qPSMA: Semiautomatic Software for Whole-Body Tumor Burden Assessment in Prostate Cancer Using ⁶⁸Ga-PSMA11 PET/CT

Abstract

Our aim was to introduce and validate qPSMA, a semiautomatic software package for whole-body tumor burden assessment in prostate cancer patients using 68 Ga-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 C11 languages. A bone mask based on CT and a normaluptake mask including organs with physiologic 68 Ga-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 SUV mean , and PSMA SUV max . Twenty 68 Ga-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. Intraand interobserver variability analyses showed high agreement (all ICCs . 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, SUV mean , and SUV max 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 5 0.001). Highly significant correlations were found between serum prostate-specific antigen value and both PSMA-TV (r 5 0.72, P , 0.001) and PSMA-TL (r 5 0.66, P 5 0.002). Conclusion: Semiautomatic analyses of whole-body tumor burden in 68 Ga-PSMA11 PET/CT is feasible. qPSMA is a robust software package that can help physicians quantify tumor load in heavily metastasized prostate cancer patients.

PSMA PET total tumor volume predicts outcome of patients with advanced prostate cancer receiving [177Lu]Lu-PSMA-617 radioligand therapy in a bicentric analysis

“…Due to the detection of both bone and soft tissue metastases, PSMA PET derived total tumor volume might be superior to bone scan derived total tumor volume [24]. Therefore, several approaches have been proposed to quantify the total tumor volume in PSMA PET: Gafita et al had proposed qPSMA, a software which segments all malignancy suspicious lesions in PSMA PET acquisitions based on a liver specific threshold [19]. Ferdinandus et al had proposed a method in which all lesions were segmented by employing an SUV threshold of 3 [12].…”

Metabolic Tumour Volume from PSMA PET/CT Scans of Prostate Cancer Patients during Chemotherapy—Do Different Software Solutions Deliver Comparable Results?

“…Going one step back, it is also unknown whether choosing different software solutions for determining metabolic tumour volume influences outcome. For calculation of PSMA-TV and TL-PSMA, different authors used different software (Syngo.via, METAVOL, LifeX or custom-made programs) and currently it is unclear whether their results are seamlessly comparable [11][12][13][14]. To address these issues, we analysed pre-and post-therapeutic 68 Ga-PSMA PET/CT scans of PCa patients receiving chemotherapy -first, with Syngo.via and afterwards with the FIJI algorithm.…”

“…However, a variety of software algorithms delivers metabolic tumour volume markers such as PSMA-TV and TL-PSMA. Accordingly, studies examining metabolic tumour volume derived from PSMA PET/CT used different software tools [11][12][13][14].…”

Interobserver agreement of [68Ga]Ga-PSMA-11 PET/CT images interpretation in men with newly diagnosed prostate cancer

“…One further refinement in the interpretation of [ 68 Ga]Ga-PSMA-11 PET/CT images is the integration of quantitative analysis to visual analysis. Recently, Gafita et al introduced a semi-automatic software to assist physicians to quantify tumour burden in cases of patients with metastatic PC [27]. In a future work, the added value of PSMA-ligand positive tumor volume (PSMA-TV), PSMA-ligand positive total lesion (PSMA-TL), PSMA-SUV mean and PSMA-SUV max as well as radiomics features will be investigated for the evaluation of intra-prostatic primary lesion.…”