Correlation Between CD4 Cell Count, HIV Viral Load, and Chest CT Findings of AIDS-associated Pulmonary Cryptococcosis

The computed tomography (CT) features of acquired immune deficiency syndrome (AIDS)-associated pulmonary cryptococcosis (PC) are correlated with the viral load of human immunodeficiency virus (HIV). An increase in CD4-positive T lymphocyte (CD4) cell count in peripheral blood after a highly active antiretroviral therapy (HAART) can reflect the morphological changes of lung lesions.

This study aimed to evaluate the correlation between CT features and HIV viral load and to determine a cut-off value for CD4 cell count increment to investigate the prognosis of PC. It also aimed to examine the morphology of PC lesions and their prognosis following HAART.

Sixty-two patients with AIDS-associated PC, confirmed by pathology or follow-up, were enrolled in this study. The CT findings were recorded and classified as nodular, cavitary, and consolidation groups and their subtypes. Forty HIV patients who had undergone HAART were screened in this study, and the outcomes of lung lesions were recorded in a follow-up of 3 - 6 months. The participants were divided into improvement and progression groups. The correlation analysis and the receiver operator characteristic (ROC) curve analysis were used to examine the correlation between CT morphology and HIV viral load and to determine the cut-off value for CD4 cell count increment. The intraclass correlation coefficient (ICC) for inter-observer agreement was also calculated.

In the nodular group, patients with miliary nodules had the highest HIV viral load in peripheral blood (miliary nodules vs. solitary nodules, P = 0.009; miliary nodules vs. multiple nodules; P = 0.024). In the cavitary group, thick-walled cavity lesions had a higher HIV viral load than thin-walled cavity lesions (thin-walled vs. thick-walled cavity lesions, P = 0.036). Changes in the morphology of lesions, indicating the progression or improvement of PC, had a positive correlation with the CD4 cell count increment (F = 4.260, P = 0.045). The cut-off value for CD4 cell count increment to differentiate the two outcomes (progression and improvement) was 44/µL. The area under the curve (AUC) was 0.851, and sensitivity, specificity, and accuracy were estimated at 0.815, 0.714, and 0.764, respectively.

In AIDS-associated PC, different types of lesions were related to the HIV viral load, and CD4 cell count increment following HAART was associated with the morphological changes of lesions. This finding can be helpful for clinicians and radiologists to make an accurate diagnosis and evaluate the treatment outcomes, as well as disease progression.