Abstract: A subtractive time of flight technique for MR angiography and quantitative blood flow measurement. Proton spins of water in the arterial supply to a tissue or organ are inverted in a steady-state fashion by applying constant amplitude off-resonance radio frequency pulses in the presence of a constant linear magnetic field gradient to effect adiabatic fast passage transport-induced inversion of spins which move in the direction of the gradient. An angiogram is formed by subtracting an image acquired with the arterial inversion pulse from a control image acquired with no arterial inversion. By inverting the spins in a steady-state manner, no cardiac gating is necessary for imaging organs. However, cardiac gating is desirable when imaging the heart so that spins of blood passing through the coronary arteries can be inverted during systole, when most of the blood is in the left ventricle, and imaged at end diastole, when most of the blood is in the coronary arteries.

Abstract: A subtractive time of flight technique for MR angiography and quantitative blood flow measurement. Proton spins of water in the arterial supply to a tissue or organ are inverted in a steady-state fashion by applying constant amplitude off-resonance radio frequency pulses in the presence of a constant linear magnetic field gradient to effect adiabatic fast passage transport-induced inversion of spins which move in the direction of the gradient. An angiogram is formed by subtracting an image acquired with the arterial inversion pulse from a control image acquired with no arterial inversion. By inverting the spins in a steady-state manner, no cardiac gating is necessary for imaging organs. However, cardiac gating is desirable when imaging the heart so that spins of blood passing through the coronary arteries can be inverted during systole, when most of the blood is in the left ventricle, and imaged at end diastole, when most of the blood is in the coronary arteries.

Abstract: A new geometry for a radio frequency coil design in which longitudinal conductors of the coil lie on two parallel planes. The currents in the conductors of one plane run in the opposite direction to those of the other plane. For the case of discrete conductors, field maps illustrate that the homogeneity and sensitivity of the biplanar design are superior to that of a saddle coil, and when the design is optimized, the homogeneity is almost as good as that for comparable discrete cosine or birdcage coil designs. The measured B1 map of an optimized, single-tuned biplanar coil in accordance with the invention thus compares favorably to that of an equivalent discrete cosine coil and demonstrates excellent homogeneity in the central region of the coil.

Abstract: A multiple tuning NMR probe includes a radio frequency (RF) probe tuned by means of a circuit which creates a multiple pole circuit response in the probe, each of the poles being sufficiently separated from each other as to cause resonance of the probe at distinct frequencies. When tuning for nuclei with resonances substantially apart, this function may be accomplished using a parallel capacitor-inductor (L-C) trap with an impedance matching network. When tuning for nuclei with substantially closely spaced resonances, a tank circuit is used which has a single resonance which is split into two resonances by strongly coupling it to another tank circuit in resonance with the sample coil tank circuit.