Abstract: System and method for actively canceling the acoustic noise generated by changes in the electric current within the gradient coils of a magnetic resonance imager based on the finding that the acoustic noise in the magnetic resonance imager is highly periodic but that the period of the magnetic resonance imager noise changes substantially during a scan. The acoustic noise signal is measured at the ears of a patient undergoing a magnetic resonance imaging, delayed by a variable number of samples and the resulting signal is subtracted from the acoustic noise signal. Magnetic resonance imaging noise cancellation occurs at the level of 20 decibels or more.

Abstract: The present invention is directed to a scanning system that uses uniform rotary motion of an optical reflector to create reciprocal linear scanning. The system converts uniform rotation into uniform longitudinal scanning. The system thereby creates mechanical reciprocal linear scanning free of reciprocally moving mechanical parts common in conventional scanning systems. In a preferred embodiment of the invention, the scanning system is incorporated within an imaging catheter for medical scanning. The optical reflector is rotatable and includes a spiral reflecting portion. The spiral reflecting portion may be a single uniform reflecting surface or may include several reflection surfaces arranged in a spiral configuration.

Abstract: A fiber optic based probe has been designed to sample the fluorescence or phosphorescence signal from animal or human tissues, such that the light intensity is not multiply scattered. This type of measurement allows a linear detection of the concentration of the luminescent compound non-invasively from the tissue. The basic principle of the fiber probe is to use fiber optics which are smaller in diameter that the average scattering length of the tissue. In order to increase the detected signal to a stronger level, multiple fibers are used by spacing them out on the surface of the tissue so that each fiber samples an isolated section of tissue. Each fiber delivers the excitation light to the tissue, and receives the emission light from the tissue. All fibers are coupled into the same detector to integrate the overall signal. Sampling of the scattered excitation signal intensity is also done to correct for changes in the scattering coefficient between tissues.

Abstract: In some dynamic applications of MRI, only a part of the field-of-view (FOV) actually undergoes dynamic changes. A class of methods, called reduced-FOV (rFOV) methods, convert the knowledge that some part of the FOV is static or not very dynamic into an increase in temporal resolution for the dynamic part, or into a reduction in the scan time. Although cardiac imaging is an important example of an imaging situation where changes are concentrated into a fraction of the FOV, the rFOV methods developed up to now are not compatible with one of the most common cardiac sequences, the so-called retrospective cine method. The present work is a rFOV method designed to be compatible with cine imaging. An increase by a factor n in temporal resolution or a decrease by n in scan time is obtained in the case where only one nth of the FOV is dynamic (the rest being considered static). Results are presented for both Cartesian and spiral imaging.

Abstract: A method of determining the viability of a hibernating or stunned myocardial segment comprises the administration of ribose, a vasodilator and an inotropic agent. The preferred agent is dobutamine, which has both a vasodilation and an inotropic effect. The segments may be identified by myocardial imaging by any known means, such as echocardiography, Thallium-201 tracing or positron emission tomography. Ribose is preferably given one minute to three hours prior to administration of the vasodilator and inotropic agents.

Abstract: A magnetic stereotaxis system (MSS) is functionally integrated with a magnetic resonance imaging (MRI) system to provide a non-invasive, radiation-free modality for integrated MRI/MMS tracking and guiding of an interventional medical device. Shielding is provided between regions where the patient is moved so that magnetic fields from one procedure do not interfere with the function or materials used in the other procedure. A process is described where a patient is moved on a track from one procedural field to another procedural field with the shield available between different zones provides for the procedures. A computer is associated with the system to supervise performance of a variety of functions and procedures within the surgical environment.