title: The effect of simultaneous use of respiratory triggering in diffusion-weighted imaging of the liver.
abstract: OBJECTIVE
  To determine the effect of simultaneous use of respiratory triggering in hepatic diffusion-weighted imaging (DWI), we compared DWI with respiratory triggering (RT-DWI) and DWI under free breathing (FB-DWI) in terms of relative contrast between hepatic tumor and surrounding liver parenchyma, apparent diffusion coefficient (ADC) measurement, and frequency of respiratory misregistration.
  
  
  METHODS
  Thirty patients (21 men, 9 women, aged 25 to 80 years) with liver metastasis or hepatocellular carcinoma in the right hepatic lobe were examined with RT- and FB-DWI. In patients having multiple tumors, up to 3 lesions were selected by mutual agreement of 2 diagnostic radiologists. Finally, 59 nodules were selected for evaluation. Relative contrast ratio (RCR) between the lesions and surrounding parenchyma and ADC were measured in each hepatic lesion in each sequence. The differences in RCR and ADC between RT- and FB-DWI were statistically analyzed using Wilcoxon's signed rank test. The frequency of respiratory misregistration advents in each sequence was visually evaluated by the 2 diagnostic radiologists and assessed using McNemar's test.
  
  
  RESULTS
  RCRs were significantly higher in RT- than in FB-DWI (P<0.001). The difference in ADC between the 2 sequences was not significant. However, ADCs tended to be more scattered in FB- than in RT-DWI. The frequency of respiratory misregistration advents was significantly higher in FB- than in RT-DWI.
  
  
  CONCLUSIONS
  FB- was inferior to RT-DWI in both contrast between tumors and surrounding liver parenchyma and in accuracy of ADC measurement as far as the numbers of excitation in each sequence were the same. For preoperative examination of hepatic resection, RT- is more suitable than FB-DWI.
authors.affiliation: Department of Diagnostic Radiology, National Cancer Center Hospital East, Chiba, Japan. kanasu@east.ncc.go.jp
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Nasu
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Kuroki
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Sekiguchi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Nawano
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008099:Liver / Q000473:pathology*; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D012119:Respiration