Rep Sebastijan, Hocevar Marko, Vaupotic Janja, Zdesar Urban, Zaletel Katja, Lezaic Luka
Department of Nuclear Medicine, University Medical Centre, Ljubljana, Slovenia.
J Radiol Prot. 2018 Mar;38(1):343-356. doi: 10.1088/1361-6498/aaa86f. Epub 2018 Jan 17.
Parathyroid subtraction scintigraphy (PSS) is the most commonly used imaging method for localisation of hyperfunctioning parathyroid glands (HPGs) in primary hyperparathyroidism (PHP), a common endocrine disorder. Hybrid (SPECT/CT) imaging with Tc-sestaMIBI (MIBI) at an early and delayed phase (dual-phase imaging) may be the most accurate conventional imaging approach, but includes additional radiation exposure due to added CT imaging. Recently, F-choline (FCH) PET/CT was introduced for HPG imaging, which can also be performed using the dual-phase approach. To date, no studies have compared organ doses and the effective dose (ED) from conventional subtraction scintigraphy, dual-phase MIBI SPECT/CT, and FCH PET/CT in the localisation of HPGs.
In addition to the comparison of the diagnostic performance of FCH PET/CT and conventional scintigraphic imaging methods, the aim of the study was to measure the organ doses and the ED for conventional subtraction parathyroid imaging protocols, using dual-phase MIBI SPECT/CT as a potential conventional imaging method of choice and FCH dual-phase PET/CT as a potential future imaging method of choice for the localisation of HPGs. Materials, methods. Thirty-six patients referred for parathyroid imaging with a clinical indication of PHP underwent preoperative PSS and dual-phase SPECT/CT imaging with the addition of FCH PET/CT. The diagnostic performance of the imaging modalities was assessed by using histology results as a gold standard. Radiation exposure was calculated for the administered activities of radiopharmaceuticals using ICRP80 weighting factors and for CT exposure at hybrid imaging using dose-length products and the ImPACT CT Patient Dosimetry Calculator.
The diagnostic performance of FCH PET/CT was significantly better than that of conventional imaging modalities (sensitivity of 97% vs 64% and 46% for MIBI SPECT/CT and PSS, respectively, with comparable specificity of over 95% for all modalities). The highest radiation exposure was caused by conventional PSS (7.4 mSv), followed by dual-phase MIBI SPECT/CT (6.8 mSv). The radiation exposure was the lowest for dual-phase FCH PET/CT imaging (2.8 mSv). The added CT imaging for both hybrid approaches did not cause significant additional radiation exposure (1.4 mSv for MIBI SPECT/CT, additional 26.4% to overall exposure; 0.8 mSv for FCH PET/CT, additional 42.4% to overall exposure).
In comparison to conventional scintigraphic imaging of HPGs, emerging hybrid (SPECT/CT, PET/CT) imaging techniques combine superior diagnostic performance with lower radiation exposure to patients.
甲状旁腺减影闪烁显像（PSS）是原发性甲状旁腺功能亢进症（PHP，一种常见的内分泌疾病）中用于定位功能亢进甲状旁腺（HPG）的最常用成像方法。采用锝-甲氧基异丁基异腈（MIBI）进行早期和延迟期的混合（SPECT/CT）成像（双期成像）可能是最准确的传统成像方法，但由于增加了CT成像，会带来额外的辐射暴露。最近，氟代胆碱（FCH）PET/CT被引入用于HPG成像，也可采用双期方法进行。迄今为止，尚无研究比较传统减影闪烁显像、双期MIBI SPECT/CT和FCH PET/CT在HPG定位中的器官剂量和有效剂量（ED）。
除比较FCH PET/CT与传统闪烁成像方法的诊断性能外，本研究的目的是测量传统甲状旁腺减影成像方案的器官剂量和ED，以双期MIBI SPECT/CT作为潜在的传统首选成像方法，以FCH双期PET/CT作为HPG定位潜在的未来首选成像方法。材料与方法。36例因PHP临床指征而转诊进行甲状旁腺成像的患者，术前接受了PSS、双期SPECT/CT成像以及FCH PET/CT检查。以组织学结果作为金标准评估成像方式的诊断性能。使用国际辐射防护委员会（ICRP）80权重因子计算放射性药物给药活度的辐射暴露，并使用剂量长度乘积和ImPACT CT患者剂量测定计算器计算混合成像时CT的辐射暴露。
FCH PET/CT的诊断性能显著优于传统成像方式（敏感性分别为97%，而MIBI SPECT/CT和PSS分别为64%和46%，所有方式的特异性均超过95%，具有可比性）。传统PSS导致的辐射暴露最高（7.4 mSv），其次是双期MIBI SPECT/CT（6.8 mSv）。双期FCH PET/CT成像的辐射暴露最低（2.8 mSv）。两种混合方法中增加的CT成像并未导致显著的额外辐射暴露（MIBI SPECT/CT为1.4 mSv，占总暴露的26.4%；FCH PET/CT为0.8 mSv，占总暴露的42.4%）。
与传统的HPG闪烁成像相比，新兴的混合（SPECT/CT、PET/CT）成像技术在诊断性能更优的同时，降低了患者的辐射暴露。
