Intracavity probes and interfaces therefor for use in obtaining images and spectra of intracavity structures using high field magnetic resonance systems

摘要

An interface device (300) for interfacing an intracavity probe comprises a magnetic resonance system (10) having a receive cycle and a transmit cycle of operation, said intracavity probe having a coil loop and a pair of output cables terminating in a connector therefor for connecting said coil loop to said interface device (300), said interface device (300) comprising: (a) a connector (303) to which said intracavity probe is connectable via said connector thereof; (b) a phase shifting network (310) linked to said connector (303), said phase shifting network (310) having first and second sub-networks (320,330) to which a first and a second of said output cables are joined, respectively, when said connectors (303) of said intracavity probe and said interface device (300) are connected, each of said output cables connected at the other end thereof across a drive capacitor in said coil loop and having an electrical length of SL + n(λ/4) wherein SL is a supplemental length whose reactance is of a same magnitude as a reactance of said drive capacitor corresponding thereto, n is an odd integer and λ is a wavelength of the operating frequency of said magnetic resonance system (10); and (c) a pair of PIN diodes (33) of which a first PIN diode is connected across an output of said first sub-network (320) and a second PIN diode is connected across an output of said second sub-network (330) such that an electrical length of each of said first and said second sub-networks (320,330) from said connector of said interface device (300) to said PIN diode corresponding thereto is λ/4; wherein when said connectors (303) of said intracavity probe and said interface device (300) are connected, said phase shifting network (310) enables said coil loop (i) during said receive cycle when said PIN diodes (33) are reversed biased to be coupled through said output cables to a probe input port of said magnetic resonance system (10) thus allowing magnetic resonance signals received from each of said output cables to be constructively combined and routed to said probe input port and (ii) during said transmit cycle when said PIN diodes (33) are forward biased to be decoupled from a transmit field of said magnetic resonance system (10) via a combined electrical length of SL + n(λ/2) of each of said output cables and said sub-network (320,330) corresponding thereto (Fig. 16).