Correlation between the Pulmonary Artery Pressure Measured in Echocardiography and Pulmonary Artery Diameter in the CT-Scan of Patients Suffering from Interstitial Lung Disease

Background: Pulmonary hypertension (PH) is a significant cause of morbidity and mortality in patients suffering from pulmonary parenchymal diseases. Diagnosis of PH has always been a major clinical dilemma due to its non-specific clinical manifestations. However, diagnosing PH and determining its severity are essential for the prognosis and treatment planning in PH patients. This study aimed at evaluating the correlation between the pulmonary artery diameter (PAD) in the CT-scan and pulmonary artery pressure (PAP) in echocardiography of patients. Materials and Methods: PAD was evaluated in the CT-scan of 117 patients suffering from interstitial lung disease (ILD) and the correlation between PAD and PAP was studied. A receiver operating characteristic curve (ROC curve) which is indicative of the precision of the diagnostic test was drawn to find the cut off point for the MPAD representing PH. The area under the curve was also calculated in order to define the discriminative power of the test. Results: PAP higher than 25 mmHg was considered as PH. PAD over 29 mm reported in the CT-scan for the diagnosis of PH in ILD patients had sensitivity of 63% and specificity of 41.5%. No significant linear correlation was found between PAD and PAP (P-value=0.17, r=0.15). The area under the ROC curve was calculated to be 0.49 in the cutoff point of 29 mm for determining PH (CI 95%=0.38-0.60, P=0.89). Conclusion: ROC curve showed a weak discriminative power. PAD had low sensitivity and specificity in the CT-scan for the diagnosis of PH. Therefore, we conclude that CT-scan alone is not helpful in finding PH cases and further examinations are required.