Longitudinal MRI and Ferritin Monitoring of Iron Overload in Chronically Transfused and Chelated Children With Sickle Cell Anemia and Thalassemia Major.

Iron overload is an ineluctable complication in chronically transfused children warranting accurate assessment to avoid related morbidity. We investigated longitudinally the relationships between ferritin levels and hepatic and cardiac T2* magnetic resonance imaging (MRI) in a cohort of chronically transfused children receiving chelation therapy. Thirty children with sickle cell anemia (SCA) and 7 with thalassemia major (TM) chelated similarly by deferasirox were analyzed. Sex ratio, age, median duration of transfusion programs (5 y; range, 2 to 14 y), median transfusion iron intake 0.54 mg/kg/d (range, 0.27 to 0.74 mg/kg/d), and median ferritin level (1550 mg/L; range, 184 to 6204 mg/L) were comparable in TM and SCA. A significant relation was found between ferritin level and transfusion iron intake (P<0.001) despite chelation therapy. Analysis of 73 hepatic T2* MRI performed yearly demonstrated severe hepatic iron overload (≥14 mg/g) in 38.3% cases and a strong relationship between serum ferritin level and liver iron content both in SCA and TM (P<0.001). Analysis of 55 cardiac T2* MRI measurements found no cardiac overload in patients with SCA. Cardiac iron overload was moderate in 4 cases and severe in 1 case of TM. In almost half the cases, ferritin trend correctly predicted hepatic iron trend, both in patients with SCA and TM but failed to predict cardiac iron trend, notably in TM patients. Despite chelation therapy, iron burden in chronically transfused patients remains a threat. Ferritin levels are associated with liver iron overload in chelated children with SCA and TM, but iron burden should be best monitored with MRI whenever the setting allows it.

The benefit of a kernel estimate based forward projection for iterative tomographic reconstruction techniques.

X-ray forward and backward projections are major steps in all iterative tomographic reconstruction techniques. To ensure the quality of the reconstruction results, the projector should fit the imaging system geometry and the x-ray physic as well as possible. In this paper, we intend to show the benefit of our proposed kernel estimate based forward projection for iterative tomographic reconstruction techniques, such as Algebraic Reconstruction Techniques (ART). The proposed projection method is independent to the volume sampling and takes into account the projection geometry (cone-beam and parallel) by simply adjusting the variable bandwidth of the kernel estimate. We show that the sample-point estimate (adaptive-bandwidth kernel estimate) based forward projection provides accurate projections and better reconstructions than the fixed bandwidth estimate based forward projection which is similar to the well known Splatting techniques.