MRI-Based Liver Iron Content Determination at 3T in Regularly Transfused Patients by Signal Intensity Ratio Using an Alternative Analysis Approach Based on R2* Theory.
OBJECTIVE
To evaluate the feasibility of addressing liver iron content (LIC) in regularly transfused patients by MR imaging at 3 T based on the signal intensity ratio (SIR). An innovative data analysis approach was developed for this purpose.


METHODS
47 consecutive examinations of regularly transfused patients were included. In all cases, we expected high LIC levels. Patients were scanned with MRI at 3 T with multi-echo gradient echo sequences (GRE) at four different flip angles between 20° and 90° with echo times (TE) ranging from 0.9 to 9.8 ms. Spin-echo protocols were acquired to determine the LIC with a reference MRI method working at 1.5 T. 3 T GRE data were analyzed using the liver-to-muscle SIR. Since the method known for 1.5 T was not expected to be applicable for analyzing 3 T data, theoretic dependence of the SIR on the LIC was derived from the equation describing R2* signal decay. Obtained SIR values were correlated to reference LIC to get a relation for calculating LIC from SIR quantities. LIC values and their uncertainties were determined from GRE data and correlated to LIC reference values. For two LIC thresholds, the diagnostic accuracy was determined.


RESULTS
LIC was reliably determined from SIR in our patient cohort even for large LIC values. Median of LIC uncertainties was 10 %, and the diagnostic accuracy was 0.92 and 0.91, respectively.


CONCLUSIONS
Determination of even high LIC, resulting in small SIR values, is feasible at 3 T using appropriate SIR analysis.


CONCLUSIONS
• Determination of Liver Iron Concentration (LIC) based on GRE MRI at 3T is feasible even for high LIC levels using Signal Intensiy Ratios. • Relative uncertainty of LIC determined with 3T GRE MRI was below 13 % in most cases. • The patient-management relevant threshold (LIC = 80 µmol/g (4.5 mg/g)) yielded an accuracy of .92 in our cohort. • The proposed method is quick and simple, both in terms of data acquisition and analysis. Citation Format: • Wunderlich AP, Cario H, Bommer M et al. MRI-Based Liver Iron Content Determination at 3T in Regularly Transfused Patients by Signal Intensity Ratio Using an Alternative Analysis Approach Based on R2* Theory. Fortschr Röntgenstr 2016; 188: 846 - 852.
Section for experimental Radiology, Universitätsklinikum Ulm, Germany.
A P
AP
Wunderlich
Children's Hospital, Universitätsklinik Ulm, Germany.
H
H
Cario
Hematology and Oncology Dept., Alb-Fils-Clinics, Göppingen, Germany.
M
M
Bommer
Dept. for Diagnostic and Interventional Radiology, Universitätsklinikum Ulm, Germany.
M
M
Beer
Dept. for Diagnostic and Interventional Radiology, Universitätsklinikum Ulm, Germany.
S A
SA
Schmidt
Diagnostic and Interventional Radiology, Klinikum Konstanz, Konstanz, Germany.
M S
MS
Juchems
D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D001803:Blood Transfusion; D003198:Computer Simulation; D005240:Feasibility Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007501:Iron / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D008954:Models, Biological; D057054:Molecular Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013789:Thalassemia / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000628:therapy*; D016896:Treatment Outcome; D055815:Young Adult
D015415:Biomarkers; D007501:Iron