Xenon-enhanced dual-energy CT lung ventilation imaging: techniques and clinical applications.

OBJECTIVE: The purpose of this article is to review the techniques, clinically relevant potential applications, and limitations of xenon-enhanced dual-energy CT of the chest. CONCLUSION: The functional evaluation of lung ventilation may be of great importance to patients with pulmonary disease. Many measures are used to assess pulmonary function, but the results are estimates of only global status rather than the regional distribution of disease. With the introduction of dual-energy CT, regional lung ventilation function can be assessed with inhaled xenon gas. This technique yields not only high-spatial-resolution anatomic information but also information about regional ventilation.

Dual-energy CT lung ventilation/perfusion imaging for diagnosing pulmonary embolism.

OBJECTIVES: To evaluate the feasibility and findings of combined dual-energy computed tomography (DECT) lung ventilation/perfusion imaging in patients with suspected pulmonary embolism (PE). METHODS: This study was institutional review board-approved and written informed consent was obtained from each patient. Thirty-two subjects (aged 11-61 years) underwent combined xenon-enhanced ventilation and iodine-enhanced perfusion DECT. Ventilation, perfusion and morphological information were visually interpreted. Ventilation/perfusion information was classified as mismatch (differing patterns) or match (concordant patterns). Adverse reactions and radiation doses were recorded for each subject. RESULTS: Of 32 patients undergoing xenon-enhanced DECT, six patients reported adverse reactions (shortness of breath, n = 2; mild dizziness, n = 3; limb numbness, n = 1). Twenty-eight of 32 patients could be included into the data analysis. PE was detected in 10/28 patients. PE-related ventilation/perfusion mismatch was found in 17 lung lobes in 8/10 patients and matched ventilation/perfusion was detected in 2 patients. Eighteen patients had no PE. In this group, there was no case of a ventilation/perfusion mismatch. Matched ventilation/perfusion impairment was seen in one patient. The overall radiation dose from two DECT acquisitions was 4.8 ± 1.4 mSv (range 2.7-7.5 mSv). CONCLUSIONS: DECT lung ventilation/perfusion imaging is feasible and can visualise ventilation/perfusion match or mismatch in patients with suspected PE. KEY POINTS: • Combined dual-energy CT lung ventilation/perfusion imaging is feasible. • Combined dual-energy CT ventilation/perfusion imaging provides lung morphological and functional information. • Dual-energy CT can demonstrate ventilation/perfusion mismatch in patients with pulmonary embolism.