PET Imaging Reveals Early Pulmonary Perfusion Abnormalities in HIV Infection Similar to Smoking

Abstract

Chronic obstructive pulmonary disease (COPD) is the most common noninfectious pulmonary disease among people living with HIV, independent of smoking. However, the cause for this enhanced susceptibility remains unclear, and the effects of HIV on pulmonary perfusion and ventilation are unknown. Methods: We used PET/CT in 46 smokers and nonsmokers, 23 of whom had documented HIV infection. Emphysema was assessed by CT and perfusion by ¹³N (¹³NN) PET scans. After removal of image noise, vertical and axial gradients in perfusion were calculated. We tested for differences in the total spatial heterogeneity of perfusion (CV²_Qtotal) and its components (CV²_Qtotal = CV²_Qvgrad [vertical gradient] + CV²_Qzgrad [axial gradient] + CV²_Qr [residual heterogeneity]) among groups. Results: There were no significant differences in demographic parameters among groups, and all subjects had minimal radiographic evidence of emphysema. Compared with controls, nonsmokers living with HIV had a significantly greater CV²_Qr/CV²_Qtotal (0.48 vs. 0.36, P = 0.05) and reduced CV²_Qvgrad/CV²_Qtotal (0.46 vs. 0.65, P = 0.038). Smokers also had a reduced CV²_Qvgrad/CV²_Qtotal, however, there was no significant difference in CV²_Qvgrad/CV²_Qtotal between smokers living with and without HIV (0.39 vs. 0.34, P = 0.58), despite a decreased vertical perfusion gradient (Qv_grad) in smokers living with HIV. Conclusion: In nonsmokers living with well-controlled HIV and minimal radiographic emphysema, HIV infection contributes to pulmonary perfusion abnormalities similar to smokers. These data indicate the onset of subclinical pulmonary perfusion abnormalities that could herald the development of significant lung disease in these susceptible individuals.