Quantitative H and hyperpolarized He magnetic resonance imaging: Comparison in chronic obstructive pulmonary disease and healthy never-smokers

Objective

The aim of this study was to quantitatively evaluate the relationship between short echo time pulmonary ¹H magnetic resonance imaging (MRI) signal intensity (SI) and ³He MRI apparent diffusion coefficients (ADC), high-resolution computed tomography (CT) measurements of emphysema, and pulmonary function measurements.

Materials and methods

Nine healthy never-smokers and 11 COPD subjects underwent same-day plethysmography, spirometry, short echo time ((TE) = 1.2 ms) ¹H and diffusion-weighted hyperpolarized ³He MRI (b = 1.6 s/cm²) at 3.0 T. In addition, for COPD subjects only, CT densitometry was also performed.

Results

Mean ¹H SI was significantly greater for never-smokers (12.1 ± 1.1 arbitrary units (AU)) compared to COPD subjects (10.9 ± 1.3 AU, p = 0.04). The ¹H SI AP-gradient was also significantly greater for never-smokers (0.40 AU/cm, R² = 0.94) compared to COPD subjects (0.29 AU/cm, R² = 0.968, p = 0.05). There was a significant correlation between ¹H SI and ³He ADC (r = −0.58, p = 0.008) and significant correlations between ¹H MR SI and CT measurements of emphysema (RA₉₅₀, r = −0.69, p = 0.02 and HU₁₅, r = 0.66, p = 0.03).

Conclusions

The significant and moderately strong relationship between ¹H SI and ³He ADC, as well as between ¹H SI and CT measurements of emphysema suggests that these imaging methods and measurements may be quantifying similar tissue changes in COPD and that pulmonary ¹H SI may be used to monitor emphysema as a complement to CT and noble gas MRI.