Magnetic fluid detection method and magnetic fluid detection apparatus

A magnetic fluid detection apparatus comprising:

• an excitation device which applies a direct-current or alternating-current magnetic field for the purpose of magnetic fluid excitation to an object of measurement in which a magnetic fluid possessing magnetism is injected from the outside into a substance in which a fluid can flow;
• measuring devices which measure the variation in the magnetic field strength caused by the magnetic field applied by said excitation device in two or more places, the measurement of the variation of the magnetic field strength is of a component of the magnetic field strength that is perpendicular to the magnetic field applied, a distance between said measuring devices is set substantially equal to the size of the site in which the magnetic fluid accumulates, the measurement of the variation of the magnetic field strength at each of the two or more places being performed interlockingly with a variation in position of the magnetic field application by the excitation device;
• a differential amplifier which receives signals from the measuring devices in said two or more places and amplifies the difference signal;
• a calculating unit which receives signals from said differential amplifier and calculates the absolute value or amplitude value of the signal strength;
• and
• a display device which receives signals from said calculating unit and displays a numerical value or waveform;
• wherein site where the largest amount of said magnetic fluid has accumulated inside said substance is identified by measuring the distortion of the local magnetic field distribution caused by the fact that the specific magnetic permeability of said magnetic fluid is higher than that of the surrounding substance.

A magnetic fluid detection method comprising:

• a step in which a magnetic fluid possessing magnetism is caused to accumulate in sentinel lymph nodes from the outside;
• an excitation step in which a direct-current or alternating-current magnetic field for exciting said magnetic fluid is applied;
• a measurement step in which the variation in the magnetic field strength caused by the applied magnetic field is measured in two or more places that are proximal to each other, the measurement of the variation of the magnetic field strength is of a component of the magnetic field strength that is perpendicular to the applied magnetic field, a distance between said magnetic field strength measurement places is set substantially equal to the size of the site in which the magnetic fluid accumulates;
• an amplification step in which the difference between the signals measured in said measurement step is amplified;
• a calculation step in which the absolute value or amplitude value of the signal amplified in said amplification step is calculated;
• and
• a search step in which a search is made for portion where said calculation step shows a maximum value by interlockingly varying a position of the magnetic field application in the excitation step and the magnetic field strength measurement in the measurement step;
• wherein sentinel lymph nodes in which the magnetic fluid has accumulated are identified by measuring the distortion of the local magnetic field distribution that results from the fact that the specific magnetic permeability of said magnetic fluid is higher than that of the surrounding substance.

A magnetic fluid detection apparatus comprising:

• an excitation device which applies a direct-current or alternating-current magnetic field for magnetic fluid excitation to living-body tissues in which a magnetic fluid possessing magnetism has been injected into areas proximal to a malignant tumor;
• measuring devices which measure the variation in the magnetic field strength caused by the magnetic field applied by said excitation device in two or more places, the measurement of the variation of the magnetic field strength is of a component of the magnetic field strength that is perpendicular to the magnetic field applied, the measurement of the variation of the magnetic field strength at each of the two or more places being performed interlockingly with a variation in position of the magnetic field application by the excitation device, a distance between said measuring devices is set approximately equal to the size of the sites in which the magnetic fluid accumulates;
• a differential amplifier which receives signals from the measuring devices in said two or more places and amplifies the difference signal;
• a calculating unit which receives signals from said differential amplifier and calculates the absolute value or amplitude value of the signal strength;
• and a display device which receives signals from said calculating unit and displays a numerical value or waveform;
• wherein sentinel lymph node which is the site where the largest amount of said magnetic fluid has accumulated is identified by measuring the distortion of the local magnetic field distribution caused by the fact that the specific magnetic permeability of said magnetic fluid is higher than that of the surrounding substance.