Heart problems may manifest themselves as subtle signs at early stages, and CT could become an important imaging modality for detecting these changes. To assess heart function, CT scanners must be fast enough to image the heart at small intervals between heartbeats. However, the development of CT scanners and protocols has focused mainly on image quality rather than on speed. Nevertheless, recent developments may put CT at the forefront of cardiac imaging, according to a review written by Dr. Lilach O. Lerman and colleagues at Mayo Clinic College of Medicine in Rochester, Minn.

Early fast CT scanners included the dynamic spatial reconstructor and the electron-beam version. Although both scanners could capture images rapidly, the increase in speed came with a loss of spatial resolution. The dynamic spatial reconstructor also demanded more computer power than was available at the time, so it became extinct. The electron-beam CT scanner was developed specifically for cardiac imaging, and it could assess many cardiac features as well as cardiac function. However, technical developments of the scanner stagnated, and only a few clinical centers have invested in one.

The newest and most popular CT imagers — helical scanners — have good spatial resolution, but the temporal resolution of many of them is insufficient for a comprehensive assessment of cardiac function. However, their popularity has spurred their development, and they soon may become suitable for evaluating all aspects of cardiac function. For instance, the first helical scanners could capture only a single slice, but now they can register 64 slices. The reviewers expect that 128- and 256-slice scanners will emerge shortly.