Oral Aylin, Yazıcı Bülent, Eraslan Cenk, Burak Zeynep
Ege University Faculty of Medicine, Department of Nuclear Medicine, İzmir, Turkey
Ege University Faculty of Medicine, Department of Radiology, İzmir, Turkey
Mol Imaging Radionucl Ther. 2018 Oct 9;27(3):99-106. doi: 10.4274/mirt.37450.
Radioiodine is the most specific radionuclide for differentiated thyroid carcinoma (DTC) imaging. Despite its high specificity and sensitivity, false-positive I-131 uptake could be seen on whole body scan (WBS) that may lead to misdiagnosis and unnecessary radioiodine treatment. In this study, we aimed to present the I-131 WBS and concomitant single photon emission computed tomography/computed tomography (SPECT/CT) images of unexpected false-positive radioiodine uptake along with the patients’ clinical outcomes and the contribution of SPECT/CT imaging.
I-131 WBSs of 1507 patients with DTC were retrospectively reviewed, and anticipated I-131 uptakes (like in breasts or thymus) were excluded from the study. The unexpected false-positive I-131 uptakes with concomitant SPECT/CT imaging were included in the study.
Twenty-one patients had 23 unexpected I-131 uptakes on WBS and concomitant SPECT/CT imaging. The vast majority (87%) of these cases were seen on post-therapeutic I-131 WBS. Most of the false-positive I-131 uptakes could be explained by SPECT/CT and radiologic findings, and were secondary to non-thyroid conditions (bronchiectasis, lung infection, subcutaneous injection into gluteal fatty tissue, aortic calcification, benign bone cyst, vertebral hemangioma, recent non-thyroid surgical procedure site, rotator cuff injury, mature cystic teratoma and ovarian follicle cyst). However, the possible reasons of 9 false-positive I-131 uptakes could not be explained by radiologic findings.
We suggest that false-positive I-131 uptake and its underlying mechanisms (inflammation, trapping, increased perfusion, etc.) must be kept in mind in patients with thyroid cancer and unexpected findings must be considered together with serum thyroglobulin levels, SPECT/CT and radiologic findings in order to avoid misdiagnosis and unnecessary radioiodine treatment.
放射性碘是分化型甲状腺癌（DTC）成像中最具特异性的放射性核素。尽管其具有高特异性和敏感性，但在全身扫描（WBS）上仍可能出现假阳性碘-131摄取，这可能导致误诊和不必要的放射性碘治疗。在本研究中，我们旨在展示意外的假阳性碘-131摄取的碘-131 WBS及同期单光子发射计算机断层扫描/计算机断层扫描（SPECT/CT）图像，以及患者的临床结局和SPECT/CT成像的作用。
回顾性分析1507例DTC患者的碘-131 WBS，研究中排除预期的碘-131摄取部位（如乳房或胸腺）。纳入意外的伴有SPECT/CT成像的假阳性碘-131摄取病例。
21例患者在WBS及同期SPECT/CT成像上有23处意外的碘-131摄取。这些病例中的绝大多数（87%）出现在治疗后的碘-131 WBS上。大多数假阳性碘-131摄取可通过SPECT/CT和影像学检查结果解释，继发于非甲状腺疾病（支气管扩张、肺部感染、臀肌脂肪组织皮下注射、主动脉钙化、良性骨囊肿、椎体血管瘤、近期非甲状腺手术部位、肩袖损伤、成熟囊性畸胎瘤和卵巢滤泡囊肿）。然而，9例假阳性碘-1摄取的可能原因无法通过影像学检查结果解释。
我们建议，甲状腺癌患者必须牢记假阳性碘-131摄取及其潜在机制（炎症、摄取、灌注增加等），为避免误诊和不必要的放射性碘治疗，必须将意外发现与血清甲状腺球蛋白水平、SPECT/CT及影像学检查结果综合考虑。
