Brigham and Women's Hospital, Medford, MA
Copyright 2016, American College of Chest Physicians. All Rights Reserved.
SESSION TITLE: Pulmonary Vascular Disease II
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 26, 2016 at 01:30 PM - 02:30 PM
PURPOSE: Patients with Pulmonary arterial hypertension (PAH) have pathologic changes to the pulmonary vasculature including pruning of the distal vessels and dilatation of proximal vessel. This suggests that advanced CT image processing can be used to complement right heart catheterization (RHC) in the diagnosis, subtyping and monitoring of PAH. While the arterial pathologic changes have been described both qualitatively and quantitatively in the past, the distinction between arterial versus venous circulation has not been reported.
METHODS: 700 patients having had a right heart catheterization (RHC) for unexplained dyspnea at the Brigham and Womens Hospital were reviewed. 179 patients were identified as having CT angiography within a year of RHC. Sixteen patients with PAH and fifteen control patients were identified. PAH patients were required to have a resting supine wedge pressure < 15 mmHg, and were identified as having group I disease. A 3D reconstruction of the intraparenchymal pulmonary vasculature was generated for each subject. The vasculature was marked as arteries and veins manually by tracing the vessels to the origins of the pulmonary artery and pulmonary veins in the right upper lobe and right lower lobe. The blood vessel volumes for each cross-sectional area and total lung blood vessel volumes were then calculated from these reconstructions. Based on prior studies, the small vessel fraction (SVF) was defined as the volume in vessels less than 5mm2 (BV5) divided by the total blood vessel volume (TBV). Non-parametric statistics (medians, inter-quartile range and Wilcoxon Rank-Sum) were used for intergroup comparisons of volume fractions while means were used for demographics and hemodynamic comparisons.
RESULTS: There were 67% females in control group and 94% females in the PAH group. The mean age of the PAH group was 63 years while the mean age for the control group was 52. The pulmonary artery pressure and pulmonary vascular resistance were significantly higher in the PAH group than in the control group (46.2 mmHg vs 15.2mmHg and 663 dyn*s/cm5 vs 94 dyn*s/cm5, respectively). PAH patients showed decreased arterial small vessel fraction as compared to controls (RUL 0.47[0.39-0.59] versus 0.66[0.59-0.74] p=0.003; RLL 0.41[0.35-0.48] versus 0.59 [0.46-0.66] p=0.005). There was no statistically significant difference in the venous small vessel fraction between the two groups (RUL 0.52 [0.43-0.63] versus 0.56[0.54-0.60] p=0.42; RLL 0.46[0.35-0.52] versus 0.51[0.43-0.59] p=0.17).
CONCLUSIONS: Patients with PAH have decreased arterial small vessel fraction in comparison to controls. A similar observation was not noted in the venous system when comparing PAH patients with controls. These findings are in congruence with the pre-capillary nature of the disease in PAH. Further investigation and validation in larger prospective cohorts will be required to substantiate the findings
CLINICAL IMPLICATIONS: These methods may potentially be used as a tool for identifying patients with PAH, differentiating disease phenotypes, assessing severity of disease and monitoring progression and/or response to treatment.
DISCLOSURE: The following authors have nothing to disclose: Ramya Radhakrishnan, Farbod Rahaghi, Jasleen Minhas, James Ross, Aaron Waxman, Raúl San José Estépar, George Washko
Imaging in diagnosis of pulmonary hypertension.
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