Usefulness of SPECT/CT in Parathyroid Lesion Detection in Patients with Thyroid Parenchymal 99mTc-Sestamibi Retention
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Parathyroid adenoma detection with dual-phase 99mTc-sestamibi (MIBI) scintigraphy depends on differential MIBI washout from thyroid. However, autoimmune thyroid disease (AITD) may cause MIBI to be retained in the thyroid gland and reduce parathyroid detection. We evaluated the impact of AITD on MIBI thyroid retention and additional benefit of SPECT/CT in these patients.
Dual phase planar MIBI and SPECT/CT was performed on 82 patients. SPECT/CT was performed immediately after delayed planar scan. Thyroid density (Hounsfield unit, CT-HU) and size were measured on CT component of SPECT/CT. MIBI uptake in early scans and retention in delayed scans were visually graded and correlated with clinical factors and CT findings. Finally, planar and SPECT/CT findings were compared for parathyroid lesion visualization according to thyroid MIBI retention.
In early scan, multivariate analysis showed only thyroid size predicted early uptake. In delayed scan, multivariate analysis showed higher visual grade in early scan, lower CT-HU or AITD were significant predictors for delayed thyroid parenchymal retention. Overall, ten more parathyroid lesions were visualized on SPECT/CT compared to planar scans (57 vs. 47, p = 0.002). SPECT/CT was especially more useful in patients with thyroidal MIBI retention, as eight out of the ten additional lesions detected were found in patients with thyroid MIBI retention.
AITD is an important factor for MIBI thyroid parenchymal retention on delayed scans, and may impede parathyroid lesion detection. Patients with MIBI retention in the thyroid parenchyma on delayed scans are likely to benefit from an additional SPECT/CT.
KeywordsAutoimmune thyroid disease 99mTc-sestamibi scintigraphy SPECT/CT Parathyroid
Compliance with Ethical Standards
Conflict of Interest
Sang Hyun Hwang, Yumie Rhee, Mijin Yun, Jung Hyun Yoon, Jeong Won Lee, and Arthur Cho declare that they have no conflict of interest.
This study was approved by the institutional review board (IRB) of our institution. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was waived because of the retrospective design of this study. We declare that this paper is solely submitted to Nuclear Medicine and Molecular Image. The content has not been published or submitted for publication elsewhere. Final approval of the version to be published was done by all authors.
The institutional review board of our institute approved this retrospective study, and the requirement to obtain informed consent was waived.
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