The application of a compact MR - compatible SPECT system for small animal SPECT / MR imaging and tracer kinetics studies

BODY: Objectives : A new F-18 agent for PET myocardial perfusion imaging (BMS747158) has been shown to have excellent image quality in a Phase I clinical trial. In a subgroup of patients undergoing imaging with this agent in a Phase II clinical trial, we assessed if dual gated perfusion study is feasible and leads to improved image quality. We generated motion free perfusion images by combining amplitude based respiratory gating and the “Motion Frozen” (MF) processing technique (JNM 2004:45:1128-34) which eliminates cardiac motion in static images. Methods : In 6 patients, PET imaging was performed in dual -cardiac and respiratorymode on a 4-ring Siemens Biograph-64. Static and 8-bin ECG-gated images using either full 5 minutes of the acquisition or a narrow range of breathing amplitude around end-expiration level keeping 30% of a 10-minute acquisition (RespiG) were reconstructed with HD●PET. MF was then applied to the gated datasets. We computed the wall/cavity contrast and contrast-to-noise ratio (CNR) to assess image quality. Wall thickness, motion, thickening and ejection fraction (EF) were also estimated with automatic quantification. Results : On average, the contrast was the same with HD●PET (9.1±3.2) and RespiG-HD●PET (9.2±2.4) but was significantly improved with MF:HD●PET (10.7±3.6) and further with MF:RespiG-HD●PET (13.0±4.8, p<0.05). CNR was 16.9±10.4 with HD●PET, 20.1±13.3 with RespiG-HD●PET, 32.6±12.2 with MF:HD●PET and 28.7±4.0 MF:RespiG-HD●PET. The wall thickness was significantly decreased with MF:RespiG-HD●PET (10.8±1.7mm) compared to HD●PET (13.6±2.1mm), RespiG-HD●PET (12.5±2.3mm) and MF:HD●PET (12.0±1.8)(all p<0.05). EF, motion and thickening did not show any significant change between any processing method. Conclusions : Dual gated perfusion imaging is feasible with a new F-18 agent and shows significantly improved image resolution, contrast and contrast-to-noise when combined with Motion Frozen processing. (no table selected) 69-year old female patient recruited in Phase II clinical trial for a new F-18 myocardial perfusion agent (BMS747158) and acquired in dual -cardiac and respiratorymode. Short axis, vertical and horizontal axis views of images reconstructed with, from top to bottom, HD●PET, respiratory gating + HD●PET, Motion Frozen + HD●PET and Respiratory gating + Motion Frozen + HD●PET.