Quantification of myocardial blood flow with /sup 13/N-ammonia and /sup 82/Rb PET - OSEM vs. FBP reconstruction

OSEM is a standard for image reconstruction in positron emission tomography (PET). However, OSEM has not been compared with filtered back projection (FBP) for the quantification of myocardial blood flow (MBF) with ¹³N-ammonia (NH3) and ⁸²Rb PET. 12 subjects with <5% likelihood of CAD had rest and stress (dipyridamole) dynamic PET with NH3 and Rb. Arterial blood and myocardial polar-map time activity curves were generated automatically and used with tracer kinetic models for quantification of MBF. A 1-compartment model was used for Rb and a 2-compartment model for NH3 to estimate the regional uptake rate constant K₁. Normal population databases were also created for NH3 and Rb using a net retention model. The databases comprised population mean and standard deviation (SD) polar-maps at rest, stress and stress/rest. There were no consistent differences between LV-median K₁ values generated with OSEM or FBP, although the rest NH3 K₁ value did decrease by 16% with OSEM (p=0.01). Peak blood values were consistently reduced by 5-10% with OSEM. At rest, the normal population database SD with OSEM was 10% higher for Rb (p=0.02) and 5% higher for NH3 (p=0.02). Conversely, the stress SD was decreased by 15% with OSEM for Rb (p<0.001) and 9% for NH3 (p<0.001). Stress/rest SD also decreased with OSEM by 15% for NH3 (p<0.001), and tended to decrease by 4% for Rb (p=0.12). The measured normal range (population SD) of stress flow and stress/rest reserve appears to be smaller with OSEM vs. FBP, which may be advantageous for the diagnosis of CAD with Rb and NH3 PET