Liver Iron Measurement by Magnetic Susceptometry

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Transcript of Liver Iron Measurement by Magnetic Susceptometry

  • *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


  • *Theory of Magnetic SusceptometryFlux :

    CReciprocity Theorem :

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    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