Assessment of iron distribution between liver, spleen, pancreas, bone marrow, and myocardium by means of R2 relaxometry with MRI in patients with β‐thalassemia major

Abstract

Purpose:To investigate the correlation between the degree of hepatic, splenic, pancreatic, vertebral bone marrow (VBM), and myocardial siderosis, as expressed by relaxation rate (R2 ϭ 1/T2) values, in patients with thalassemia. Materials and Methods:R2 relaxation rate values of liver, spleen, VBM, pancreas, and myocardium were estimated in 68 consecutive transfusion-dependent patients with ␤-thalassemia major and 10 healthy controls using a respiratory triggered 16-echo Carr-Purcell-Meiboom-Gill (CPMG) spin echo sequence. Results:Hepatic R2 values were significantly increased in all 68 patients; VBM, pancreatic, and myocardial R2 values were increased in 67/68, 35/47, and 47/61 patients, whereas five patients showed decreased pancreatic R2 attributed to fatty degeneration. Of the 39 nonsplenectomized patients, splenic R2 values were decreased in 30 and normal in nine patients. Hepatic R2 values correlated with splenic (r ϭ 0.63, P Ͻ 0.001), VBM (r ϭ 0.52, P Ͻ 0.001), but not with myocardial and pancreatic R2 values. Conclusion:Despite positive correlations between the degree of hepatic, splenic, and VBM siderosis, as expressed by respective R2 values, there was variability of iron distribution patterns in thalassemic patients. Unpredictable patterns of iron distribution may be seen, such as normal signal of the spleen in the presence of siderotic liver, resembling primary hemochromatosis. Fatty degeneration of the pancreas was not uncommon.

Regional and global pancreatic T*2 MRI for iron overload assessment in a large cohort of healthy subjects: Normal values and correlation with age and gender

“…The iron accumulates primarily in the liver, then in the endocrine glands and only later in the heart (1,2). Increased iron deposit is cytotoxic and may cause organ dysfunction (3).…”

Use of fat suppression in R2 relaxometry with MRI for the quantification of tissue iron overload in beta-thalassemic patients

“…Moreover, two recent studies by De Assis et al [26] and Noetzli et al [33] claim that iron deposition in pancreas follows a similar pathway with iron accumulation in cardiac muscle but occurs earlier; therefore accurate identification of iron deposition in the pancreas might serve as an early predictor of cardiac siderosis. Previous studies have found no correlation or weak correlations between pancreatic siderosis and ferritin, or between pancreatic and hepatic siderosis as expressed by any MR measurement including R 2 , R 2 * relaxometry [18][19][20][21][22][23][24] or SIR on in-phase and out-of-phase images. In accordance with these publications, we did not manage to document a statistically significant correlation between pancreatic R 2 , without fat suppression, and ferritin or hepatic R 2 .…”

“…To the best of our knowledge, no previous study has applied fat suppression in multiecho sequences for R 2 or R 2 ⁎ relaxometry for iron overloaded tissues well known to contain significant amounts of fat [18][19][20][21][22][23][24][25]. Schwenzer et al [32] have been the only group that had applied fat suppression in a multiecho gradient sequence for T2* calculation in a large cohort of 129 healthy subjects, and they found a significant correlation between hepatic T2* and ferritin (r=0.62) but no correlation between pancreatic T2* and ferritin.…”

“…Moreover, in extrahepatic tissues with iron overloaded and large amounts of fat, such as the pancreas and vertebral bone marrow, MR determination of iron cannot be representative of the degree of iron deposition due to severe fat influences. This may explain why MR measurements for pancreas and bone marrow with any method have yielded no correlation or poor correlations with indices of iron stores such as serum ferritin or hepatic siderosis so far, even in studies with large numbers of patients with iron overload pathologic conditions [18][19][20][21][22][23][24][25][26]. Recent research studies report methods of R 2 * quantification of liver iron after correction for fat [27] or allow discrimination of fat and water by separate reconstruction on opposed-phase images [28].…”

Magnetic Resonance Imaging Versus Serum Ferritin Levels in Detection of Liver and Cardiac Iron Overload in Non-Transfusion Dependent Thalassemia

“…Accordingly the existence of factors like transfusion history, chelation therapy or co-pathology has an impact on the location and extent of cardiac iron accumulation [23,24]. Therefore, it is recommended that the decision for the start and regimen of chelation therapy should be spared for older age group patients with regular transfusion, cardiac hemosiderosis or liver fibrosis [17].…”