NMR flow imaging using a composite excitation field and magnetic field gradient sequence

Patent · Tue Sep 29 00:00:00 EDT 1987

OSTI ID:5895528

Moran, P R

In a gyromagnetic resonance instrument which performs a measurement cycle in which a FID signal produced by gyromagnetic material which is subjected to a polarizing magnetic field and has a magnetic moment is detected and processed to produce an indication of the amount of magnetization. This patent describes an improvement comprising: excitation means for applying an excitation field to the gyromagnetic material at the Larmor frequency of the gyromagnetic material and at a controllable strength and phase; magnetic field gradient mean for applying a magnetic field to the gyromagnetic material which has a gradient in a controlled direction; and control means coupled to the excitation means and the magnetic field gradient means and being operable to perform a measurement cycle that produces a FID signal indicative of the motion of gyromagnetic material, the measurement cycle including: (a) applying a first excitation field pulse which tips the net magnetic moment of the gyromagnetic material away from the direction of the polarizing magnetic field; (b) applying a motion sensitizing magnetic field gradient to the gyromagnetic material which has alternating polarity with respect to the net magnetic moment of the gyromagnetic material and in which the gradient is oriented to the direction in which motion is to be measured; (c) applying a second excitation field pulse having a strength and phase which substantially restores the magnetic moment of stationary gyromagnetic material to the direction of the polarizing magnetic field.

• Assignee: Wisconsin Alumni Research Foundation, Madison, WI
• Patent Number(s): US 4697149
• OSTI ID: 5895528
• Resource Relation: Patent File Date: Filed date 9 Nov 1985
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
IMAGE TUBES
DESIGN
GYROMAGNETIC RATIO
NUCLEAR MAGNETIC RESONANCE
CONTROL SYSTEMS
ELECTROMAGNETIC PULSES
EXCITATION
IMAGE PROCESSING
LARMOR RADIUS
MAGNETIC FIELDS
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
MATERIALS
MEASURING METHODS
MOTION
SIGNALS
ELECTROMAGNETIC RADIATION
ENERGY-LEVEL TRANSITIONS
MAGNETIC RESONANCE
PHYSICAL PROPERTIES
PROCESSING
PULSES
RADIATIONS
RESONANCE
420800* - Engineering- Electronic Circuits & Devices- (-1989)