TY - JOUR T1 - qPSMA: Semiautomatic Software for Whole-Body Tumor Burden Assessment in Prostate Cancer Using <sup>68</sup>Ga-PSMA11 PET/CT JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1277 LP - 1283 DO - 10.2967/jnumed.118.224055 VL - 60 IS - 9 AU - Andrei Gafita AU - Marie Bieth AU - Markus Krönke AU - Giles Tetteh AU - Fernando Navarro AU - Hui Wang AU - Elisabeth Günther AU - Bjoern Menze AU - Wolfgang A. Weber AU - Matthias Eiber Y1 - 2019/09/01 UR - http://jnm.snmjournals.org/content/60/9/1277.abstract N2 - Our aim was to introduce and validate qPSMA, a semiautomatic software package for whole-body tumor burden assessment in prostate cancer patients using 68Ga-prostate-specific membrane antigen (PSMA) 11 PET/CT. Methods: qPSMA reads hybrid PET/CT images in DICOM format. Its pipeline was written using Python and C++ languages. A bone mask based on CT and a normal-uptake mask including organs with physiologic 68Ga-PSMA11 uptake are automatically computed. An SUV threshold of 3 and a liver-based threshold are used to segment bone and soft-tissue lesions, respectively. Manual corrections can be applied using different tools. Multiple output parameters are computed, that is, PSMA ligand–positive tumor volume (PSMA-TV), PSMA ligand–positive total lesion (PSMA-TL), PSMA SUVmean, and PSMA SUVmax. Twenty 68Ga-PSMA11 PET/CT data sets were used to validate and evaluate the performance characteristics of qPSMA. Four analyses were performed: validation of the semiautomatic algorithm for liver background activity determination, assessment of intra- and interobserver variability, validation of data from qPSMA by comparison with Syngo.via, and assessment of computational time and comparison of PSMA PET–derived parameters with serum prostate-specific antigen. Results: Automatic liver background calculation resulted in a mean relative difference of 0.74% (intraclass correlation coefficient [ICC], 0.996; 95%CI, 0.989;0.998) compared with METAVOL. Intra- and interobserver variability analyses showed high agreement (all ICCs &gt; 0.990). Quantitative output parameters were compared for 68 lesions. Paired t testing showed no significant differences between the values obtained with the 2 software packages. The ICC estimates obtained for PSMA-TV, PSMA-TL, SUVmean, and SUVmax were 1.000 (95%CI, 1.000;1.000), 1.000 (95%CI, 1.000;1.000), 0.995 (95%CI, 0.992;0.997), and 0.999 (95%CI, 0.999;1.000), respectively. The first and second reads for intraobserver variability resulted in mean computational times of 13.63 min (range, 8.22–25.45 min) and 9.27 min (range, 8.10–12.15 min), respectively (P = 0.001). Highly significant correlations were found between serum prostate-specific antigen value and both PSMA-TV (r = 0.72, P &lt; 0.001) and PSMA-TL (r = 0.66, P = 0.002). Conclusion: Semiautomatic analyses of whole-body tumor burden in 68Ga-PSMA11 PET/CT is feasible. qPSMA is a robust software package that can help physicians quantify tumor load in heavily metastasized prostate cancer patients. ER -