Department of Neuropsychiatry, Sapporo Medical University, Sapporo, Hokkaido, Japan.
Dement Geriatr Cogn Disord. 2009;28(4):330-7. doi: 10.1159/000251935. Epub 2009 Oct 23.
BACKGROUND/AIMS: It is often difficult to distinguish idiopathic normal pressure hydrocephalus (iNPH) from other neurodegenerative disorders such as Alzheimer's disease (AD). To understand the characteristic pattern of blood flow in iNPH, we performed brain perfusion SPECT and analyzed the results by using the easy Z-score imaging system (eZIS).
Subjects were 12 patients with probable iNPH and 10 probable AD patients with prominent ventriculomegaly. They underwent brain perfusion SPECT using (99m)Tc-ethylcysteinate dimer as a tracer.
The two-tailed view display in eZIS demonstrated an obvious two-layer structure consisting of decreased blood flow around the corpus callosum and, in iNPH, enhanced perfusion in areas surrounding the cingulate gyrus in the sagittal view, while no AD cases showed these findings.
Hypoperfusion around the corpus callosum in iNPH could be, at least partially, a false-positive finding due to an insufficient anatomical standardization of SPECT images caused by an abnormally enlarged ventricle. Increased blood perfusion in the external layer adjacent to the hypoperfused area might be caused by increased radioisotope count per volume resulting from exclusion of cerebral cortex by a dilated ventricle. Our results demonstrate that a two-layer appearance revealed by the two-tailed view analysis of brain perfusion SPECT using eZIS could be a means to detect iNPH.
背景/目的：特发性正常压力脑积水（iNPH）与阿尔茨海默病（AD）等其他神经退行性疾病的鉴别往往较为困难。为了了解 iNPH 的血流特征模式，我们进行了脑灌注 SPECT 检查，并使用易于 Z 分数成像系统（eZIS）对结果进行了分析。
研究对象为 12 例可能患有 iNPH 和 10 例伴有明显脑室扩大的可能 AD 患者。他们使用（99m）Tc-乙基半胱氨酸二聚体作为示踪剂进行脑灌注 SPECT。
eZIS 的双侧视图显示出明显的两层结构，包括胼胝体周围血流减少，而在 iNPH 中，在矢状视图中，扣带回周围区域的灌注增强，而没有 AD 病例显示这些发现。
iNPH 胼胝体周围的低灌注可能至少部分是由于 SPECT 图像的解剖标准化不足而导致的假阳性发现，这是由于异常扩大的脑室造成的。与灌注不足区域相邻的外层的血流增加可能是由于扩张的脑室排除了大脑皮层，导致每体积的放射性同位素计数增加所致。我们的研究结果表明，使用 eZIS 的脑灌注 SPECT 双侧视图分析显示的双层外观可能是检测 iNPH 的一种手段。
