Evaluation of Registration of PET Images With CT Images

We describe the evaluation of the registration of Positron Emission Tomography (PET) scans with X-ray Computed Tomography (CT) scans of the human brain. A CT scan and a PET scan of the same person were obtained with fiducial markers placed on the person\u27s head. The CT scan and the PET scan were then registered, first by using the fiducial markers, and next by applying the registration method currently under question, completely ignoring fiducial markers. In both cases, the positions of fiducial markers in PET scan and the positions of corresponding fiducial markers in CT scan were compared. The results based on aligning only one patient scans are encouraging, and in the future we hope to obtain more PET and CT scan pairs to validate the registration method

Preliminary Clinical Evaluation of Elastic Matching System

In order to evaluate the performance of our elastic matching system, we have created a digitized atlas from a young normal male brain, using 135 myelin-stained sections at 700 micron spacing. Software was written to enter and edit regional anatomic contours, which were stacked and aligned to create a 3D atlas. We then evaluated the matching system by comparing computer generated contours with expert-defined contours for several subcortical structures, based on CT scans from six neurologically normal patients. The error in positioning, as defined by the distance between the centers of gravity, averaged 4.2 mm for the computer and 1.7 mm for the worst expert\u27s reading, with the computer-drawn region frequently inscribed within that of the expert. Comparison was also made for each structure by determining the volume of overlap and the volumes not overlapping. On average, the computer\u27s agreement with the experts was about 20% less than the agreement among the experts. This was a preliminary test of the system using only subcortical structures. The results are promising, and techniques are being implemented to overcome the current deficiencies

Cube Analyzer - A Medical Image Analysis Program

The Cube Analyzer is a group of programs designed to analyze three-dimensional tomographic data such as CT, PET and MRI scans. It is designed to work on a Unix workstation running X-windows, and was programmed in C. Cube Analyzer provides the user with an interactive system by which he can view the scans, define regions of interest (ROI), and extract data. The system can be used alone to analyze images, or combined with the elastic matching software package to analyze computer-generated ROI\u27s