title: Hepatic Arterial Phase in Gadoxetic Acid-Enhanced Liver Magnetic Resonance Imaging: Analysis of Respiratory Patterns and Their Effect on Image Quality.
abstract: OBJECTIVE
  The aims of this study were to objectively evaluate patient respiration and breathing change after contrast injection and to assess its potential impact on image quality for the hepatic arterial phase in gadoxetic acid-enhanced magnetic resonance imaging.
  
  
  METHODS
  This retrospective study was approved by the institutional review board, and the requirement for informed consent was waived. One hundred fifty-four patients underwent gadoxetic acid-enhanced liver magnetic resonance imaging with a 13-second breath-hold hepatic arterial phase. During the acquisition of precontrast and hepatic arterial phases, the respiratory motion signal was acquired and graded on a 4-point scale based on the SD of the respiratory waveform, with the highest grade indicating the worst breath-hold. Breath-holding grades 3 and 4 for the hepatic arterial phases were considered as breath-holding difficulty during the hepatic arterial phase. Gadoxetic acid-related dyspnea was defined as when the SD value of respiratory waveform during the hepatic arterial phase was 200 greater than that of the precontrast image. Then, the precontrast and hepatic arterial phase images were evaluated with respect to overall image quality and motion artifact using a 5-point scale, with the highest score indicating the worst image quality. In the hepatic arterial phase, the correlation between breath-holding degree and image quality parameters was evaluated using Pearson correlation. The differences in mean image quality scores between patients with and without gadoxetic acid-related dyspnea were evaluated using Student t test.
  
  
  RESULTS
  Based on the analysis of the respiratory waveforms, the incidence of breath-holding difficulty during the hepatic arterial phase was 23.4% (33/154), and the incidence of gadoxetic acid-related dyspnea was 6.5% (10/154). By image analysis, the incidence of a degraded hepatic arterial phase (overall image quality score ≥4) was 5.2% (8/154). During the hepatic arterial phase, the breath-holding degree correlated with overall image quality and motion artifacts (r = 0.564 and 0.578, respectively). Patients with gadoxetic acid-related dyspnea showed significantly worse image qualities of the hepatic arterial phase than patients without gadoxetic acid-related dyspnea (all, P < 0.001), although image qualities for the precontrast image were not statistically significant between the 2 groups (all, P > 0.05).
  
  
  CONCLUSIONS
  The objective analysis of respiratory patterns during a breath-hold is feasible and useful for evaluating gadoxetic acid-related dyspnea and its effect on image quality analysis.
authors.affiliation: From the *Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine; †Siemens Healthcare, Seoul, South Korea; ‡Oncology Application Predevelopment, Siemens Healthcare, Erlangen, Germany; and §Radiology & Interventional, Bayer HealthCare, Seoul, South Korea.
authors.forename: Yang Shin
authors.initials: YS
authors.lastname: Park
authors.forename: Chang Hee
authors.initials: CH
authors.lastname: Lee
authors.forename: Jung Lim
authors.initials: JL
authors.lastname: Yoo
authors.forename: In Seong
authors.initials: IS
authors.lastname: Kim
authors.forename: Berthold
authors.initials: B
authors.lastname: Kiefer
authors.forename: Seung Tae
authors.initials: ST
authors.lastname: Woo
authors.forename: Kyeong Ah
authors.initials: KA
authors.lastname: Kim
authors.forename: Cheol Min
authors.initials: CM
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D062485:Breath Holding / Q000187:drug effects*; D003287:Contrast Media / Q000009:adverse effects; D004417:Dyspnea / Q000139:chemically induced*; D005240:Feasibility Studies; D005260:Female; D019786:Gadolinium DTPA / Q000009:adverse effects*; D049690:History, Ancient; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008113:Liver Neoplasms / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009038:Motion; D015203:Reproducibility of Results; D015656:Respiratory Mechanics / Q000187:drug effects; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA