Positron emission tomography tracers in medullary thyroid carcinoma: Current evidence and emerging targets

Table 3 Summary of key evidence for emerging positron emission tomography tracers in metastatic medullary thyroid carcinoma

Tracer platform	Target	Key advantage(s)	Ref.	Key finding(s)
CCK2R/minigastrin	CCK2R	Expressed in about 92% of MTCs	Günther et al[24], 2024	Proof-of-concept PET imaging with high tumour uptake (SUVmax 7.4)
		Complete theranostic platform (68Ga, 177Lu, 225Ac)	Holzleitner et al[25], 2025	Preclinical 225Ac alpha therapy showed 4.5-fold survival benefit
FAPI	FAP	Targets tumour stroma, not tumour cells	Kong et al[27], 2025	Head-to-head vs FDG: 98% vs 66% detection rate; SUVmax 11.7 vs 2.6; changed management in 32% of patients
		Very high tumour-to-background contrast
Novel SSTR	SSTR	18F-labelling overcomes 68Ga generator limitations	Kunte et al[20], 2025	18F-SiTATE PET burden correlated with calcitonin levels (r = 0.771)
		Improved logistics and potentially higher resolution

This table introduces the novel tracers, summarizing their target, key advantages, and the most impactful early clinical findings. CCK2R: Cholecystokinin-2 receptor; MTCs: Medullary thyroid carcinomas; FAPI: Fibroblast activation protein inhibitor; FAP: Fibroblast activation protein; SSTR: Somatostatin receptor; SUVmax: Standardised uptake value maximum; FDG: Fluorodeoxyglucose; ¹⁸F-SiTATE: 18F-labelled silicon-containing somatostatin receptor ligand; PET: Positron emission tomography; ⁶⁸Ga: Gallium-68; ¹⁷⁷Lu: Lutetium-177; ²²⁵Ac: Actinium-225.