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CC BY 4.0 · World J Nucl Med 2024; 23(02): 110-118
DOI: 10.1055/s-0044-1786529
Original Article

Time-of-Flight PET/CT Imaging of Ga-68-Dotatate: Normal Pattern, SUV Quantification, and Differences from Non-Time-of-Flight Imaging

Authors

  • Matthew Clifton Miller

    1   School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States

  • Avani T. Bansal

    2   The Potomac School, McLean, Virginia, United States

  • Daniel Wingard

    3   USA Radiology, WRNMMC, Bethesda, Maryland, United States

  • Maria Liza Lindenberg

    4   Molecular Imaging Program, NCI, NIH, Washington, DC, United States

  • Derek J. Stocker

    5   Nuclear Medicine, WRNMMC, Bethesda, Maryland, United States

  • Stephen Adler

    6   SAIC PET Physicist, Chevy Chase, Maryland, United States

  • Kalpna Prasad

    5   Nuclear Medicine, WRNMMC, Bethesda, Maryland, United States

Funding None.
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Abstract

Purpose The biodistribution of gallium-68-dotatate (Ga-68-dotatate) and standardized uptake values (SUVs) using non-time-of-flight (TOF) positron emission tomography/computed tomography (PET/CT) cameras is well established. However, with the eventual retirement of older PET cameras and their replacement with newer, highly sensitive TOF PET/CT cameras, where SUVmax measurements are reportedly higher, updated knowledge of normal SUVmax range is needed and, to our knowledge, not previously reported. Our objectives are as follows:

  1. To establish normal Ga-68-dotatate TOF SUVmax database for common structures and to aid the visual detection of abnormalities objectively.

  2. To compare SUVmax values using the TOF and non-TOF algorithms.

Methods Fifty consecutive patients referred routinely to our nuclear medicine service (20 men, 30 women; median age 55 years) with presumed neuroendocrine tumors underwent Ga-68-dotatate scans on a PET-CT camera having capability of reconstructing both TOF/non-TOF images. Region of interests (ROIs) were drawn around 24 normal structures as well as the primary lesion with abnormal radiotracer uptake and SUVmax was measured. The same ROI was analyzed using both algorithms simultaneously and both TOF and non-TOF SUVmax values were compared.

Results Twelve hundred ROIs were evaluated. Non-TOF Ga-68-dotatate uptake in normal structures was in alignment with previously published studies. As compared to non-TOF, TOF images had better target to background ratios visually. TOF SUVmax was higher for all structures except for lung and brain. TOF SUVmax was more than double in adrenals/uncinate process of the pancreas; approximately 1.8 times in abnormal lesions, lymph nodes, pineal gland; and greater than 1.5 times in thyroid, breast, and pancreatic head.

Conclusion Normal database of Ga-68-dotatate TOF SUVmax is provided for common structures to aid visual detection of abnormalities objectively. Overall, TOF SUVmax measures higher in identical ROIs, with abnormal lesions measuring approximately 1.8 times higher versus non-TOF technology. These findings need to be taken in consideration when comparing patient scans imaged on different PET/CT technologies.

Keywords

NET - dotatate - TOF - PET/CT

Contributorship/Institutional Acknowledgements

The views expressed in this manuscript are those of the author(s) and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or U.S. Government.




Publication History

Article published online:
07 May 2024

© 2024. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

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