associated conditions, it is necessary to establish some basic information regarding the stability and validity of the techniques. The purpose of this study is to evaluate rCBF in individuals with HIV/AIDS with and without concomitant drug abuse. Specifically, we will determine the extent to which rCBF is stable over 24 weeks of study, and determine the criterion validity of the MRI technique using concomitant O15 -water positron emission tomography (PET) measures of RCBF. Individuals with HIV/AIDS may have difficulty thinking. Individuals who use drugs may also have difficulty with their thinking. It is also true that people with HIV/AIDS or who use drugs may have problems with their circulation (blood vessels). This could mean that not enough blood is getting to the brain, or that the blood vessels in the brain do not respond correctly when the brain needs more blood. It is possible to measure blood flow in the brain using a technique called magnetic resonance imaging, which can take pictures showing how fast blood is moving through various parts of the brain. The purpose of this exploratory study is to begin to use this new technology to study blood flow in the brains of people with HIV/AIDS and drug abuse. We are interested in knowing whether changes in their circulation may be responsible for some of the changes in their ability to think.