Dipyridamole-induced stress - variability in {sup 82}Rb PET kinetic studies in the anesthetized canine
- Lawrence Berkeley National Lab., CA (United States); and others
Reproducibility and variability of dipyridamole-induced stress in the myocardium as measured with {sup 82}Rb PET kinetics was tested in a series of replicated studies on six dogs using the Donner 600-Crystal Positron Tomograph (4.5mm FWHM with {sup 82}Rb). A single lateral slice through the myocardium was imaged in a baseline resting state, and again immediately after an infusion of dipyridamole (0.6 mg/kg over 4 min). Blood samples taken at 1 minute intervals were assayed with HPLC. A two compartment model with parameters k{sub 1} (uptake rate), k{sub 2} (wash-out rate), and f{sub v} (vascular fraction) was fit to the data. Stress-state k{sub 1} estimates were compared with rest-state k{sub 1} estimates and dipyridamole levels in the blood to ascertain any dependencies between them. In a multiple regression of the stress-k{sub 1} on both the rest-k{sub 1} and the mean dipyridamole concentration (0-4 min), the rest-k{sub 1} is significant (p=0.032) as a predictor and the dipyridamole concentration is borderline significant (p=0.060). Together they explain about 35% of the variability in the stress-k{sub 1}. Analysis of variance shows no significant between-animal effects for either the rest-k{sub 1} or the stress-k{sub 1} estimates but a significant (p=0.032) between-animal effect for the dipyridamole concentration. Dipyridamole is routinely used to induce stress for kinetic PET cardiac studies, but its contribution to variability in the rest-stress test has not been examined. These studies show that dipyridamole pharmacokinetic variability within and between animals has an effect on the stress-k{sub 1} estimate, but the effect is small. The statistically significant correlation of the rest- and stress-k{sub 1} values suggests that the ratio of K{sub 1} (stress/rest) is a more stable indicator of the stress response than the stress-k{sub 1} values alone.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 447770
- Report Number(s):
- CONF-960659-; ISSN 0161-5505; CNN: Grant HL47675; Grant HL25840; TRN: 97:000961-0050
- Journal Information:
- Journal of Nuclear Medicine, Vol. 37, Issue Suppl.5; Conference: 43. annual meeting of the Society of Nuclear Medicine, Denver, CO (United States), 3-6 Jun 1996; Other Information: PBD: May 1996
- Country of Publication:
- United States
- Language:
- English
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