Tomohiro Namimoto MD, Presenter: Nothing to Disclose

Seitaro Oda MD, Abstract Co-Author: Nothing to Disclose

Toshiaki Shimonobo, Abstract Co-Author: Nothing to Disclose

Kosuke Morita, Abstract Co-Author: Nothing to Disclose

Shinichi Nakamura MD, PhD, Abstract Co-Author: Nothing to Disclose

Yasuyuki Yamashita MD, Abstract Co-Author: Nothing to Disclose

To intraindividually compare a low tube voltage, low contrast material dose computed tomographic (CT) iterative reconstruction (IR) algorithm technique with an automatic tube current modulation (ATCM) technique and a standard contrast material dose CT protocol in terms of image quality, radiation dose, and signal-to-noise ratio (SNR) during the hepatic arterial (AP), portal (PP) and venous phase (VP).

Twenty-five patients known liver cirrhosis underwent 64-section multidetector CT. Two imaging protocols-80 kVp and 386 mA with IR by using low contrast material dose (450 mgI/kg) (protocol A) and previous 120 kVp and ATCM with filtered back projection (FBP) by using a standard contrast material dose (600 mgI/kg) (protocol B) -were intraindividually compared during the hepatic AP, PP and VP of contrast enhancement. Paired t tests were used to compare liver, aorta, portal vein (at only PP), and inferior vena cava (IVC) (at only VP) SNR for each lesion, and effective dose between the two data sets. Two readers qualitatively assessed the two data sets in a blinded and independent fashion. Wilcoxon-Mann-Whitney statistical analysis was performed on this assessment.

Mean radiation was significantly lower for the 80 kVp protocol A than for the 120 kVp protocol in all phases (AP -32.8% ; PP -30.2%, VP -25.3%). SNR was significantly higher for the 450 mgI/kg protocol A than for the 600 mgI/kg protocol B at all anatomic sites in all phases (AP liver 14.8%, aorta 24.3%; PP liver 16.8%, aorta 28.9%, portal vein 30.5%; VP liver 13.5% aorta 34.39%, IVC 19.8%). With qualitative analysis, image noise and diagnostic accuracy for the protocol A were significantly higher than for the protocol B; artifacts for the protocol A were significantly lower than for the protocol B; no statistically significant differences were found in image sharpness.

Given a low tube voltage, IR algorithm CT with a low contrast material dose results in better contrast enhancement than a standard voltage ATCM FBP technique CT with a standard contrast material dose in all three hepatic phases.

A low tube voltage iterative reconstruction algorithm CT with a low contrast material dose is better contrast enhancement than a standard CT with a standard contrast material dose in abdominal CT.

Namimoto, T, Oda, S, Shimonobo, T, Morita, K, Nakamura, S, Yamashita, Y, Improvement of Image Quality of Low Radiation Dose and Low Contrast Material Dose Abdominal CT in Patients with Cirrhosis: Intraindividual Comparison of Low Tube Voltage with Iterative Reconstruction Algorithm and Automatic Tube Current Modulation.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11010108.html