Quantitative cardiac perfusion evaluation using first-pass contrast-enhanced magnetic resonance imaging
The measurement of the blood flow to the myocardium (or cardiac perfusion) is important for the clinical assessment of ischemia. Magnetic resonance imaging (MRI) may provide a technique for the quantitative assessment of cardiac perfusion that is potentially superior to other imaging modalities. However, to date, there is no standard method for the quantitative assessment of cardiac perfusion with MRI. This dissertation describes the development and implementation of a method for measuring the absolute blood flow in the myocardium in ml/min/g of tissue. This method includes: modifications to the fast gradient echo-echo planar imaging pulse sequence typically used for the acquisition of a time series of T1-weighted images in first-pass contrast-enhanced perfusion studies; a novel theory-based image signal calibration approach; a study of the spatial homogeneity of the preconditioning saturation RF pulses used to achieve T1-weighting; the development of an integrated GUI-based software for image processing and analysis; a tracer kinetics model used to generate blood flow estimates from observed tracer concentration-time curves. Our novel theory-based image signal calibration method relies on normalization of the T1-weighted images by an initial proton density-weighted image, the use of robust saturation RF pulses for consistent TI weighting, and dual-delay-time acquisitions for improving the dynamic range of the arterial input function determination. The signal calibration technique is used to map signal-time curves that correspond to the dynamic image enhancement during the passage of the tracer bolus through the heart to T1-time curves, and then to corresponding [Gd]-time curves. The [Gd]-time curves for the left ventricular cavity and the myocardium represent the inputs to the tracer kinetics model, which is used to fit the observed data and generate blood flow estimates. The described quantitative cardiac perfusion measurement method is used to measure blood flow in preliminary in vivo studies. We obtain reasonable absolute blood flow for rest and stress, and we see a clear increase in myocardial blood flow during adenosine stress. We conclude that this method can constitute the basis for a future clinically-oriented quantitative evaluation of cardiac perfusion. ^
Engineering, Biomedical|Engineering, Electronics and Electrical|Health Sciences, Radiology|Biophysics, Medical
"Quantitative cardiac perfusion evaluation using first-pass contrast-enhanced magnetic resonance imaging"
(January 1, 2005).
Dissertations available from ProQuest.