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. 2020 Feb;61(2):189-193.
doi: 10.2967/jnumed.119.227207. Epub 2019 Jul 19.

Can the Injected Dose Be Reduced in 68Ga-PSMA-11 PET/CT While Maintaining High Image Quality for Lesion Detection?

Isabel Rauscher  1 , Wolfgang P Fendler  2   3 , Thomas A Hope  4 , Andrew Quon  3 , Stephan G Nekolla  5 , Jeremie Calais  3 , Antonia Richter  5 , Bernhard Haller  6 , Ken Herrmann  2   3 , Wolfgang A Weber  5 , Johannes Czernin  3 , Matthias Eiber  5   3
Affiliations

Can the Injected Dose Be Reduced in 68Ga-PSMA-11 PET/CT While Maintaining High Image Quality for Lesion Detection?

Isabel Rauscher et al. J Nucl Med. 2020 Feb.

Abstract

Our purpose was to define a clinically useful lower limit of injected dose for 68Ga-prostate-specific membrane antigen (PSMA)-11 PET/CT imaging of prostate cancer. Methods:68Ga-PSMA-11 PET/CT was performed on 11 patients. PET was acquired in list mode and reconstructed using a 3-min full acquisition, a 2-min acquisition, and a 1-min acquisition to generate images obtained with three thirds (standard dose), two thirds (low dose), and one third (very low dose) of the injected dose, respectively. Overall image quality (5-point scale) was assessed, and the detectability of PSMA-positive lesions was determined by 3 readers and compared with the reference standard. Results: Image quality declined with decreasing dose (mean score of 4.1 ± 0.4 for the standard dose, 3.4 ± 0.7 for the low dose, and 1.9 ± 0.4 for the very low dose; all P < 0.05). Readers 1, 2, and 3 correctly identified the lesions (n = 21) at a rate of 100%, 100%, and 95% with the standard dose; 95%, 81%, and 90% with the low dose; and 71%, 76%, and 59% with the very low dose, respectively. Conclusion:68Ga-PSMA-11 dose reduction is not feasible without a negative impact on image quality and lesion detectability.

Keywords: PSMA; dose reduction; image dose; prostate cancer.

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Figures

FIGURE 1.
FIGURE 1.
Graph illustrating applied standard dose and simulated low and very low doses in all patients in MBq/kg of BW.
FIGURE 2.
FIGURE 2.
Mean image quality and standard dose for all 3 readers of PET datasets obtained with standard dose, low dose, and very low dose. Dashed line indicates cutoff for adequate image quality.
FIGURE 3.
FIGURE 3.
68Ga-PSMA-11 PET/CT images of 75-y-old patient (patient 7) with biochemical recurrence after radical prostatectomy (PSA value, 4 ng/mL at time of imaging). (A and B) Lymph node metastasis (arrows) was classified correctly by all 3 readers on PET performed with standard dose (A) and low dose (B), although mean lesion detectability decreased from 2.67 for standard dose to 2.33 for low dose. (C) On PET performed with very low dose, 2 readers missed this lesion because of increased image noise (mean lesion detectability, 0.67). (D) Corresponding CT image shows small, morphologically unobtrusive lymph node (arrow).
See this image and copyright information in PMC

Comment in

  • Lesion Detection and Administered Activity.
    McCready VR, Dizdarevic S, Beyer T. McCready VR, et al. J Nucl Med. 2020 Sep;61(9):1406-1410. doi: 10.2967/jnumed.120.244020. Epub 2020 Apr 3. J Nucl Med. 2020. PMID: 32245895 No abstract available.

References

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