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Influence of the analysis technique on estimating hepatic iron content using MRI
Author(s) -
Ibrahim ElSayed H.,
Khalifa Ayman M.,
Eldaly Ahmed K.
Publication year - 2016
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.25317
Subject(s) - range (aeronautics) , nuclear medicine , exponential function , mathematics , content (measure theory) , analytical chemistry (journal) , biomedical engineering , statistics , nuclear magnetic resonance , materials science , physics , medicine , chemistry , mathematical analysis , chromatography , composite material
Purpose To investigate the effect of the analysis technique on estimating hepatic iron content using MRI. Materials and Methods We evaluated the influences of single‐exponential (EXP), bi‐exponential (BEXP), and exponential‐plus‐constant (CEXP) models; and pixel‐wise (MAP), average (AVG), and median (MED) signal calculation methods on T2* measurement using numerical simulations, calibrated phantoms, and nine patients scanned on 3 Tesla MRI, based on regression, correlation, and t‐test statistical analysis. Results The T2* measurement error varied from 9 to 51% in the numerical simulations (T2*: 5–20 ms), depending on signal‐to‐noise ratio (SNR; range: 8–233) with significant ( P < 0.05) difference between actual and predicted values. The MAP method performed well (error < 10%) at high SNR (>100), but resulted in severe estimation errors at low SNR (<50). The EXP model resulted in significant measurement differences ( P < 0.05) compared with all other methods, irrespective of SNR. In vivo T2* values ranged from 3.1 to 53.6 ms, depending on the amount of iron overload and implemented analysis method. The BEXP (range: 3.7–50 ms) and CEXP (range: 3.8–53.6 ms) models, and the AVG (range: 3.2–38.8 ms) and MED (range: 3.1–38.5 ms) methods provided more accurate measurements than the EXP model (range: 3.1–18.3 ms) and MAP (range: 3.8–53.6 ms) method, respectively ( P < 0.05). The BEXP and CEXP models provided very similar measurements ( P > 0.87). Similarly, the AVG and MED methods provided very similar results ( P > 0.97), with slightly better performance of the AVG method. Conclusion Different analysis techniques show different performances based on the fitting model and signal calculation method. Based on this study, the CEXP model and AVG method are recommended due to simpler implementation and less influence by the selected analysis region. J. Magn. Reson. Imaging 2016;44:1448–1455.