Prospective comparison of dual-energy CT aortography using 70% reduced iodine dose versus single-energy CT aortography using standard iodine dose in the same patient.

Abstract

To compare dual-energy computed tomography (DECT) aortography using a 70% reduced iodine dose to single-energy CT (SECT) aortography using a standard iodine dose in the same patient. Twenty-one patients with a prior SECT aortography using standard iodine dose had DECT aortography using 70% reduced iodine dose. Section120 kVp images were compared to DECT images reconstructed at both 50 and 77keV. Reviewers measured image noise and attenuation in the aorta at eight locations from proximal to distal and subjectively scored vascular enhancement on a four-point scale. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The volume CT dose index (CTDIvol) for each exam was recorded. Mean iodine dose was 50g for SECT and 15g for DECT (70% reduction). Mean aortic attenuation was similar for section120 kVp (350±67 HU) and DECT 50keV (338±57 HU, p=0.547) but was lower at 77keV (152±23 HU). Measured image noise was greatest at 50keV (12±5 HU) and was lowest at 77keV (7±2 HU, p>0.001). There was no difference in SNR or CNR between 120 kVp and 50keV (p>0.05). Mean subjective vascular enhancement scores for SECT were between good and excellent (3.33-3.69), and for DECT at 50keV were between moderate and good (2.54-2.93, p<0.0001). CTDIvol was 13.6mGy for SECT and 13.1mGy for DECT (p=0.637). 70% Reduced iodine DECT aortography may result in similar aortic attenuation, CNR, SNR, and lower although acceptable subjective image scores when compared to standard iodine SECT aortography in the same patient.