The Short Breath-Hold Technique, Controlled Aliasing in Parallel Imaging Results in Higher Acceleration, Can Be the First Step to Overcoming a Degraded Hepatic Arterial Phase in Liver Magnetic Resonance Imaging A Prospective Randomized Control Study Jung Lim Yoo, MD, Chang Hee Lee, MD, PhD, Yang Shin Park, MD, Jeong Woo Kim, MD, Jongmee Lee, MD, Kyeong Ah Kim, MD, Hae Young Seol, MD, and Cheol Min Park, MD Objective: The aim of this study was to assess whether a short breath-hold tech- nique can improve hepatic arterial phase (HAP) image quality in gadoxetic acid– enhanced magnetic resonance (MR) imaging compared with a conventional long breath-hold technique. Materials and Methods: Institutional review board approval and patient consent were obtained for this prospective randomized control study. One hundred nine- teen patients undergoing gadoxetic acid–enhanced MR imaging were randomly assigned to groups A or B. Group A patients underwent an 18-second long breath-hold MR technique (conventional VIBE [volumetric interpolated breath- hold examination] technique with GRAPPA [generalized autocalibrating partially parallel acquisition]), and group B patients underwent a 13-second short breath- hold MR technique (VIBE technique with CAIPIRINHA [controlled aliasing in parallel imaging results in higher acceleration]). Respiratory-related graphs of the precontrast and HAP were acquired. The breath-hold degree was graded based on the standard deviation (SD) value of respiratory waveforms. Gadoxetic acid–related dyspnea was defined as when the SD value of the HAP was 200 greater than that of the precontrast phase without degraded image quality in the portal and transitional phases (SD value of the HAP - SD value of the precontrast phase). The overall image quality and motion artifacts of the precontrast and HAP images were evaluated. The groups were compared using the Student t or Fisher exact test, as appropriate. Results: The incidence of breath-holding difficulty (breath-hold grades 3 and 4) during the HAP was 43.6% (27/62) and 36.8% (21/57) for group A and B, re- spectively. The SD value during the precontrast phase and the SD value difference between the precontrast and HAP were both significantly higher in group A than in group B (P = 0.047 and P = 0.023, respectively). Gadoxetic acid–related dys- pnea was seen in 19.4% (12/62) of group A and 7.0% (4/57) of group B. Group B showed better precontrast and HAP image quality than group A (P < 0.001). De- graded HAP (overall image quality ≥4) was observed in 9.7% (6/62) and 3.5% (2/57) of group A and B, respectively. Conclusions: The short breath-hold MR technique, CAIPIRINHA, showed bet- ter HAP image quality with less degraded HAP and a lower incidence of breath- hold difficulty and gadoxetic acid–related dyspnea than the conventional long breath-hold technique. Key Words: gadoxetic acid, liver, magnetic resonance imaging, breath-hold, hepatic arterial phase, dyspnea (Invest Radiol 2016;00: 00–00) T he hepatic arterial phase (HAP) in liver magnetic resonance imag- ing (MRI) is a critical phase essential for detection and characteri- zation of focal liver lesions. 1–4 The image quality of the HAP must be optimal without artifacts to accurately diagnose focal liver lesions. Re- cently, gadoxetic acid–enhanced MRI has been widely used for liver imaging as it offers standard dynamic images as well as hepatobiliary phase images within only 20 minutes. 2,3,5–8 However, degraded HAP imaging has been more frequently reported with contrast-enhanced MRI using gadoxetic acid than with other gadolinium contrast agents. 1,6,9–11 There have been previous reports on gadoxetic acid–related acute tran- sient dyspnea that may cause respiratory motion-related artifacts in the HAP, leading to suboptimal or nondiagnostic HAP imaging. 6,9–11 Accord- ing to previous reports, the incidence of “transient severe motion” in the HAP ranges from 4.8% to 18.3%. 6,9–13 Dyspnea, whether induced by gadoxetic acid or as the result of breathlessness due to long breath- hold time, may disturb breath-holding and degrade HAP image quality. Therefore, reducing breath-hold time during the HAP may be crucial in reducing dyspnea and motion artifacts resulting in improved HAP image quality. Evaluating breath-hold degree may be important for main- taining optimal HAP image quality because poor breath-holding can cause degradation of image quality. 14 In a previous study, breath- holding difficulty was evaluated directly and objectively by assessing respiratory-related graphs, and the breath-hold degree correlated with the overall image quality and motion artifacts. 14 Therefore, evaluating the degree of breath-hold objectively and directly by analyzing respira- tory patterns may be useful for image quality analysis. To the best of our knowledge, no other study has prospectively evaluated differences in image quality and respiratory patterns between short and long breath- hold MR techniques. The purpose of this prospective randomized control study was to assess whether a short breath-hold technique can improve HAP image quality in gadoxetic acid–enhanced MRI compared with a conventional long breath-hold technique and also to objectively evaluate if shortening breath-hold time can reduce gadoxetic acid–related respiratory diffi- culty by evaluating respiratory-related graphs. MATERIALS AND METHODS This prospective observational study was approved by the in- stitutional review board. Before the investigation, the adequate sam- ple size was estimated as 128 patients using the independent z-test. We verbally explained to the patients the purpose and method of this study and emphasized that there was no additional harm in partici- pating in the study as they would receive the standard amount of Received for publication November 20, 2015; and accepted for publication, after revision, November 29, 2015. From the Department of Radiology, Korea University Guro Hospital, Korea Univer- sity College of Medicine, Seoul, South Korea. Conflicts of interest and sources of funding: Supported by a research grant from Bayer Korea Ltd (ISS#17153). The authors report no conflicts of interest. Supplemental digital contents are available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.investigativeradiology.com). Correspondence to: Chang Hee Lee, MD, PhD, Department of Radiology, Korea Uni- versity Guro Hospital, Korea University College of Medicine, 80 Guro-dong, Guro-gu, Seoul 152-703, South Korea. E-mail: chlee86@korea.ac.kr. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0020-9996/16/0000–0000 DOI: 10.1097/RLI.0000000000000249 ORIGINAL ARTICLE Investigative Radiology • Volume 00, Number 00, Month 2016 www.investigativeradiology.com 1 Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. This paper can be cited using the date of access and the unique DOI number which can be found in the footnotes.