Role of serial fluorodeoxyglucose positron emission tomography-computed tomography (18FDG-PET-CT) in assessing treatment response in treatment naïve chronic pulmonary aspergillosis subjects

Background: The role of 2-deoxy-2-18(F) fluoro-D-glucose (FDG) positron emission tomography (PET)-computed tomography (CT) in assessing treatment response in chronic pulmonary aspergillosis (CPA) remains to be determined.

Objective: To compare changes in FDG-PET/CT parameters in CPA subjects with treatment success or failure.

Methods: We treated consecutive treatment-naïve CPA subjects with six months of oral itraconazole. We performed PET-CT at baseline and six months. A multi-disciplinary team categorized response as treatment success or failure. We recorded the maximum standardised uptake value (SUVmax), SUVpeak, and total glycolytic activity (TLG). After treatment, FDG uptake similar to the background uptake or ≥13 units decline in Z-score was considered a complete metabolic response (CMR). A >25%, >30%, and > 45% decline in SUVmax, SUVpeak, and TLG was labelled as a partial metabolic response (PMR). A >30%, >30%, or >75% increase in the SUVmax, SUVpeak, and TLG represented progressive metabolic disease.

Results: We included 94 CPA subjects (63 males) with a mean age of 46.2 years. A follow-up PET-CT was performed on 77 subjects. We recorded treatment success and failure in 43 and 34 subjects. The median SUVmax at baseline was 6.7, which significantly reduced with treatment. CMR was seen in 18.6% of those with treatment success and none with treatment failure. A higher proportion of subjects with treatment success achieved PMR. 19% of the subjects with treatment success had progressive metabolic disease.

Conclusion: FGD-PET/CT demonstrated metabolic activity in all CPA subjects. Most PET-CT parameters improved with treatment; however, one-fifth of the subjects were misclassified on PET-CT.