title: Semiquantitative Parameters in PSMA-Targeted PET Imaging with18F-DCFPyL: Variability in Normal-Organ Uptake.
abstract: 18F-DCFPyL is a small-molecule inhibitor of the prostate-specific membrane antigen that has shown promise for evaluation of primary and metastatic prostate cancer using PET. Measuring the variability in normal-organ uptake of18F-DCFPyL is necessary to understand its biodistribution, aid image interpretation, judge the reliability of scan quantification, and provide a basis for therapeutic monitoring.Methods:Sixty-five consecutive18F-DCFPyL PET/CT scans from 64 patients with a history of prostate cancer were analyzed. Volumes of interest were defined for the lacrimal glands, major salivary glands, liver, spleen, and both kidneys. The mean SUV normalized to body mass or to lean body mass (SUL) was calculated for each volume of interest. The average SUV across all scans, the SD, and the coefficient of variation (COV) for each organ were calculated. The same parameters were also derived for a 3-cm sphere drawn in the center of the right lobe of the liver.Results:The average SUVmeanfor all selected organs measured was 6.6 ± 1.8 for the right lacrimal gland, 6.4 ± 1.8 for the left lacrimal gland, 9.1 ± 2.0 for the right parotid gland, 9.0 ± 2.1 for the left parotid gland, 9.6 ± 2.3 for the right submandibular gland, 9.4 ± 2.2 for the left submandibular gland, 5.0 ± 0.7 for the whole liver, 5.1 ± 0.7 for a 3-cm sphere in the liver, 4.0 ± 1.5 for the spleen, 20.1 ± 4.6 for the right kidney, and 19.4 ± 4.5 for the left kidney. SULmeanwas lower overall, although demonstrating similar trends. The COV of SUVmeanand SULmeanwas lower in the liver (13.8% and 14.5%, respectively) than in any other organ and was less than the comparable COV for18F-FDG PET. The COV of SUVmeanand SULmeanin the 3-cm sphere in the liver was also low and similar to the variability in the whole liver (14.2% and 14.7%, respectively).Conclusion:18F-DCFPyL uptake in normal liver demonstrates less variability than in other18F-DCFPyL-avid organs, and its variability is less than the reported variability of18F-FDG in liver. Variability was slightly less for SUVmeanthan for SULmean, suggesting that SUVmeanmay be the preferable parameter for quantification of images obtained with18F-DCFPyL.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.|Department of Radiology, Shandong Provincial Hospital, Shandong University, Jinan City, Shandong Province, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Rowe
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Leal
authors.affiliation: James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Gorin
authors.affiliation: James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Mohamad E
authors.initials: ME
authors.lastname: Allaf
authors.affiliation: James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Ashley E
authors.initials: AE
authors.lastname: Ross
authors.affiliation: James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins University School of Medicine, Baltimore, Maryland; and.|Department of Medical Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Pienta
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Martin A
authors.initials: MA
authors.lastname: Lodge
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland mpomper@jhmi.edu.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Pomper
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000954:Antigens, Surface / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism; D003198:Computer Simulation; D043425:Glutamate Carboxypeptidase II / Q000378:metabolism*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008239:Lysine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D008954:Models, Biological; D009928:Organ Specificity; D057089:Pathology, Molecular / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014508:Urea / Q000031:analogs & derivatives* / Q000493:pharmacokinetics
chemical_list: C572626:2-(3-(1-carboxy-5-((6-fluoropyridine-3-carbonyl)amino)pentyl)ureido)pentanedioic acid; D000954:Antigens, Surface; D014408:Biomarkers, Tumor; D019275:Radiopharmaceuticals; D014508:Urea; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II; D008239:Lysine
keywords: SUV; molecular imaging; positron emission tomography; prostate cancer; prostate-specific membrane antigen