Ralf W. Bauer MD, Presenter: Research Consultant, Siemens AG Speakers Bureau, Siemens AG

Isabel Radtke BSC, Abstract Co-Author: Nothing to Disclose

Martin Uecker, Abstract Co-Author: Research collaboration, Siemens AG

Shuo Zhang MS, Abstract Co-Author: Research collaboration, Siemens AG

Kai Tobias Block, Abstract Co-Author: Employee, Siemens AG

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

Josef Matthias Kerl MD, Abstract Co-Author: Research Consultant, Siemens AG Speakers Bureau, Siemens AG

Thomas Josef Vogl MD, PhD, Abstract Co-Author: Nothing to Disclose

Maya Christina Larson, Abstract Co-Author: Nothing to Disclose

Radial k-space sampling often suffers from artifacts and low signal when aiming at high temporal resolution. We investigated the role of iterative reconstruction concerning image quality and temporal resolution of a novel TrueFISP sequence based on radial k-space sampling (rTrueFISP) for real-time functional cardiac evaluation compared to standard balanced steady-state free precision (bSSFP).

12 healthy volunteers (mean age 27 y, mean heart rate 71±10 bpm) underwent 1.5 T cardiac MRI. Single-shot short axis views (8 mm slabs, 20% gap) were acquired with a) retrospectively ECG-gated segmented bSSFP in breath-hold and b) free breathing non-ECG-synchronized rTrueFISP with sliding-window (5 subframes) or iterative image (IR) reconstruction with a temporal resolution per single image of 36 fr/s. Left ventricular functional parameters (EDV, ESV, EF) were determined according to the Simpson’s rule with bSSFP representing the reference standard. Contrast-to-noise-ratio (CNR) of myocardium/blood pool was calculated. Subjective image quality was assessed by two radiologists (1=excellent, 6=non-diagnostic).

LV functional parameters showed strong correlation (r=0.97-98; p<0.001) between bSSFP and rTrueFISP with both different ways of image reconstruction (EF: 68±6% vs. 67±6% vs 66±6%). CNR (15.2 vs. 8.5 vs. 16.4) and overall subjective image quality (1.9±0.8 vs. 1.6±0.5) significantly improved with IR compared to sliding-window rTrueFISP and was comparable to bSSFP. Foremost, artifact burden was significantly reduced.

The implementation of iterative image reconstruction in real-time free-breathing non-ECG-gated rTrueFISP imaging significantly reduces artifacts and improves overall image quality, while the accuracy of LV functional analysis in comparison with the standard ECG-gated breath-hold cine bSSFP sequences was maintained.

With improved image quality real-time cardiac MRI with radial k-space sampling took an important step for the acceptance and robustness of this novel sequence for clinical use in actual patients.

Bauer, R, Radtke, I, Uecker, M, Zhang, S, Block, K, Graf, T, Kerl, J, Vogl, T, Larson, M, True Real-Time Cardiac MRI with Radial K-Space Sampling in Free Breathing without ECG-synchronization—Improved Image Quality with Iterative Image Reconstruction.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12026589.html