Assessment of regional lung function with multivolume ¹H MR imaging in health and obstructive lung Disease: Comparison with ³He MR imaging

Purpose: To introduce a method based on multivolume proton (hydrogen [¹H]) magnetic resonance (MR) imaging for the regional assessment of lung ventilatory function, investigating its use in healthy volunteers and patients with obstructive lung disease and comparing the outcome with the outcome of the research standard helium 3 (³He) MR imaging.

Materials and Methods: The institutional review board approved the HIPAA-compliant protocol, and informed written consent was obtained from each subject. Twenty-six subjects, including healthy volunteers (n = 6) and patients with severe asthma (n = 11) and mild (n = 6) and severe (n = 3) emphysema, were imaged with a 1.5-T whole-body MR unit at four lung volumes (residual volume [RV], functional residual capacity [FRC], 1 L above FRC [FRC+1 L], total lung capacity [TLC]) with breath holds of 10-11 seconds, by using volumetric interpolated breath-hold examination. Each pair of volumes were registered, resulting in maps of ¹H signal change between the two lung volumes. ³He MR imaging was performed at FRC+1 L by using a two-dimensional gradient-echo sequence. ¹H signal change and ³He signal were measured and compared in corresponding regions of interest selected in ventral, intermediate, and dorsal areas.

Results: In all volunteers and patients combined, proton signal difference between TLC and RV correlated positively with ³He signal (correlation coefficient R² = 0.64, P < .001). Lower (P < .001) but positive correlation results from ¹H signal difference between FRC and FRC+1 L (R² = 0.44, P < .001). In healthy volunteers, ¹H signal changes show a higher median and interquartile range compared with patients with obstructive disease and significant differences between nondependent and dependent regions.

Conclusion: Findings in this study demonstrate that multivolume ¹H MR imaging, without contrast material, can be used as a biomarker for regional ventilation, both in healthy volunteers and patients with obstructive lung disease.