Interactive 3D segmentation of MRI and CT volumes using morphological operations.

Analysis of tomographic volume imagery would be greatly facilitated if the objects within the volume could be presented in three-dimensionally (3D) rendered views. Such a capability has not been developed in large part because the problem of image segmentation remains unsolved. We describe a new approach that circumvents this problem by allowing the human user to segment images interactively using morphology functions. This segmentation is performed concurrently with 3D visualization providing direct visual feedback to guide the user in the segmentation process. Thus, rather than attempting to duplicate the complex and poorly understood human pattern recognition capability, our approach uses the human's own judgment and knowledge. We present a research study to demonstrate the general feasibility of this approach using MR and CT images. The massive data and computational requirements for interactive 3D image processing exceed current processor limits, but the increased capacities of the next generation of computers are expected to make this approach practical.

Application of a connected-voxel algorithm to MR angiographic data.

A connected-voxel algorithm (CVA) that improves the contrast and conspicuity of blood vessels in maximum-intensity-projection (MIP) magnetic resonance (MR) angiography is described. Images from a variety of anatomic regions in healthy volunteers were calculated with either an MIP procedure alone or with data that had first been processed with the CVA. A low-signal-intensity threshold is first applied to separate groups of voxels associated with different vessels from one another and to eliminate the contribution from low-intensity stationary material. The remaining voxels are grouped by a connectivity criterion into discrete "objects." Vessels are represented by extended objects, and small objects are discarded. The CVA, therefore, reduces the full three-dimensional data set into a small number of discrete objects. It is a powerful technique that can be used to remove signal from vessels overlying the vessel of interest, to separate objects representing arterial flow from those representing venous flow, to eliminate flow artifact from projection images, and to more completely retain signal within the vascular lumen. This technique has been successfully demonstrated with MR angiography in healthy volunteers.

Bundling--new products, new markets, low risk.

It has long been a marketing axiom that customers buy bundles of satisfaction, not products. It follows, then, that they'll respond to certain combinations of products and services--air conditioners with free installation, combinations of software packages, or season tickets with parking privileges. The difficulty is in devising the bundles that both appeal to consumers and give cost or demand enhancing benefits to the producer. Eppen, Hanson, and Martin argue that the best approach is to treat bundles not as marketing gimmicks but as new products. They offer seven guidelines for creating competitive bundles and a framework for implementing them.