Pathophysiological mechanisms leading to pulmonary hypertension (PH) are complex. Quantitative computed tomography (QCT) can help us to study morphological alterations in patients with PH. These CT morphometrics are useful to predict the degree of PH severity at least in PH secondary to chronic obstructive pulmonary disease (COPD). We hypothesized that assessing lung perfusion using dual energy CT (DECT) can refine our knowledge on PH pathophysiology and help to predict PH severity irrespective of its etiology

Pulmonary hypertension (PH) is a serious disease with poor prognosis and high morbidity and mortality. It is defined as an increase in mean pulmonary arterial pressure (mPAP) above or equal to 25 mmHg measured by right heart catheterization, which is an invasive technique.

Computed tomography (CT) plays an important role in the classification of PH and the identification of pulmonary etiologies responsible for PH (chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis...) or signs of chronic thromboembolic PH (CTEPH).

Quantitative CT allows accurate analysis of the morphological changes found in PH and leading to a better understanding of the complex interactions involved (arterial and bronchial remodeling in PH secondary to COPD, inflammation etc.).

Dual energy CT acquisition has shown its interest in helping to diagnose pulmonary embolism. It provides information on pulmonary perfusion by performing iodine mapping and measuring pulmonary perfusion blood volume (PVB).

This project intends to study morphological and functional alterations at bronchial and vascular levels in PH patients using quantitative DECT and to examine their impact to predict existence and severity of PH irrespective of its etiology. To measure from DECT scan images, cross sectional area of small pulmonary vessels (CSA), bronchial wall thickness (WT) and pulmonary perfusion blood volume. To collect data from right heart catheterization, echocardiography, pulmonary functional tests and blood tests. All these examinations will be performed in routine care within a week after the patient is referred to our institution. Statistical analysis of these parameters could lead to a multivariate model able to predict existence and severity of PH.

In addition, DECT allows the use of low energy (low Kilovoltage), which increases contrast and improves segmentation of the pulmonary arteries. Thus, peripheral pulmonary arteries and veins can be distinguishable in order to evaluate not just the sectional area of the small pulmonary vessels but also 3D volume of small pulmonary arteries (VSA). This technical modification would make it possible to refine the quantitative exploration of the vascular compartment of PH

Inclusion Criteria:

• adults (18 years old and over)
• Patient with PH diagnosed at right heart catheterization
• Availability of a dual energy chest CT scans with contrast injection performed as part of standard patient workup
• Patient's consent or authorisation for data processing.

Exclusion Criteria:

• patient without any chest CT scan available or planned in the patient workup