Single-photon emission tomography with a 12-pinhole collimator.

To assess the advantages of more complete angular sampling and of more views in the tomographic reconstruction process, tomographic imaging with a 12-pinhole (12PH) collimator has been compared with 7-pinhole tomography (7PH). The 12PH system gives a 50% increase in sensitivity but resolution degrades more rapidly with depth. The 7PH and 12PH systems provide similar accuracy of detection of lesions in a myocardial ring phantom. The 7PH images, however, demonstrated more noise and "ripple" artifacts. The 12PH system offers a larger reconstruction volume and generates fewer artifacts when the collimator is misaligned with the myocardial long-axis, thus making patient positioning less critical than with 7PH. A disadvantage is that individual views are minified by the 12PH collimator, and a 256 X 256 image matrix should be used during image acquisition to limit digital sampling errors.