['To compare picture archiving and communication system (PACS) image display in so-called stack mode with conventional image display, tile mode, in efficacy of analysis of three-dimensional structure on computed tomographic (CT) scans.', 'A complex three-dimensional phantom composed of 20 entangled tubes was constructed and scanned. The resultant images were transferred to a PACS for analysis. Five experienced CT radiologists were asked to unravel the tubes by identifying their ends and to perform this task in both stack and tile modes. The time taken and any errors were recorded.', 'All five radiologists performed considerably faster in stack mode than in tile mode; the speed varied by a factor of 3.2-5.7 times. The results of a paired t test showed this difference to be significant (P = .0002). Furthermore, no mistakes were made in stack mode, while two mistakes were made in tile mode.'] Does interpretation of CT scan with PACS image display in stack mode?