Department of Molecular Imaging in Medicine, Graduate School of Medicine, Osaka University, 2-1, Yamadaoka, Suita, Osaka, 565-0871, Japan.
Shionogi & Co., Ltd, 1-8, Doshomachi 3-Chome, Chuo-ku, Osaka, 541-0045, Japan.
Ann Nucl Med. 2023 Apr;37(4):227-237. doi: 10.1007/s12149-022-01819-4. Epub 2023 Jan 19.
C-PHNO is a PET radioligand most specific to dopamine D receptor (DR). The long scan duration of 120 min used in quantification of C-PHNO binding to DR in previous studies is challenging to subjects. The main objective of this study was to investigate the effects of shorter scan times on the binding of C-PHNO to DR and test-retest reliability using the latest digital whole-body PET system.
Two 120-min C-PHNO brain scans were performed in 7 healthy subjects using a digital whole-body PET/CT. The binding potential relative to non-displaceable tracer in the tissue (BP) of DR-rich regions: the pallidum, ventral striatum (VST), substantia nigra (SN) and hypothalamus, were quantified using the simplified reference tissue model. The bias, correlation, and test-retest reliability of BP, which includes the test-retest variability (TRV) and intraclass correlation coefficient (ICC), were evaluated and compared between scans of shorter durations (40-110 min post-injection) and the original 120-min scan acquisitions.
Progressively, shorter scan durations were associated with underestimation of BP, slightly decreased correlation with 120-min derived BP, and decrease in test-retest reliability. The BP values of the pallidum, VST and SN from the shortened 90-min scans showed excellent correlation with those derived from the 120-min scans (determination coefficients > 0.98), and the bias within 5%. The test-retest reliability of BP in these regions derived from 90-min scan (TRV of 3% in the VST and pallidum, 7% in the SN and the ICC exceeded 0.88) was comparable to those obtained in previous 120-min studies using brain-dedicated PET scanners. In the hypothalamus, the BP values obtained from scan-time less than 110 min showed bias larger than 5% and the TRV more than 9%.
The scan-time shortening causes bias and decreasing test-retest reliability of C-PHNO BP. However, in the whole-body PET system, 90-min scan duration was sufficient for estimating the C-PHNO BP in the DR-rich striatum and SN with small bias and at the test-retest reliability comparable to those derived from 120-min scans using the brain-dedicated PET systems.
C-PHNO 是一种对多巴胺 D 受体（DR）具有最高特异性的 PET 示踪剂。先前研究中，对 C-PHNO 与 DR 结合的定量分析需要长达 120 分钟的扫描时长，这给受试者带来了挑战。本研究的主要目的是探讨使用最新的全身数字 PET 系统，缩短扫描时间对 C-PHNO 与 DR 结合的影响，以及测试-重测可靠性。
对 7 名健康受试者进行了两次 120 分钟的 C-PHNO 脑部扫描，使用全身数字 PET/CT 完成。使用简化参考组织模型，对富含 DR 的区域（苍白球、腹侧纹状体（VST）、黑质（SN）和下丘脑）的组织中与不可置换示踪剂相比的结合潜能（BP）进行定量。评估并比较了较短（注射后 40-110 分钟）和原始 120 分钟扫描采集之间的 BP 偏倚、相关性和测试-重测可靠性，包括测试-重测变异性（TRV）和组内相关系数（ICC）。
随着扫描时间的缩短，BP 值逐渐出现低估，与 120 分钟衍生 BP 的相关性略有下降，且测试-重测可靠性降低。来自缩短至 90 分钟的扫描的苍白球、VST 和 SN 的 BP 值与 120 分钟扫描的 BP 值具有极好的相关性（决定系数 > 0.98），且偏倚在 5%以内。来自 90 分钟扫描的这些区域的 BP 的测试-重测可靠性（VST 和苍白球的 TRV 为 3%，SN 的 TRV 为 7%，ICC 超过 0.88）与先前使用脑部专用 PET 扫描仪进行的 120 分钟研究中获得的结果相当。在下丘脑，扫描时间少于 110 分钟时获得的 BP 值的偏倚大于 5%，且 TRV 大于 9%。
扫描时间缩短会导致 C-PHNO BP 的偏倚和测试-重测可靠性降低。然而，在全身 PET 系统中，90 分钟的扫描时长足以用于估计富含 DR 的纹状体和 SN 中的 C-PHNO BP，其偏倚较小，与使用脑部专用 PET 系统进行 120 分钟扫描的结果相当。
