¹⁸F-Choline PET/CT as a New Tool for Functional Imaging of Non-Proliferating Secreting Neuroendocrine Tumors

Abstract

Choline is an essential component for the formation of new cell membrane and the current understanding is that increased choline uptake in cancer lesions is explained by -and roughly correlates with -cellular proliferation. 18 F-fluoromethylcholine, a radiolabeled PET-tracer, is increasingly used for the detection of proliferating cancers with PET/ CT (choline PET), for example for restaging of recurrent prostate carcinoma. However, clinical findings have suggested that choline uptake may not always be related to proliferation. We present three cases with a carcinoid of the lung with high uptake of radiolabeled choline on PET/CT and a low Ki-67 proliferation index as demonstrated by immunostaining. Although the mechanism behind the enhanced uptake in well-differentiated neuroendocrine tumors is not yet fully understood, for clinical practice this finding means that not every highly choline-avid lesion represents an aggressive cancer; the diagnosis of a functional neuroendocrine tumor should be considered as well.

An Incidental Pancreatic Finding at 18F-Choline PET/CT: Chronic Mass-Forming Pancreatitis

“…The distribution of FCH is physiological in the pancreas as in the liver, spleen, salivary, and lacrimal glands [1]. The uptake of choline is also present in many cancers and in the immune cells as macrophages, present in inflammatory processes [9][10][11]. This is the first case of CMFP detected by FCH.…”

Triple Tracer Positivity in Metastatic Lymph Nodes from Well-Differentiated Neuroendocrine Tumor in MEN-1 Syndrome

“…Few case reports have shown increased 99m Tc-sestamibi uptake in primary malignant and metastatic NETs such as carcinoid tumors, paragangliomas, and primary neuroendocrine neoplasms (6)(7)(8). In a case series of 3 bronchial carcinoids having low Ki-67 (nonaggressive neoplasm), 18 F-fluorocholine showed tumor avidity, which was secondary to cholinergic autocrine loop overexpression and high turnover of intracellular vesicles (9). We present the current MEN-1 case showing avidity with 3 different tracers ( 68 Ga-DOTANOC, 99m Tcsestamibi, and 18 F-fluorocholine) because of different uptake mechanisms, highlighting the diverse characteristics of the tumor.…”

Using Molecular Imaging to Enhance Decision Making in the Management of Pituitary Adenomas

“…However, to date, support for such a role is limited to a small number of case reports of incidentally detected pituitary macroadenomas (60,61). It is also unclear whether uptake in PAs is dependent on cellular proliferation (with incorporation into cell membranes), or reflects other aspects of choline transport/metabolism, as has been proposed for other welldifferentiated endocrine tumors (62).…”