- Workshop presentation
- Open Access
Accelerated delayed enhancement imaging of myocardial infarction with through-time radial GRAPPA
© Sayin et al.; licensee BioMed Central Ltd. 2014
- Published: 16 January 2014
- Delayed Enhancement
- Gadopentetate Dimeglumine
- Delay Contrast Enhancement
- Radial Sampling
- Delayed Enhancement Imaging
Delayed contrast enhancement (DCE) imaging is a well-established MRI technique for the evaluation of myocardial infarction (MI) and tissue viability . Inversion-recovery (IR) is used to visualize the hyperenhanced regions of scar after injection of Gd-DTPA. Mid-diastolic segmented k-space coverage is typical, requiring several heartbeats to reconstruct an image . More recently, Cartesian single-shot trueFISP imaging, has achieved free-breathing acquisitions though spatial resolution is traded for imaging speed and multiple heartbeats may be needed to increase SNR through averaging . Alternatively, radial imaging can achieve higher degrees of acceleration, and should produce sharper images in patients with high heart-rates and with shorter or non-existent quiescent periods. We demonstrate the feasibility of IR-DCE imaging with a rapid radial sequence accelerated using through-time radial GRAPPA with and without multi-heartbeat averaging.
With ACUC approval, one swine with antero-septal MI was imaged at 1.5T (Avanto, Siemens Medical Systems, Erlangen, Germany). Images were acquired 15-25 min after administration of a single dose of gadopentetate dimeglumine. An 8-fold (R = 8) acceleration was achieved with radial sampling and 16 spokes were acquired per image, yielding a temporal footprint of 70 ms per image. Through-time radial GRAPPA  was used to reconstruct 1.56 × 1.56 mm2 resolution images. For calibration of the weights, 80 fully-sampled (128 spokes) frames were acquired prior to infusion of contrast. An ECG-triggered IR-prepared gradient-echo sequence was utilized with FOV: 200 mm, 128 × 128 matrix, slice thickness: 7.0 mm, TR: 4.4 msec, BW: 797 Hz/Px, TI: 250-350 ms. Image reconstruction utilized a remote server with multi-CPUs and a GPU,6 enabling low-latency reconstructions with real-time inline display . Short and long axis views were acquired. Images captured in single heartbeats were compared to images reconstructed after k-space averaging (8 heartbeats).
The high rates of sub-sampling enabled by through-time radial GRAPPA make DCE imaging with improved temporal resolution and spatial resolution possible, while maintaining contrast. Accelerated radial acquisitions have the potential to deliver single heart beat high-resolution DCE images without the need for breath-holds or complicated motion-correction methods.
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