PT  - JOURNAL ARTICLE
AU  - Wendy Siman
AU  - S. Cheenu Kappadath
TI  - Comparison of Step-and-Shoot and Continuous-Bed-Motion PET Modes of Acquisition for Limited-View Organ Scans
AID  - 10.2967/jnmt.117.195438
DP  - 2017 Dec 01
TA  - Journal of Nuclear Medicine Technology
PG  - 290--296
VI  - 45
IP  - 4
4099  - http://tech.snmjournals.org/content/45/4/290.short
4100  - http://tech.snmjournals.org/content/45/4/290.full
SO  - J. Nucl. Med. Technol.2017 Dec 01; 45
AB  - Continuous-bed-motion (CBM) acquisition mode has been made commercially available in PET/CT scanners. CBM mode is designed for whole-body imaging, with a long scan length (multiple axial fields of view [aFOVs]) and short acquisition duration (2–3 min/aFOV). PET/CT has recently been used after 90Y-microsphere therapy to quantify 90Y activity distribution in the liver. Here we compared counting efficiencies along the bed-motion direction (z-axis) between CBM and step-and-shoot (SS) acquisition modes for limited-view organ scans, such as 90Y PET/CT liver studies, that have short scan lengths (≤2 aFOVs) and long acquisition durations (10–30 min/aFOV). Methods: The counting efficiencies, that is, analytic sensitivities, in SS mode (single-aFOV and multiple-aFOV scans) and CBM mode were theoretically derived and experimentally validated using a cylindric 68Ge phantom. The sensitivities along the z-axis were compared between the SS and CBM modes. Results: The analytic and experimental count profiles were in good agreement, validating the analytic models. For fixed scan durations, the overall coincidence counting efficiency in CBM mode was lower (∼60%) than those in SS modes, and the maximum sensitivity in CBM mode was 50% or less of that in 1-aFOV SS mode and 100% or less of that in 2-aFOV SS mode. Conclusion: The ability of CBM mode to tailor-fit the PET/CT scan length and local scan duration is not realized in studies with a short scan length (≤30 cm) and long scan duration (20 min/aFOV for the scanner). SS acquisition mode is preferable to CBM mode for limited-view organ and count-starved scans, such as 90Y PET/CT liver scans, because of the higher counting efficiency of SS mode, which leads to better image quality and quantification precision.