Figure 1.
Flowchart of patient recruitment.
RHC = right-sided heart catheterization, CT = computed tomography, PH = pulmonary hypertension
Figure 2.
Flowchart of the automatic vessel extraction algorithm.
(top) Sample CT image, (2nd row) lung, airway segmentation and the vessel enhancement filter response superimposed on the CT image, (3rd row) vessel enhancement filter response restricted to the region of interest, (bottom row, left) connected centerlines, (bottom row, right) 3D rendering of the lung vessel centerlines. Inset shows the computation of distance metric (DM). The sum of distances along the 3D points of the vessel is divided by the length of the straight path between the two endpoints (first and last 3D point of the vessel segment).
Table 1.
Patient characteristics.
Table 2.
Values of distance metric, fractal dimension and number of vessel segments.
Table 3.
Correlations with clinical parameters (Spearman r and p-value) for n = 24 patients.
Figure 3.
Correlation of distance metric with patient clinical parameters.
Correlation of distance metric with (A) mean pulmonary arterial pressure (mPAP), and (B) pulmonary vascular resistance (PVR; R = linear correlation coefficient, r = Spearman correlation coefficient, ** p<0.01, *** p<0.001). (C) Receiver-operating curve for DM determining mPAP >25 mmHg (AUC: area under the curve). (D) Distribution of distance metric according to the WHO classification of the patients. (solid lines represent mean and standard error of mean; p value shows significant difference between WHO class II and III).
Figure 4.
Correlation of distance metric with oxygen exchange parameters.
Correlation of distance metric with arterio-venous difference in oxygen content (AVDO2, A), arterial (art SO2, B) and venous (ven SO2, C) oxygen saturation (R = linear correlation coefficient, ρ = Spearman correlation coefficient, ** p<0.01, *** p<0.001).
Figure 5.
Correlation of fractal dimension with clinical parameters.
Correlation of 3D fractal dimension (FD) with (A) mean pulmonary arterial pressure (mPAP), and (B) pulmonary vascular resistance (PVR; R = linear correlation coefficient, ρ = Spearman correlation coefficient, ns - not significant).
Figure 6.
Correlation of fractal dimension with oxygen exchange parameters.
Correlation of 3D fractal dimension with arterio-venous difference in oxygen content (AVDO2, A), arterial (art SO2, B) and venous (ven SO2, C) oxygen saturation (R = linear correlation coefficient, ρ = Spearman correlation coefficient, * p<0.05, ns - not significant).