01 March 2017 by Nick Rahaghi

CT measures of intraparenchymal arterial and venousvolume distribution in pulmonary hypertension

Introduction

CT derived quantification of vascular morphology may be useful for detection, classification and understanding of pulmonary vascular disease. Changes such as pruning and proximal dilation of the vessels have been described in pulmonary hypertension, but the differential effect on arterial and venous pulmonary circulation has not been well characterized. In this study, we attempted to quantify blood volume distribution in small and large sized vessels in the arterial and venous pulmonary vasculature using clinically acquired CT scans.

Methods

A cohort of 700 patients evaluated for unexplained dyspnea at Brigham and Women’s Hospital was retrospectively identified. 179 patients had CT angiography within 1 year of RHC. 49 patients with PH(15 Group II, 16 PAH, and 18 CTEPH) and 15 subjects with no pulmonary vascular disease were identified. Lung segmentation and 3D reconstruction of parenchymal vasculature was generated as previously described.   Arteries and veins were manually labeled in the right lung. Primary analysis focused on the small vessel fraction, the fraction of volume in vessels with cross sectional area of less than 5mm2, divided by the total vessel volume. Medians, inter-quartile range and Wilcoxon Rank-Sum Test, (SAS 9.3) were used for group comparisons.

Results

Arterial small vessel fraction was significantly lower in all groups of PH: Group I (0.45[0.40-0.52]  p=0.001); Group II (0.42[0.37-0.48] p=0.0002;  Group IV (0.49[0.40-0.58] p=0.001); as compared to controls (0.60[0.54-0.66]). In the venous pulmonary vasculature, however, the difference reached statistical significance only in Group II patients (0.43[0.41-0.50] p=0.008) but not in Group I (0.49[0.40-0.55] p=0.09) or group IV (0.51[0.44-0.58]) p=0.09) subject compared to controls (0.54[0.49-0.58]).

Conclusions

Arterial remodeling can be observed and quantified using CT imaging in patients with both pre-capillary and post-capillary PH compared to controls without any pulmonary vascular disease. Venous volume redistribution measured by small vessel fraction is additionally present in post-capillary disease.

About the author


profile picture of Nick Rahaghi

Nick Rahaghi

Fellow

Harvard Medical School

United States

Key Contributors

Farbod Nicholas Rahaghi,* Ramya Radhakrishnan, Jasleen Minhas, Erik Ayala, James C Ross#, Raúl San José Estépar# , Aaron B Waxman, George R Washko. *Primary Author and PVRI member, Brigham and Women’s Hospital, Pulmonary and Critical Care Division of Department of Medicine 75 Francis Street, PBB – CA 3 Boston, MA 02115 # Department of Radiology, Harvard School of Medicine


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