Arun P. Tirumalai

Method and apparatus for generating large compound ultrasound image

An image registration method and apparatus is provided in which consecutive ultrasonic image frames are correlated in order to derive transducer motion information. Since ultrasonic images from real-time scanning operations are highly correlated from one frame to another, the individual images can be divided into several smaller sub-image regions and a very fast and robust image motion detection algorithm utilized to measure the sub-image motion. This algorithm uses a fast adaptive coarse/fine minimum-sum-absolute-difference (MSAD) search strategy to compute an initial estimation of the local motion vectors. The initial estimation is combined with two measurement parameters by use of a fuzzy logic technique to derive a final estimation of the local motion vectors. The final local motion vectors are applied to a least-squares (L-S) process in order to estimate global image motion. Finally, a fast display technique generates compound images based on the derived global image motion.

Evidential reasoning for building environment maps

We address the problem of building a map of the environment utilizing sensory depth information obtained from multiple viewpoints. The desired representation of the environment is in the form of a finite-resolution three-dimensional grid of voxels. Each voxel within the grid is assigned a binary value corresponding to its occupancy state. We present an approach for multi-sensory depth information assimilation based on the Dempster-Shafer theory for evidential reasoning. This approach provides a mechanism to explicitly model ignorance which is desirable when dealing with an unknown environment. We present results obtained from this approach on a laboratory stereo sequence and contrast these with results obtained from the traditional Bayesian approach. >

New ultrasound image display with extended field of view

The narrow fields of view obtained from real-time ultrasound transducers, especially with linear array transducers, allow focused evaluation of a specific site but often without any anatomic reference. To allow medical ultrasound imaging to be used in more diverse clinical settings, we have created a new acquisition and display process that allows extended field of view (XFOV) imaging. To produce an XFOV image, extended acoustic slices are obtained by maneuvering the transducer along the body surface or inside. As the images are acquired, they are correlated, aligned, and spliced together into a long composite view, all without the use of a position sensor. This computationally intensive process involves image registration, geometric image transformation, panoramic image construction, and image display. The XFOV process executes in real-time on our programmable ultrasound processing subsystem, the programmable ultrasound image processor, which fits within an existing ultrasound system and supports native ultrasound signal and image processing.