Paul Apfaltrer MD, Presenter: Nothing to Disclose

Harald Schoendube PhD, Abstract Co-Author: Employee, Siemens AG Stockholder, Siemens AG

U. Joseph Schoepf MD, Abstract Co-Author: Research Consultant, Bayer AG Research Grant, Bayer AG Research Consultant, Bracco Group Research Grant, Bracco Group Research Consultant, General Electric Company Research Grant, General Electric Company Research Consultant, Siemens AG Research Grant, Siemens AG

Andreas Schindler, Abstract Co-Author: Nothing to Disclose

Thomas Allmendinger, Abstract Co-Author: Employee, Siemens AG

Ullrich Ebersberger MD, Abstract Co-Author: Nothing to Disclose

Thomas G. Flohr PhD, Abstract Co-Author: Employee, Siemens AG

To evaluate the effect of a temporal resolution improvement method (TRIM) at cardiac CT on diagnostic image quality for coronary artery assessment.

The TRIM-algorithm employs an iterative approach to reconstruct images from less than 180º of projections and uses a histogram constraint to prevent the occurrence of limited-angle artifacts. This algorithm was applied in 11 obese patients (7 men, 67.2±9.8yrs) who had undergone 2nd generation dual-source cardiac CT with 120kV, 175-426mAs, and 500msec gantry rotation. All data were reconstructed with a temporal resolution of 250msec using traditional filtered-back-projection (FBP) and of 200msec using the TRIM-algorithm. Contrast attenuation and contrast-to-noise-ratio (CNR) were measured in the ascending aorta. The presence and severity of coronary motion artifacts was rated on a 4-point Likert scale (1=no motion, 4=non-diagnostic).

All scans were considered of diagnostic quality. Mean BMI was 34.2±5kg/m2. Average heart rate was 60±9bpm. Mean effective dose was 13.5±4.6mSv. When comparing FBP- and TRIM-reconstructed series, the attenuation within the ascending aorta (392±70.7 vs. 396.8±70.1HU, p>0.05) and CNR (13.2±3.2 vs. 11.7±3.1, p>0.05) were not significantly different. A total of 110 coronary segments were evaluated. All studies were deemed diagnostic; however, there was a significant (p<0.05) difference in the severity scores distribution of coronary motion artifacts between FBP (median=2.5) and TRIM (median=2.0) reconstructions.

The TRIM-algorithm evaluated here allows diagnostic imaging quality of the coronary arteries despite 500msec gantry rotation.

Possible applications include improvement of cardiac imaging on slower gantry rotation systems or mitigation of the trade-off between temporal resolution and image noise in obese patients.

Apfaltrer, P, Schoendube, H, Schoepf, U, Schindler, A, Allmendinger, T, Ebersberger, U, Flohr, T, Enhanced Temporal Resolution in Computed Tomography of the Heart Using a Novel CT Image Reconstruction Algorithm: Initial Patient Experience.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12024361.html