Intraluminal, intracavity, intravascular, and intracardiac treatments and diagnosis of medical conditions utilizing minimally invasive procedures are effective tools in many areas of medical practice. These procedures are typically performed using imaging and treatment catheters that are inserted percutaneously into the body and into an accessible vessel of the vascular system at a site remote from the vessel or organ to be diagnosed and/or treated, such as the femoral artery. The catheter is then advanced through the vessels of the vascular system to the region of the body to be treated. The catheter may be equipped with an imaging device, typically an ultrasound imaging device, which is used to locate and diagnose a diseased portion of the body, such as a stenosed region of an artery. For example, U.S. Pat. No. 5,368,035, issued to Hamm et al., the disclosure of which is incorporated herein by reference, describes a catheter having an intravascular ultrasound imaging transducer.
FIG. 1a shows an example of an imaging transducer assembly 1 known in the art. The imaging transducer 1 is typically within the lumen 10 of a guidewire (partially shown), having an outer tubular wall member 5. To obtain an image of a blood vessel, the imaging transducer assembly 1 may be inserted into the vessel. The transducer assembly 1 may then rotate while simultaneously emitting energy pulses, e.g., ultrasound waves, at portions of the vessel from within the vessel and receiving echo or reflected signals.
Turning to FIG. 1b, it is known in the art that an imaging console 20 having a display screen, a processor and associated graphics hardware (not shown) may be coupled with the imaging transducer assembly 1 to form a medical imaging system 30. The imaging console 20 processes the received echo signals from the imaging transducer assembly 1 and forms images of the area being imaged. To form the images, the imaging console 20 draws multiple lines, known as “radial lines”, (not shown) on the display screen that each correspond to an angular position of the transducer assembly 1. The processor of the imaging console 20 assigns brightness values to pixels of the lines based on magnitude levels of the echo signals received from the transducer assembly 1 at the angular positions corresponding to the lines. A drawing that includes a large number of these radial lines results in an image such as an intravascular ultrasound (IVUS) image (not shown). Such an image may show, among other things, the texture of the area being imaged, such as the smoothness or the roughness of the surface of the area being imaged.
An example of an image 70 having a large range of magnitudes and a number of texturally distinct regions 80 is shown in FIG. 1c. Texture and the correct discrimination of the underlying surface are important in medical imaging. Such information is helpful to radiologists and other clinicians who seek to diagnose pathology. It is often the case in medical imagery that an abnormality is detectable only as a subtle variation in texture. Accordingly, an improved system and method for detecting and presenting such textural information would be desirable.