Page 28 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt

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CTPA image analyses
CTPA studies were analyzed using a Sectra PACS IDS7 workstation. Measurements were performed by an investigator from the department of pulmonary diseases under supervision of a radiologist with special interest in thorax imaging. Intraobserver variability was tested by repeated measurements in 10 CT studies. To test interobserver variability, measurements were repeated in 20 CT studies by another investigator from the same department. Both observers were blinded to patients’ medical history, hemodynamic data and diagnosis.
CTPA parameters
PA/AAAX - Maximum diameters of the main pulmonary artery (PA) and ascending aorta (AA) were obtained at the level of the bifurcation of the pulmonary trunk according to previous studies [11, 12]. PA and AA measurements were done on the same image in the axial view (figure 1A). Afterwards the PA/AA ratio was calculated.
RV/LVAX - Maximum transverse diameters of the RV and LV, defined as the widest distance of the endocardium between the interventricular septum and the free wall, were measured in the axial plane perpendicular to the long axis of the heart. Maximum diameters of the RV and LV were not necessarily obtained from the same image. Subsequently the RV/LV ratio was calculated (figure 1B). RV/LV4CH - Multiplanar reconstruction (MPR) was used to manually reconstruct a 4CH view in the same manner as described earlier [18, 20]. Similar to the ventricular measurements in the axial view, the maximum transverse diameters of the RV and LV were obtained from the 4CH view and the RV/LV ratio was calculated. Again maximum diameters of the RV and LV were not necessarily acquired from the same image (figure 1C).
Statistical analysis
Continuous data are presented as mean ± standard deviation (SD) and absolute numbers for categorical variables. Differences between mean values from precapillary pulmonary hypertension patients and control subjects were analyzed using the unpaired Student t test (variables with a normal distribution) or Mann-Whitney U tests (variables not normally distributed). Intra and- interobserver variability of the three CTPA parameters were analyzed using simple linear regression analysis. Univariable binary logistic regression analysis was used to test the predictive value of the three different CTPA parameters separately for precapillary pulmonary hypertension.