Large Language Models for Patient Education in Cardiovascular Imaging: Prospective Observational Comparative Study - Ahmed Marey; Basudha Pal; Ayşenur Buz Yaşar; Shree Rath; Giulia Francese; Hossam M Ghorab; Julia Niemierko; Muhammad Shah Wali Jamal; Muhammad Umair (JMIR Formative Research, 2026)