Measurement of regional lung function in rats using hyperpolarized 3helium dynamic MRI

• Published in: Magnetic resonance in medicine Vol. 49; no. 1; pp. 78 - 88
• Main Authors: Chen, Ben T., Brau, Anja C.S., Johnson, G. Allan
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc., A Wiley Company 01.01.2003; Williams & Wilkins
• Subjects: Animals; Biological and medical sciences; constant flow ventilation; Female; Helium; hyperpolarized helium; Image Processing, Computer-Assisted; Investigative techniques, diagnostic techniques (general aspects); Isotopes; Lung - anatomy & histology; Lung - physiology; lung structure; Magnetic Resonance Imaging, Cine; Medical sciences; MRI; Phantoms, Imaging; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Rats; Rats, Sprague-Dawley; regional lung function; Respiratory Mechanics; Respiratory system; Tidal Volume; Visualization; lung structure; Rat; MRI; Lung; Rodentia; Regional; Nuclear magnetic resonance imaging; regional lung function; Dynamic method; Image quality; Helium ion; Vertebrata; Mammalia; Lung function; Animal; Medical imagery; hyperpolarized helium; Technique; constant flow ventilation; Hyperpolarization
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.10336

Dynamic regional lung function was investigated in rats using a radial acquisition cine (RA‐CINE) pulse sequence together with hyperpolarized (HP) 3He gas delivered by a constant flow ventilator. Based on regional differences in the behavior of inspired air, the lung was conceptually divided into two regions (the major airways and the peripheral airspace) for purposes of functional analysis. To measure regional function in the major airways, a large RF flip angle (24°) was applied to reduce 3He magnetization in the peripheral airspace, and signal intensity (SI) was normalized with the projected airway diameter to estimate local airflow. Higher normalized signal intensity was observed in the left branch airway as compared to the right branch airway. To determine regional function in the peripheral airspace, a small RF flip angle (6°) was used. Incremental increases of peripheral SI in successive lung images were consistent with the increase in lung volume. A new “skipping” scanning strategy using dummy frames allows a trade‐off between the number of frames acquired for dynamic information, the RF flip angle, and the penetration depth of 3He magnetization into the lung. This work provides a novel approach to simultaneously assess dynamic regional function and morphology. Magn Reson Med 49:78–88, 2003. © 2003 Wiley‐Liss, Inc.