Method and apparatus for making an image of a lumen or other body cavity and its surrounding tissue

Claim 3

The method of claim 1, wherein the coded line has a color code applied to indicate tissue stiffness.

Claim 4

The method of claim 1, wherein the state of mechanical stress in steps a) and b) is accomplished by expansion of a balloon in said lumen or cavity.

Claim 5

The method of claim 1 wherein the lumen or cavity comprises an artery and the transducer is inserted in the artery, and said steps a) and b) are performed at different pressures within a cycle of pressure pulsation of the artery.

Claim 6

The method of claim 1, wherein in step d) use is made of relative displacement of said echo signals from steps a) and b)in order to determine the tissue stiffness.

Claim 7

The method of claim 5, wherein the determination of tissue stiffness is made by using the displacement of a peak in an amplitude image of said echo signals.

Claim 8

The method of claim 1, wherein the tissue stiffness is determined by using decorrelation measurements.

Claim 9

Apparatus for making an image of a lumen or other body cavity and its surrounding tissue in a body comprising a transducer arranged for insertion in the lumen or cavity and for emitting ultrasound signals to be directed towards a wall of said lumen or cavity, and for collecting echo signals, and comprising processing means arranged for processing echo signals to form an image of the lumen or cavity and its surrounding tissue, and to derive information concerning the stiffness of the tissue around the lumen or cavity from the emitted and collected signals, which information can be displayed in the image that has been formed, wherein the transducer and the processing means are arranged to perform the steps comprising of: a) after insertion of the transducer in a lumen or cavity surrounded by its tissue obtaining one or more echo signals from tissue in a chosen direction, said tissue assumed to be at a given state of mechanical stress; b) obtaining one or more echo signals from said tissue in said chosen direction, after the given state of mechanical stress has changed; c) determining in a manner known per se of the extent of the cavity in said chosen direction in order to identify the lumen-tissue boundary; d) comparing the echo signals from steps a) and b) starting at the lumen-tissue boundary and for a finite depth in the tissue to obtain a parameter indicative of tissue stiffness of the inner layer of tissue in said chosen direction; e) performing the steps a) to d) for a number of directions; f) deriving and displaying the conventional echo image of the cavity or lumen and its surrounding tissue from the echo signals obtained in step a); g) presenting in the image obtained in step f) the tissue stiffness as a one-dimensional coded line along the lumen-tissue boundary.

Claim 10

Apparatus for making an image of a lumen or other body cavity and its surrounding tissue in a body comprising a transducer arranged for insertion in the lumen or cavity and for emitting ultrasound signals to be directed towards a wall of said lumen or cavity, and for collecting echo signals, and comprising processing means arranged for processing echo signals to form an image of the lumen or cavity and its surrounding tissue, and to derive information concerning the stiffness of the tissue around the lumen or cavity from the emitted and collected signals, which information can be displayed in the image that has been formed, wherein the transducer and the processing means are arranged to perform the steps comprising of: a) after insertion of the transducer in a lumen or cavity surrounded by its tissue obtaining one or more echo signals from tissue in a chosen direction, said tissue assumed to be at a given state of mechanical stress; b) obtaining one or more echo signals from said tissue in said chosen direction, after the given state of mechanical stress has changed; c) determining in a manner known per se of the extent of the cavity in said chosen direction in order to identify the lumen-tissue boundary; d) comparing the echo signals from steps a) and b) starting at the lumen-tissue boundary and for a finite depth in the tissue to obtain a parameter indicative of tissue stiffness of the inner layer of tissue in said chosen direction; e) performing the steps a) to d) for a number of directions; f) deriving and displaying the conventional echo image of the cavity or lumen and its surrounding tissue from the echo signals obtained in step a); g) presenting in the image obtained in step f) the tissue stiffness as a one-dimensional coded line along the lumen-tissue boundary.

Claim 13

A method as defined in claim 9, wherein the echo time shift information in step d) is determined by using at least two range gates.

Claim 14

A method as defined in claim 10, wherein the coded line along the lumen-tissue boundary is color coded to indicate different tissue stiffness areas.

Claim 15

A method as defined in claim 10, wherein the the tissue stiffness as a coded line along the lumen-tissue boundary.

Claim 16

A method as defined in claim 12, wherein the echo time shift information obtained in step d) is divided by the distance between the at least two range gates in order to determine the parameter indicative of tissue stiffness.