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Medical Physics

Magnetic reading

Equipment detects whether there is an excess of iron in the liver of people who have many blood transfusions

After more than five years of studies, researchers from the University of São Paulo (USP), in Ribeirão Preto, concluded the construction of a device capable of measuring the quantity of iron in the organism, without the need for biopsy. The analysis is done by means of the intensity of the magnetic field emitted by this chemical element, which is mainly concentrated in the liver. An excessive level in this organ, which absorbs and retains some 75% of the total of this substance in the body, can lead to the destruction of the cells, causing fibrosis, cirrhosis, etc. The heart and the spleen may also be affected.

The problems related to high concentrations of iron in the organisms are faced mainly by people who are given constant blood transfusions. This is the case of the bearers of beta thalassemia major a disturbance in the synthesizing of hemoglobin (the red blood cells) which causes iron to accumulate in the liver or also from falciform anemia and other kinds of chronic anemia. Another disease is hemochromatosis, the excessive absorption of iron ingested in food. Patients with these ailments are going to reap great benefits with the equipment.

The first is the elimination of a biopsy, an invasive and expensive surgical procedure that consists of taking out a sample of the organ for chemical analysis, through an incision. The apparatus also makes it possible to quantify precisely the iron existing in the liver, facilitating clinical control, with medicines prescribed in the right amount. According to physician Dimas Tadeu Covas, a director of the Ribeirão Preto Hemocenter, it will be particularly useful for patients who need treatment on the basis of chemical chelation substances that join up with the iron and prompt its excretion from the organism, helping to determine the period needed for the treatment.

Called biosusceptometer, the apparatus was developed, and is now installed in a space of roughly 12 square meters, at the Biomagnetism Laboratory of the Physics and Mathematics Department of USP’s School of Philosophy, Sciences and Literature (FFCLRP) in Ribeirão Preto. The apparatus has now passed through the National Ethics and Research Committee (Conep), in Brasilia, a body connected with the Ministry of Health. After approval, measurements were taken of the levels of iron in the livers of 32 healthy individuals and 42 patients with an excess of this substance in their organisms. The whole system is based on a superconducting magnetic sensor called Squid (superconducting quantum interference devices), the most sensitive detector of magnetic flux there is, which measures the concentration of magnetized elements in very small quantities.

“As the magnetic field emitted by hepatic iron is very weak (10 million times smaller than the field applied), the whole system has to be non-magnetic, to make its measurement possible. That is why in the whole space where the biosusceptometer is installed, we use wood, Formica, plastic, nothing that contains any metal”, says physicist Antônio Adilton Carneiro, the author of a thesis for a doctorate “A Superconducting AC Biosusceptometer for Quantifying Hepatic Iron”, supervised by Professor Oswaldo Baffa Filho, the coordinator of the Biomagnetism Laboratory.

Commercial scale
The idea of quantifying hepatic iron using a superconducting biosusceptometer is not original. There is already commercial equipment produced by an American company, with costs of around US$ 1 million. There are groups in the United States, in Germany and in Italy that are studying hepatic iron levels with this commercial apparatus. “We are producing similar results with technology developed in Ribeirão Preto. The cost of our equipment was about ten times lower”, says Carneiro.

The construction of the equipment generated various innovative systems, and one of them may have widespread use in other equipment that does not need magnetic fields and conducting material, like, for example, Magnetic Resonance Images. The innovation lies in the bed for positioning the patient. It makes vertical movements possible, with the assistance of a pneumatic transport mechanism that earned a patent, filed with the National Institute of Industrial Property (INPI) and funded by FAPESP’s Nucleus for Patenting and Licensing Technology (Nuplitec). The pneumatic system for the bed is made up of non-magnetic material, and it makes it possible to shift a patient with a precision of a tenth of a millimeter. Another advantage of the pneumatic mechanism is its low cost, which makes it possible for it to be produced on an industrial scale.

Although it shows advantages over apparatuses to be found around the world, the biosusceptometer developed at USP is not to be mass produced at this stage. “The costs are very high, and we would have to work with extremely specialized personnel, which would make our researches impracticable”, explains Baffa Filho. The researchers believe that a mere three units would be enough to meet the demand for these examinations in Brazil, where there are between 400 and 600 patients cataloged as needing regular blood transfusions.

The existing apparatus is going to be installed in the Ribeirão Preto Hemocenter Foundation, connected with USP’s Hospital and Clinics in the same city. This may also make it possible to measure the demand for the equipment, which should determine which places can receive a second biosusceptometer unit, since it would not be worthwhile to maintain a large number of apparatuses in different locations.

The Project
Pneumatic System in Large Dimensions for Platform Lifting (nº 02/08044-2); Modality Intellectual Property Support Program (PAPI); Coordinator Antônio Adilton Oliveira Carneiro – School of Philosophy, Sciences and Literature at USP in Ribeirão Preto; Investment R$ 6,000.00