Liver fat: effect of hepatic iron deposition on evaluation with opposed-phase MR imaging.
OBJECTIVE
To retrospectively determine the effect of liver iron deposition on the evaluation of liver fat by using opposed-phase magnetic resonance (MR) imaging.


METHODS
Committee on Human Research approval was obtained, and compliance with HIPAA regulations was observed. Patient consent was waived by the committee. Thirty-eight patients with cirrhosis (30 men, eight women; mean age, 58 years; range, 34-76 years) who underwent abdominal MR imaging and had contemporaneous liver biopsy were retrospectively identified. Two radiologists independently quantified liver fat according to the relative loss of signal intensity and compared this loss on opposed-phase and in-phase T1-weighted gradient-echo images. Liver fat percentage and presence of iron deposition were independently recorded by a pathologist. Generalized linear models, which included a mixed-random effects model, were used to determine the effect of iron deposition on the Spearman correlation coefficient for relative signal intensity loss versus histopathologically determined fat percentage.


RESULTS
Liver iron deposition was found in 25 of 38 patients. Liver fat percentage (mean, 3%; range, 0%-25%) was identified histopathologically in 14 of 38 patients and in nine of 25 patients with iron deposition. For both readers, relative signal intensity loss at opposed-phase imaging was closely and significantly correlated (P < .05) with histopathologically determined liver fat percentage in patients without iron deposition (r = 0.7 for reader 1, r = 0.6 for reader 2), but no such correlation was found in patients with iron deposition (r = 0.1 for reader 1, r = -0.31 for reader 2; P > .05).


CONCLUSIONS
Signal intensity loss on in-phase images caused by the presence of liver iron is a potential pitfall in the determination of liver fat percentage at opposed-phase MR imaging in chronic liver disease.
Westphalen
Antonio C A
AC
Department of Radiology, University of California San Francisco, 505 Parnassus Ave, San Francisco, CA 94143-0628, USA.
Qayyum
Aliya
A
Yeh
Benjamin M
BM
Merriman
Raphael B
RB
Lee
Julie A
JA
Lamba
Amit
A
Lu
Ying
Y
Coakley
Fergus V
FV
D000273:Adipose Tissue / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D001707:Biopsy, Needle; D017352:Echo-Planar Imaging / Q000379:methods; D005234:Fatty Liver / Q000175:diagnosis* / Q000378:metabolism; D005260:Female; D006498:Hepatectomy; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted; D007501:Iron / Q000378:metabolism*; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008103:Liver Cirrhosis / Q000378:metabolism / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
D007501:Iron