Progression of emphysema evaluated by MRI using hyperpolarized 3he (hp 3he) measurements in patients with alpha-1-antitrypsin (a1at) deficiency compared with CT and lung function tests

Abstract

The progression of emphysema is traditionally measured by pulmonary function test, with forced expiratory volume in 1 s (FEV(1)) being the most accepted and used measurement. However, FEV(1) is insensitive in detecting mild/slow progression of emphysema because of low reproducibility as compared to yearly decline. To investigate the progression of emphysema over a period of 2 years using diffusion-weighted hyperpolarized (HP) (3)He magnetic resonance imaging (MRI) in patients with alpha-1-antitrypsin (A1AT) deficiency. Nine patients with severe A1AT deficiency were studied over a period of 2 years (baseline, year 1, and year 2) with HP (3)He MRI using apparent diffusion coefficient (ADC), lung function tests (FEV(1) and carbon monoxide lung diffusion capacity [D(L,CO)]), and computed tomography (CT) using densitometric parameters (15th percentile density [CT-PD15] and relative area of emphysema below -910 HU [CT-RA-910]). Seven patients were scanned three times, one patient two times, and one patient only at baseline. The mean increase in ADC values from first to last HP (3)He MR scanning was 3.8% (0.014 cm(2)/s [SD 0.024 cm(2)/s]; not significant). The time trends for FEV(1), D(L,CO), CT-PD15, and CT-RA-910 were all statistically significant. We found a high correlation between ADC and D(L,CO) (P<0.001). This pilot study indicates the possible use of nonionizing HP (3)He MRI for monitoring the progression of emphysema. However, in the future, larger studies are needed to confirm these preliminary results.