Clinical PET: Repositioning Myocardial Studies After Bicycle Exercise

Abstract

Objective: Myocardial viability studies were assessed for repositioning accuracy as adequate or inadequate by evaluation of NH₃/FDG image correspondence and detection of measured attenuation correction (MSATN) artifacts.

Methods: Myocardial viability studies using ¹³N-ammonia (NH₃) and ¹⁸F-fluorodeoxyglucose (FDG) were evaluated in 29 normal subjects (21 rest and exercise, 7 exercise only and 1 rest only). Patients were positioned in the ECAT III gantry, and selected body landmarks were registered with the imaging bed. MSATN data were acquired. For exercise studies, upright bicycle exercise was then performed off the imaging bed. Intravenous NH₃ or FDG was injected during exercise and the patient was repositioned and imaged.

Results: Analysis revealed repositioning accuracy of 96% for rest NH₃, 91% for rest FDG, 57% for exercise NH₃ and 50% for exercise FDG.

Conclusion: The problems encountered with repositioning make upright bicycle exercise for cardiac PET restrictive for routine clinical use with existing technology.