Clinical Advancements in Angiographic Imaging

phaseXact™ – Automatic Phase Cardiac Reconstruction Average Number of Cardiac CT Images Reviewed 2000 Number of Images 1500 1000 Conventional 500 0 phaseXact Reconstruction Method Figure 3: Since phaseXact only reconstructs the optimal phase, only one phase is sent to the workstation instead of 3 or more with the conventional method. This graph shows the number of images sent to the workstation and analyzed by the reading physician for 12 consecutive patients using the conventional method and using phaseXact. The advantage of phaseXact is its analytical approach to motion assessment. In contrast to the coarse method of manually evaluating phases 5% apart, phaseXact’s direct cardiac motion measurement automates a non-clinical task by allowing the computer to do what it is best at: namely, performing a large number of calculations in a very short time. This automation not only provides more precise and accurate phase selection, but it also leads to a signiﬁcantly enhanced workﬂow with the knowledge that the empirically determined optimal data set has been automatically selected. In order to determine the optimal phase, phaseXact quantiﬁes the anatomic differences between two images reconstructed at the same craniocaudal position at slightly different cardiac phases by subtracting one image from the other (Figure 1a and 1b). When the two images are subtracted, any portion of the cardiac anatomy that is stationary will overlap perfectly and subtract to zero, as with object number 4 in Figure 1c. Conversely, anatomy that moves between the two closely spaced phases will have a nonzero difference, depicted as a bright “ghost” image shown in objects 1, 2, 3, and 5 in Figure 1c. Greater motion within a structure at a given phase leads to more ghosting and results as a higher total intensity on the subtraction image (objects 1 and 5, Figure 1c). On the other hand, if the compared images are reconstructed at a phase with little motion (Figure 1d-f) the total intensity of the difference image is considerably less. Therefore, the overall intensity of the difference image at any phase provides a measure of the magnitude of motion at that phase. This process is carried out for spatial positions encompassing the entire volume and all cardiac phases in 1 msec increments after the Rpeak, yielding an entire image volume motion map (Figure 2). Each point on the map represents the cardiac motion at a given phase and spatial location. While this would be an overwhelming manual task, phaseXact completes the analysis in less than 1 minute. Once the motion map is generated, phaseXact automatically determines the phase or phases with the least amount of motion. Since the map is brightest where cardiac motion is highest and darkest where the heart motion is minimized, phaseXact chooses the darkest areas of the A B Figure 4: Case reconstructed at 70% (A) vs phaseXact at 710 msec (B). The phaseXact shows signiﬁcant clarity even over a case that is diagnostically adequate. 6 Oc tober 2 0 0 7 A public ation produced by Toshiba Medic al Sys t ems

Table of Contents Feed for the Digital Edition of Clinical Advancements in Angiographic Imaging

Contents PhaseXact™: Automatic Phase Cardiac Reconstruction Giant Internal Carotid Aneurysm Non-Contrast SSFP Time-SLIP Imaging: Renal Artery Stenosis Springhill Medical Center: A Partnership to Improve Patient Safety Anterior Cerebral Artery Aneurysm Right Coronary Artery (RCA) lesion with SUREPlaque analysis Neurovascular CTA: When every second counts

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