Balazs Ruzsics MD, Presenter: Nothing to Disclose

Mulugeta Gebregziabher PhD, Abstract Co-Author: Nothing to Disclose

Heon Lee MD, PhD, Abstract Co-Author: Nothing to Disclose

Robin Brothers RT, Abstract Co-Author: Nothing to Disclose

Philip Costello MD, Abstract Co-Author: Research grant, Bracco Group Research grant, Siemens AG Research grant, General Electric Company

U. Joseph Schoepf MD, Abstract Co-Author: Speakers Bureau, Bracco Group Speakers Bureau, General Electric Company Speakers Bureau, Bayer AG Speakers Bureau, TeraRecon, Inc Medical Advisory Board, Bracco Group Medical Advisory Board, General Electric Company Medical Advisory Board, Bayer AG Research grant, Bayer AG Research grant, Bracco Group Research grant, General Electric Company Research grant, Bayer AG Research grant, Siemens AG

To compare automatic selection of the cardiac phase with the least cardiac motion for image reconstruction at coronary CT angiography (cCTA) with manual phase selection by a human observer.

Under an IRB waiver and in HIPAA compliance we analyzed data of 100 patients who had undergone contrast enhanced, retrospectively ECG-gated cCTA on a dual-source CT scanner. One experienced observer used a series of image reconstructions in 5% increments across the RR cycle on a single level to visually identify the end-systolic and end-diastolic phase with the least cardiac motion for image reconstruction. The same data sets were then reconstructed using an automatic phase finding algorithm based on a 4D weighting function of cardiac motion maps within the entire scan volume. The agreement of automated phase selection with the observer's choice and the occurrence and severity of stair-step and motion artifacts were evaluated for both reconstruction methods (t-test).

On average, the automatic phase finding algorithm determined the most suitable (i.e. with the least cardiac motion) systolic reconstruction phase at 40.11±6.29%RR compared with 40.07±5.58%RR by the human observer (p=NS). The most suitable diastolic phase was found at 72.71±7.37%RR by the automatic algorithm, compared with 76.43±6.35%RR by the observer (p<0.05). Mean disagreement between the two methods for systolic and diastolic phase selection were -0.04±7.02% and 3.73±8.1%, respectively. No statistically significant difference was found between automatically and visually determined reconstruction phases regarding motion and stair-step artifacts in either systole or diastole (p>0.05).

There is no significant difference between an automatic phase finding algorithm and visual selection by an experienced observer for determining the systolic phase with the least cardiac motion for image reconstruction at cCTA. Slight differences exist for diastole; however, these do not impact diagnostic image quality.

Automatic phase selection has good agreement with visual selection by an experienced observer, yields diagnostic results, and thus may improve cardiac CT workflow and reduce human error.

Ruzsics, B, Gebregziabher, M, Lee, H, Brothers, R, Costello, P, Schoepf, U, Automatic Cardiac Phase Selection for Image Reconstruction at Coronary CT Angiography.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6005969.html