Compartmental modeling of 18FDG in the heart using dynamic SPECT

Dynamic PET imaging of ¹⁸FDG in the heart has been shown to provide valuable diagnostic and prognostic information in terms of myocardial viability. With the use of three detector systems and 511 keV collimators, dynamic SPECT ¹⁸FDG may be feasible. It is of interest to determine if dynamic SPECT imaging of myocardial ¹⁸ FDG with a compartmental modeling approach can result in accurate parameter estimates, thereby providing quantitative data for assessment of coronary disease. A computer simulation and two canine studies were used to investigate imaging ¹⁸FDG with dynamic SPECT. Time-activity curves for blood and the myocardium were simulated with values from published dynamic PET studies. Sub-projections were calculated around each projection angle at a fine temporal resolution and integrated to reflect the inconsistencies inherent with serial (SPECT) projection acquisitions. Point response and realistic noise levels were incorporated. The projections were reconstructed with ML-EM (no point response modeled). Useful parameter estimates were obtained from regions of interest the size of one-quarter of a slice. In addition, dynamic ¹⁸FDG imaging of two canines was performed. Reasonable parameter estimates in the canine studies were obtained using the left ventricle as one large region and incorporating plasma samples for the input function