Developing a novel positronium biomarker for cardiac myxoma imaging.

"Declarations Ethics approvalThis study was approved by the Bioethical Commission of the Jagiellonian University (approval number 1072.6120.123.2017). Consent to participateInformed consent was obtained from all individual participants included in the study. Competing interestsThe authors have no competing interests relevant to this study. Competing interests The authors have no competing interests relevant to this study."

"Funding We acknowledge the financial support by the Foundation for Polish Science through the TEAM POIR.04.04.00-00-4204/17 Programme, the National Science Centre through Grants Nos. 2017/25/N/NZ1/00861 and 2021/42/A/ST2/00423, 2021/43/B/ST2/02150, the Ministry of Education and Science through Grants Nos. SPUB/SP/490528/2021, K/ZDS/007227, N41/DBS/000230, and Jagiellonian University via project CRP/0641.221.2020, and the SciMat and qLife budget under the program Excellence Initiative Research University at the Jagiellonian University."