Detection of Unilateral Axillary Nodal Uptake Both at 68Ga-DOTATOC and 18F-FDG PET/CT After 1 Week From COVID-19 Vaccine.

ABSTRACT: Recently, vaccination against COVID-19 has gained wide diffusion, especially among vulnerable individuals, such as cancer patients. At the same time, patients have been undergoing PET/CT examinations after vaccination in an increasing number, and cases of false-positive axillary nodal uptake have been described, mostly at 18F-FDG PET. Here, we describe the case of both 68Ga-DOTATOC and 18F-FDG axillary nodal uptake in a young woman affected by a metastatic retroperitoneal paraganglioma.

Metastasis From Clear Cell Renal Cell Carcinoma Mimicking Well-Differentiated Pancreatic Neuroendocrine Tumor at 18F-FDG and 68Ga-DOTATOC PET/CT.

ABSTRACT: Dual-tracer PET/CT with both 18F-FDG and 68Ga-DOTA-conjugated peptides is currently used in clinical routine for characterizing pNET (pancreatic masses suspicious for neuroendocrine tumor). We describe here the case of a 81-year-old man with a pancreatic lesion showing high 68Ga-DOTATOC uptake and mild 18F-FDG avidity, thus suggesting a well-differentiated pNET, which resulted at endoscopic ultrasound-guided fine-needle aspiration to be a clear cell renal cell carcinoma metastasis. In fact, the patient had right nephrectomy for clear cell renal cell carcinoma 27 years earlier. This case puts light on the role of PET/CT with 68Ga-DOTATOC in imaging RCC, a field which deserves to be further explored.

Novel Experience in Hybrid Tracers: Clinical Evaluation of Feasibility and Efficacy in Using ICG-99mTc Nanotop for Sentinel Node Procedure in Breast Cancer Patients.

PURPOSE: The clinical introduction of a radioactive and fluorescent hybrid tracer allowed for preoperative lymphatic mapping and intraoperative real-time fluorescence tracing of the sentinel lymph node (SLN) by a single injection. The aim of this feasibility study is to evaluate the first-in-human use of the hybrid tracer by combining indocyanine green (ICG) and radiocolloid based on Nanotop compound (99mTc Nanotop) for SLN biopsy (SLNB) in breast cancer patients. METHODS: The day before surgery, ICG-99mTc Nanotop was injected periareolarly in breast cancer patients scheduled for SLNB. Planar lymphoscintigraphic (PL) and SPECT/CT images were then acquired. An intraoperative optonuclear probe was used to detect SLN gamma and fluorescent signals. The harvested SLNs were examined by hematoxylin-eosin staining, and patients were clinically evaluated 1 month after surgery. RESULTS: Twenty-one consecutive patients were enrolled. The PL and SPECT/CT techniques identified at least 1 SLN in all patients for a preoperative sentinel detection rate of 100%. SPECT/CT revealed 3 additional lymph nodes in the same nodal basin, which had not been visualized on conventional PL (κ = 0.747; P < 0.005). All 30 preoperative SLNs were localized and excised up to 16 hours after injection. The counts measured via gamma tracing showed a very strong correlation with those measured via near-infrared fluorescent tracing (P < 0.005, r = 0.964). No adverse reactions were observed. CONCLUSIONS: The SLNB technique used with the ICG-99mTc Nanotop tracer resulted to be feasible, reliable, and safe. This hybrid compound allowed us to obtain excellent performance in terms of both preoperative lymphatic mapping and intraoperative SLN detection in breast cancer patients.

The sentinel lymph node biopsy technique in papillary thyroid carcinoma: The issue of false-negative findings.

BACKGROUND: The management of papillary thyroid carcinoma (PTC) is changed after introduction of sentinel lymph node biopsy (SNB) technique for nodal staging. Some debate still surrounds the accuracy of this procedure in terms of wide heterogeneity of sentinel lymph node detection and false-negative findings. AIM: to identify the key issues which make it difficult the usefulness of SNB in PTC. METHODS: A comprehensive computer literature search of meta-analyses published in PubMed/MEDLINE and Cochrane library database until June 30, 2019 was conducted. We used a search algorithm based on this combination of terms: (i) "thyroid neoplasm" or "thyroid cancer" or "thyroid carcinoma" or "thyroid malignancy" or "meta-analysis" or "systematic review") AND (ii) "sentinel lymph node biopsy". RESULTS: Comparing 4 written meta-analyses published in the literature, the diagnostic performance of SNB technique in PTC has been summarized. Relatively high false-negative rates (FNR) were reported for each SNB methods: vital-dye (VD: 12.7%; 7%; 0-38%), 99mTc-nanocolloid planar lymphoscintigraphy with the use of intraoperative hand-held gamma probes (LS: 11.3%; 16%; 0-40%), combined LS with VD (LS+VD: 0%; 0-17%), LS with the additional contribution of preoperative SPECT/CT (7-8%). CONCLUSION: Evidence-based data about the diagnostic performance of SNB in PTC are increasing. The nuclear medicine community should reach a consensus on the operational definition of the SLN to better guide the surgeon in identifying the lymph nodes most likely contain metastatic cells. Standardization of SLN identification, removal and analysis are required.