Tissue Iron Distribution Assessed by MRI in Patients with Iron Loading Anemias

Abstract

Bone marrow, spleen, liver and kidney proton transverse relaxation rates (R2), together with cardiac R2* from patients with sickle cell disease (SCD), paroxysmal nocturnal hemoglobinuria (PNH) and non-transfusion dependent thalassemia (NTDT) have been compared with a control group. Increased liver and bone marrow R2 values for the three groups of patients in comparison with the controls have been found. SCD and PNH patients also present an increased spleen R2 in comparison with the controls. The simultaneous measurement of R2 values for several tissue types by magnetic resonance imaging (MRI) has allowed the identification of iron distribution patterns in diseases associated with iron imbalance. Preferential liver iron loading is found in the highly transfused SCD patients, while the low transfused ones present a preferential iron loading of the spleen. Similar to the highly transfused SCD group, PNH patients preferentially accumulate iron in the liver. A reduced spleen iron accumulation in comparison with the liver and bone marrow loading has been found in NTDT patients, presumably related to the differential increased intestinal iron absorption. The correlation between serum ferritin and tissue R2 is moderate to good for the liver, spleen and bone marrow in SCD and PNH patients. However, serum ferritin does not correlate with NTDT liver R2, spleen R2 or heart R2*. As opposed to serum ferritin measurements, tissue R2 values are a more direct measurement of each tissue’s iron loading. This kind of determination will allow a better understanding of the different patterns of tissue iron biodistribution in diseases predisposed to tissue iron accumulation.

Iron storage in liver, bone marrow and splenic Gaucheroma reflects residual disease in type 1 Gaucher disease patients on treatment

“…Frequent blood transfusions and ineffective erythropoiesis with increased intestinal absorption of iron are the main causes of iron overload in haemoglobinopathies (Rund & Rachmilewitz, ; Hankins et al , ; Porter & Garbowski, ). Organ iron accumulation visualized with MRI in patients with these disorders showed a similar pattern of iron storage as in the current study in GD (Gutierrez et al , ; Wood et al , ). Whether multiple transfusions played a role in the GD population is uncertain, as the transfusion history was not different between GD patients with abnormal iron storage and those without.…”

1H-MRS of femoral red and yellow bone marrow fat composition and water content in healthy young men and women at 3 T

“…The spectral linewidth of RBMV increased linearly with the water content, indicating that RBM tissue induces line broadening by magnetic susceptibility effects. This can be attributed to tissue heterogeneity and/or iron deposits in RBM [21].…”

Iron quantification with susceptibility

“…However, this approach does not reflect iron concentration in the liver and other organs, and might even be misleading, as demonstrated for cardiac iron overload in patients with thalassemia . MRI‐related iron measurements in these organs seem to provide a more accurate assessment .…”

“…Severe iron overload in the human heart is considered to be a risk factor for heart diseases and is routinely assessed by MRI relaxometry , where T 2 * mapping has shown a strong positive linear correlation with heart iron concentration . A good correlation has also been observed in other organs, including the liver, spleen, kidneys, lungs and bone marrow . Only little is known about the dominant iron compounds and their distribution on a subcellular level, but there is much evidence that, in these organs, most of the iron is stored in ferritin .…”