Comparison of Multiple Segmentation Methods for Volumetric Delineation of Primary Prostate Cancer with Prostate-Specific Membrane Antigen-Targeted 18F-DCFPyL PET/CT.

This study aimed to assess the accuracy of intraprostatic tumor volume measurements on prostate-specific membrane antigen-targeted 18F-DCFPyL PET/CT made with various segmentation methods. An accurate understanding of tumor volumes versus segmentation techniques is critical for therapy planning, such as radiation dose volume determination and response assessment. Methods: Twenty-five men with clinically localized, high-risk prostate cancer were imaged with 18F-DCFPyL PET/CT before radical prostatectomy. The tumor volumes and tumor-to-prostate ratios (TPRs) of dominant intraprostatic foci of uptake were determined using semiautomatic segmentation (applying SUVmax percentage [SUV%] thresholds of SUV30%-SUV70%), adaptive segmentation (using adaptive segmentation percentage [A%] thresholds of A30%-A70%), and manual contouring. The histopathologic tumor volume (TV-Histo) served as the reference standard. The significance of differences between TV-Histo and PET-based tumor volume were assessed using the paired-sample Wilcoxon signed-rank test. The Spearman correlation coefficient was used to establish the strength of the association between TV-Histo and PET-derived tumor volume. Results: Median TV-Histo was 2.03 cm3 (interquartile ratio [IQR], 1.16-3.36 cm3), and median TPR was 10.16%. The adaptive method with an A40% threshold most closely determined the tumor volume, with a median difference of +0.19 (IQR, -0.71 to +2.01) and a median relative difference of +7.6%. The paired-sample Wilcoxon test showed no significant difference in PET-derived tumor volume and TV-Histo using A40%, A50%, SUV40%, and SUV50% threshold segmentation algorithms (P > 0.05). For both threshold-based segmentation methods, use of higher thresholds (e.g., SUV60% or SUV70% and A50%-A70%) resulted in underestimation of tumor volumes, and use of lower thresholds (e.g., SUV30% or SUV40% and A30%) resulted in overestimation of tumor volumes relative to TV-Histo and TPR. Manual segmentation overestimated the tumor volume, with a median difference of +2.49 (IQR, 0.42-4.11) and a median relative difference of +130%. Conclusion: Segmentation of intraprostatic tumor volume and TPR with an adaptive segmentation approach most closely approximates TV-Histo. This information might be used to guide the primary treatment of men with clinically localized, high-risk prostate cancer.

Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2023 Nov 30 [Epub ahead of print]

Felicia Wang, Chen Liu, Igor Vidal, Margarita Mana-Ay, Andrew F Voter, Lilja B Solnes, Ashley E Ross, Andrei Gafita, Edward M Schaeffer, Trinity J Bivalacqua, Kenneth J Pienta, Martin G Pomper, Martin A Lodge, Daniel Y Song, Jorge D Oldan, Mohamad E Allaf, Angelo M De Marzo, Sara Sheikhbahaei, Michael A Gorin, Steven P Rowe

School of Medicine, Johns Hopkins University, Baltimore, Maryland., Key Laboratory of Carcinogenesis and Translational Research, Ministry of Education, Beijing, China., Department of Pathology, School of Medicine, Johns Hopkins University, Baltimore, Maryland., Northwestern Medicine, Chicago, Illinois., Russell H. Morgan Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins University, Baltimore, Maryland., Department of Urology, Feinberg School of Medicine, Northwestern Medicine, Chicago, Illinois., Division of Urology, Perelman Center for Advanced Medicine, University of Pennsylvania, Philadelphia, Pennsylvania., Brady Urological Institute, School of Medicine, Johns Hopkins University, Baltimore, Maryland., Molecular Imaging and Therapeutics, University of North Carolina, Chapel Hill, North Carolina; and., Milton and Carroll Petrie Department of Urology, Icahn School of Medicine at Mount Sinai, New York, New York., Molecular Imaging and Therapeutics, University of North Carolina, Chapel Hill, North Carolina; and .