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Antonio SOLAZZO 1, Vitaliano BUFFA 1, Maria C. TODARO 2, Barbara SESSA 1, Manuela MADAU 1, Monica LUZIETTI 1, Margherita TRINCI 1, Vittorio MIELE 1
1 Department of Cardiovascular and Emergency Radiology, S. Camillo-Forlanini Hospital, Rome, Italy; 2 Cardiology Unit, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
BACKGROUND: Ionizing radiation is the main limit of CT angiography because it entails the risk of inducing carcinogenesis, particularly in patients who require a life-long follow-up. The aim of the current study is to compare qualitatively and quantitatively a virtual non-contrast reconstruction (VNC) reconstruction to a non-enhanced phase in order to assess whether VNC reconstruction might be effective enough to replace the non-enhanced phase during the follow-up of patients affected by abdominal aortic aneurysms.
METHODS: We included 196 patients (M=159, F=37, mean age 76±8.2) referred to perform a dual-energy CTA of the abdominal aorta for abdominal aortic aneurysm detection or surveillance. VNC reconstructions were compared to non-enhanced phase by two radiologists in consensus to evaluate image quality, calcium subtraction, acceptance level for diagnostic purposes and to perform a quantitative measure of density within aortic lumen. Furthermore, cumulative effective dose (ED) reduction was evaluated by replacing the non-enhanced phase with a VNC reconstruction.
RESULTS: Image quality was good for VNC reconstructions, excellent for non-enhanced acquisitions. Calcification over-subtraction in VNC images was classified as minimal in 50%, moderate in 29.0%, severe in 2.5%,while the mean density at the level of the abdominal aorta was 38.3±6.4 HU for VNC reconstructions, and 40.7±5.7 HU for non-enhanced acquisitions. Acceptance level of VNC reconstructions was complete in 86.2% of cases, with restrictions in 13.8%, no acceptance in none circumstance. The replacement of non-contrast scan with a VNC reconstruction allows to reduce the cumulative ED of 39.7%.
CONCLUSIONS: Acceptance level of VNC reconstructions allows to use them for diagnostic purposes in replacement of non-enhanced acquisitions reducing the cumulative effective dose.