European Radiology

, Volume 18, Issue 2, pp 253–262 | Cite as

Validation of a raw data-based synchronization signal (kymogram) for phase-correlated cardiac image reconstruction

  • Dirk Ertel
  • Tobias Pflederer
  • Stephan Achenbach
  • Marc Kachelrieß
  • Peter Steffen
  • Willi A. Kalender


Phase-correlated reconstruction is commonly used in computed tomography (CT)-based cardiac imaging. Alternatively to the commonly used ECG, the raw data-based kymogram function can be used as a synchronization signal. We used raw data of 100 consecutive patient exams to compare the performance of kymogram function to the ECG signal. For objective validation the correlation of the ECG and the kymogram was assessed. Additionally, we performed a double-blinded comparison of ECG-based and kymogram-based phase-correlated images. The two synchronization signals showed good correlation indicated by a mean difference in the detected heart rate of negligible 0.2 bpm. The mean image quality score was 2.0 points for kymogram-correlated images and 2.3 points for ECG-correlated images, respectively (3: best; 0: worst). The kymogram and the ECG provided images adequate for diagnosis for 93 and 97 patients, respectively. For 50% of the datasets the kymogram provided an equivalent or even higher image quality compared with the ECG signal. We conclude that an acceptable image quality can be assured in most cases by the kymogram. Improvements of image quality by the kymogram function were observed in a noticeable number of cases. The kymogram can serve as a backup solution when an ECG is not available or lacking in quality.


Spiral CT Cardiac imaging ECG Kymogram Heart motion 



We are grateful to the CT division of Siemens Medical Solutions for financial support of this study. We also wish to acknowledge Katja Scholz for her assistance with the statistical analysis tools.


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Copyright information

© European Society of Radiology 2007

Authors and Affiliations

  • Dirk Ertel
    • 1
  • Tobias Pflederer
    • 2
  • Stephan Achenbach
    • 2
  • Marc Kachelrieß
    • 1
  • Peter Steffen
    • 3
  • Willi A. Kalender
    • 1
  1. 1.Institute of Medical Physics (IMP)University of Erlangen-NürnbergErlangenGermany
  2. 2.Department of Internal Medicine IIUniversity of Erlangen-NürnbergErlangenGermany
  3. 3.Multimedia Communications and Signal ProcessingUniversity of Erlangen-NürnbergErlangenGermany

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