Head-to-head comparison of two collagen-specific PET/CT tracers, [18F]D3Col ([18F]R16-129) and [18F]Col45, for in-vivo quantification of post-infarct myocardial remodeling
July 3
Background: A novel collagen-I–targeting radioprobe, [18F]D3Col ([18F]R16-129), designed for real-time evaluation of post-injury extracellular matrix dynamics, is reported. The tracer is a deuterated N-methyl analogue of Col45 (florbecollagen f18), an agent cleared in 2013 for clinical fibrosis imaging. Isotopic substitution can modulate tracer pharmacokinetics and potentially enhance image quality. We performed a head-to-head comparison of these two probes in subjects with established post-infarct myocardial remodeling. A separate biodistribution study was undertaken in six healthy volunteers to estimate radiation dose.
Results: Eight patients with prior anterior wall infarction (mean age 61.1 ± 10.0 years; mean LVEF 45 ± 8 %) underwent paired 90-min dynamic PET/CT acquisitions (323 ± 31 MBq [18F]D3Col or [18F]Col45). Standardized Uptake Value Ratios (SUVR, 50–70 min) and Distribution Volume Ratios (DVR) were calculated for 43 predefined myocardial regions. Mean SUVR across infarcted segments was 1.65 ± 0.21 for [18F]Col45 and 1.65 ± 0.23 for [18F]D3Col, while global DVRs were 1.36 ± 0.14 and 1.37 ± 0.13, respectively. Linear regression revealed strong inter-tracer concordance (R² = 0.80–0.90) with slopes of ~0.9 (SUVR) and ~1.0 (DVR). No artifacts or confounds affecting visual interpretation were observed with [18F]D3Col relative to [18F]Col45.
Conclusions: Deuteration at the N-methyl position did not confer measurable advantage in vivo. Nevertheless, [18F]D3Col exhibited binding characteristics indistinguishable from its non-deuterated predecessor, supporting its utility as an alternative probe for non-invasive mapping of collagen deposition during cardiac repair.
Trial registration: Clinicaltrials.org, NCT03902548. Registered 01/07/2018. © The Author(s) 2025.