P6161The evaluation of the effectiveness of the treatment of patients with chronic thromboembolic pulmonary hypertension using subtraction CT pulmonary angiography
Authors: Demchenkova A , Veselova T , Martynyuk T , Danilov N , Mershin K , Ternovoy S , Chazova I 
Published: October 2019

Abstract

Introduction
Chronic thromboembolic pulmonary hypertension (CTEPH) is a life-threatening delayed complication of acute pulmonary embolism. It is characterized by chronic obstruction of the branches of the pulmonary artery, arteriopathy and vasoconstriction of small vessels, that ultimately leading to right ventricular failure. Subtraction CT pulmonary angiography (CTPA) allows to perform a comprehensive the assessment of the state of the vascular bed and pulmonary perfusion, it is especially important for pathological changes in the distal branches of the pulmonary artery. Analysis of perfusion defects in combination with the standard protocol of CTPA can increase the diagnostic value of the method in examining patients with CTEPH that will select the optimal treatment strategy with the possibility of an objective assessment of its effectiveness.

Purpose
The aim of this work was to determine the possibilities of the method of subtraction CTPA in the evaluation of the effectiveness of the treatment of patients with CTEPH.

Methods and materials
Primary and repeated subtraction CTPA was performed 36 patients with the diagnosis of CTEPH (10 patients after surgical treatment, 13 patients after endovascular treatment and 13 patients after initiation of PAH-specific therapy) (figure).All patients were examined on 320-detector row CT scanner using the standard protocol Lung subtraction. Using subtraction CTPA was calculated of CT-scores of obstruction and perfusion defect. The data of primary and repeated CT studies were compared with the clinical and hemodynamic status of patients. CT color-coded iodine images were produced by subtraction of non-contrast from contrast images.

Results
According to repeated CTPA a decrease of the degree of obstruction was observed in 18 out of 36 (50%) patients: in 10 (100%) patients from the surgical treatment group and 8 (61.5%) patients from the endovascular treatment group. Subtraction CTPA was a good quality for interpreting perfusion maps in 28 of 36 (77.8%) patients.Evaluation of the dynamics of perfusion disorders was not performed in 8 patients: in 3 patients from the surgical treatment group and 5 patients from the endovascular treatment group. Improvement of lung perfusion according to perfusion maps was determined in 18 out of 28 (64.3%) patients: 7 (100%) patients from the surgical treatment group, 5 (62.5%) patients from the endovascular treatment group, and 6 (46.2%) patients from the group of drug treatment. Improvement of clinical and hemodynamic parameters was observed in all patients in the surgical and endovascular treatment groups. There was no statistically significant improvement in clinical and hemodynamic parameters in the drug treatment group.

Conclusion
The results of the study demonstrated the possibility of using subtraction CTPA for an objective assessment of the effectiveness of the treatment of patients with CTEPH.