The aim of the study is to determine relevant hemodynamic parameters for the diagnostics of pulmonary arterial hypertension (PAH) by dynamic contrast enhanced dual-energy CT (DE-CT). In this prospective study the investigators validate DE-CT results of patients against hemodynamic parameters from right heart catheterisation and control the results by other clinical investigations. The investigators expect that using this non-invasive method, parameters relevant for the diagnosis of the patients with PAH, like pulmonary blood volume, blood flow and perfusion heterogeneity, can be determined.

Pulmonary arterial hypertension (PAH) is a rare, life-threatening disease. It is characterized by the elevation of pulmonary arterial pressure and pulmonary vascular resistance. A remodeling of small pulmonary vessels characterized by the proliferation of the adventitia, the hypertrophy of the media and fibrosis of the intima can be observed on the microscopic level.

Non-invasive techniques for hemodynamic assessment and identification of early pulmonary vascular remodeling and pulmonary hypertension have a marked practical advantage as compared to invasive right heart catheterization, however, their accuracy and reliability is not well established.

In the present study the investigators examine patients who are scheduled for a thorax CT with an additional dynamic contrast-enhanced DE-CT protocol and derive established parameters for the diagnosis of PAH as well as novel parameters from the CT scans. These are compared to results from the right-heart catheterization and other investigations routinely carried out on these patients.

Inclusion Criteria:

• patients with right heart catheterization data

Exclusion Criteria:

• patients with decreased renal function
• patients who received CT in the previous six months
• intolerance of contrast material
• other standard CT contraindications