心肌双同位素符合/单光子成像的可行性

Feasibility of dual-isotope coincidence/single-photon imaging of the myocardium.

作者信息

Di Bella E V, Kadrmas D J, Christian P E

机构信息

Medical Imaging Research Laboratory, Department of Radiology, University of Utah, Salt Lake City, Utah 84108, USA.

出版信息

J Nucl Med. 2001 Jun;42(6):944-50.

PMID:11390561

Abstract

UNLABELLED

Hybrid PET scanners offer the possibility of obtaining myocardial viability information from coincidence imaging of the positron emitter (18)F-FDG and perfusion measurements from a single-photon tracer-potentially simultaneously. This new approach is less costly and more readily available than dedicated PET and offers potential for improved FDG resolution and sensitivity compared with SPECT with 511-keV collimators. Simultaneous imaging of the coincidence and single-photon events offers the further advantages of automatic image registration and reduced imaging time. However, the feasibility of simultaneous coincidence/single-photon imaging or even immediately sequential imaging is unknown. In this study, the potential of using standard low-energy high-resolution (LEHR) collimators with hybrid PET to obtain coincidence and SPECT data was assessed.

METHODS

Phantom and human studies were performed to investigate the effect of LEHR collimators on FDG coincidence imaging with a hybrid PET system, the effect of the presence of (99m)Tc during FDG coincidence imaging with LEHR collimators, and the effect of the presence of FDG during (99m)Tc SPECT imaging.

RESULTS

FDG images were somewhat degraded (a measure of myocardial nonuniformity increased 10%) with LEHR collimators. With 148 MBq (4 mCi) (99m)Tc present during FDG imaging of a phantom, image quality was maintained and the number of detected coincidences changed by <5%. With (99m)Tc/(18)F whole-body ratios of 7:1, crosstalk from (18)F photons accounted for the majority of counts in the (99m)Tc SPECT images and resulted in severe artifacts. The artifacts were decreased with a simple crosstalk correction scheme but remained problematic.

CONCLUSION

(99m)Tc/(18)F ratios of at least 9:1 and state-of-the-art reconstruction and crosstalk correction are likely to be required to perform immediately sequential coincidence/single-photon imaging of the myocardium with clinically useful results. Additional challenges remain before simultaneous imaging of coincidence events and single photons can be realized in practice.

摘要

未标记

混合型正电子发射断层扫描仪（PET）提供了从正电子发射体（18）F-FDG的符合成像以及单光子示踪剂的灌注测量中获取心肌存活信息的可能性——有可能同时进行。这种新方法比专用PET成本更低且更容易获得，并且与带有511千电子伏特准直器的单光子发射计算机断层扫描（SPECT）相比，在FDG分辨率和灵敏度方面具有提升潜力。同时对符合事件和单光子事件进行成像还具有自动图像配准和减少成像时间的进一步优势。然而，同时进行符合/单光子成像甚至立即顺序成像的可行性尚不清楚。在本研究中，评估了使用标准低能高分辨率（LEHR）准直器与混合型PET获取符合和SPECT数据的潜力。

方法

进行了体模和人体研究，以调查LEHR准直器对混合型PET系统进行FDG符合成像的影响、在使用LEHR准直器进行FDG符合成像期间（99m）Tc的存在所产生的影响，以及在（99m）Tc SPECT成像期间FDG的存在所产生的影响。

结果

使用LEHR准直器时，FDG图像有所退化（心肌不均匀性测量值增加了10%）。在体模的FDG成像期间存在148兆贝可（4毫居里）（99m）Tc时，图像质量得以维持，检测到的符合事件数量变化<5%。当（99m）Tc/（18）F全身比例为7:1时，来自（18）F光子的串扰占（99m）Tc SPECT图像中计数的大部分，并导致严重伪影。通过简单的串扰校正方案，伪影有所减少，但仍然存在问题。