For the biomedical engineer, cardiac MRI represents an opportunity to study the function of the heart and use this insight to design better biomedical devices. Because of the increasing relevance of cardiac MRI in the clinical arena, it will become
Fig. 23. Signal intensity (SI) curve for a myocardial sector in the lateral wall. Each of the data points (circles) represents the mean SI measured in the images for the user-defined myocardial sector. The images were acquired with a fast, Trweighted gradient echo sequence during injection of a 0.075 mmol/kg bolus of Gd-DTPA (gadolinium diethylenetriamine pentaacetic acid), an extracellular magnetic resonance contrast agent. The gamma variate function can only be used to fit the portion of the tissue curve corresponding to the first pass of the contrast agent. The gray curve represents the best fit of the gamma variate function to be part of the experimental data, covering the range indicated by the vertical arrows. The gamma variate fit was extrapolated to the end of the measurement range. In many cases, the end of the first pass and the appearance of the recirculation component can be best ascertained from the SI changes observed in the left ventricular blood pool. Also shown are semiquantitative perfusion parameters such as the slope, peak SI, and the time from the foot to the peak tp.
important to address the challenges inherent in the use of cardiac MRI in patients with implanted devices.
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