9:45-10:00. Superimposition of EBCT Determined Coronary Calcium Deposits onto Myocardial PET Perfusion Images by Rubidium-82 and Nitrogen-13 Ammonia for Assessment of Flow Limiting Defects.

Calcium localization by Electron Beam CT (EBCT) in the coronary arteries is becoming an important non-invasive method for screening asymptomatic patients for early coronary atherosclerosis. However, the relationship between coronary artery calcium deposits and myocardial perfusion abnormalities has not been established. We have developed software to superimpose location of coronary calcium by EBCT onto PET myocardial perfusion images, so that we can determine the role of location and amount of calcium in the arteries to flow-limiting perfusion defects by PET.EBCT and PET transaxial images are each first converted to three-dimensional arrays of 1 mm voxels. The resulting two image volumes sets are displayed so that a vertical line can be drawn from the clavicle to the spine for proper rotation of the body. The rotated images are then displayed superimposed and are shifted in the vertical, horizontal, and the long axis directions to co-register the EBCT and PET images. The EBCT images are windowed for calcium Houndsfield numbers and calcium location is added to the PET images as a maximum intensity value in the image. The modified PET image volume is then translated back to the PET data format and reprocessed using cardiac analysis software such that the calcium location is superimposed on the PET myocardial perfusion images.Preliminary results of the PET-EBCT superimposition program correlate with location of coronary calcium by EBCT and PET perfusion defects following stress. This technique may be useful for identifying flow-limiting calcium deposits in the coronary arteries.

Trabeculectomy and modifications of trabeculectomy.

Seventy-four trabeculectomies have been reviewed and discussed. Intraocular pressure 20 mm Hg or lower was achieved in 74.2% at the end of six months and in 66% one year postoperatively. The influence of age and sex on postoperative maintainance of intraocular pressure has also been discussed. There was not a statistical difference in results when the sex of the patients were compared. Patients under age forty did poorly in this series as compared to patients over age forty-one. Tenonectomy and cautery to the posterior edges of the scleral flap have been beneficial. The insertion of a gel film or silastic implant under the posterior edge of the scleral flap has been studied but in too few patients to draw any valid conclusions. In general, our results have been satisfactory with very few operative or postoperative complications.