Liver iron quantification by MRI (1.5 Tesla)
Type in the mean values of MR signal given by ROIs, up to three for the liver and one or two for the paraspinal muscles. Do not put decimal values, measure is not so precise !
TR / TE / PA°
T1 : GRE 120 / 4 / 90°
PD : GRE 120 / 4 / 20°
T2 : GRE 120 / 9 / 20°
T2+ : GRE 120 / 14 / 20°
T2++ : GRE 120 / 21 / 20°
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This algorithm calculates liver iron concentration (LIC) from every MR sequence and then try to select the most appropriate result. Check the different values to validate the automatic selection.
Usually the various LIC are close. However:
- in case of slight overload, 40 - 100 µmol/g, accuracy is better with the most sensitive MR sequences which are selected to give the result. Less sensitive MR sequences (T1 and PD) underestimate the overload.
- in case of moderate overload, 100 - 200 µmol/g, sensitives sequences (T2 and T2+) are saturated and underestimate the concentration. Less sensitive MR sequences (T1 and PD) are then more precise,
- in case of major overload, less sensitive sequences become also saturated when the LIC is above 300 µmol/g.
Updated: November 26, 2003