FALSE POSITIVE RADIOIODINE POST-ABLATION SCAN IN SCALP REGION IN A WOMAN WHO USED HAIR COLORING REVEALED BY SPECT/CT.

OBJECTIVE: Radioiodine ablation with iodine-131 is a standard therapeutic procedure for patients diagnosed with differentiated thyroid carcinoma (DTC). We present a contamination artifact on whole-body scan (WBS), after radioiodine ablation due to papillary thyroid carcinoma. The hybrid imaging resolved the question of metastasis versus contamination. METHODS: In the case of 35-year-old female patient we used a General Electric hybrid gamma camera with a high-energy-general-purpose collimator for performing WBS, and single photon emission computed tomography combined with low dose computed tomography (SPECT/CT) for the detection of any residual thyroid tissue or meta-static disease and at the same time ablation and treatment of any confirmed metastasis. RESULTS: A thyroid scan showed activity in the remnant thyroid tissue of the right lobe, but also laterally in the calvaria (left temporal region). The patient's neck ultra-sound and thyroglobulin level were not in favor of metastasis. A false positive finding due to hair coloring was concluded with SPECT/CT hybrid imaging. CONCLUSION: SPECT/CT scan can contribute to establishing a final diagnosis in patients being evaluated for atypical locations of radioactive iodine accumulation after ablative doses of radioactive iodine, distinguishing between metastases from DTC and false positive accumulations or artifacts.

Thyroid cancer detection rate and associated risk factors in patients with thyroid nodules classified as Bethesda category III.

Background Ultrasound guided fine-needle aspiration (FNA) is a standard procedure for thyroid nodules management and selecting patients for surgical treatment. Atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS), as stated by The Bethesda System for Reporting Thyroid Cytopathology, is a diagnostic category with an implied malignancy risk of 5-15%. The aim of our study was to review cytology and histopathology reports, as well as clinical and ultrasound data, for thyroid nodules reported as AUS/FLUS, in order to evaluate the malignancy rate and to assess factors associated with malignant outcome. Patients and methods A total of 112 AUS/FLUS thyroid nodules in 105 patients were evaluated, of which 85 (75.9%) were referred to surgery, 21 (18.8%) were followed-up by repeat FNA and 6 nodules (5.3%) were clinically observed. Each was categorized in two final diagnostic groups - benign or malignant, which were further compared to clinical data of patients and ultrasonographic features of the nodules. Results Final diagnosis of malignancy was reached in 35 cases (31.2%) and 77 (68.8%) had benign lesions. The most frequent type of cancer was papillary thyroid carcinoma (PTC) - 58.1% PTC and 25.8% had follicular variant of PTC. Patients' younger age, smaller nodule size, hypoechoic nodule and presence of calcifications were shown to be statistically significant risk factors for malignancy. Conclusions The rate of malignancy for the AUS/FLUS diagnostic category in our study was higher than estimated by the Bethesda System. Clinical and ultrasound factors should be considered when decision for patient treatment is being made.

Absent 99mTc-MIBI Uptake in the Thyroid Gland during Early Phase of Parathyroid Scintigraphy in Patients with Primary and Secondary Hyperparathyroidism.

BACKGROUND: Thyroid uptake of technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) during parathyroid scintigraphy can be affected by various conditions. AIM: To evaluate the frequency of absent 99mTc-MIBI uptake by the thyroid gland in the early phase of dual-phase parathyroid scintigraphy. METHODS: The early planar images of dual phase Tc99m MIBI parathyroid scintigraphy from 217 patients performed between 2014 and 2017 were retrospectively analysed. Patients were divided into two groups. The first group included 147 patients with primary hyperparathyroidism and the second group included 70 patients with chronic renal failure. Patient records, laboratory and ultrasonographic data were analysed in all patients. Descriptive statistic was used for data analysis. RESULTS: Out of all patients in the first group, 18 patients (12.24%) showed absent thyroid uptake. Thyroidectomy was performed in 44.4% of these patients, and the rest of them had some thyroid disease. Only one patient had no thyroid or another chronic disease. In the second group, 8 patients (11.42%) presented with absent thyroid uptake of MIBI. Among them, 5 patients had no history of thyroid disease and had been on hemodialysis programme, and 3 patients had hypothyroidism. CONCLUSION: Absent 99mTc-MIBI uptake in the thyroid during the early phase of parathyroid scintigraphy is most frequently related to thyroid disease. A small proportion of patients with chronic renal failure can present with absent 99mTc-MIBI uptake in the thyroid as well. The mechanism for this alteration is still unclear and needs further investigation.