Rodriguez G, Vitali P, Calvini P, Bordoni C, Girtler N, Taddei G, Mariani G, Nobili F
Service of Clinical Neurophysiology, Department of Internal Medicine, University of Genoa, Viale Benedetto XV, 6, I-16132, Genoa, Italy.
Psychiatry Res. 2000 Dec 4;100(2):65-74. doi: 10.1016/s0925-4927(00)00071-8.
Perfusion and metabolic studies in patients with Alzheimer's disease (AD) have so far yielded conflicting results on the functional status of the hippocampal region, whose deep location in the brain makes it critical to optimize the image-reconstruction technique employed in emission tomography. We used a brain-dedicated device (CERASPECT) to perform single photon emission computed tomography (SPECT) studies with 99mTc-hexamethylpropylene-amine-oxime in 22 consecutive patients (mean age: 74+/-6.5 years) with mild [mini-mental status examination (MMSE) score > or =15, mean 20.8+/-3.2], probable AD. The control subjects were 11 healthy elderly people (mean age: 70.5+/-6.5 years). In patients, the total score on the selective reminding test (SRT) was used as an index of memory function. Counts from a hippocampal and a temporoparietal region of interest in each hemisphere were referred to the average thalamic counts. To optimize SPECT images, we used conventional filtered back-projection (FBP) reconstruction and a new iterative method of conjugate gradients (CG), which takes into account the geometrical and physical characteristics of the gamma-camera. Hippocampal perfusion in the two hemispheres was significantly lower in patients than in control subjects, regardless of which reconstruction method was used, and correlated with the MMSE score. The correlation between hippocampal perfusion and the SRT score was significantly (bootstrap procedure) higher with the CG method than with the FBP method (CG: r=0.52 and 0.54; FBP: r=0.39 and 0.47, for the right and left hemisphere, respectively). These results show hippocampal hypoperfusion in patients with mild AD, a correlation between hippocampal perfusion and the severity of cognitive impairment, and enhanced identification of these subtle perfusional changes with the use of an alternative image-reconstruction method that improves the spatial resolution of SPECT images.
迄今为止，针对阿尔茨海默病（AD）患者的灌注和代谢研究，在海马区功能状态方面得出了相互矛盾的结果。海马区位于大脑深处，因此优化发射断层扫描中使用的图像重建技术至关重要。我们使用一台脑部专用设备（CERASPECT），对22例连续的轻度[简易精神状态检查表（MMSE）评分≥15，平均20.8±3.2]、可能患有AD的患者（平均年龄：74±6.5岁）进行了99mTc-六甲基丙烯胺肟单光子发射计算机断层扫描（SPECT）研究。对照组为11名健康老年人（平均年龄：70.5±6.5岁）。在患者中，选择性提醒测试（SRT）的总分用作记忆功能指标。每个半球海马区和颞顶区感兴趣区域的计数与丘脑平均计数进行比较。为了优化SPECT图像，我们使用了传统的滤波反投影（FBP）重建和一种新的共轭梯度迭代方法（CG），该方法考虑了伽马相机的几何和物理特性。无论使用哪种重建方法，患者两侧海马区的灌注均显著低于对照组，且与MMSE评分相关。CG方法中海马区灌注与SRT评分之间的相关性（自举法）显著高于FBP方法（右侧和左侧半球，CG：r = 0.52和0.54；FBP：r = 0.39和0.47）。这些结果表明，轻度AD患者存在海马区灌注不足，海马区灌注与认知障碍严重程度之间存在相关性，并且使用一种可提高SPECT图像空间分辨率的替代图像重建方法能够增强对这些细微灌注变化的识别。
