Iron Overload Calculator (MRI)

Liver iron concentration from R2* or T2*, and myocardial iron from cardiac T2*

Liver measurement

What was measured

R2* (s⁻¹)

T2* (ms)

Liver value

s⁻¹

Field strength

Body weight, kg (optional — for total body iron)

R2* is taken from a multi-echo gradient-echo sequence; T2* = 1000 / R2*. The T2* calibration is published for 1.5 T only.

Results

Liver iron concentration (LIC)

—

mg Fe / g dry weight

Total body iron stores

—

10.6 × LIC (Angelucci 2000); a body weight turns it into grams of iron.

No R2* map? Fit T2* from the echoes

Enter the echo times and the signal intensity of a liver ROI. Echoes that have fallen into the noise are dropped before fitting.

TE, ms	Signal intensity

Noise floor (optional)

Fitted T2*

—

Heart

Mid-septal cardiac T2*, ms

Myocardial iron

—

mg Fe / g dry weight

Cardiac and liver iron do not track each other — a normal liver does not exclude cardiac loading.

Formulas

LIC from R2* (Hernando 2023)

\( \text{LIC} = a\,R2^{*} + b \)

1.5 T: a = 2.603·10⁻², b = −0.16
2.89 T: a = 1.400·10⁻², b = −0.03
3.0 T: a = 1.349·10⁻², b = −0.03

LIC from T2* at 1.5 T (Garbowski 2014)

\( \text{LIC} = 31.94\,(T2^{*})^{-1.014} \)

T2* in ms, LIC in mg Fe/g dry weight

Myocardial iron (Carpenter 2011)

\( [\text{Fe}] = 45.0\,(T2^{*})^{-1.22} \)

Multi-echo fit: S(TE) = S₀·exp(−TE/T2*), least squares on ln S

Clinical bands

LIC, mg Fe/g dry	Interpretation
< 1.8	Normal
1.8 – 3.2	Mild overload
3.2 – 7.0	Moderate overload
7.0 – 15.0	Severe overload
> 15.0	Extreme overload

Cardiac T2*, ms	Interpretation
≥ 20	No significant myocardial iron
10 – 20	Myocardial iron loading
6 – 10	Severe — relative risk of heart failure 160
< 6	Very severe — heart failure in 47 percent of patients within one year

Sources

Hernando D et al. Multicenter reproducibility of liver iron quantification with 1.5-T and 3.0-T MRI. Radiology 2023;306(2):e213256. doi:10.1148/radiol.213256
Garbowski MW et al. Biopsy-based calibration of T2* magnetic resonance for estimation of liver iron concentration and comparison with R2 Ferriscan. J Cardiovasc Magn Reson 2014;16:40. doi:10.1186/1532-429X-16-40
Wood JC et al. MRI R2 and R2* mapping accurately estimates hepatic iron concentration in transfusion-dependent thalassemia and sickle cell disease patients. Blood 2005;106(4):1460–5. doi:10.1182/blood-2004-10-3982
Reeder SB et al. Quantification of liver iron overload with MRI: review and guidelines from the ESGAR and SAR. Radiology 2023;307(1):e221856. doi:10.1148/radiol.221856
Carpenter JP et al. On T2* magnetic resonance and cardiac iron. Circulation 2011;123(14):1519–28. doi:10.1161/CIRCULATIONAHA.110.007641
Anderson LJ et al. Cardiovascular T2-star (T2*) magnetic resonance for the early diagnosis of myocardial iron overload. Eur Heart J 2001;22(23):2171–9. doi:10.1053/euhj.2001.2822
Kirk P et al. Cardiac T2* magnetic resonance for prediction of cardiac complications in thalassemia major. Circulation 2009;120(20):1961–8. doi:10.1161/CIRCULATIONAHA.109.874487
Angelucci E et al. Hepatic iron concentration and total body iron stores in thalassemia major. N Engl J Med 2000;343(5):327–31. doi:10.1056/NEJM200008033430503
Wood JC. Guidelines for quantifying iron overload. Hematology Am Soc Hematol Educ Program 2014;2014(1):210–5. doi:10.1182/asheducation-2014.1.210

A calibration belongs to the sequence it was derived from: R2* measured with a different protocol or vendor can read differently. Fat, fibrosis and motion all shift R2*.