High-resolution computed tomography (CT) is an essential diagnostic tool for invasive mould disease (IMD) in patients with haematological malignancies but is infrequently performed in the first 72 h of neutropenic fever until after chest X-ray (CXR). We hypothesised that early (< 48 h) low-dose CT (LD-CT; 90% reduction in radiation dose) combined with CT pulmonary angiography (CTPA) to detect the venous occlusion sign (VOS) inside suspected infiltrates could improve IMD diagnosis.

We prospectively studied 68 consecutive adult patients undergoing treatment for haematological malignancies who developed fever following chemotherapy or haematopoietic stem cell transplantation. Within 48 h of fever, patients underwent a standard CXR followed by LD-CT imaging and CTPA if eligible based on baseline imaging findings; the same protocol was performed in 42/68 (61.7%) of patients at day 7 follow-up. The diagnostic performance of CT signs for EORTC/MSG-defined proven, probable, and possible IMD was analysed at both imaging periods.

The baseline LD-CT was positive for abnormalities in 43/68 (63%) of patients within 48 h of fever and 35/42 (83%) of patients at the follow-up exam. Amongst these 43 patients, CTPA was performed in 17/43 (39%) and in 18/35 (51%) at D + 7 follow-up. A positive VOS was associated with the highest estimated positive likelihood ratio for EORTC/MSG-defined proven, probable, or possible IMD at baseline (20.6; 95% CI 1.4–311.2) and at day 7 follow-up (19.0; 95% CI 0.93–300.8) followed by the baseline non-contrast enhanced hypodense sign (18.3; 0.93–361.7), reverse halo (11.0; 0.47–256.5), halo sign (8.68;3.13–24.01) and air-crescent sign at day 7 (16.7; 0.93–301.0). However, a negative VOS was the only CT sign at baseline or day 7 associated with sufficiently low negative likelihood ratio (0.05;0.001–0.8) to possibly support ruling-out IMD in patients with positive CT findings.

Early LD-CT combined with CTPA shows promise for improving the early radiographic diagnosis of IMD.