Mok Greta S P, Ho Cobie Y T, Yang Bang-Hung, Wu Tung-Hsin
Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Avenida da Universidade, Taipa, Macau, SAR, China.
Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan.
J Nucl Cardiol. 2016 Oct;23(5):1072-1079. doi: 10.1007/s12350-015-0140-5. Epub 2015 May 2.
Previously, we proposed interpolated averaged CT (IACT) for improved attenuation correction (AC) in thoracic PET/CT. This study aims to evaluate its feasibility and effectiveness on cardiac PET/CT.
We simulated (18)F-FDG distribution using the XCAT phantom with normal and abnormal cardiac uptake. Average activity and attenuation maps represented static PET and respiration average CT (ACT), respectively, while the attenuation maps of end-inspiration/expiration represented 2 helical CTs (HCT). IACT was obtained by averaging the 2 extreme phases and the interpolated phases generated between them. Later, we recruited 4 patients who were scanned 1 hr post 315-428 MBq (18)F-FDG injection. Simulated and clinical PET sinograms were reconstructed with AC using (1) HCT, (2) IACT, and (3) ACT. Polar plots and the 17-segment plots were analyzed. Two regions-of-interest were drawn on lesion and background area to obtain the intensity ratio (IR).
Polar plots of PETIACT-AC were more similar to PETACT-AC in both simulation and clinical data. Artifacts were observed in various segments in PETHCT-AC. IR differences of HCT as compared to the phantom were up to ~20%.
IACT-AC reduced respiratory artifacts and improved PET/CT matching similarly to ACT-AC. It is a promising low-dose alternate of ACT for cardiac PET/CT.
此前，我们提出了插值平均CT（IACT）用于改善胸部PET/CT中的衰减校正（AC）。本研究旨在评估其在心脏PET/CT中的可行性和有效性。
我们使用具有正常和异常心脏摄取的XCAT体模模拟（18）F-FDG分布。平均活性图和衰减图分别代表静态PET和呼吸平均CT（ACT），而吸气末/呼气末的衰减图代表2个螺旋CT（HCT）。IACT通过对2个极端相位以及它们之间生成的插值相位进行平均获得。随后，我们招募了4例患者，在注射315 - 428 MBq（18）F-FDG后1小时进行扫描。使用（1）HCT、（2）IACT和（3）ACT对模拟和临床PET正弦图进行AC重建。分析极坐标图和17节段图。在病变和背景区域绘制2个感兴趣区以获得强度比（IR）。
在模拟和临床数据中，PETIACT-AC的极坐标图与PETACT-AC更相似。在PETHCT-AC的各个节段中观察到伪影。与体模相比，HCT的IR差异高达约20%。
IACT-AC减少了呼吸伪影，并且与ACT-AC类似地改善了PET/CT匹配。它是心脏PET/CT中ACT的一种有前景的低剂量替代方法。
