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Quantitative Test-Retest Measurement of Ga-68-PSMA-HBED-CC in Tumor and Normal Tissue
Journal article   Open access   Peer reviewed

Quantitative Test-Retest Measurement of Ga-68-PSMA-HBED-CC in Tumor and Normal Tissue

Janet H. Pollard, Caleb Raman, Yousef Zakharia, Chad R. Tracy, Kenneth G. Nepple, Tim Ginader, Patrick Breheny and John J. Sunderland
The Journal of nuclear medicine (1978), Vol.61(8), pp.1145-1152
08/01/2020
DOI: 10.2967/jnumed.119.236083
PMID: 31806776
url
https://doi.org/10.2967/jnumed.119.236083View
Published (Version of record) Open Access

Abstract

The PET radiotracer Ga-68-PSMA (prostate-specific membrane antigen)-HBED-CC (N,N'-bis [2-hydroxy-5-(carboxyethyl)benzyl]ethylenedi-amine-N,N'-diacetic acid) shows potential as an imaging biomarker for recurrent and metastatic prostate cancer. The purpose of this study was to determine the repeatability of Ga-68-PSMA-HBED-CC in a test-retest trial in subjects with metastatic prostate adenocar-cinoma. Methods: Subjects with metastatic prostate cancer under-went 2 PET/CT scans with Ga-68-PSMA-HBED-CC within 14 d (mean, 6 +/- 4 d). Lesions in bone, nodes, prostate/bed, and visceral organs, as well as representative normal tissues (salivary glands and spleen), were segmented separately by 2 readers. Absolute and per-centage differences in SUVmax and SUVmean were calculated for all test-retest regions. Repeatability was assessed using percentage dif-ference, within-subject co-efficient of variation (wCV), repeatability co-efficient (RC), and Bland-Altman analysis. Results: Eighteen subjects were evaluated, 16 of whom demonstrated local or metastatic dis-ease on Ga-68-PSMA-HBED-CC PET/CT. In total, 136 lesions were segmented in bone (n = 99), nodes (n = 27), prostate/bed (n = 7), and viscera (n = 3). The wCV for SUVmax was 11.7% for bone lesions and 13.7% for nodes. The RC was +/- 32.5% SUVmax for bone lesions and +/- 37.9% SUVmax for nodal lesions, meaning 95% of the normal variability between 2 measurements will be within these numbers, so larger differences are likely attributable to true biologic changes in tumor rather than normal physiologic or measurement variability. wCV in the salivary glands and spleen was 8.9% and 10.7% SUVmean, respectively. Conclusion: Repeatability measurements for PET/CT test-retests with Ga-68-PSMA-HBED-CC showed a wCV of 12%- 14% SUVmax and an RC of +/- 33%-38% SUVmax in bone and nodal lesions. These estimates are an important aspect of Ga-68-PSMA-HBED-CC as a quantitative imaging biomarker. These estimates are similar to those reported for F-18-FDG, suggesting that Ga-68-PSMA-HBED-CC PET/CT may be useful in monitoring response to therapy.
Life Sciences & Biomedicine Radiology, Nuclear Medicine & Medical Imaging Science & Technology

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