In view of recent applications in cardiovascular and functional brain imaging, this work revisits the basic performance characteristics of spiral imaging in direct comparison to echo-planar imaging (EPI) and conventional rapid gradient-echo imaging. Using both computer simulations and experiments on phantoms and human subjects at 2.9 T, the study emphasizes single-shot applications and addresses the design of a suitable trajectory, the choice of a gridding algorithm, and the sensitivity to experimental inadequacies. As a general result, the combination of a spiral trajectory with regridding of the k-space data poses no principle obstacle for high-quality imaging. On the other hand, experimental difficulties such as gradient deviations, resonance offset contributions, and concomitant field effects cause more pronounced and even less acceptable image artifacts than usually obtained for EPI. Moreover, when ignoring parallel imaging strategies that are also applicable to EPI, improvements of image quality via reduced acquisition periods are only achievable by interleaved multishot spirals because partial Fourier sampling and rectangular fields of view (FOVs) cannot be exploited for nonCartesian trajectories. Taken together, while spiral imaging may find its niche applications, most high-speed imaging needs are more easily served by EPI. ALTHOUGH SPIRAL SCANNING TRAJECTORIES have been known since the early days of rapid scan magnetic resonance imaging (MRI), spiral imaging never became a widely accepted and clinically used method. More recently, however, based on significant hardware improvements in the development of flexible gradient systems, spiral scanning has regained interest with applications in cardiovascular and functional brain imaging. Due to its ability to acquire the k-space data of a twodimensional image after only a single radio frequency (RF) excitation, single-shot spiral imaging emerges as a competing technique to echo-planar imaging (EPI).In principle, spiral trajectories offer some inherent refocusing of motion-and flow-induced phase errors (1-3) not delivered by conventional phase-and frequency-encoding gradients, that is Cartesian trajectories that scan the k-space along straight lines. Furthermore, spiral trajectories allow for an efficient and temporally flexible sampling of k-space as shorter pathways are required to cover a desired region and the data acquisition may start in the center of k-space. These advantages are counterbalanced by practical difficulties that-at least in the eyes of a typical MRI userrender spiral imaging a technical challenge that seems to be better suited for a few expert users. It is therefore the primary aim of this article to provide a comprehensive review of the basic performance characteristics of (single-shot) spiral imaging in direct comparison with EPI. Furthermore, the analysis attempts to sort out whether spiral imaging suffers problems of a principle nature other than EPI or whether existing complications represent mere difficulties that are to be overcome...