Measurement of liver iron overload: noninvasive calibration of MRI-R2* by magnetic iron detector susceptometer.

An accurate assessment of body iron accumulation is essential for the diagnosis and therapy of iron overload in diseases such as thalassemia or hemochromatosis. Magnetic iron detector susceptometry and MRI are noninvasive techniques capable of detecting iron overload in the liver. Although the transverse relaxation rate measured by MRI can be correlated with the presence of iron, a calibration step is needed to obtain the liver iron concentration. Magnetic iron detector provides an evaluation of the iron overload in the whole liver. In this article, we describe a retrospective observational study comparing magnetic iron detector and MRI examinations performed on the same group of 97 patients with transfusional or congenital iron overload. A biopsy-free linear calibration to convert the average transverse relaxation rate in iron overload (R(2) = 0.72), or in liver iron concentration evaluated in wet tissue (R(2) = 0.68), is presented. This article also compares liver iron concentrations calculated in dry tissue using MRI and the existing biopsy calibration with liver iron concentrations evaluated in wet tissue by magnetic iron detector to obtain an estimate of the wet-to-dry conversion factor of 6.7 ± 0.8 (95% confidence level).

Total iron-overload measurement in the human liver region by the magnetic iron detector.

An accurate assessment of body iron accumulation is essential for the diagnosis and therapy of iron overload in diseases, such as hemochromatosis, thalassemia and other forms of severe anemias. The magnetic iron detector (MID) is a room-temperature susceptometer, which measures the total iron overload in the liver. Since February 2005, about 600 patients have been assessed using this device. The iron overload is obtained by calculating the difference between the measured magnetization signal of the patient and the patient's background signal. The latter is the magnetization signal that the patient would generate with normal iron content. This study presents the method for calculating the background signal of healthy volunteers and the application of the same method to patients with iron burden in order to evaluate their overload. The present MID sensitivity is 0.8 g and the reproducibility of the iron overload measurement of the same patients is lower than 0.5 g. The MID does not require calibration with liver biopsies. We correlated the MID measurements with the results of 26 biopsies (R = 0.62), 64 superconducting quantum interference device susceptometer measurements (R = 0.79), 666 serum ferritin concentration measurements (R = 0.72), and 41 MRI- R2* measurements (R = 0.71).

Haemopoietic growth factors in myelodysplastic syndromes: towards patient-oriented therapy?

Recombinant human erythropoietin (r-EPO) has been used in Myelodysplastic Syndrome (MDS) patients with anaemia since the early nineties. In low-risk MDS patients, other haemopoietic growth factors (HGFs) (granulocyte-colony stimulating factor, G-CSF, granulocyte-macrophage-colony stimulating factor, GM-CSF, and interleukin 3, IL-3) have been used to synergise the effects of r-EPO on erythroid growth and to increase neutrophil count in patients with severe neutropenia. In high-risk MDS, or in patients with post-MDS AML, myeloid HGFs have been used to push blasts into the S-phase, thus increasing their sensitivity to antiblastic drugs. Several trials have shown that r-EPO can increase haemoglobin levels and improve QoL in patients with anaemia associated to MDS. The selection of patients with a high probability of response to HGFs is based on the careful consideration of several clinical and biological parameters, i.e., among others, basal EPO and transfusional needs, disease duration, FAB or WHO subtypes, and IPSS score. Treatment of anaemic MDS patients with HGFs should become "patient oriented" and different types, schedules, and duration of treatment have to be designed according to the specific criteria which most likely predict, for each individual patient, the best chance of responding favourably to therapy.