¹⁹F MRI radiomic features: in vitro and in vivo repeatability.

Abstract

<h4>Objective</h4>Using radiomics to compute quantitative imaging features may reveal information beyond standard magnetic resonance imaging (MRI) metrics. We aim to investigate the test-retest repeatability of ¹⁹F MRI radiomic features in phantoms containing two perfluorocarbons and to validate these findings in a pilot in vivo mouse tumor model.<h4>Materials and methods</h4>Two phantoms containing perfluoropolyether (PFPE) or perfluoro-15-crown-5 ether (PFCE) were repeatedly scanned (intrasession and intersession) using a 7-T system equipped with a dual-tuned ¹H/¹⁹F volume coil. Radiomic features were extracted and assessed for stability using the concordance correlation coefficient (CCC) ≥ 0.85 and normalized dynamic range ≥ 0.90. A separate in vivo test-retest experiment was conducted in tumor-bearing mice injected with a PFPE nanoemulsion.<h4>Results</h4>A total of 194 scans and 772 segments were evaluated across the PFPE phantom, PFCE phantom, and in vivo experiments. In both phantoms, radiomic features displayed high intrasession repeatability (median CCC up to 0.886) but decreased intersession repeatability (median CCC down to 0.683). Intensity features were consistently more repeatable (p < 0.003) than shape or texture features. We found that 23.1% (466/2,013) of features were repeatable across phantoms. In vivo pilot scans showed that 86.1% (401/466) of these phantom-stable features, or ~20.0% overall, remained repeatable under physiological conditions.<h4>Conclusion</h4>Several ¹⁹F MRI-derived features exhibited excellent short-term repeatability, and a considerable proportion proved robust to intersession variability. These robust features may reliably capture ¹⁹F signals under both phantom and physiological conditions, paving the way for more quantitative imaging analysis in this modality and encouraging general reproducibility of data.<h4>Relevance statement</h4>KEY POINTS: We analyzed 194 ¹⁹F MRI scans and 772 segments obtained in phantoms at 7 T. Cross-agent stability identified 466 radiomic features meeting concordance correlation coefficient ≥ 0.85 and normalized dynamic range ≥ 0.90. Of these phantom-stable features, 401 of 466 remained stable in vivo in a tumor mouse model. Intensity features were most repeatable, while shape features were least stable across sessions. Median concordance correlation coefficient dropped from 0.886 intrasession to 0.683 intersession.