Computed tomography chest imaging for the detection of pulmonary hypertension in patients with post-tuberculosis lung disease

Background Pulmonary hypertension (PH) after tuberculosis is increasingly recognised as important in high-burden tuberculosis settings. However, the ability of computed tomography (CT) imaging to accurately detect PH remains unclear. Objectives To evaluate the performance of standard CT measurements in detecting PH in patients with post-tuberculosis lung disease (PTLD), and to determine the potential role of CT imaging as a screening tool in this population. Methods A retrospective study of patients with PTLD was conducted from January 2019 to September 2021. Adult patients with both a CT chest scan and an echocardiogram performed within 9 months of each other were enrolled. A diagnosis of PH by echocardiography was made if the right ventricular systolic pressure (RVSP) was ≥36 mmHg or the peak tricuspid regurgitant jet velocity (TRVmax) >2.8 m/s. Radiological criteria for PH included a pulmonary artery/ascending aorta (PA/AA) diameter ratio >1, pulmonary artery diameter (PAD) ≥29 mm (males) or ≥27 mm (females), and right ventricle/left ventricle (RV/LV) diameter ratio ≥1.28. Spirometry was also performed. Results Of 173 patients with PTLD, 52 met the inclusion criteria. Significant correlations were found between the CT-measured PA/AA ratio and RVSP (p=0.0083) and TRVmax (p=0.0582), but not between the CT-measured RV/LV ratio and RVSP (p=0.1729) or TRVmax (p=0.0749). PAD was also significantly correlated with RVSP (p=0.0011) and TRVmax (p=0.0023). The PA/AA ratio identified patients with PH on echocardiography with ~100% sensitivity, 65% specificity and a positive predictive value of 39.1%, indicating a high potential for false-positive diagnosis. The forced vital capacity was 13.7% lower in patients with PH than in those without (p=0.044); however, the forced expiratory volume in 1 second was not statistically different. Conclusion A low PA/AA ratio can be used to rule out the diagnosis of PH in PTLD, but a high PA/AA ratio requires further investigation for PH. Study synopsis What the study adds. This study investigated the use of computed tomography (CT) chest imaging to detect pulmonary hypertension (PH) in patients with post-tuberculosis lung disease (PTLD). It revealed significant correlations between the CT-measured pulmonary artery/ascending aorta (PA/AA) diameter ratio and pulmonary artery diameter (PAD), and echocardiographic measures of PH. Notably, a low PA/AA ratio effectively rules out PH, while a high ratio warrants further investigation. Implications of the findings. These findings suggest that CT imaging, particularly PA/AA ratio measurements, could serve as a valuable initial screening tool for ruling out PH in patients with PTLD, particularly in settings with limited access to echocardiography. However, a high PA/AA in PTLD requires confirmation of PH by other means, owing to a low positive predictive value.