title: An in vitro and in vivo analysis of the correlation between susceptibility-weighted imaging phase values and R2* in cirrhotic livers.
abstract: OBJECTIVE
  To establish a baseline of susceptibility-weighted imaging (SWI) phase value as a means of detecting iron abnormalities in cirrhotic liver and to analyze its relationship with R2*.
  
  
  METHODS
  Sixteen MnCl(2) phantoms, thirty-seven healthy individuals and 87 cirrhotic patients were performed SWI and multi-echo T2*-weighted imaging, and the signal processing in NMR (SPIN) software was used to measure the radian on SWI phase images and the R2* on T2* maps. The mean minus two times standard deviation (SD) of Siemens Phase Unit (SPU) in healthy individuals was designated as a threshold to separate the regions of interest (ROIs) into high- and low-iron areas in healthy participants and cirrhotic patients. The SWI phase values of high-iron areas were calculated. The R2* values was measured in the same ROI in both healthy participants and patients.
  
  
  RESULTS
  SWI phase values correlated linearly with R2* values in cases of MnCl(2) concentrations lower than 2.3 mM in vitro (r = -0.996, P<0.001). The mean value and SD of 37 healthy participants were 2003 and 15 (SPU), respectively. A threshold of 1973 SPU (-0.115 radians) was determined. The SWI phase value and R2* values had a negative correlation in the cirrhotic patients (r = -0.742, P<0.001). However, no similar relationship was found in the healthy individuals (r = 0.096, P = 0.576). Both SWI phase values and R2* values were found to have significant correlations with serum ferritin concentrations in 42 patients with blood samples (r = -0.512, P = 0.001 and r = 0.641, P<0.001, respectively).
  
  
  CONCLUSIONS
  SWI phase values had significant correlations with R2* after the establishment of a baseline on the phase image. SWI phase images may be used for non-invasive quantitative measurement of mild and moderate iron deposition in hepatic cirrhosis in vivo.
authors.affiliation: Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Tao
authors.forename: Jiuquan
authors.initials: J
authors.lastname: Zhang
authors.forename: Yongming
authors.initials: Y
authors.lastname: Dai
authors.forename: Zhonglan
authors.initials: Z
authors.lastname: You
authors.forename: Yi
authors.initials: Y
authors.lastname: Fan
authors.forename: Jinguo
authors.initials: J
authors.lastname: Cui
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005293:Ferritins / Q000097:blood; D006801:Humans; D007501:Iron / Q000378:metabolism; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008103:Liver Cirrhosis / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D055815:Young Adult
chemical_list: D005293:Ferritins; D007501:Iron