2. National Institute of Nuclear Physics, Genoa, Italy.
3. E.O. Ospedali Galliera, Genoa, Italy.
Background: The knowledge of liver iron overload is essential for the diagnosis and the therapy of diseases which induce systemic iron overload in the body. The liver needle biopsy is a well-known invasive method to measure liver iron concentration. The Magnetic Iron Detector (MID) susceptometer has proven to be a non-invasive apparatus capable of measuring the iron overload in the whole liver and also managing the follow-up therapy.
Methods: The iron overload is obtained by calculating the difference between the magnetization signal of the patient and his/her background signal, which is defined as the magnetization signal that the patient would generate with the basal iron content. The first order approximation of the background signal is calculated from a 3D-laser-scan of the body of the patient. A calibration with healthy volunteers is needed to obtain a model for the calculation of the background signal.
Results and Conclusions: From 2005, the MID was used by the Galliera Hospital (Genoa, Italy) and about 2000 evaluations of iron overload were carried out with this instrument. A new generation of MID was developed to substitute the former susceptometer. The project for this new apparatus was started in 2009 and the new version was installed in February 2012 at Galliera Hospital where it is currently in use. The paper describes the new generation of MID and shows how it works focusing on the improvements regarding the engineering of the apparatus, the user interface and the measurement time. Moreover, we herein report the measurement performed on a phantom, the results of the calibration with 69 healthy volunteers and the description of the model by which we calculate the background signal.
Keywords: Liver iron overload, liver iron concentration, magnetic iron detector, susceptometry