1. 1 Non-invasive measurement of the iron overload in the human body SIF 05 Catania, 09/28/2005 Mauro Marinelli, 1,2 Barbara Gianesin, 1,2 Antonella Lavagetto, 3 Martina Lamagna, 3 Eraldo Oliveri, 1,2 Giuliano Sobrero, 2 Laura Terenzani, 3 Gian Luca Forni 3 1 Physics Department, University of Genova, Genova Italy 2 National Institute of Nuclear Physics (INFN) Genova 3 Centro della Microcitemia e Anemie Congenite, Ospedali Galliera, Genova, Italy THALAS - Gr V INFN

2. 2 Problema medico Patients suffering from Cooley’s anemia (Thalassemia major) need frequent blood transfusions. Transfused red cell iron accumulates in tissues and organs with toxic effects The most common method for iron evaluation is the liver biopsy Assessment of body-iron accumulation is essential for managing therapy of iron-chelating diseases characterized by iron overload such as thalassemia, hereditary hemochromatosis, and other forms of severe anemia. "Although chemical analysis of liver biopsy samples is considered the gold standard for determining the Liver Iron Concentration …..concern has been raised that variability in the distribution of liver iron deposition exists and might lead to errors as high as 200% in assessing body iron burden by biopsy." Am J Clinical Phathology 2005; 123; 146-152

3. 3 Biosusceptometry Magnet Pickup Biosusceptometry The magnetic field flux, threaded with the pickup, is slightly modified by the diamagnetic (mainly from water) and paramagnetic (iron) properties of tissues.

4. 4 The magnetization is proportional to the iron concentration and to the applied magnetic field The magnetic moments of the iron atoms are randomly oriented when no magnetic field is applied. In the presence of the applied magnetic field the magnetic moments line up. The thermal motion keeps them from lining up entirely, but there is some net alignment. Magnetic moments

5. 5 Curie law p iron effective magnetic moment (Bohr magneton) Ferric iron (Fe 3+ ) ionp = 5.9 Ferritin-Hemosiderin ironp  4 The apparatus calibration has been verified by checking the Curie law with solutions of hexahydrate ferric chloride (FeCl 3 ·6H 2 O) Susceptibilities arise from competition between the aligning effect of the applied field and thermal vibrations.

6. 6 Iron contribution 01000200010000 ~400 normal value 400-1000 light overload 1000-2000 moderate overload > 2000 severe overload The iron contribution to the magnetic field is about 10% of the water contribution Solution 620  g Fe /cc (p=4) The magnetic field, near the surface of the spherical sample of water, is 9 ppm smaller than the field present without the sample Water Applied magnetic field

7. 7 SQUID Susceptometer R. Fisher, E. Eich, R. Engelhardt, H. C. Heinrich, M. Kessler and P. Nielsen, “The calibration problem in liver iron susceptometry, ” in Advances in biomagnetism, S.J. Williamson et al., Ed. New York, 1990, pp. 501–504.

8. 8 Susc ratti 1 The magnetic field flux, threaded with the pickup coil, is modified by the apparatus thermal expansion. It is necessary for temperature control on the milliKelvin scale to reach the required sensitivity. Twelve living rats has been measured with a smaller prototype susceptometer Magnet Pickup

9. 9 Susc ratti 2 Marinelli M. 1, Gianesin B. 1, Avignolo C. 2, Minganti V. 3, Parodi S. 4 1 Dpt. of Physics, and National Institute of Nuclear Physics (INFN) 2 Dpt. of Oncology, Biology and Genetics 3 Dpt. of Chemistry and Pharmaceutical and Alimentary Technology 4 Department of Oncology, Biology and Genetics, and National Inst. for Res. on Canc. of Genoa (IST), University of Genoa, Genoa, Italy

10. 10 (OP) (IP) (IP) (OP) (OM) (IM) Fiberglas structure Thermal shield Magnets and shield THALAS - Gr V INFN

11. 11 Biosusceptometer The magnetic field in this entire region is lower than 1.9 10 -2 T CEI EN 60601-2-3, 1997-02

12. 12 Inner magnets Outer magnets Magnet construction Magnets

13. 13 Foto magneti e pick-up Magnets Pickup

14. 14 IM-IP OM-OP IM IP I=38A rms f=234.5Hz g max ~ 1100V/m 3 IM-IP OM OP I=19A rms f=195Hz g max ~ 800 V/m 3 OM-OP

15. 15 IM-OP OM-IP OM IP OM-IP I=19A rms f=195Hz g max ~ 2600 V/m 3 OP IM IM-OP I=38A rms f=234.5Hz g max ~ 1500V/m 3

16. 16 x 0 Stretcher We average a few differences between the signals with the stretcher in and out of the sensitivity region to account for the changes of the environment magnetic properties. This body position is to scan the whole torso. Simply shifting the body allows measuring the magnetic signal of other body parts, for instance the head.

17. 17 Magnetization flux Eddy current flux Eddy Current Signal Because of the inductance of the eddy currents loops within the sample and the solution resistivity the delay of the eddy currents relative to the induced electric field is negligible. This is true also for the eddy currents induced in the human body. Magnetization signal Eddy Current signal y x

18. 18 Variando la concentrazione di NaCl in soluzione con 2l acqua deionizzata si osserva: il diamagnetismo del sale sul segnale in fase le correnti parassite sul segnale a 90 h=15cm r=7.75cm

19. 19 Phantom Small holes are evenly distributed on each of the phantom plastic slices. We poured paramagnetic powder, equivalent to 3 g of Fe 3+ and 15 g of Fe 3+, inside the holes placed in the phantom liver region. Because of ~100 nV error the minimum quantity of detectable iron inside the entire liver region of the phantom is ~130 mg of Fe 3+ or ~270 mg of iron with an effective magnetic moment of 4  B.

20. 20 x 0 V010

21. 21 V037

22. 22 Patient P002 and volunteer V005 have similar anthropometric characteristics P002 – V005

23. 23 Patient P002 after four months under iron depletive therapy P002 …therapy

24. 24 Patient P029 before and after the spleenectomy P029 …spleenectomy

25. 25 Patient P003 before and after 12 phlebotomies P003 12 phlebotomies

26. 26 Iron overload signal of iron overload: difference between the actual magnetization signal and the signal estimate of the patient, supposed depleted by the iron overload. Phantom signals

27. 27 The eddy current signal does not depend on the iron In all the patient measurements we never noticed the iron overload skewness on the eddy current signal. The concentration of iron in the tissues as free aqua ions is not significant. [ J. F. Schenck, E. A. Zimmerman, “Review Article High- field magnetic resonance imaging of brain iron: birth of a biomarker?,”N.M.R. Biomed, no. 17, pp. 433-445, 2004]

28. 28 Eddy current and magnetization signals The eddy current and magnetization signals of a person without iron overload have a similar dependence on the body size. The estimation of the signal of the patient, supposed depleted by the iron overload is strongly based on his eddy curent signal.

29. 29 P029 The expected magnetization signal from the statistical model using the eddy current signal and the other patient's data measured before the spleenectomy

30. 30 P002 Statistical Estimate

31. 31 P003 Statistical Estimate Iron overload : March 7, 2005: ~10 g May 27, 2005: ~7.5 g The iron removed by the 12 phlebotomies is 2.7g

32. 32 Measured and calculated magnetization signal of a few volunteers

33. 33 Errors

34. 34 Correlation with therapy The measured reduction of the iron overload is compared with its estimate according with the therapy.

35. 35 Correlation with serum-ferritin Correlation of the iron overloads of all 40 patients measured with their blood serum-ferritin

36. 36 Correlation with SQUID The Liver Iron Concentration (LIC) via SQUID susceptometry, on a subset of 30 patients, is compared with the LIC obtained by the susceptometer data.

37. 37 Referto

38. 38 AB C D Calibration A 1 liter B 2 liter C 3 liter D 4 liter