G Model EURR-6734; No. of Pages 6
ARTICLE IN PRESS European Journal of Radiology xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad
Dose-reduced CT with model-based iterative reconstruction in evaluations of hepatic steatosis: How low can we go? Koichiro Yasaka a,∗ , Masaki Katsura a , Masaaki Akahane b , Jiro Sato a , Izuru Matsuda c , Kuni Ohtomo a a
Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan NTT Medical Center Tokyo, 5-9-22 Higashi-Gotanda, Shinagawa-ku, Tokyo 141-8625, Japan c Kanto Rosai Hospital, 1-1 Kizukisumiyoshi-cho, Nakahara-ku, Kawasaki, Kanagawa 211-8510, Japan b
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Article history: Received 16 January 2014 Received in revised form 21 March 2014 Accepted 22 March 2014 Keywords: Model-based iterative reconstruction Computed tomography Dose reduction CT attenuation Hepatic steatosis
a b s t r a c t Purpose: To determine whether dose-reduced CT with model-based iterative image reconstruction (MBIR) is a useful tool with which to diagnose hepatic steatosis. Materials and methods: This prospective clinical study approved by our Institutional Review Board included 103 (67 men and 36 women; mean age, 64.3 years) patients who provided written informed consent to undergo unenhanced CT. Images of reference-dose CT (RDCT) with filtered back projection (RFBP) and low- and ultralow-dose CT (dose-length product; 24 and 9% of that of RDCT) with MBIR (L-MBIR and UL-MBIR) were reconstructed. Mean CT numbers of liver (CT[L]) and spleen (CT[S]), and quotient (CT[L/S]) of CT[L] and CT[S] were calculated from selected regions of interest. Bias and limits of agreement (LOA) of CT[L] and CT[L/S] in L-MBIR and UL-MBIR (vs. R-FBP) were assessed using Bland–Altman analyses. Diagnostic methods for hepatic steatosis of CT[L] < 48 Hounsfield units (HU) and CT[L/S] < 1.1 were applied to L-MBIR and UL-MBIR using R-FBP as the reference standard. Results: Bias was larger for CT[L] in UL-MBIR than in L-MBIR (−3.18 HU vs. −1.73 HU). The LOA of CT[L/S] was larger for UL-MBIR than for L-MBIR (±0.425 vs. ±0.245) and outliers were identified in CT[L/S] of ULMBIR. Accuracy (0.92–0.95) and the area under the receiver operating characteristics curve (0.976–0.992) were high for each method, but some were slightly lower in UL-MBIR than L-MBIR. Conclusion: Dose-reduced CT reconstructed with MBIR is applicable to diagnose hepatic steatosis, however, a low dose of radiation might be preferable. © 2014 Elsevier Ireland Ltd. All rights reserved.
1. Introduction The reported prevalence of hepatic steatosis is 14–31% [1–3]. Hepatic steatosis of grafts for living donor liver transplantation increases the risk of primary non-function and delayed graft dysfunction, although macrovesicular steatosis
ARTICLE IN PRESS European Journal of Radiology xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad
Dose-reduced CT with model-based iterative reconstruction in evaluations of hepatic steatosis: How low can we go? Koichiro Yasaka a,∗ , Masaki Katsura a , Masaaki Akahane b , Jiro Sato a , Izuru Matsuda c , Kuni Ohtomo a a
Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan NTT Medical Center Tokyo, 5-9-22 Higashi-Gotanda, Shinagawa-ku, Tokyo 141-8625, Japan c Kanto Rosai Hospital, 1-1 Kizukisumiyoshi-cho, Nakahara-ku, Kawasaki, Kanagawa 211-8510, Japan b
a r t i c l e
i n f o
Article history: Received 16 January 2014 Received in revised form 21 March 2014 Accepted 22 March 2014 Keywords: Model-based iterative reconstruction Computed tomography Dose reduction CT attenuation Hepatic steatosis
a b s t r a c t Purpose: To determine whether dose-reduced CT with model-based iterative image reconstruction (MBIR) is a useful tool with which to diagnose hepatic steatosis. Materials and methods: This prospective clinical study approved by our Institutional Review Board included 103 (67 men and 36 women; mean age, 64.3 years) patients who provided written informed consent to undergo unenhanced CT. Images of reference-dose CT (RDCT) with filtered back projection (RFBP) and low- and ultralow-dose CT (dose-length product; 24 and 9% of that of RDCT) with MBIR (L-MBIR and UL-MBIR) were reconstructed. Mean CT numbers of liver (CT[L]) and spleen (CT[S]), and quotient (CT[L/S]) of CT[L] and CT[S] were calculated from selected regions of interest. Bias and limits of agreement (LOA) of CT[L] and CT[L/S] in L-MBIR and UL-MBIR (vs. R-FBP) were assessed using Bland–Altman analyses. Diagnostic methods for hepatic steatosis of CT[L] < 48 Hounsfield units (HU) and CT[L/S] < 1.1 were applied to L-MBIR and UL-MBIR using R-FBP as the reference standard. Results: Bias was larger for CT[L] in UL-MBIR than in L-MBIR (−3.18 HU vs. −1.73 HU). The LOA of CT[L/S] was larger for UL-MBIR than for L-MBIR (±0.425 vs. ±0.245) and outliers were identified in CT[L/S] of ULMBIR. Accuracy (0.92–0.95) and the area under the receiver operating characteristics curve (0.976–0.992) were high for each method, but some were slightly lower in UL-MBIR than L-MBIR. Conclusion: Dose-reduced CT reconstructed with MBIR is applicable to diagnose hepatic steatosis, however, a low dose of radiation might be preferable. © 2014 Elsevier Ireland Ltd. All rights reserved.
1. Introduction The reported prevalence of hepatic steatosis is 14–31% [1–3]. Hepatic steatosis of grafts for living donor liver transplantation increases the risk of primary non-function and delayed graft dysfunction, although macrovesicular steatosis
