基于循证医学的定量SPECT显像的潜在临床应用

An evidence-based review of quantitative SPECT imaging and potential clinical applications

SPECT常被认为无法进行定量测量，但随着多模态γ相机（SPECT/CT）、图像重建算法及复杂补偿技术用于光子衰减和散射等技术的出现，目前SPECT已经可以开展类似于PET的定量（如kBq·cm－3，标准摄取值）。该综述阐述了SPECT定量证据及其临床应用，通过体内评估SPECT数据重建，提高定量准确性。SPECT重建时基于CT补偿校正，对99Tcm显像的定量测量可精确到其已知体内放射性浓度的±10%以内，文章也介绍了对其他放射性核素的定量测量。与PET相比，尽管SPECT的光子检测效率（灵敏度）及空间分辨率较低，但在某些方面SPECT却有一定的优势，如其所使用的放射性核素具有较长的半衰期，同时可以通过脉冲高度频谱区分不同的放射性标记物，从而开展多种示踪剂的研究。

SPECT has traditionally been regarded as nonquantitative. Advances in multimodality γ-cameras (SPECT/CT), algorithms for imagereconstruction, and sophisticated compensation techniques to correct for photon attenuation and scattering have, however,now made quantitative SPECT viable in a manner similar to quantitative PET (i.e., kBq?cm?3, standardized uptake value). This review examines the evidence for quantitative SPECT and demonstrates clinical studies inwhich the accuracy of the reconstructed SPECT data has been assessed in vivo. SPECT reconstructions using CT-based compensationcorrections readily achieve accuracy for 99mTc to within ±10% of the known concentration of the radiotracer in vivo. Quantification with other radionuclides is also beingintroduced. SPECT continues to suffer from poorer photon detection efficiency (sensitivity) and spatial resolution than PET;however, it has the benefit in some situations of longer radionuclide half-lives, which may better suit the biologic processunder examination, as well as the ability to perform multitracer studies using pulse height spectroscopy to separate differentradiolabels.