False-Negative 68 Ga-FAPI PET/CT in Pediatric Thyroid Medullary Carcinoma Seen With 68 Ga-DOTATOC PET/CT and 18 F-FDG PET/CT.

ABSTRACT: In adults, 68 Ga-FAP inhibitor ( 68 Ga-FAPI) PET/CT outperforms 68 Ga-radiolabeled somatostatin analog peptides ( 68 Ga PET/CT) and 18 F-FDG PET/CT in detecting thyroid lesions. This is the case of a 13-year-old boy newly diagnosed with medullary thyroid cancer with high calcitonin level. 68 Ga PET/CT revealed the presence of only a primary thyroid lesion. Proven to be superior in detecting metastasis, 68 Ga-FAPI PET/CT was performed. The results came out negative for primary and potential metastatic lesions. This case sheds shed light on false-negatives reported in 68 Ga-FAPI PET/CT scans in pediatric patients, emphasizing the need for alternate radiotracers when a negative study is met.

Clinico-social factors to choose radioactive iodine dose in differentiated thyroid cancer patients: an Asian survey.

OBJECTIVE: This survey was designed to investigate the practice of radioactive iodine (RAI) therapy and clinico-social factors related to RAI dose in differentiated thyroid cancer (DTC) patients among Asian countries. MATERIALS AND METHODS: A survey questionnaire was mailed to Asian Nuclear Medicine physicians that addressed the infrastructure, general regulations on RAI therapy, adherence to recommendations, RAI dose selection, factors to elevate RAI dose, and follow-up protocols in DTC patients. Contrived RAI practice recommendations were based on key international guidelines. RESULTS: A total of 38 institutes from 20 Asian countries were enrolled. Dose administration criterion was 30 mCi, but release criterion was variable (5-70 µSv/h). When the administered RAI dose was classified according to three risk stratifications, RAI dose distribution was variable, especially in the low-risk group. In this group, 14.0% of respondents preferred no ablation, 54.5% were treated with 0-30 mCi, 21.5% were treated with 30-50 mCi, and 10.0% were administered even higher doses of 80-100 mCi. The major factors that influenced the elevated RAI doses in the respondents included high serum thyroglobulin (Tg), inadequate information on lymph node involvement, and histopathology reporting. Although serum Tg measurement is included in most of the institutes as a follow-up tool, neck ultrasound was omitted in 25% and in another 25% a whole-body scan was not included. CONCLUSION: Different RAI dose ranges are used in the low-risk group probably because the enrolled physicians consider RAI dose elevation on the basis of clinico-social factors beyond pre-existed guidelines. Our study may enable closer harmonization of RAI therapy practice in Asian countries.

Assessment of segmental left ventricular thickening in diabetic type II obese patients with normal myocardial perfusion scan.

OBJECTIVE: The aim of this study is to investigate whether gated single photo emission tomography (gSPET) can be used to detect subclinical left ventricular systolic dysfunction (LVSD) in obese diabetic type II patients. SUBJECTS AND METHODS: We retrospectively reviewed gSPET images of 190 patients with diabetes mellitus type II (DM II) (137 females and 53 males) with normal myocardial perfusion and normal ejection fraction (EF). Standardized twenty segment polar maps of thickening and motion were generated. Correlation between body mass index (BMI) and thickening for each segment was performed. RESULTS: Statistically significant results were reported in female patients including: negative correlation between BMI and EF (-0.19, P=0.03). End diastolic volume (EDV) also significantly increased with increasing BMI (0.25, P<0.01). There was also statistically significant negative correlation between septal thickening and BMI segment 15 (-0.19, P=0.02), segment 16 (-0.22, P=0.01), segment 18 (-0.20, P=0.01), segment 19 (-0.25, P=0.003), segment 20 (-0.2, P=0.02)]. No statistical significant correlation was found between thickening and BMI in male patients. CONCLUSION: This is the first time where thickening as measured by gSPET has been used to demonstrate subclinical LVSD in DM II obese patients. The relationship between gender and obesity on cardiovascular function and structure needs further investigations.