Date Published: July 18, 2016
Publisher: Springer US
Author(s): Jurgen H. Runge, Erik M. Akkerman, Marian A. Troelstra, Aart J. Nederveen, Ulrich Beuers, Jaap Stoker.
To compare three types of MRI liver iron content (LIC) measurement performed in daily clinical routine in a single center over a 6-year period.
Patients undergoing LIC MRI-scans (1.5T) at our center between January 1, 2008 and December 31, 2013 were retrospectively included. LIC was measured routinely with signal intensity ratio (SIR) and MR-relaxometry (R2 and R2*) methods. Three observers placed regions-of-interest. The success rate was the number of correctly acquired scans over the total number of scans. Interobserver agreement was assessed with intraclass correlation coefficients (ICC) and Bland–Altman analysis, correlations between LICSIR, R2, R2*, and serum values with Spearman’s rank correlation coefficient. Diagnostic accuracies of LICSIR, R2 and serum transferrin, transferrin-saturation, and ferritin compared to increased R2* (≥44 Hz) as indicator of iron overload were assessed using ROC-analysis.
LIC MRI-scans were performed in 114 subjects. SIR, R2, and R2* data were successfully acquired in 102/114 (89%), 71/114 (62%), and 112/114 (98%) measurements, with the lowest success rate for R2. The ICCs of SIR, R2, and R2* did not differ at 0.998, 0.997, and 0.999. R2 and serum ferritin had the highest diagnostic accuracies to detect elevated R2* as mark of iron overload.
SIR and R2* are preferable over R2 in terms of success rates. R2*’s shorter acquisition time and wide range of measurable LIC values favor R2* over SIR for MRI-based LIC measurement.
The online version of this article (doi:10.1007/s00261-016-0831-7) contains supplementary material, which is available to authorized users.
This study shows that for routine clinical MRI-based LIC measurements SIR and R2* are more often successful than R2. Interobserver agreement was near perfect (ICC > 0.9) for all methods. R2 and R2* methods provided relaxation rates when the SIR-threshold (>350 µmol/g) was already exceeded. This gives them an advantage over SIR in subjects with transfusional hemosiderosis (at least 55% of our population), when LIC values can easily surpass 350 µmol/g. The combination of high success rate, high interobserver agreement, ability to detect changes in LIC over a wide range of LIC values, and single breath-hold acquisition favors the R2* method for LIC measurement.