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"Treatment Effect of Balloon Pulmonary Angioplasty in CTEPH, Quantified by Automatic Comparative Imaging in CTPA"

Zhiwei Zhai, Hideki Ota, Marius Staring, Jan Stolk, Koichiro Sugimura, Kei Takase and Berend C. Stoel

Abstract

Objectives: Balloon pulmonary angioplasty (BPA) in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH) can have variable outcomes. To gain more insight into this variation, we designed a method for visualizing and quantifying changes in pulmonary perfusion by automatically comparing CT pulmonary angiography (CTPA) before and after BPA treatment. We validated these quantifications of perfusion changes against hemodynamic changes measured with right-heart catheterization (RHC).

Materials and Methods: We studied 14 consecutive CTEPH patients (12 females; age:70.5 ± 24), who underwent CTPA and RHC, before and after BPA. Post-treatment images were registered to pre-treatment CT scans (using the Elastix toolbox) to obtain corresponding locations. Pulmonary vascular trees and their centerlines were detected using a graph-cuts method and a distance transform method, respectively. Areas distal from vessels were defined as pulmonary parenchyma. Subsequently, the density changes within the vascular centerlines and parenchymal areas were calculated and corrected for inspiration level differences. For visualization, the densitometric changes were displayed in color-coded overlays. For quantification, the median and inter-quartile range (IQR) of the density changes in the vascular and parenchymal areas (ΔVD and ΔPD) were calculated. The recorded changes in hemodynamic parameters, including changes in systolic, diastolic, mean pulmonary artery pressure (ΔsPAP, ΔdPAP and ΔmPAP, respectively) and vascular resistance (ΔPVR), were used as reference assessments of the treatment effect. Spearman’s correlation coefficients were employed to investigate the correlations between changes in perfusion and hemodynamic changes.

Results: Comparative imaging maps showed distinct patterns in perfusion changes among patients. Within pulmonary vessels, the IQR of ΔVD correlated significantly with ΔsPAP (R= 0.58, p=0.03), ΔdPAP (R= 0.71, p=0.005), ΔmPAP (R= 0.71, p=0.005) and ΔPVR (R= 0.77, p=0.001). In the parenchyma, the median of ΔPD had significant correlations with ΔdPAP (R= 0.58, p=0.030) and ΔmPAP (R= 0.59, p=0.025).

Conclusions: Comparative imaging analysis in CTEPH patients offers insight into differences in BPA treatment effect. Quantification of perfusion changes provides non-invasive measures that reflect hemodynamic changes.

 

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Copyright © 2017 by the authors. Published version © 2017 by Lippincott Williams & Wilkins, Inc. Personal use of this material is permitted. However, permission to reprint or republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works, must be obtained from the copyright holder.

 

BibTeX entry

@article{Zhai:2017,
author = "{Zhiwei Zhai and Hideki Ota and Marius Staring and Jan Stolk and Koichiro Sugimura and Kei Takase and Berend C. Stoel}",
title = "{Treatment Effect of Balloon Pulmonary Angioplasty in CTEPH, Quantified by Automatic Comparative Imaging in CTPA}",
journal = "{Investigative Radiology}",
pages = "{-}",
year = "{2017}",
}

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