Kaiss Shanneik PhD, Presenter: Nothing to Disclose

Marc Kachelriess PhD, Abstract Co-Author: Nothing to Disclose

Willi A. Kalender PhD, Abstract Co-Author: Nothing to Disclose

To evaluate image quality as a function of the heart rate and compare single-segment and multi-segment image reconstruction techniques.

An anthropomorphic dynamic cardiac phantom was used to move a 100 µm tungsten sphere on realistic 3D paths. Heart rates were varied from 40 to 120 bpm. ECG-correlated data were acquired with standard cardiac protocols using a 64-slice CT scanner (Siemens Medical Solutions, Forchheim, Germany) with 0.33 s gantry rotation time. Data were reconstructed at 10% intervals throughout the R-R interval. A quality measure based on the full volume at half maximum (FVHM) of the point spread function of the moving sphere was used for numerical assessment of image quality. Single-segment reconstruction was used and for heart rates > 65 bpm additionally multi-segment reconstructions were performed. Image quality was correlated to the heart rate and the benefit of multi-segment reconstruction evaluated.

Mean image quality determined by the FVHM was better for heart rates ≤ 65 bpm with a FVHM value of 3.7 mm^3 compared to 4.2 mm^3 in heart rates > 65 bpm. However, multi-segment reconstruction slightly improved image quality at heart rates above 65 bpm (indicated by a FVHM improvement of 9 %). While for heart rates ≤ 75 bpm best image quality was found in images reconstructed at diastole, at higher heart rates it shifted to systole. There was a good overall correlation between image quality and heart rate (R=0.88, p=0.05).

The FVHM quality indicator can be used to assess the image quality and artifact content in an image. Our results show that multi-segment reconstruction yielded better image quality compared to single-slice reconstruction. Further, an improvement of image quality can be seen in systole compared to diastole but it remains to be seen if a shift from mid-diastole to systole at increased heart rate affects the diagnostic value.

W.A.K.: Consultant to Siemens Medical Solutions

Shanneik, K, Kachelriess, M, Kalender, W, Heart Rate Dependency of Image Quality Using Multi-segment Reconstruction Algorithms.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4417620.html