NMR System for the non-invasive study of phosphorus metabilism
First Claim
1. An analytic apparatus for obtaining metabolism information from a living body member comprising a hollow electromagnet having an inner space for receiving the body member, said space having means providing a substantially uniform high-intensity magnetic field and containing a probe coil with which the body member is engageable when received in said space, means generating a radio-frequency signal with a carrier frequency corresponding to the nuclear magnetic resonance frequency of a metabolite in the tissue of the body member, means to repetitively apply short pulses of said radio-frequency signal to said probe coil, whereby to excite nuclear resonance responses of the metabolite, radio frequency demodulation means tuned substantially to said resonance responses, control logic means controlling the application of said radio-frequency signal pulses to said probe coil, circuit means connecting the probe coil to the demodulation means and including switch means, said switch means having transistor controlled means to greatly increase the impedance between the probe coil and the demodulation means responsive to application of said radio-frequency signal pulses, means to substantially remove said impedance after a predetermined period of application of said short pulses to the probe coil, and signal conversion means connected to the output of said demodulation means for converting the output signals of the demodulation means into a representation of the intensities versus frequency shift of the free induction decays of the respective metabolite components of the tissue.
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Abstract
A nuclear magnetic resonance analytic apparatus for obtaining tissue metabolism information from a living body member. The apparatus consists of a large high-intensity electromagnet with an inner space having a uniform magnetic field, for receiving the body member. The space has a probe coil mounted therein with which the body member is engageable. For phosphorus-31 metabolite, there is provided a 24.33 MHz RF generator connected through a control logic section and a driver unit to the probe coil via a transmitter/receiver switching unit arranged to in effect switch the probe coil from a normal connection with a demodulation circuit to the driver unit responsive to a burst of RF pulse energy applied to the switching unit by the driver unit via the control logic section by command of a computer. The control logic section controls the system so as to first apply short pulses of the RF signal to the probe coil for a predetermined excitation time period, gating-off the demodulation unit. After this excitation period, the transmitter circuit is disabled, the demodulation circuit is gated-on, and the switching unit restores the normal connection of the probe coil to the demodulation unit, allowing the free induction decay signals sensed by the probe coil to be demodulated and furnished in analog form to the computer, which converts these analog signals into representations of the intensities versus frequency shift of the respective metabolite components of the tissue. Means is provided for applying a predetermined simulated free induction decay signal to the demodulation circuit for testing the apparatus.
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Citations
14 Claims
- 1. An analytic apparatus for obtaining metabolism information from a living body member comprising a hollow electromagnet having an inner space for receiving the body member, said space having means providing a substantially uniform high-intensity magnetic field and containing a probe coil with which the body member is engageable when received in said space, means generating a radio-frequency signal with a carrier frequency corresponding to the nuclear magnetic resonance frequency of a metabolite in the tissue of the body member, means to repetitively apply short pulses of said radio-frequency signal to said probe coil, whereby to excite nuclear resonance responses of the metabolite, radio frequency demodulation means tuned substantially to said resonance responses, control logic means controlling the application of said radio-frequency signal pulses to said probe coil, circuit means connecting the probe coil to the demodulation means and including switch means, said switch means having transistor controlled means to greatly increase the impedance between the probe coil and the demodulation means responsive to application of said radio-frequency signal pulses, means to substantially remove said impedance after a predetermined period of application of said short pulses to the probe coil, and signal conversion means connected to the output of said demodulation means for converting the output signals of the demodulation means into a representation of the intensities versus frequency shift of the free induction decays of the respective metabolite components of the tissue.
Specification