Single-breathhold cardiac T1, T2, T2*, and fat fraction mapping at 0.55T using dual rosette trajectory MRF and a deep image prior reconstruction

Motivation: 0.55T systems have been introduced as a potential way to reduce the cost of MRI, but techniques need to be adapted for this field strength. Goal(s): In this work, a rosette cardiac Magnetic Resonance Fingerprinting approach is presented to map T1, T2, T2*, and proton density fat fraction at 0.55T. Approach: Efficient mapping is enabled through a multi-echo MRF deep image prior reconstruction and an acquisition that utilizes two different rosette trajectory shapes to make efficient use of limited respiratory and cardiac windows. Results: We demonstrate good agreement in phantoms, and compare values obtained in 6 healthy subjects to those published in literature. Impact: To reduce the time and number of breathholds required for a cardiac scan, we introduce a method for acquiring cardiac T1, T2, T2*, and proton density fat fraction maps at 0.55T from a single breathhold, 16-heartbeat sequence.