CT-derived vascular pruning assessment in portopulmonary hypertension

Portopulmonary hypertension(PoPH) is characterized by pathological lung vascular remodeling resulting in elevated pulmonary vascular resistance. However, the extent and distribution of vascular remodeling and its relationship to clinical features remains unknown. To assess vascular remodeling, we measured and compared the percentage of distal small vessels(<5 mm2 in cross-sectional area, BV5) from CT chest scans between PoPH patients, scleroderma without lung involvement(SSc-only as a negative control), and SSc-with pulmonary hypertension(SSc-PH as a positive control). To account for variations in blood vessel volume based on overall body size, we normalized BV5 to total lung blood vessel volume(BV5/TBV). 30 PoPH, 33 SSc-only, and 37 SSc-PAH patients were included. The clinical characteristics and hemodynamics of PoPH patients are summarized in Figure1A. Compared to the SSc-only group, PoPH patients had a significantly lower BV5/TBV (Figure1B-E), suggestive of vascular pruning. BV5/TBV in PoPH was visually comparable and statistically indistinguishable from that in the SSc-PH group, and strongly correlated with PASP assessed by transthoracic echocardiography(R= -0.43, p<0.001). Compared to SSc-only, PoPH and SSc-PH patients exhibit a significantly lower BV5/TBV suggestive of greater vascular pruning secondary to lung vascular disease. Our results indicate BV5/TBV may have value in improving the sensitivity of screening and diagnosis in PoPH.