van Dijk Joris D, Jager Pieter L, Ottervanger Jan Paul, Slump Cornelis H, de Boer Jaep, Oostdijk Adrianus H J, van Dalen Jorn A
Department of Nuclear Medicine, Isala Hospital, Zwolle, The Netherlands MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
Department of Nuclear Medicine, Isala Hospital, Zwolle, The Netherlands.
J Nucl Med Technol. 2015 Mar;43(1):36-40. doi: 10.2967/jnmt.114.148601. Epub 2015 Jan 22.
Myocardial perfusion imaging (MPI) with SPECT is widely adopted in clinical practice but is associated with a relatively high radiation dose. The aim of this study was to determine the minimum product of tracer dose and scan time that will maintain diagnostic value for cadmium zinc telluride (CZT) SPECT MPI.
Twenty-four patients underwent clinically indicated stress MPI using CZT SPECT and a body weight-dependent (3 MBq/kg) (99m)Tc-tetrofosmin tracer dose. Data were acquired for 8 min in list mode. Next, images were reconstructed using 2-, 4-, 6-, and 8-min time frames. Differences between the 8-min reference scan and the shorter scans were determined in segmental uptake values (using the 17-segment cardiac model), ejection fraction, and end-diastolic volume. A 5% difference in segmental uptake was considered to significantly influence the diagnostic value. Next, the quality of the 4-, 6-, and 8-min scans was scored on a 4-point scale by consensus by 3 experienced nuclear medicine physicians. The physicians did not know the scan time or patient information.
Differences in segmental uptake values, ejection fraction, and end-diastolic volume were greater for shorter scans than for the 8-min reference scan. On average, the diagnostic value was influenced in 7.7 segments per patient using the 2-min scans, in comparison to 2.0 and 0.8 segments per patient using the 4- and 6-min scans, respectively. In addition, the 4-min scans led to a significantly reduced image quality compared with the 8-min scans (P < 0.05). This was not the case for the 6-min scan.
Six minutes was the shortest acquisition time in stress MPI using CZT SPECT that did not affect the diagnostic value for a tracer dose of 3 MBq/kg. Hence, the patient-specific product of tracer dose and scan time can be reduced to a minimum of 18 MBq·min/kg, which may lower the effective radiation dose for patients to values below 1 mSv.
单光子发射计算机断层扫描（SPECT）心肌灌注成像（MPI）在临床实践中被广泛应用，但辐射剂量相对较高。本研究的目的是确定维持碲化镉锌（CZT）SPECT MPI诊断价值所需的示踪剂剂量与扫描时间的最小乘积。
24例患者接受了临床指征的负荷MPI检查，采用CZT SPECT和根据体重确定的（3 MBq/kg）锝-99m替曲膦示踪剂剂量。以列表模式采集8分钟的数据。接下来，使用2分钟、4分钟、6分钟和8分钟的时间帧重建图像。在节段摄取值（使用17节段心脏模型）、射血分数和舒张末期容积方面，确定8分钟参考扫描与较短扫描之间的差异。节段摄取差异5%被认为会显著影响诊断价值。接下来，由3名经验丰富的核医学医师通过共识对4分钟、6分钟和8分钟扫描的质量进行4分制评分。医师不知道扫描时间或患者信息。
较短扫描的节段摄取值、射血分数和舒张末期容积的差异大于8分钟参考扫描。平均而言，使用2分钟扫描时，每位患者有7.7个节段的诊断价值受到影响，而使用4分钟和6分钟扫描时，每位患者分别为2.0个和0.8个节段。此外，与8分钟扫描相比，4分钟扫描导致图像质量显著降低（P < 0.05）。6分钟扫描情况并非如此。
6分钟是使用CZT SPECT进行负荷MPI检查时最短的采集时间且不影响3 MBq/kg示踪剂剂量的诊断价值所需的时间。因此，示踪剂剂量与扫描时间按患者个体计算的乘积可降至最低18 MBq·min/kg，这可能会将患者的有效辐射剂量降低至1 mSv以下。
