131 Arterial spin labeled myocardial perfusion imaging with background suppression: initial results
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BioMed Central
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Meeting abstract
131 Arterial spin labeled myocardial perfusion imaging with background suppression: initial results Zungho Zun*1, Eric C Wong2 and Krishna S Nayak1 Address: 1University of Southern California, Los Angeles, CA, USA and 2University of California, San Diego, CA, 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):A32
doi:10.1186/1532-429X-10-S1-A32
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/A32 © 2008 Zun et al; licensee BioMed Central Ltd.
Introduction The use of arterial spin labeling (ASL) for assessing myocardial perfusion has several advantages over existing techniques. ASL does not rely on contrast agents, can achieve arbitrarily high resolution, and is naturally quantitative. ASL is widely used for assessing cerebral blood flow. However, its application to myocardial blood flow has been limited [1,2]. Current subtractive methods suffer from artifacts stemming from high LV blood signal including Gibbs ringing and mis-registration. In this work, we investigate the use of background suppression (BGS) [3,4] in the context of ASL cardiac perfusion imaging using flow-sensitive alternating inversion recovery (FAIR) [5].
Methods Experiments were performed in five healthy volunteers on a GE Signa 3.0 T EXCITE scanner. The FAIR-BGS pulse sequence is illustrated in Figure 1. BGS was achieved using a saturation – inversion – inversion preparation scheme that suppresses signal from a broad range of T1s including myocardium (1000–1200 ms) and blood (1400–1600 ms) at 3 T [6]. Adiabatic pulses (BIR4 and hyperbolic secant) were used to reduce sensitivity to B0 and B1 inhomogeneity. Cardiac-gated FAIR imaging was implemented by alternating the first inversion pulse between non-selective and slab-selective to generate control and tagged images respectively. A snapshot SSFP acquisition is used for its high SNR efficiency. Imaging parameters were flip angle = 40°, TR = 3.2 ms, FOV = 20 cm, matrix size = 96 × 96, and slice thickness = 10 mm. Perfusion rate is calculated using: f = (MTagged - MControl)/(MO·RR·(1-exp(-TS/
T1))·exp(-(TI1+TI2)/T1)). The first inversion and imaging are fixed to occur at the same cardiac phase (mid-diastole) so that the inversion slab contains the imaging slice, and the calculated perfusion rate provides the average perfusion rate over one heartbeat.
Results Fig. 2a–d contains a baseline image (no preparation), BGS control image, BGS tagged image, and difference image (tagged – control) from a short-axis view in one representative subject. Using conventional prescan calibration, blood and myocardial signals were suppressed to
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