Significance of Normal Lung Volume on Quantitative CT Imaging Analysis in Group 1 and Group 3 Pulmonary Hypertension

Figures

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  Figure 1. Flow chart showing patient selection. A total of 157 patients were included in the present study based on the inclusion and exclusion criteria. HRCT = high-resolution CT; mPAP = mean pulmonary arterial pressure; PAWP = pulmonary arterial wedge pressure; PFT = pulmonary function testing; PH = pulmonary hypertension; PVR = pulmonary vascular resistance; RHC = right heart catheterization.

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  Figure 2. Analysis of quantitative normal lung volume on chest high-resolution CT (HRCT) imaging using a 3-dimensional image analysis system (Synapse Vincent version 6.1; Fujifilm Corporation). A-C, The lung areas on HRCT imaging are identified—coronal section (A) and axial section (B)—and the total lung volume is abstracted and synthesized (C). D, The red spaces in the lungs represent abnormal areas identified by –1024 to –950 Hounsfield units (HU), and the areas of –950 to –600 HU are defined as normal lung volume.

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  Figure 3. Histograms showing the distribution of %NLV. A, Histogram showing the distribution of %NLV in all patients. %NLV is presented using mean ± SD and median (interquartile range). B, Stratified histogram of %NLV according to the classification of lung parenchymal change on high-resolution CT imaging interpretation. %NLV in the three groups are presented as the mean ± SD. C, Stratified histogram of %NLV according to the classification of PH subgroups. %NLV in the three groups is presented as mean ± SD. %NLV = percentage of normal lung volume to the whole lungs; PH, pulmonary hypertension.

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  Figure 4. A-C, Scatterplots and regression lines showing the association percentage of NLV to the whole lungs (%NLV) with pulmonary function testing parameters: FVC % predicted (A), FEV1 % predicted (B), and Dlco % predicted (C). Correlation coefficients (r) and probability values (P) are presented in each figure. Dlco, diffusing capacity of the lungs for carbon monoxide.

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  Figure 5. Survival analysis. A, Receiver operating characteristic curve obtained by logistic regression analysis to estimate the relationship between the %NLV and 3-year survival. The arrow point indicates the optimal cutoff of %NLV for 3-year survival. B, Comparison of Kaplan-Meier curves of 5-year survival between patients with %NLV of ≥ 83.2% and < 83.2%. C, Kaplan-Meier curves showing patients with %NLV of ≥ 83.2% further divided into two subgroups according to the severity of ventilatory impairment and the survival curves. AUC = area under the receiver operating characteristic curve; %NLV = percentage of normal lung volume to the whole lungs; RHC = right heart catheterization.