*Magnetic Susceptometry

( Liver Iron Measurement )

*Liver Iron Measurement

*Liver Iron MeasurementTotal iron content in a normal adult body = 4 g

Iron content residing in liver = 1 gNormal iron concentration = Cfe = 200 g /g of liver tissue

*Liver Iron Measurement1- Liver Biopsy ( painful, highly invasive, fatal )

2- Nuclear Resonant Scattering of X-rays ( Requires high radiation dose from a short lived isotope)

3- Computed Tomography (CT)

4- Magnetic Resonance Imaging (MRI)

5- Magnetic SusceptometryDiagnosis methods

They may be able to detect iron overload but do not extend to lower levels

*Liver Iron MeasurementThis technique measures the induced paramagnetic response from iron stored in the liver to a weak external magnetic field in the region of the abdomen.

LiverExternal magnetic FieldM

SQUID DetectorB ~ 10-9 to 10-12 Tesla

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xyzField pointSource pointMagnetic susceptibility : Theory of Magnetic Susceptometry

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*Theory of Magnetic SusceptometryFlux :

CReciprocity Theorem :

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xyz

Pickup coilTheory of Magnetic Susceptometry

*Theory of Magnetic SusceptometrySusceptometry is an INVERSE problem

*Liver Iron Measurement

1- Liver 1530 cm3

2- Lung

3- Other tissuesLiverLungsModeling the human body

*Liver Iron MeasurementIn the absence of Liver iron and air into the Lungs the flux change should be due to presence of tissue.

It can be cancelled out by using a water bag between the pickup coil and the torso

Torso ModelingWater bagLiverLung

*Liver Iron Measurement

Torso Modeling~ 17 mm~ 50 mm

*Liver Iron Measurement

Water bagLiverLung

1- Homogeneous magnetizing field

2- Localized magnetizing fieldMagnetizing Field

*Liver Iron Measurement

Water bagLiverLung1- Homogeneous magnetizing field (Rubins coil)

*Liver Iron Measurement

Water bagLiverLung2- Localized magnetizing field(Small ring coil)

*Liver Iron Measurement

Water bagLiverLung

1- Second order axial gradiometer

2- First order planar gradiometer Pickup coil

*Liver Iron Measurement

Water bagLiverLung1- Second order axial gradiometer

*Liver Iron Measurement

Water bagLiverLung2- First order planar gradiometer

*Liver Iron Measurement

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