Morita Keishin, Maebatake Akira, Iwasaki Rina, Shiotsuki Yuki, Himuro Kazuhiko, Baba Shingo, Sasaki Masayuki
Division of Medical Quantum Science, Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Radiological Science Course, Department of Health Sciences, School of Medicine, Kyushu University, Fukuoka, Japan.
Asia Ocean J Nucl Med Biol. 2018 Spring;6(2):120-128. doi: 10.22038/aojnmb.2018.10330.
The purpose of this study was to examine the optimal reconstruction parameters for brain dopamine transporter SPECT images obtained with a fan beam collimator and compare the results with those obtained by using parallel-hole collimators.
Data acquisition was performed using two SPECT/CT devices, namely a Symbia T6 and an Infinia Hawkeye 4 (device A and B) equipped with fan-beam (camera A-1 and B-1), low- and medium-energy general-purpose (camera A-2 and B-2), and low-energy high-resolution (camera A-3 and B-3) collimators. The SPECT images were reconstructed using filtered back projection (FBP) with Chang's attenuation correction. However, the scatter correction was not performed. A pool phantom and a three-dimensional (3D) brain phantom were filled with I solution to examine the reconstruction parameters. The optimal attenuation coefficient was based on the visual assessment of the profile curve, coefficient of variation (CV) [%], and summed difference from the reference activity of the pool phantom. The optimal Butterworth filter for the 3D-brain phantom was also determined based on a visual assessment. The anthropomorphic striatal phantom was filled with I solution at striatum-to-background radioactivity ratios of 8, 6, 4, and 3. The specific binding ratio (SBR) of the striatum (calculated by the CT method) was used to compare the results with those of the parallel-hole collimators.
The optimal attenuation coefficients were 0.09, 0.11, 0.05, 0.05, 0.11, and, 0.10 cm for cameras A-1, A-2, A-3, B-1, B-2, and B-3, respectively. The cutoff frequencies of the Butterworth filter were 0.32, 0.40, and 0.36 cycles/cm for camera A, and 0.46, 0.44, and 0.44 cycles/cm for camera B, respectively. The recovery rates of the SBR with camera A were 51.2%, 49.4%, and 45.6%, respectively. The difference was not statistically significant. The recovery rates of the SBR with camera B were 59.2%, 50.7%, and 50.8%, respectively. Camera B-1 showed significantly high SBR values.
As the findings indicated, the optimal reconstruction parameters differed according to the devices and collimators. The fan beam collimator was found to provide promising results with each device.
本研究旨在探讨使用扇形束准直器获得的脑多巴胺转运体单光子发射计算机断层扫描（SPECT）图像的最佳重建参数，并将结果与使用平行孔准直器获得的结果进行比较。
使用两台SPECT/CT设备进行数据采集，即配备扇形束准直器（相机A-1和B-1）、低能和中能通用准直器（相机A-2和B-2）以及低能高分辨率准直器（相机A-3和B-3）的Symbia T6和Infinia Hawkeye 4（设备A和B）。SPECT图像采用带张式衰减校正的滤波反投影（FBP）进行重建。然而，未进行散射校正。用碘溶液填充一个体模和一个三维（3D）脑模，以检查重建参数。最佳衰减系数基于对轮廓曲线的视觉评估、变异系数（CV）[％]以及与体模参考活性的总和差异。还基于视觉评估确定了3D脑模的最佳巴特沃斯滤波器。在纹状体与背景放射性比值为8、6、4和3的情况下，用人造纹状体模填充碘溶液。纹状体的特异性结合率（通过CT方法计算）用于将结果与平行孔准直器的结果进行比较。
相机A-1、A-2、A-3、B-1、B-2和B-3的最佳衰减系数分别为0.09、0.11、0.05、0.05、0.11和0.10 cm。相机A的巴特沃斯滤波器截止频率分别为0.32、0.40和0.36周/cm，相机B的截止频率分别为0.46、0.44和0.44周/cm。相机A的特异性结合率（SBR）恢复率分别为51.2％、49.4％和45.6％。差异无统计学意义。相机B的SBR恢复率分别为59.2％、50.7％和50.8％。相机B-1显示出显著较高的SBR值。
如研究结果所示，最佳重建参数因设备和准直器而异。发现扇形束准直器在每种设备上均能提供有前景的结果。
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