|A&C: MRI out-of-phase imaging. B&D: MRI in-phase imaging|
Signal decrease of the liver on B&D (in-phase images) when compared with A&C (out-of-phase images). Note innumerable Gandy-Gamna bodies in the spleen.
- Hemochromatosis = iron overload
- Primary vs. secondary hemochromatosis
- Primary: autosomal recessive genetic disorder involving increased iron absorption. This is the most common genetic disease in white population
- Secondary: nongenetic causes of iron accumulation in organs such as cirrhosis, myelodysplastic syndrome, thalassemia
- Diagnosis is made with serum ferritin level and transferrin saturation index (but low sensitivity and specificity), genetic test and biopsy. Biopsy is reference standard
- Imaging such as non-contrast CT and MRI can be used to diagnose hemochromatosis but MRI is the best method
- Iron accumulation in tissues cause local distortion of magnetic fields and spin relaxation, resulting in shortening T1, T2 and esp. T2*
- Loss of signal intensity in affected organs proportional to iron deposition
- Dual-sequence (gradient in and out of phase) is typically used
- Decreased signal intensity on in-phase images compared with out-of-phase images "opposite of hepatic steatosis"
- General MR protocols are not adequate to estimate hepatic iron concentration. Special sequences (i.e., GRE T2* with progressively longer echo times) are needed for this purpose
- Iron excess deposition may suggest etiology
- Reticuloendothelial system (i.e., liver and spleen): secondary hemochromatosis
- Parenchymal depositition pattern (i.e., liver only, possible pancreas): primary hemochromatosis or chronic anemia with insufficient erythropoiesis
- Mixed deposition pattern (atypical distribution): anemia+multiple blood transfusions
This patient has hemochromatosis secondary to cirrhosis.
Queiroz-Andrade M et al. MR imaging findings of iron overload. RadioGraphics 2009;29:1575-1589.