Background: Lymphangioleiomyomatosis (LAM) is a rare systemic disease primarily affecting females that is characterized by the formation of pulmonary cysts. Scarce data are available to predict disease outcome in LAM and there is a paucity of data on radiological assessments.

Aim: To evaluate a novel radiological method for risk stratification of LAM patients.

Methods: We retrospectively analyzed 80 LAM patients from two European tertiary ILD referral centers. Cyst volume was assessed and calculated on baseline high-resolution computed tomography (HRCT) as the percentage of total lung volume applying the software Yet Another CT-Analyzer (YACTA). Pulmonary function tests (PFT)-parameters were then correlated with cyst volume index (CVI).

Results: Mean patient age at diagnosis was 43.5±12.2 years, mean FEV1 was 72.7±21.5%, mean DLCOSB was 57.9±18.1%. 41 patients were treated with mTOR inhibitors. Mean cyst volume (n=63) was 9.7±9.4%, range: 0-35%. We found a significant negative correlation (r= -0.61, R2=0.37, p<0.0001) between CVI and FEV1. Similarly, CVI and diffusing capacity for carbon monoxide (DLCOSB) correlated negatively (r= -0.65, R2=0.42, p<0.0001).

Conclusion: CVI assessment by YACTA might be a useful index for risk stratification and prognosis estimation in patients with LAM.