PT - JOURNAL ARTICLE AU - Rudolf A. Werner AU - Ralph A. Bundschuh AU - Lena Bundschuh AU - Mehrbod S. Javadi AU - Jeffrey P. Leal AU - Takahiro Higuchi AU - Kenneth J. Pienta AU - Andreas K. Buck AU - Martin G. Pomper AU - Michael A. Gorin AU - Constantin Lapa AU - Steven P. Rowe TI - Interobserver Agreement for the Standardized Reporting System PSMA-RADS 1.0 on <sup>18</sup>F-DCFPyL PET/CT Imaging AID - 10.2967/jnumed.118.217588 DP - 2018 Dec 01 TA - Journal of Nuclear Medicine PG - 1857--1864 VI - 59 IP - 12 4099 - http://jnm.snmjournals.org/content/59/12/1857.short 4100 - http://jnm.snmjournals.org/content/59/12/1857.full SO - J Nucl Med2018 Dec 01; 59 AB - Recently, the standardized reporting and data system for prostate-specific membrane antigen (PSMA)–targeted PET imaging studies, termed PSMA-RADS version 1.0, was introduced. We aimed to determine the interobserver agreement for applying PSMA-RADS to imaging interpretation of 18F-DCFPyL (2-(3-{1-carboxy-5-[(6-18F-fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid) PET examinations in a prospective setting mimicking the typical clinical workflow at a prostate cancer referral center. Methods: Four readers (2 experienced readers (ERs, &gt;3 y of PSMA-targeted PET interpretation experience) and 2 inexperienced readers (IRs, &lt;1 y of experience)), who had all read the initial publication on PSMA-RADS 1.0, assessed 50 18F-DCFPyL PET/CT studies independently. Per scan, a maximum of 5 target lesions was selected by the observers, and a PSMA-RADS score for every target lesion was recorded. No specific preexisting conditions were placed on the selection of the target lesions, although PSMA-RADS 1.0 suggests that readers focus on the most avid or largest lesions. An overall scan impression based on PSMA-RADS was indicated, and interobserver agreement rates on a target lesion–based, on an organ-based, and on an overall PSMA-RADS score–based level were computed. Results: The number of target lesions identified by each observer was as follows: ER 1, 123; ER 2, 134; IR 1, 123; and IR 2, 120. Among those selected target lesions, 125 were chosen by at least 2 individual observers (all 4 readers selected the same target lesion in 58 of 125 [46.4%] instances, 3 readers in 40 of 125 [32%], and 2 observers in 27 of 125 [21.6%]). The interobserver agreement for PSMA-RADS scoring among identical target lesions was good (intraclass correlation coefficient [ICC] for 4, 3, and 2 identical target lesions, ≥0.60, respectively). For lymph nodes, an excellent interobserver agreement was derived (ICC, 0.79). The interobserver agreement for an overall scan impression based on PSMA-RADS was also excellent (ICC, 0.84), with a significant difference for ER (ICC, 0.97) vs. IR (ICC, 0.74) (P = 0.005). Conclusion: PSMA-RADS demonstrated a high concordance rate in this study, even among readers with different levels of experience. This finding suggests that PSMA-RADS can be effectively used for communication with clinicians and can be implemented in the collection of data for large prospective trials.