Objectives: Somatostatin is an endocrine peptide hormone that regulates neurotransmission and cell proliferation by interacting with G protein-coupled somatostatin receptors (SSTRs). SSTRs are specific molecular targets of several radiotracers for neuroendocrine tumor (NET) imaging. Gallium-68 ( 68 Ga)-DOTA-TATE is widely used for positron emission tomography/computed tomography (PET/CT) imaging of SSTRs and has shown a higher affinity for SSTR2, the most common SSTR subtype found in NETs. We aimed to analyze the distribution pattern of 68 Ga-DOTA-TATE in normal subjects. Methods: A total of 617 consecutive 68 Ga-DOTA-TATE PET/CT whole-body scans performed in our department from May 2015 through April 2020 with known or suspected neuroendocrine malignancies, mostly to evaluate adrenal adenomas, were retrospectively analyzed by 2 nuclear medicine physicians. One hundred eighteen subjects without a diagnosis of NET, with no tracer avid lesion of NET on 68 Ga-DOTA-TATE PET/CT, and followed up for at least 6 months (average 2-3 years) without any biochemical, clinical, or imaging findings suggestive of NET were included in this study. Results: The highest uptake of 68 Ga-DOTA-TATE was noted in the spleen followed by the kidneys, adrenal glands, liver, stomach, small intestine, prostate gland, pancreas head, pancreas body, thyroid gland, and uterus, in descending order. Minimal to mild uptake was detected in the submandibular glands, parotid glands, thymus, muscles, bones, breast, lungs, and mediastinum. Conclusion: Our study shows the biodistribution pattern of 68 Ga-DOTA-TATE in normal subjects and the ranges of the maximum standard uptake value (SUV max ) and SUV mean values of 68Ga-DOTA-TATE obtained in several tissues for reliably identifying malignancy in 68 Ga-DOTA-TATE PET/CT studies.

We present FDG PET/CT findings of a human immunodeficiency virus-positive patient suspicious for lung cancer with a solitary metastasis to the adrenal gland. Wedge resection of the pulmonary nodules revealed Nocardia infection and a repeat FDG PET/CT imaging after the antibiotic treatment demonstrated complete metabolic response of the adrenal lesion and pulmonary nodules. It should be kept in mind that nocardiosis may present with FDG-avid lesions masquerading as malignancies in immunocompromised patients.

Papillary carcinoma of thyroid (PTC) is the most common neoplasm of the thyroid gland that usually invades lymphatics rather than blood vessels. Hematogenous metastasis of PTC is rare, and distant metastasis to the liver is even rarer. Selective internal radiation therapy with 90Y microspheres is a well-recognized technique in the treatment of liver metastases. Herein, we present a case of PTC with radioactive iodine-negative hepatic metastasis detected by 18F-FDG PET/CT and treated with selective internal radiation therapy.

Background: In the last years, Selective Internal Radiation Therapy (SIRT), using biocompatible Yttrium-90 (90Y) labeled microspheres have emerged for the treatment of malignant hepatic tumors. Unfortunately, a significant part of 90Ylabeled microspheres may shunt to the lungs after intraarterial injection. It can be predictable by infusing technetium-99 m-labeled macro-aggregated albumin particles through a catheter placed in the proper hepatic artery depending on the lobe to be treated with performing a quantitative lung scintigraphy. Radiation pneumonitis (RP) can occur 1 to 6 months after the therapy, which is a rare but severe complication of SIRT. Prompt timing of steroid treatment is important due to its high mortality rate. On the other hand, pulmonary diffusion capacity measured by carbon monoxide (DLCO) is an excellent way to measure the diffusing capacity because carbon monoxide is present in minimal amount in venous blood and binds to hemoglobin in the same manner as oxygen. Some authors reported that the most consistent changes after radiation therapy (RT) are recorded with this quantitative reproducible test. The relationship between the proportional reductions in DLCO and the severity of RP developing after this therapy may prove to be clinically significant. Case presentation: We herein present a patient who developed RP after SIRT that could be quantified using DLCO. To the best of our knowledge, this case is the first who developed unexpected RP after SIRT with significant decrease in DLCO with internal radiation exposure. Conclusions: RP is a very rare complication and may lead to a fatal outcome. Decline in DLCO could be a valuable parameter for follow-up and to identify potential candidates for RP and could be also another trigger for administration of steroid therapy with prompt timing in this patient group.

Paget’s disease is a chronic benign bone disease characterized by excessive and abnormal bone remodeling. Monostotic Paget’s disease accounts for only 20% of the cases, and the monostotic form involving the vertebra with the Mickey Mouse sign is very rare. Herein, we report a case of suspected bony metastasis in the second lumbar vertebra that was diagnosed as Paget’s disease because of the Mickey Mouse sign on bone scintigraphy, and the diagnosis was confirmed by biopsy. Therefore, bone scintigraphy may provide a positive contribution to the diagnosis, and may help to avoid unnecessary biopsy in cases with specific signs and patterns.