In vivo regional ventilation mapping using fluorinated gas MRI with an x-centric FGRE method

• Published in: Magnetic resonance in medicine Vol. 74; no. 2; pp. 550 - 557
• Main Authors: Ouriadov, Alexei V., Fox, Matthew S., Couch, Marcus J., Li, Tao, Ball, Iain K., Albert, Mitchell S.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01-08-2015; Wiley Subscription Services, Inc
• Subjects: Administration, Inhalation; Algorithms; Animals; fluorine-19; Fluorine-19 Magnetic Resonance Imaging - methods; Gases - pharmacokinetics; Image Enhancement - methods; Image Interpretation, Computer-Assisted - methods; lung; Pilot Projects; Pulmonary Ventilation - physiology; Radiopharmaceuticals - pharmacokinetics; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Sensitivity and Specificity; Signal Processing, Computer-Assisted; ventilation; x-centric; lung; x-centric; fluorine-19; ventilation
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.25406

Purpose
Inert fluorinated gas lung MRI is a new and promising alternative to hyperpolarized gas lung MRI; it is less expensive and does not require expensive isotopes/polarizers. The thermally polarized nature of signal obtained from fluorinated gases makes it relatively easy to use for dynamic lung imaging and for obtaining lung ventilation maps. In this study, we propose that the sensitivity and resolution of fluorine‐19 (19F) in vivo images can be improved using the x‐centric pulse sequence, thereby achieving a short echo time/pulse repetition time. This study is a transitional step for converting to more sustainable gases for lung imaging.
Methods
A 19F‐resolution phantom was used to validate the efficiency of performing the x‐centric pulse sequence on a clinical scanner. Ventilation maps were obtained in the lungs of five normal rats with a washout approach (adapted from Xe‐enhanced computed tomography [Xe‐CT] regional ventilation mapping), using mixtures of either sulfur hexafluoride/oxygen or perfluoropropane/oxygen and a two‐breath x‐centric method.
Results
Fractional ventilation (r) values obtained in this study (0.35–0.46 interval) were in good agreement with previously published values for 3He/129Xe. Calculated r gradients agreed well with published gradients obtained in rats with Xe‐CT measurements.
Conclusions
These results suggest that fluorinated gases can be reliably used in vivo in dynamic lung studies as an alternative to 3He/129Xe. Magn Reson Med 74:550–557, 2015. © 2014 Wiley Periodicals, Inc.