Abdominal rapid-kVp-switching dual-energy MDCT with reduced IV contrast compared to conventional MDCT with standard weight-based IV contrast: an intra-patient comparison

Perform intra-patient comparison of attenuation values on lower keV dual-energy abdominal CT images using reduced IV contrast dose compared to conventional single energy polychromatic beam abdominal MDCT images using standard IV contrast dose. IRB approved retrospective evaluation of consecutive adults who had both standard IV contrast dosage conventional multiphasic MDCT (SECT) and reduced IV contrast dosage rapid kV-switching dual-energy multiphasic MDCT (rsDECT) of the abdomen. Arterial phase dual-energy 52, 70 and 78 keV simulated monoenergetic HU were compared (t test) to arterial phase SECT HU for: aorta, liver, pancreas, psoas, and hepatic/pancreatic tumors. Contrast to noise ratios (CNR), IV contrast dose reduction and dose-length product (DLP) were recorded. Two blinded independent readers evaluated the CT datasets for subjective image quality based on a five point scale. Twenty-nine scan pairs in 24 subjects (13 M, mean age 64, weight 76.7 kg) were evaluated. Mean reduction in IV contrast dose was 37 %. Mean +/- A SD HU on 52 keV rsDECT vs. SECT were: aorta 534 +/- A 138 vs. 271 +/- A 69; liver 88 +/- A 24 vs. 67 +/- A 16; pancreas 140 +/- A 60 vs. 89 +/- A 40; psoas 63 +/- A 15 vs. 50 +/- A 12 (all p < 0.001). Noise was higher for 52 keV compared to SECT (p < 0.001); CNRs were not significantly different. Mean +/- A SD DLP for rsDECT was 1421 +/- A 563 and SECT 1335 +/- A 562 mGy center dot cm (p = 0.640). For tumor vs. nontumoral parenchyma, mean absolute contrast difference was 58.4 HU on 52 keV, and 29.0 HU on SECT. Nearly all images were rated as good or excellent and there were no statistically significant differences in image quality between the DECT and SECT images. Statistically significant gains in vascular and parenchymal enhancement without adverse effect on CNR or lesion contrast were observed in this intra-patient comparison using reduced IV contrast dose rsDECT compared to standard weight-based IV dose conventional SECT.