IV New Patents

4742302

NUCLEAR MAGNETIC RESONANCE IMAGING

INSTALLATION

Eric Breton, Voisins les Bretonneaux, France as- signed to Thomson-CGR

In order to generate a radiofrequency excitation signal in an installation for NMR imaging, the envelope of the radiofrequency pulse is deduced from the shape of the selected cross-section which would result from application of a radiofrequency pulse having an envelope representing the desired selected cross-section shape.

4742303

DEPTH AND REFOCUSING PULSES FOR USE WITH

INHOMOGENEOUS RADIOFREQUENCY COILS IN

NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

Max Bendall, Burbank, Queensland, Australia

In a pulsed nuclear magnetic resonance method of analysis, a series of phase cycled radiofre- quency pulses of the form 2 theta; theta( + i-x); (2 theta( + /-, + /-y))4, called a depth pulse scheme, may be applied using an irradiation coil which provides an inhomogeneous radiofrequency field across the sample volume, so that signals may only be detected from sample regions where the pulse angle theta is close to m pi/2, where m is an odd integer. However, signals from regions where theta = 3 pi/2 or 5 pi/2, if such regions ex- ist, can be eliminated by varying some of the pulses from their ideal theta of 2 theta values. The sample discrimination afforded by means of these pulse schemes may be improved by using static or pulsed magnetic field gradients or by using more than one radiofrequency coil.

4742304

MULTIPLE TUNING NMR PROBE

Mitchell D Schnall, John S Leigh, V Harihara Subramanian assigned to Phospho-Energetics Inc; Trustees of the Univ of Pennsylvani

A multiple tuning NMR probe includes a radio frequency (RF) probe tuned by means of a cir-

cuit which creates a multiple pole circuit response in the probe, each of the poles being sufficiently separated from each other as to cause resonanceof the probe at distinct frequencies. When tuning for nuclei with resonances substan- tially 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.

4742311

CIRCUIT ARRANGEMENT WITH A LOAD CONNECTED TO THE

OUTPUT OF AN AMPLIFIER ESPECIALLY FOR NMR

Zwart Alfred J Van der, Eindhoven, Nether- lands assigned to U S Philips Corporation

A circuit in which a load connected to the output of an amplifier, and in particular for the gradient coil arrangement in a nuclear magnetic resonance tomography unit. To reduce the power loss in the amplifier, especially where, as in NMR tomography, high currents must be switched in relatively short time intervals, the supply voltage for the amplifier is delivered by a dc. voltage generator the output voltage of which follows the input voltage in steps, but always remains a certain amount larger than the output voltage of the amplifier assigned to the respective input voltage.

4746865

METHOD AND SYSTEM FOR MAGNETIC RESONANCE

IMAGING

Takao Kasugai, Ootawara, Japan assigned to Kabushiki Kaisha Toshiba

A magnetic resonance imaging system has an ex- citation section, a signal collecting section, a first image processor, a maximum value detector. a threshold setting section, and a second image processor. The excitation section applies pre- determined magnetic fields to a patient to excite a magnetic resonance phenomenon therein. The signal collecting section collects magnetic resonance signals produced by the magnetic