Diagnostic accuracy of dual-echo (in- and opposed-phase) T1-weighted gradient recalled echo for detection and grading of hepatic iron using quantitative and visual assessment.
OBJECTIVE
Detection and quantification of hepatic iron with dual-echo gradient recalled echo (GRE) has been proposed as a rapid alternative to other magnetic resonance imaging (MRI) techniques. Co-existing steatosis and T1 weighting are limitations. This study assesses the accuracy of routine dual-echo GRE.


METHODS
Between 2010 and 2013, 109 consecutive patients underwent multi-echo (ME) MRI and dual-echo GRE for quantification of hepatic iron. Liver iron concentration (LIC) was calculated from ME-MRI. Relative signal intensity (RSI) and fat signal fraction (FSF) were calculated from dual-echo GRE. Four radiologists subjectively evaluated dual-echo GRE (±subtraction). Diagnostic accuracy was compared between techniques and correlated with biopsy using Fisher's exact test, Spearman correlation and regression.


RESULTS
The sensitivity of visual detection of iron ranged from 48 to 55%. Subtraction did not increase sensitivity (p < 0.001). Inter-observer variability was substantial (κ = 0.72). The specificity of visual detection of iron approached 100% with false-positive diagnoses observed using subtraction. LIC showed a higher correlation with histopathological iron grade (r = 0.94, p < 0.001) compared with RSI (r = 0.65, p = 0.02). Univariate regression showed an association between RSI and LIC (B = 0.98, p < 0.001, CI 0.73-1.23); however, the association was not significant with multi-variate regression including FSF (p = 0.28).


CONCLUSIONS
Dual-echo GRE has low sensitivity for hepatic iron. Subtraction imaging can result in false-positive diagnoses.


CONCLUSIONS
• Routine liver MRI studies cannot effectively screen patients for iron overload. • Concomitant hepatic steatosis and iron limits diagnostic accuracy of routine liver MRI. • Dual-echo GRE subtraction imaging causes false-positive diagnoses of iron overload. • Dedicated MRI techniques should be used to diagnose and quantify iron overload.
The Ottawa Hospital, The University of Ottawa, 1053 Carling Avenue; , Ottawa, Ontario, Canada, K1Y 4E9, nschieda@toh.on.ca.
Nicola
N
Schieda
Subramaniyan
S
Ramanathan
John
J
Ryan
Maneesh
M
Khanna
Vivek
V
Virmani
Leonard
L
Avruch
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017352:Echo-Planar Imaging / Q000379:methods*; D005234:Fatty Liver / Q000175:diagnosis* / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007501:Iron / Q000032:analysis*; D019190:Iron Overload / Q000175:diagnosis* / Q000378:metabolism; D008099:Liver / Q000737:chemistry* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D055815:Young Adult
D007501:Iron