Invasive pulmonary aspergillosis (IPA) is a frequent infectious complication in neutropenic patients which is associated with a high mortality. IPA is suspected if antibiotic resistant-fever and infiltrates develop in neutropenic patients. The diagnostic yield of bronchoscopy with BAL for IPA is only 30% due to the fact that aspergillus is usually found intravascular. Typical signs on CT scan include the halo sign and consolidations with central necrosis. This study was undertaken to analyze the diagnostic value of CT angiography and to define whether signs of angio-invasiveness are more specific than other CT-signs for IPA.
Consecutive immunocompromised patients with antibiotic resistant fever (n=30) underwent pulmonary CT angiographies (16 detector multislice CT) (n=41). CT scans were analyzed for infiltrate, consolidations and the halo sign. CTA were examinated for vessel occlusion. CTA was considered positive if signs of vessel occlusion were detected.
A total of 47 lesions were noticed in 23 CTs (56%). Conversely, in 18 CTs no lesions were found. Histological examination was performed in 33 lesions (12 patients) and not available in 14 lesions (11 patients). In cases with histological examination, CTA was positive (vessel occlusion) in 13 of 16 histologically proven IPA lesions and in 2 non-fungal infiltrates. CTA was negative in 15 lesions with non-fungal etiology and in 3 lesions with documented IPA. In cases without histological confirmation (11 patients, 14 lesions) final diagnosis was based on clinical outcome and CT follow-up. CTA was positive in 6 cases with possible IPA (defined according to guidelines) and negative in 8 lesions without evidence of IPA (hematoma; fibrosing alveolitis; bacterial pneumonia). The overall sensitivity of the CTA sign was 86.4% and the specificity 92.0%. In comparison, the classical halo sign had a sensitivity of only 36.4% and a specificity of 84.0% to detect IPA.
CT angiography has a higher sensitivity than the classical CT-signs to detect IPA in neutropenic patients.
Multislice CT angiography seems to be an excellent diagnostic method to diagnose invasive pulmonary aspergillosis.
Michael Tamm, None.