Invasive pulmonary aspergillosis in neutropenic patients: Early diagnosis by thoracic high-resolution CT scan.

Abstract

e19713 Background: The aim of this study was to determine the utility of thoracic high resolution CT scan (HRCT) in the characterization of lung infiltrates for the early diagnosis of invasive pulmonary aspergillosis (IPA) in febrile neutropenic patients. Methods: We included hematology patients (acute leukemia/aplastic anemia) with febrile neutropenia in this study. We took chest x-rays at admission and at onset of fever or development of respiratory signs/symptoms. We did HRCT scan of the chest when fever had lasted for more than 4 days of antibiotic therapy or if the patient had signs/symptoms suggestive of pulmonary involvement or when chest X- ray showed abnormalities. Patterns of parenchymal infiltrates and the presence of nodular lesions, halo sign, cavitation, air crescent sign and fungal ball were noted. IPA was classified as proven, probable or suspected as per EORTC case definitions [excluding radiological criteria]. Calculation of sensitivity and specificity of HRCT in diagnosing IPA was based on these groups. Results: We studied 76 febrile episodes. Chest x-ray abnormalities were seen in 49 (61%) patients.HRCT scan of the chest showed abnormalities in 63 (84%) patients. Normal chest x-ray with abnormal CT was seen in 19(24%) patients. Typical CT findings included nodules in 24 (43%), nodules with halo sign in 19 (34%), segmental consolidation in 34 (61%), cavitation/air crescent sign in 9 (16%), fungal ball in 4(7%), pleural effusion in 11(20%) and hilar/paratracheal lymphadenopathy in 7 (13%). Multiple abnormalities were seen in 36 (47) % of cases. There were 32 cases of suspected IPA and 1 probable IPA. The overall sensitivity and specificity of HRCT for diagnosing IPA was 96% and 65% respectively. The sensitivity and specificity of the halo sign was 39% and 81% and that of the air crescent sign was 27% and 94%. Some of the larger nodules and consolidations in patients with suspected IPA showed a central hypodensity on non-contrast CT (‘hypodense sign’). These radiological findings were useful in the early institution of anti-fungal therapy in these patients. Conclusions: High resolution CT scan is superior to conventional chest x-ray for the early diagnosis of IPA in neutropenic patients.