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

Background: 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. Purpose: 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. Material and Methods: 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]). Results: 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