PET能够早期检查早老性痴呆

 
 
根据一项研究报道，PET扫描使用放射性示踪剂使用18氟标记的荧光脱氧葡萄糖(FDG)，能够有效地检查出现轻度认知障碍的阿尔茨海默病（Alzheimer病，AD）患者。

“使用FDG的PET扫描代表一种最有前景的诊断AD的工具，”该项研究的首席作者、慕尼黑技术大学(Germany; www.tu-muenchen.de)核医学科高级医师 Alexander Drzezga说。实际上，使用FDG的PET扫描 “或许是最佳的确定最可能发展味AD的MCI患者的工具。”该研究结果发表在2005年10月的《核医学会核医学期刊》之上。

轻度认知障碍(MCI)是一个描述轻度但是能够测量的认知功能（例如记忆功能）损害的术语。MCI患者还没有表现出痴呆的特征，但是该疾病是AD的朕兆，根据Drzezga医生的说法，只需要数年就可能发展成该病。许多MCI患者随着时间出现思考能力的进行性下降，Alzheimer病是主要的原因。

“MCI发生率很高，将在1年内发展成为Alzheimer病；但是这些患者中的一部分或许永远不会发展成痴呆，甚至随着时间症状会得以改善，”Drzezga说。绝大多数MCI患者在开始PET检查显示出典型AD损害，将在16个月内发展成为痴呆，根据一项30例患者的临床研究结果显示。他补充说，在开始PET检查没有出现异常的患者病情则保持稳定。

根据Drzezga医生的研究，患Alzheimer病的患者大脑糖代谢模式出现特异性的异常改变，在病变涉及的区域出现下降。使用FDG的PET扫描能够对区域性的大脑糖代谢进行评估。Drzezga报道说，研究显示 “大脑糖代谢的检查，在分子水平上真实反映了与Alzheimer病相关的病理改变，分子扫描成像方法的PET适合在根据神经生理学检查诊断Alzheimer病之前，描述MCI患者大脑的细微变化。

研究结果还显示，使用FDG的PET检测Alzheimer病的精确性要比使用APOEe4危险因子的基因筛查精确的多。

PET Can Detect Alzheimer’s Disease
 
Positron emission tomography (PET) imaging used with the radiotracer 18F-fluorodeoxyglucose (FDG) appears to be an effective tool in detecting Alzheimer’s disease (AD) in patients who have mild cognitive impairment (MCI), according to new research.

“PET imaging with FDG represents one of the most promising tools for diagnosis of Alzheimer’s,” said Alexander Drzezga, M.D., the lead author of the study and a senior physician with the department of nuclear medicine at the Technical University of Munich (Germany; www.tu-muenchen.de). In fact, using PET imaging with FDG “may be the best indicator for determining which MCI patients are most at risk of developing Alzheimer’s.” The study was published in the October 2005 issue of the Society of Nuclear Medicine’s Journal of Nuclear Medicine.

Mild cognitive impairment (MCI) is a term used to describe a slight but measurable deterioration of cognitive capabilities, such as memory function. Patients with MCI do not yet display the characteristics for the diagnosis of dementia, but the disorder is seen as a precursor to AD, which can take years to develop in an individual, according to Dr. Drzezga. Many patients with MCI develop a progressive decline in their thinking capacities over time, and Alzheimer’s disease is typically the underlying cause.

“A high percentage of MCI patients will develop Alzheimer’s disease within a year; however, some of these patients will never develop dementia and may even improve with time,” said Dr. Drzezga. Most MCI patients who showed abnormalities typical of AD in their original PET scan developed dementia within 16 months, according to results from the 30-patient study. Most patients who did not demonstrate abnormalities in their original PET scan remained stable, he added.

Patients with Alzheimer’s show characteristic alterations of the cerebral glucose metabolic pattern, with a decrease in affected brain regions, according to Dr. Drzezga. PET imaging with FDG provides an assessment of regional cerebral glucose metabolism. The study showed that “the analysis of cerebral glucose metabolism actually reflects ongoing pathological changes associated with Alzheimer’s disease on a molecular level and that the molecular imaging method PET is capable of depicting subtle changes in the brain of MCI patients before a diagnosis of Alzheimer’s based on neuropsychological evaluation is possible,” reported Dr. Drzezga.

The study revealed that PET with FDG has a considerably higher accuracy for detecting Alzheimer’s than genetic screening for the APOEe4-risk factor.