1082 Free-breathing single-shot DENSE myocardial strain imaging using deformable registration
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Meeting abstract
1082 Free-breathing single-shot DENSE myocardial strain imaging using deformable registration Yuan Le*1, Peter Kellman1, Eric E Bennett1, Alex Lin2, Christophe Chefd'Hotel3, Christine H Lorenz3 and Han Wen1 Address: 1National Institutes of Health, Bethesda, MD, USA, 2California Institute of Technology, Pasadena, CA, USA and 3SIEMENS, Malvern, PA, USA * Corresponding author
from 11th Annual SCMR Scientific Sessions Los Angeles, CA, USA. 1–3 February 2008 Published: 22 October 2008 Journal of Cardiovascular Magnetic Resonance 2008, 10(Suppl 1):A207
doi:10.1186/1532-429X-10-S1-A207
Abstracts of the 11th Annual SCMR Scientific Sessions - 2008
Meeting abstracts – A single PDF containing all abstracts in this Supplement is available here. http://www.biomedcentral.com/content/pdf/1532-429X-10-S1-info.pdfThis abstract is available from: http://jcmr-online.com/content/10/S1/A207 © 2008 Le et al; licensee BioMed Central Ltd.
Introduction Free-breathing scans are often desirable in patients who find breath-holding difficult. We present a new approach for free-breathing myocardial strain imaging with displacement-encoding (DENSE) [1]. It acquires images with a single-shot sequence and removes respiratory motion using deformable registration.
Methods All volunteers (n = 4) were scanned on a 1.5 T Siemens Avanto scanner. A multi-slice, single-shot DENSE sequence (Fig. 1) with true-FISP readout (Fig. 2) [2,3] and FOV-selective excitation [4] was used to acquire 3 shortaxis slices in a heartbeat. Ramped flip-angles through the readout train equalized the echo amplitudes. Displacement-encoding and image acquisition were placed at endsystole and late-diastole respectively, in order to capture the accumulated wall strain of systolic contraction. Imaging parameters were true-FISP echo spacing of 2.5 ms, matrix size of 128 × 40, FOV of 512 × 120 mm with restricted excitation (equivalent to a matrix of 128 × 96 with 3/4 phase-encode FOV), slice thickness of 6–8 mm, and ECG triggering every 2 RR intervals. A data set contained 270 images of 3(slices) × 3(encoding directions) × 30(repetitions). The encoding directions were oblique and combined in-plane encoding moments of 4.0 mm/ radian with a through-slice (Z) moment of 1.0 mm/ radian. This Z moment was sufficient to suppress the unwanted DC and conjugate-echo signal in the single-
shot sequence [4,5]. Each direction was acquired in a separate heartbeat. The total scan time was 3 – 4 minutes. Image registration used a deformable algorithm [6]. The registered images produced 90 strain maps = 3(slices) × 30(repetitions). These were averaged over the repetitions to produce average strain maps for the slices. A correlation threshold was used to remove occasional images of poor registration quality due to ECG mistrigger.
Figure Time line1 of left ventricle contraction, ECG and the sequence Time line of left ventricle contraction, ECG and the sequence.
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