Department of Nuclear Medicine Technology, Gunma Prefectural College of Health Sciences, Maebashi, Japan.
Ann Nucl Med. 2011 Jan;25(1):69-74. doi: 10.1007/s12149-010-0430-6. Epub 2010 Oct 19.
Cerebral SPECT images require high spatial and contrast resolution for precise evaluation of the abnormal tracer distribution in the brain. A shorter data acquisition time is preferable so that artifacts due to patient movement are avoided. We tried to shorten data acquisition time applying larger sampling angle and offset acquisition method, in which half degree of the step angle was shifted in the opposite gamma camera of the dual-detector SPECT system.
A simulation study was performed with a 3-dimensional mathematical phantom. The phantom studies were performed with a hot-rod phantom and a brain phantom. A clinical study with ⁹⁹(m)Tc-ECD SPECT was also performed on a patient who had a cerebral infarction. Reconstruction of images was done for the normal 6° and 12° onset and 12° offset. Data for the 12° offset were acquired by shifting of sampling angles of the opposite detector by half (6°) of the sampling angles of 12°. The MLEM algorithm was used for image reconstruction. Image qualities in the simulation study, the phantom studies, and the clinical study were compared for the 6° and 12° onset, and for the 12° offset by quantitative analysis with use of profile curves.
Analysis of the profile curves revealed that the image quality of the 12° offset was better than that of the 12° onset and compared to that of the 6° onset in the simulation study, the phantom studies, and the clinical study.
The present study indicates that wide-angle offset data acquisition improves the image resolution of brain SPECT compared to onset data acquisition with the same sampling time.
脑 SPECT 图像需要高空间和对比度分辨率，以便精确评估大脑中异常示踪剂的分布。较短的数据采集时间是优选的，以避免由于患者运动导致的伪影。我们尝试通过应用更大的采样角度和偏移采集方法来缩短数据采集时间，在该方法中，双探头 SPECT 系统的相反伽马相机中沿相反方向移动半度的步角。
通过三维数学体模进行模拟研究。体模研究使用热棒体模和脑体模进行。还对患有脑梗死的患者进行了 ⁹⁹(m)Tc-ECD SPECT 的临床研究。对正常的 6°和 12°起始以及 12°偏移进行图像重建。通过将相反探测器的采样角度偏移半度（12°）来采集 12°偏移的数据。使用 MLEM 算法进行图像重建。通过使用轮廓曲线进行定量分析，比较了模拟研究、体模研究和临床研究中 6°和 12°起始以及 12°偏移的图像质量。
轮廓曲线分析表明，在模拟研究、体模研究和临床研究中，12°偏移的图像质量优于 12°起始，并且与 6°起始相当。
本研究表明，与相同采样时间的起始数据采集相比，广角偏移数据采集可提高脑 SPECT 的图像分辨率。
