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.