Can Zero Echo Time (ZTE) Magnetic Resonance Imaging Sequences Detect Signal from Collagen Backbone Protons?

Ultrashort echo time (UTE) and zero echo time (ZTE) sequences have been extensively investigated for imaging of short T2 species. The ZTE sequence has a shorter effective TE than UTE and may be superior in imaging ultrashort T2 species. This study investigated whether ZTE could directly image collagen backbone protons in bovine cortical bone and human patellar tendon samples after D2O exchange and freeze-drying. Our experimental results demonstrate that collagen backbone protons are "invisible" with ZTE, which may not be able to directly image species with T2s of ~10 µs.