Comparison of hyperpolarized 3 He MRI rat lung volume measurement with micro‐computed tomography

In this study, the upper‐limit volume (gas plus partial tissue volume) as well as absolute volume (gas only) of lungs measured with hyperpolarized 3 He‐MR imaging is compared with that determined by micro‐computed tomography (CT) under similar ventilation conditions in normal rats. Five Brown Norway rats (210–259 g) were ventilated with O 2 , alternately with 3 He, using a computer‐controlled ventilator, and 3D density‐weighted images of the lungs were acquired during a breath hold after six wash‐in breaths of 3 He. The rats were then transferred to a micro‐CT scanner, and a similar experimental setup was used to obtain images of the lungs during a breath hold of air with an airway pressure equal to that of the MR imaging breath hold. The upper‐limit and absolute volumes obtained from 3 He‐MR and micro‐CT methods were not significantly different ( p  > 0.05). The good agreement between the lung volumes measured with the two imaging methods suggests that 3 He‐MR imaging can be used for quantitative analysis of lung volume changes in longitudinal studies without the exposure to the ionizing radiation which accompanies micro‐CT imaging. Copyright © 2010 John Wiley & Sons, Ltd.