Real-time free-breathing cardiac imaging with self-calibrated through-time radial GRAPPA

Ozan Sayin, Haris Saybasili, M. Muz Zviman, Mark Griswold, Henry Halperin, Nicole Seiberlich, Daniel A. Herzka

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Purpose: Real-time free-breathing cardiac imaging with highly undersampled radial trajectories has previously been successfully demonstrated using calibrated radial generalized autocalibrating partially parallel acquisition (rGRAPPA). A self-calibrated approach for rGRAPPA is proposed that removes the need for the calibration prescan. Methods: To investigate the effect of various parameters on image quality, a comprehensive imaging study on one normal swine was performed. Root mean squared errors (RMSEs) were computed with respect to gold standard acquisitions, and several acquisition/reconstruction strategies were compared. Additionally, the method was tested on 13 human subjects, and RMSEs relative to standard through-time radial GRAPPA were computed. Results: Real-time images with high spatiotemporal resolution were obtained. Image quality was comparable to calibrated through-time rGRAPPA with endocardial and epicardial borders clearly delineated. In the swine, the average RMSE between self-calibrated and gold-standard calibrated images was 5.18 ± 0.84%. In normal human subjects, the average RMSE between self-calibrated and calibrated through-time rGRAPPA was 3.79 ± 0.64%. For lower accelerations rates (R = 6-8) image quality was similar to comparable calibrated scans though RMSE increased for higher degrees of undersampling (R = 12–16). Conclusion: Highly accelerated real-time imaging with undersampled radial trajectories without additional calibration data is feasible. Image quality was acceptable for real-time cardiac MRI applications demanding high speed. Magn Reson Med 77:250–264, 2017.

Original languageEnglish (US)
Pages (from-to)250-264
Number of pages15
JournalMagnetic resonance in medicine
Issue number1
StatePublished - Jan 1 2017


  • cardiac magnetic resonance imaging
  • non-Cartesian GRAPPA
  • parallel imaging
  • real-time imaging
  • self-calibration

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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