The Use of ^99mTc-HYNIC-TOC and ¹⁸F-FDG PET/CT in the Evaluation of Duodenal Neuroendocrine Tumor with Atypical and Extensive Metastasis Responding Dramatically to a Single Fraction of PRRT with ¹⁷⁷Lu-DOTATATE

Abstract

This report describes a case of extensive diffuse bone marrow involvement with bilateral breast metastases from duodenal neuroendocrine tumor giving rise to a superscan-like appearance on somatostatin receptor–targeted ^99mTc-hydrazinonicotinamide-TOC scintigraphy. The metastatic lesions demonstrated partial concordance with ¹⁸F-FDG PET/CT findings, signifying varying tumor biology and heterogeneity among metastatic lesions in the same individual, as illustrated with a dual-tracer approach. There was a dramatic symptomatic and biochemical response and better health-related quality of life with a single fraction of peptide receptor radionuclide therapy with ¹⁷⁷Lu-DOTATATE, and radiologically there was stable disease at that point.