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Improvement of Image Quality at 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 Standard Tube Voltage

Namimoto, Tomohiro MD, PhD; Oda, Seitaro MD, PhD; Utsunomiya, Daisuke MD, PhD; Shimonobo, Toshiaki RT; Morita, Sosuke RT; Nakaura, Takeshi MD, PhD; Yamashita, Yasuyuki MD, PhD

Journal of Computer Assisted Tomography: July/August 2012 - Volume 36 - Issue 4 - p 495–501
doi: 10.1097/RCT.0b013e31825b821f
CT and Digital Techniques

Objective To intraindividually compare a low–tube voltage, low–contrast material dose computed tomography (CT) reconstructed with iterative reconstruction (IR) algorithm at standard tube voltage reconstructed with filtered back projection (FBP) and standard–contrast material dose during liver dynamic CT.

Materials and Methods Twenty-five patients with liver cirrhosis underwent 64-section multidetector CT. One hundred twenty kilovolt (peak) (kV[p]) with standard contrast material dose of 600 mg of iodine per kilogram (protocol A) and 80 kV(p) with low–contrast material dose of 450 mg of iodine per kilogram (protocol B) CT image sets were reconstructed by using FBP algorithm and that of using IR algorithm with a 60%/40% blend of IR-FBP reconstruction at 80-kV(p) image set (protocol C). Scans obtained during 3 hepatic phases were subjected to quantitative and qualitative analysis.

Results The mean radiation dose and the contrast medium dose were significantly lower under protocols B and C than under protocol A. In all hepatic phases, all signal-to-noise and contrast-to-noise ratios were greater under protocol C than under other protocols at all anatomic sites. Qualitative analysis showed that image noise and diagnostic acceptability were significantly higher under protocol C.

Conclusion In all hepatic phases, a low–tube voltage, low–contrast material dose CT with IR algorithm yielded better contrast enhancement and image quality than a standard tube voltage, standard contrast material dose CT with FBP in thin adult patients.

From the *Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University; and †Department of Radiology, Kumamoto University Hospital, Kumamoto, Japan.

Received for publication February 10, 2012; accepted April 20, 2012.

Reprints: Tomohiro Namimoto, MD, PhD, Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1, Honjyo, Kumamoto, 860-8556, Japan (e-mail:

The authors report no conflicts of interest.

Copyright © 2012 Wolters Kluwer Health, Inc. All rights reserved.