Giubbini Raffaele, Milan Elisa, Marcassa Claudio, Paghera Barbara, Fracassi Federica, Camoni Luca, Rodella Carlo, Bertagna Francesco, Motta Federica, Bertoli Mattia, Campini Riccardo
Chair of Nuclear Medicine and Nuclear Medicine Unit, Department of Medical Imaging, University and Spedali Civili, Piazza Spedali Civili, 1, Brescia, Italy.
Nuclear Medicine Unit, San Giacomo Apostolo Hospital, Castelfranco Veneto, TV, Italy.
J Nucl Cardiol. 2016 Dec;23(6):1335-1339. doi: 10.1007/s12350-015-0142-3. Epub 2015 May 13.
123I-MIBG has been widely used in patients with heart failure and neurological disorders. The patients are pre-treated with Lugol's oral solution or potassium perchlorate to prevent thyroid uptake of unlabeled 123I to limit the thyroid radiation exposure. However, despite the inhibition of the iodide pump, the thyroid is frequently visualized. The aim of this study was to study the pattern of thyroid uptake.
We reviewed the 123I-MIBG images of 57 patients studied in three different centers in Italy for cardiac (n = 42) or neurological (n = 15) indications. They were imaged at 15 minutes and 4 hours after injection and in all patients, the thyroid was included in the imaging field of view. In 2 of the 3 centers, the patients were pre-treated with Lugol's oral solution and/or potassium perchlorate (group 1) but in the third center, they were not (group 2). The following imaging parameters were evaluated: heart-to-mediastinum ratio (H/M), thyroid-to-mediastinum ratio (T/M) at 4 hours, and tracer wash out from the heart (HWO) and from the thyroid (TWO).
In the cardiac patients, the HWO was 22.98 ± 7.16% and TWO was 11.4 ± 11.86% (P < .0001). The TWO was 12.2 ± 13.1% in group 1 and 10.05 ± 8.97% in group 2 (P = NS). In the neurological patients the HWO was 26 ± 8.1% and the TWO was 20.32 ± 6.41 (P < .05). The difference in TWO was statistically significant (P < .01) between cardiac and neurological patients, whereas the HWO was not. The 4-hour H/M was 1.49 ± 0.23 in cardiac patients vs 1.4 ± 0.39 in neurological patients (P = NS). The 4-hour T/M was 1.33 ± 0.3 in cardiac patients vs 1.15 ± 0.13 in neurological patients (P < 0.05).
The thyroid visualization in MIBG imaging is likely an expression of thyroid sympathetic innervation. The differences in TWO and T/M ratio in cardiac and neurological patients probably express differences in thyroid dopaminergic receptors. Thus, pre-treatment with potassium perchlorate or Lugol's solution may not be justified in patients undergoing 123I-MIBG imaging in whom the risk of side effects due to pre-treatment could be higher than the risk due to thyroid radiation exposure.
123I-间碘苄胍（123I-MIBG）已广泛应用于心力衰竭和神经系统疾病患者。患者需用卢戈氏口服溶液或高氯酸钾进行预处理，以防止甲状腺摄取未标记的123I，从而限制甲状腺辐射暴露。然而，尽管碘泵受到抑制，但甲状腺仍常显影。本研究的目的是研究甲状腺摄取模式。
我们回顾了在意大利三个不同中心因心脏（n = 42）或神经（n = 15）指征接受研究的57例患者的123I-MIBG图像。在注射后15分钟和4小时对他们进行成像，所有患者的甲状腺均包含在成像视野内。在三个中心中的两个，患者用卢戈氏口服溶液和/或高氯酸钾进行预处理（第1组），但在第三个中心，未进行预处理（第2组）。评估了以下成像参数：4小时时的心脏与纵隔比值（H/M）、甲状腺与纵隔比值（T/M），以及示踪剂从心脏（HWO）和从甲状腺（TWO）的清除情况。
在心脏疾病患者中，HWO为22.98±7.16%，TWO为11.4±11.86%（P <.0001）。第1组的TWO为12.2±13.1%，第2组为10.05±8.97%（P =无显著性差异）。在神经系统疾病患者中，HWO为26±8.1%（P =无显著性差异）。心脏疾病和神经系统疾病患者之间TWO的差异具有统计学意义（P <.01），而HWO无差异。心脏疾病患者4小时时的H/M为1.49±0.23，神经系统疾病患者为1.4±0.39（P =无显著性差异）。心脏疾病患者4小时时的T/M为1.33±0.3，神经系统疾病患者为1.15±0.13（P < 0.05）。
MIBG成像中的甲状腺显影可能是甲状腺交感神经支配的一种表现。心脏疾病和神经系统疾病患者在TWO和T/M比值上的差异可能反映了甲状腺多巴胺能受体的差异。因此，对于接受123I-MIBG成像的患者，用高氯酸钾或卢戈氏溶液进行预处理可能不合理，因为预处理导致副作用的风险可能高于甲状腺辐射暴露的风险。
