114 The Relationship between signal intensity and myocardial gadolinium concentration for three MR perfusion pulse seque
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Meeting abstract
114 The Relationship between signal intensity and myocardial gadolinium concentration for three MR perfusion pulse sequences: implications for measuring absolute myocardial blood flow Daniel C Lee*, Nils P Johnson and Kathleen R Harris Address: Northwestern University Feinberg School of Medicine, Chicago, IL, 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):A15
doi:10.1186/1532-429X-10-S1-A15
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/A15 © 2008 Lee et al; licensee BioMed Central Ltd.
Background
Methods
Absolute myocardial blood flow (in ml/min/g) can be calculated from CMR first-pass perfusion studies by modelbased deconvolution of the left ventricular blood pool and myocardial signal intensity-time curves. This technique is increasingly being applied to calculate myocardial blood flow in various cardiovascular diseases [1-3]. A basic assumption of the deconvolution technique is that signal intensity is proportional to gadolinium concentration in both the blood pool and myocardium. Dual-bolus [4] and dual-echo [5] techniques have been proposed to address the known nonlinear signal response of the blood pool to gadolinium. Based on phantom studies or signal response to escalating Gd dose, recent reports suggest that despite its low signal, the myocardial response to gadolinium is also nonlinear [6,7]. The myocardial signal response to myocardial gadolinium concentration needs to be defined for common perfusion pulse sequences to guide the appropriate application of absolute perfusion measurements by deconvolution.
Imaging was performed in two purpose-bred hounds, chronically instrumented with left atrial, right atrial, and aortic catheters on a 1.5 T clinical MR scanner (Siemens Sonata). As regional gadolinium concentration can be calculated from the longitudinal relaxation rate (1/T1), cardiac T1 can therefore be measured from T1 mapping performed using a modified Look-Locker technique (MOLLI) [8]. During a constant slow infusion of Gd, a single mid-ventricular short axis slice was alternately imaged for 1) signal intensity by SR-EPI, SR-FLASH, or IRSSFP and 2) T1 mapping (MOLLI). Infusion experiments were performed with an infusion rate of 0.5 mmol/min in order to span the myocardial signal range expected in response to a 0.05 mmol/kg IV bolus. Signal intensity values were normalized to correct for coil inhomogeneity and the baseline signal. The increase in normalized signal intensity and gadolinium concentration were plotted against the time of infusion. The signal intensity and gadolinium concentration curves as functions of time were interpolated using a
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