Free breathing hyperpolarized 3He lung ventilation spiral MR imaging

Area of Science:

• Medical Imaging
• Pulmonary Medicine
• Biophysics

Background:

• Current hyperpolarized He lung ventilation MRI requires breath-holding, limiting its use in critical care and pediatric patients.
• Intensive care unit (ICU) patients and very young children often cannot comply with breath-holding instructions.

Purpose of the Study:

• To develop and evaluate a free-breathing protocol for hyperpolarized He lung ventilation MRI.
• To enable lung ventilation imaging in patients unable to cooperate with breath-holding maneuvers.

Main Methods:

• A spiral imaging sequence was implemented on a 1.5-T MRI scanner.
• Free-breathing ventilation images were acquired in vitro and in spontaneously breathing rabbits.
• Dynamic images were reconstructed using retrospective Cine synchronization, and MR signal dynamics were modeled.

Main Results:

• High-temporal-resolution (50 ms) cine ventilation images were successfully reconstructed in rabbits.
• Gas volume variations and time-to-maximum maps were generated.
• A numerical model accurately predicted MR signal dynamics and allowed extraction of ventilation parameters.

Conclusions:

• Free-breathing hyperpolarized He MRI enables lung ventilation imaging without breath-holds or ventilation devices.
• The developed protocol is suitable for critically ill or pediatric patients.
• Numerical modeling can optimize acquisition parameters and extract physiological information from ventilation dynamics.