Lobaugh N J, Caldwell C B, Black S E, Leibovitch F S, Swartz R H
Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada.
J Nucl Med. 2000 Jan;41(1):45-56.
The purpose of this study was to generate anatomically guided region-of-interest (ROI) brain SPECT templates based on scans of elderly healthy volunteers. We describe normal tracer uptake and hemispheric asymmetries for each of 3 camera systems and compare these characteristics among systems.
99mTc-hexamethyl propyleneamine oxime SPECT scans were acquired from 28 elderly healthy volunteers (mean age [+/-SD], 70.3 +/- 6.5 y) on a single-head rotating gamma camera (n = 15) or on dual- (n = 18) or triple-head (n = 13) cameras. The average number of counts in each ROI was calculated and referenced to counts in a cerebellar ROI, providing semiquantitative regional cerebral blood flow (rCBF) ratios. For the templates and ROI map, base images of a healthy volunteer were obtained with each camera. Data from individuals scanned with 2 cameras on the same day (n = 15) were used to evaluate rCBF differences across cameras. For each camera, averaged SPECT templates were made using automated image registration. The base volunteer's T1-weighted MR image was converted to stereotactic space with dimensions similar to those of the SPECT templates, and 79 bilateral ROIs were defined. To obtain ROI rCBF ratios, we aligned individual images to their appropriate template and then to this modified MR image.
The ROI coefficients of variation indicated that the fit of the ROIs was acceptable (0.07-0.35). Mean rCBF ratios ranged from 0.57 to 1.0, 0.67 to 1.01, and 0.63 to 1.00 for single-, dual-, and triple-head cameras, respectively. The cuneus, occipital cortex, occipital pole, middle temporal gyrus, and posterior middle frontal gyrus showed consistent hemispheric asymmetry (right side greater than left side in 83%-100% of individuals). Mean rCBF ratios did not differ between dual- and triple-head cameras, whereas the ratios for single- and dual-head cameras differed significantly (39 ROIs differed), even after smoothing and filtering the dual-head images to the level of the single-head images.
The use of SPECT templates based on elderly healthy volunteers is an important feature of this technique because most available templates have used young individuals. Another important feature is the use of MR image-based ROIs. These procedures are versatile because they use more than 1 camera. They can easily be implemented in clinical and research settings to detect camera-specific, abnormal deviations in rCBF ROI ratios and asymmetry magnitudes in diseases associated with aging, such as stroke and dementia.
本研究的目的是基于老年健康志愿者的扫描生成解剖学引导的感兴趣区（ROI）脑SPECT模板。我们描述了3种相机系统各自的正常示踪剂摄取和半球不对称性，并比较了各系统之间的这些特征。
对28名老年健康志愿者（平均年龄[±标准差]，70.3±6.5岁）进行99mTc-六甲基丙烯胺肟SPECT扫描，使用单头旋转γ相机（n = 15）、双头（n = 18）或三头（n = 13）相机。计算每个ROI中的平均计数，并参考小脑ROI中的计数，得出半定量的局部脑血流量（rCBF）比值。对于模板和ROI图谱，使用每种相机获取一名健康志愿者的基础图像。同一天使用2种相机扫描的个体（n = 15）的数据用于评估不同相机间的rCBF差异。对于每种相机，使用自动图像配准制作平均SPECT模板。将基础志愿者的T1加权MR图像转换为与SPECT模板尺寸相似的立体定向空间，并定义79个双侧ROI。为了获得ROI的rCBF比值，我们将个体图像与相应模板对齐，然后再与修改后的MR图像对齐。
ROI的变异系数表明ROI的拟合度是可接受的（0.07 - 0.35）。单头、双头和三头相机的平均rCBF比值分别为0.57至1.0、0.67至1.01和0.63至1.00。楔叶、枕叶皮质、枕极、颞中回和额中回后部显示出一致的半球不对称性（83% - 100%的个体右侧大于左侧）。双头和三头相机的平均rCBF比值没有差异，而单头和双头相机的比值有显著差异（39个ROI不同），即使在将双头图像平滑和滤波到单头图像的水平之后也是如此。
基于老年健康志愿者的SPECT模板的使用是该技术的一个重要特征，因为大多数现有的模板使用的是年轻人。另一个重要特征是基于MR图像的ROI的使用。这些程序具有通用性，因为它们使用了不止一种相机。它们可以很容易地在临床和研究环境中实施，以检测与衰老相关疾病（如中风和痴呆）中rCBF ROI比值和不对称程度的特定相机异常偏差。
