Agreement between manual relaxometry and semi-automated scanner-based multi-echo Dixon technique for measuring liver T2* in a pediatric and young adult population.
BACKGROUND
Commercially available 3D multi-echo Dixon (mDixon) sequences provide parametric maps of liver T2*, obviating manual curve fitting that is often required with conventional gradient recalled echo (GRE)-based multi-echo relaxometry, potentially simplifying clinical work flow.


OBJECTIVE
The purpose of our study was to compare T2* values generated by a 3D mDixon sequence to values generated by GRE-based T2* relaxometry with manual curve fitting in a pediatric and young adult population.


MATERIALS AND METHODS
We reviewed clinical MRI exams performed at 1.5T for liver iron content estimation between February 2015 and June 2016 that included both mDixon and multi-echo GRE pulse sequences. We obtained mean T2* measurements based on each sequence by drawing regions of interest on each of four axial slices through the mid-liver. We compared mDixon-based and GRE-based T2* measurements using paired t-tests and assessed agreement using single-measure intra-class correlation coefficients and Bland-Altman difference plots.


RESULTS
One hundred nine patients met inclusion criteria (site 1=82; site 2=27). Mean age was 12.4±5.8 years, and 42 subjects (39%) were female. There was no statistically significant difference in mean T2* values for the two sequences (pooled means: 11.7±11.0 [GRE] vs. 11.7±10.9 ms [mDixon]; P=0.93). There was excellent absolute agreement between sequences (intraclass correlation coefficient [ICC]=0.98 for patients at both sites, confidence interval [CI]: 0.97-0.98 with mean bias of 0.0 ms [-4.2 ms to +4.2 ms]).


CONCLUSION
3D mDixon is accurate for measuring liver T2* and can likely replace 2D GRE-based relaxometry.
['Serai|Suraj D|SD|', 'Smith|Ethan A|EA|', 'Trout|Andrew T|AT|', 'Dillman|Jonathan R|JR|']
D000293:Adolescent D000328:Adult D002648:Child D002675:Child, Preschool D005260:Female D006801:Humans D021621:Imaging, Three-Dimensional D007223:Infant D019190:Iron Overload D008099:Liver D008279:Magnetic Resonance Imaging D008297:Male D015203:Reproducibility of Results
Relaxometry Liver Iron Children Magnetic resonance imaging Multi-echo Dixon sequence T2* imaging