Invasive pulmonary aspergillosis (IPA) is a significant cause of morbidity and mortality especially in immunocompromised patients, and extensive work has been done in the field of diagnostic imaging. The purpose of our study was to evaluate functional metabolic image findings of 18F-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) in the patients with invasive and noninvasive forms of pulmonary aspergillosis (IPA and NIPA, respectively).
We retrospectively reviewed 24 consecutive patients who had pulmonary aspergillosis among the patients who underwent 18F-FDG PET/CT to evaluate lung mass or fever of unknown origin. Demographic feature, multiplicity, visually analyzed 18F-FDG uptake patterns (isometabolic halo, isometabolic nodule, hypermetabolic nodule, or other), and the peak standardized uptake value (SUVpeak) of the pulmonary lesions on PET/CT were evaluated.
Of these 24 patients, 8 were diagnosed with IPA and 16 with NIPA. Patients with IPA were significantly younger (48 vs 62 years), and immunocompromised conditions were more frequently observed in these cases (88% vs 6%). Multiple lesions were noted in 50% (4 of 8) and 19% (3 of 16) of IPA and NIPA patients, respectively, and the predominant patterns on 18F-FDG PET/CT were the hypermetabolic nodule pattern (6 of 8 patients, 75%) and the isometabolic halo pattern (8 of 16 patients, 50%) in IPA and NIPA patients, respectively. The isometabolic halo pattern was not observed in IPA patients. The median SUVpeak was 4.5 (range, 1.3–8.9) and 1.6 (range, 0.5–3.1) in IPA and NIPA, respectively.
18F-FDG PET/CT findings differ between IPA and NIPA patients. Pulmonary aspergillosis in immunocompromised status with a hypermetabolic nodule pattern on 18F-FDG PET/CT seems to have high possibility of IPA. In contrast, an isometabolic halo pattern and an isometabolic nodule pattern on 18F-FDG PET/CT seem to have high possibility of NIPA.