Abstract:
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Purpose: The purpose of this study was to investigate the myocardial fatty acid metabolism in patients with ischemic heart disease (IHD) and hypertrophic cardiomyopathy (HCM) from dynamic SPECT through a compartment model analysis.
Methods and Materials: Fourteen patients with ischemic heart disease and 17 patients with hypertrophic cardiomyopathy were studied. Iodine-123 beta-methyl-iodophenyl-pentadecanoic acid (I-123 BMIPP) dynamic SPECT and myocardial perfusion SPECT were performed in them within 2 weeks. After an injection of I-123 BMIPP (111MBq), the dynamic SPECT was performed on a three-headed digital gamma camera system. The myocardial perfusion SPECT was performed with Tc-99m Tetrofosmin (740MBq) on the same system. The left ventricular myocardium was divided into 13 segments in short axis and vertical long axis images, and these 403 segments were categorized according to the findings on myocardial perfusion SPECT and clinical information as normal, IHD and HCM. By using the time-activity curves (TACs) of these segments as response tissue functions and the TACs of Aorta as input functions, we analyzed I-123 BMIPP pharmacokinetics through a 2-compartment model. A nonlinear least square method was used to determine these parameters. All of these data were converged, and we could obtain the rate constants in all cases. We defined k1 as influx rate constant, k2 as outflux rate constant and k3 as specific uptake rate constant. And we calculated k1/k2, k3 and clearance (k1k2/(k2+k3)).
Results: The average of k1/k2, k3 and clearance value from normal myocardium segments were 0.590325±0.219418, 0.001758±0.015258 and 0.028318±0.062742, respectively. These value from ishemic myocardium and hypertrophic cardiomyopathy segments were 0.525904±0.203597, 0.002636±0.001773, 0.005174±0.015002, 0.477738±0.268375, 0.004739±0.018439 and 0.033426±0.057727, respectively. Statistically significant differences were seen in clearance (p<0.05) between normal and IHD. The parameters, k1/k2 and k3 showed statistically significant differences (p<0.001 and p<0.05, respectively) between normal and HCM, but clearance did not.
Conclusion: A compartment model analysis could be useful to clarify the myocardial fatty acid metabolism in patients with IHD and HCM.
Okizaki MD, A,
An Investigation for the Myocardial Fatty Acid Metabolism Using a Compartment Analysis in Patients with Ischemic Heart Disease and Hypertrophic Cardiomyopathy. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3106990.html
