Performance of list-mode data acquisition with ECAT EXACT HR positron emission scanner

Recently list mode (event-by-event) data acquisition with positron emission tomography (PET) has been widely noticed because the list mode acquisition is superior to the conventional frame mode data acquisition in terms of (1) higher efficiency of data storage, (2) higher temporal resolution and (3) higher flexibility of data manipulation. The aim of this study is to investigate the performance of list mode data acquisition with ECAT HR and HR + PET scanners(CTI PET Systems). The cylindrical phantom (16 cm diameter and 16 cm long) filled with ¹¹C solution for HR and ¹⁵O solution for HR+ was scanned several times varying the radioactivity with list mode and frame mode acquisitions. The scans with the septa (2D mode) and without the septa (3D mode) were also carried out in order to evaluate the effect of interplane septa on quality of the list mode data. The acquired list mode data were sorted to sinogram and reconstructed using filtered back-projection algorithm. The count rate performance of the list mode data was comparable to the frame mode data. However list mode acquisition could not be performed if radioactivity in the field-of-view was high (more than 3 mCi for 3D mode) due to lack of transfer speed for sending data from memory to hard disk. 10 replicated data set from one list mode data were generated to estimate the noise in the reconstructed image. The reconstructed images with 3D mode has more than 60% better signal-to-noise ratio compared to the image with 2D mode. Generated file size of list mode was also evaluated. In the case of HR+ with 3D list mode, list mode data with 2.31 MBytes/s for 1mCi injection were generated. Out results suggest that careful attention must be paid for protocol of the list mode data acquisition in order to obtain the highest performance of the PET scanner.