Skip to main content

Quantification of left ventricular ejection fraction using through-time radial GRAPPA for real-time imaging


Cardiac MRI requires a steady cardiac rhythm for ECG-gating, and multiple breath-holds to minimize respiratory artifacts. By employing a non-Cartesian parallel imaging in form of through-time radial GRAPPA [1], accelerated imaging can be performed with temporal resolutions of < 50 ms, obviating the need for gating or breath-holding. breath-holding. We tested the hypothesis that volumetric measurements in the LV obtained with the real-time method could replace traditional measurements.


A total of 31 subjects (23 patients, 8 volunteers) were scanned on a 1.5T Avanto or 1.5T Espree scanner (Siemens Medical Solutions, Erlangen, Germany) using a combined spine and abdominal receiver array with 12 to 15 channels. The gold-standard cardiac functional examination was performed in a short-axis orientation with ECG gating, requiring 12-16 breathholds with the following parameters: Cartesian bSSFP sequence, TR~31-62 ms, in plane resolution = 1.4-2.6 mm2, slice thickness = 6-8 mm, cardiac phases = 18-30. The real-time scans (26 calibration frames per slice and accelerated acquisition) were performed immediately following the gold-standard scan with no ECG gating or breath-holding: radial bSSFP sequence, TR= 2.64 ms, resolution = 2.3 mm2, slice thickness = 6-8 mm. A data acceleration factor of R=8 (16 projections for 128 x 128 matrix) was used such that the temporal resolution for real-time imaging was 42.2 ms per image. Calibration data for non-Cartesian GRAPPA reconstruction was acquired without ECG gating or breath-holds. After data collection and reconstruction, the blood volume in the left ventricle was assessed to determine the ESV, EDV, and EF for both methods.


Bland-Altman analysis [2] was used to analyze the agreement between the two methods. This showed that 30 of the 31 of the EF measurements using traditional breath-hold imaging and the real-time free breathing method were within the 95% limits of agreement. The mean difference in LVEF between the two methods was -2% (breath-hold minus real-time). All 31 measurements of EDV using both methods were within 95% limits of agreement. The mean difference in EDV between the two methods was -4ml. 30/31 measurements of ESV using both methods were within the 95% limits of agreement. The mean difference in ESV between the two methods was 2 ml. The differences in EF, EDV, and ESV are not clinically significant [3].


Our results show no significant statistical or clinical difference between volumetric analysis determined using standard breathhold cine imaging and through-time radial GRAPPA. This indicates that standard method can be replaced by the real-time imaging approach which can be used even for patients with arrhythmia or difficulty with breath-holding.


This work was funded by Case Western Reserve University/Cleveland Clinic CTSA UL1 RR024989, and NIH/NIBIB R00EB011527.

Figure 1

Bland Altman plot of agreement of ejection fractions measured by standard breath-hold technique versus real-time free-breathing technique.

Figure 2

Short axis images of the left ventricle obtained by standard breath-hold method and real-time radial GRAPPA.


  1. 1.

    Seiberlich N, et al: . MRM. 2011, 65 (2): 492-505.

    PubMed Central  Article  PubMed  Google Scholar 

  2. 2.

    Altman DG, et al: . The Statistician. 1983, 32 (3): 307-317. 10.2307/2987937.

    Article  Google Scholar 

  3. 3.

    Pattynama PM, et al: . Radiology. 1993, 187: 261-8.

    CAS  Article  PubMed  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Vidya Nadig.

Rights and permissions

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Reprints and Permissions

About this article

Cite this article

Nadig, V., Yeh, V., Gulani, V. et al. Quantification of left ventricular ejection fraction using through-time radial GRAPPA for real-time imaging. J Cardiovasc Magn Reson 15, P45 (2013).

Download citation


  • Respiratory Artifact
  • Calibration Frame
  • bSSFP Sequence
  • Breathing Method
  • Combine Spine