PT - JOURNAL ARTICLE AU - Michael Rusnak AU - Kristin McBride TI - Total Body PET Patient Positioning for Optimal Diagnostic and Research Scans DP - 2020 May 01 TA - Journal of Nuclear Medicine PG - 3122--3122 VI - 61 IP - supplement 1 4099 - http://jnm.snmjournals.org/content/61/supplement_1/3122.short 4100 - http://jnm.snmjournals.org/content/61/supplement_1/3122.full SO - J Nucl Med2020 May 01; 61 AB - 3122Objectives: PET/CT scans are utilized across the world for human and animal research, along with a myriad of clinical applications. Current singleConventional (~15-25 cm axial field of view) bed PET/CT scanners dominate theis landscape for human imaging; the next generation of scannershowever the, like uExplorer, utilize consecutive rings of detectors to create the world’s first Ttotal Bbody PET scanner, utilizes consecutive self-contained scanner units to create achieve an extremely long axial field of view (1.94 meters long). This paper will looks at the dual challenges associated with patient positioning for obtaining optimal PET and CT images. Methods: A total of 3018 PET/CT scans were acquired with a mix of research and clinical protocols. Images were analyzed visually by a radiologist; CT image review focused on chest/abdomen and head/neck areas. The CT data was evaluated for quality differences between scans with the patient’s arms up and down using “low” (140 kVp, 50 mAs; ~10 mSv) and “ultra-low” (140 kVp, 5 mAs; ~1 mSv) exposure protocols. Special emphasis was placed on reviewing the head and neck area on PET images. Transverse brain slices were compared between similar subjects within different units of the scanner. Input from the manufacturer regarding uExplorer’s sensitivity profile was considered. Also, patient comfort levels were probed by technologists before and after the scans which ranginged from 20 to 60 minutes apiecein duration. Results: Visually CT images present the most drastic quality differences between patients scanned with arms up, and those scanned with arms down. The extra mass of the arms introduces noise and artifacts, which degrades the quality of acquired images and accuracy of SUVs. While PET images do notw show apparent visual differences in quality, information from the sensitivity profile suggests the area of interest should be placed between the second and second-to-last units to obtain an optimal PET scan. Scans lasting an hour or more are best accomplished with patients’ arms down; even though CT image quality is compromised over the chest and abdomen, patient comfort allows long duration scanning without major motion artifacts in most cases. Conclusions: The optimal patient positioning will depend on the type of study being performed, length of scanning, and area of interest. For clinical F18 FDG scans, patients should be positioned arms up with head to thighs in the gantry iso-center. An arms down, whole body scan should be acquired if indicated (i.e. melanoma or lower extremity tumor involvement). Brain scans are best acquired with arms down, head in gantry iso-center. For research exams, mostly whole body techniques have been utilized so far, with patient’s arms up or down depending on scan duration, patient habitus, and injection considerations (delayed or flow dynamic study).