Worsening respiratory function in mechanically ventilated intensive care patients: Feasibility and value of xenon-enhanced dual energy CT.

OBJECTIVES: To evaluate the feasibility and incremental diagnostic value of xenon-enhanced dual-energy CT in mechanically ventilated intensive care patients with worsening respiratory function. METHODS: The study was performed in 13 mechanically ventilated patients with severe pulmonary conditions (acute respiratory distress syndrome (ARDS), n=5; status post lung transplantation, n=5; other, n=3) and declining respiratory function. CT scans were performed using a dual-source CT scanner at an expiratory xenon concentration of 30%. Both ventilation images (Xe-DECT) and standard CT images were reconstructed from a single CT scan. Findings were recorded for Xe-DECT and standard CT images separately. Ventilation defects on xenon images were matched to morphological findings on standard CT images and incremental diagnostic information of xenon ventilation images was recorded if present. RESULTS: Mean xenon consumption was 2.95l per patient. No adverse events occurred under xenon inhalation. In the visual CT analysis, the Xe-DECT ventilation defects matched with pathologic changes in lung parenchyma seen in the standard CT images in all patients. Xe-DECT provided additional diagnostic findings in 4/13 patients. These included preserved ventilation despite early pneumonia (n=1), more confident discrimination between a large bulla and pneumothorax (n=1), detection of an airway-to-pneumothorax fistula (n=1) and exclusion of a suspected airway-to-mediastinum fistula (n=1). In all 4 patients, the additional findings had a substantial impact on patients' management. CONCLUSIONS: Xenon-enhanced DECT is safely feasible and can add relevant diagnostic information in mechanically ventilated intensive care patients with worsening respiratory function