Methods and systems for determining vascular bodily lumen information and guiding medical devices

Abstract

Methods and systems for determining information about a vascular bodily lumen are described. An exemplary method includes generating an electrical signal, delivering the electrical signal to a plurality of excitation elements in the vicinity of the vascular bodily lumen, measuring a responsive electrical signal from a plurality of sensing elements in response to the delivered electrical signal, and determining a lumen dimension. Specific embodiments include generating a multiple frequency electrical signal. Another embodiment includes measuring a plurality of responsive signals at a plurality of frequencies. Still other embodiments include using spatial diversity of the excitation elements. Yet other embodiments use method for calibration and de-embedding of such measurements to determine the lumen dimensions. Diagnostic devices incorporating the method are also disclosed, including guide wires, catheters and implants. The methods and systems described herein are advantageous as they do not include injecting a second fluid for the measurements.

We claim: 
     
         1 . A method for estimating electrical parameters of an electrical load network, comprising:
 providing an interconnecting network with known electrical parameters, where the interconnecting network connects one or more electrical sources, electrical measurement apparatus at the proximal end, and the electrical load network at the distal end;   measuring an electrical response via the electrical measurement apparatus for the connected electrical load network; and   de-embedding the electrical effects of the interconnecting network from the measured response to estimate the electrical parameters of the electrical load network;   wherein the interconnecting network comprises more than two ports,   wherein a number of unknown electrical parameters in the electrical load network does not exceed a number of ports of the electrical network.   
     
     
         2 . The method of  claim 1  where the electrical parameters are determined via a best fit estimate. 
     
     
         3 . The method of  claim 1  where the electrical parameters comprise a Z parameter of the load network. 
     
     
         4 . The method of  claim 1  where the electrical parameters comprise a Y parameter of the load network. 
     
     
         5 . A method to estimate electrical parameters of an electrical load network comprising:
 providing a plurality of interconnecting networks with known electrical parameters of each, where each of the interconnecting networks connect one or more electrical sources, electrical measurement apparatus at the proximal end, and the electrical load network at the distal end;   sequentially measuring a plurality of electrical responses via the measurement apparatus for the electrical load network connected distally to each of the plurality of interconnecting networks; and,   determining electrical parameters of the load network from the plurality of measurements by de-embedding the electrical effects of the corresponding interconnecting network;   wherein each of the interconnecting networks comprises more than two ports;   wherein the electrical load network comprises more than one port.   
     
     
         6 . The method of  claim 5  where the parameters of the load are determined using a best fit estimate 
     
     
         7 . The method of  claim 5  where estimated electrical parameters of the load network is a Z parameter of the load network. 
     
     
         8 . The method of  claim 5  where estimated electrical parameters of the load network is a Y parameter of the load network. 
     
     
         9 . A method for estimating electrical parameters of an electrical load network, comprising:
 providing an interconnecting network, that connects one or more electrical sources, electrical measurement apparatus at a proximal end, and the electrical load network at a distal end, wherein the interconnecting network comprises a connection of a plurality of sub-networks having predetermined initial electrical parameters;   measuring an electrical response via the electrical measurement apparatus for the connected electrical load network;   combining effects of each of the plurality of sub-networks to obtain an equivalent electrical effect of a combined interconnecting network; and,   de-embedding electrical effects of the combined interconnecting network from the measured response to estimate electrical parameters of the electrical load network,   wherein at least one of the plurality of sub-networks comprises more than two ports.