Feasibility of low-concentration iodinated contrast medium with lower-tube-voltage dual-source CT aortography using iterative reconstruction: comparison with automatic exposure control CT aortography.

Abstract

To evaluate the feasibility of low-concentration contrast medium (CM) for vascular enhancement, image quality, and radiation dose on computed tomography aortography (CTA) using a combined low-tube-voltage and iterative reconstruction (IR) technique. Ninety subjects underwent dual-source CT (DSCT) operating in dual-source, high-pitch mode. DSCT scans were performed using both high-concentration CM (Group A, n=50; Iomeprol 400) and low-concentration CM (Group B, n=40; Iodixanol 270). Group A was scanned using a reference tube potential of 120kVp and 120 reference mAs under automatic exposure control with IR. Group B was scanned using low-tube-voltage (80 or 100kVp if body mass index ≥25kg/m(2)) at a fixed current of 150mAs, along with IR. Images of the two groups were compared regarding attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), iodine load, and radiation dose in various locations of the CTA. In comparison between Group A and Group B, the average mean attenuation (454.73±86.66 vs. 515.96±101.55 HU), SNR (25.28±4.34 vs. 31.29±4.58), and CNR (21.83±4.20 vs. 27.55±4.81) on CTA in Group B showed significantly greater values and significantly lower image noise values (18.76±2.19 vs. 17.48±3.34) than those in Group A (all Ps<0.05). Homogeneous contrast enhancement from the ascending thoracic aorta to the infrarenal abdominal aorta was significantly superior in Group B (P<0.05). Low-concentration CM and a low-tube-voltage combination technique using IR is a feasible method, showing sufficient contrast enhancement and image quality.