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

Abstract

(1) Background: Prostate-specific membrane antigen (PSMA)-derived tumour volume (PSMA-TV) and total lesion PSMA (TL-PSMA) from PSMA PET/CT scans are promising biomarkers for assessing treatment response in prostate cancer (PCa). Currently, it is unclear whether different software tools for assessing PSMA-TV and TL-PSMA produce comparable results. (2) Methods: 68Ga-PSMA PET/CT scans from n = 21 patients with castration-resistant PCa (CRPC) receiving chemotherapy were identified from our single-centre database. PSMA-TV and TL-PSMA were calculated with Syngo.via (Siemens) as well as the freely available Beth Israel plugin for FIJI (Fiji Is Just ImageJ) before and after chemotherapy. While statistical comparability was illustrated and quantified via Bland-Altman diagrams, the clinical agreement was estimated by matching PSMA-TV, TL-PSMA and relative changes of both variables during chemotherapy with changes in serum PSA (ΔPSA) and PERCIST (Positron Emission Response Criteria in Solid Tumors). (3) Results: Comparing absolute PSMA-TV and TL-PSMA as well as Bland–Altman plotting revealed a good statistical comparability of both software algorithms. For clinical agreement, classifying therapy response did not differ between PSMA-TV and TL-PSMA for both software solutions and showed highly positive correlations with BR. (4) Conclusions: due to the high levels of statistical and clinical agreement in our CRPC patient cohort undergoing taxane chemotherapy, comparing PSMA-TV and TL-PSMA determined by Syngo.via and FIJI appears feasible.

Molecular imaging and biochemical response assessment after a single cycle of [225Ac]Ac-PSMA-617/[177Lu]Lu-PSMA-617 tandem therapy in mCRPC patients who have progressed on [177Lu]Lu-PSMA-617 monotherapy

“…Comparing the TLP and MTV values before tandem therapy, a high correlation ( r = 0.99 with p < 0.01) was observed as both reflect the total tumour burden. In assessing response, TLP and MTV provided a concordance of 100%, which is in line with the results of Hartrampf et al 34 . No correlation between pre-therapeutic TLP or MTV and PSA was noted in our cohort ( r = 0.03 with p = 0.90 and r = 0.11 with p = 0.67, respectively).…”

Concordance between Response Assessment Using Prostate-Specific Membrane Antigen PET and Serum Prostate-Specific Antigen Levels after Systemic Treatment in Patients with Metastatic Castration Resistant Prostate Cancer: A Systematic Review and Meta-Analysis

“…(3) volumetric measurements can be reproducibly performed using commercially available software [20]; and (4) tumor volumetry on PET have achieved encouraging results in different cancers [33,34]. Nevertheless, the biologic meaning of each PSMA response parameter is not fully understood.…”

“…Of these article, 35 were selected for full-text, among which 25 were excluded due to the following reasons: (1) not metastatic CRPC (n = 10); (2) did not assess response on PSMA PET (n = 4); (3) comparison between PSA and PSMA PET responses dichotomized to response vs. non-response not possible (n = 10); and (4) focused on the flare phenomenon (n = 1). Ultimately, ten studies were included in our meta-analysis [15][16][17][18][19][20][21][22][23][24].…”

“…The overall quality of the studies was considered good (Figure 2). Regarding the patient selection domain, three studies had unclear risk of bias as these studies were retrospectively designed and it was not clear whether patients were consecutively enrolled [20,23,24]. Regarding the index test domain, there was unclear risk of bias in one study because the definition of PET response criterion was unclear [16].…”

“…A baseline PSMA PET is also highly recommended in patients with CRPC for accurate assessing of disease extent (i.e., non-metastatic, oligometastatic vs. polymetastatic) [13] and appropriate selection of therapeutic strategy including metastasis-derived therapy or systemic treatment [14]. Based on this, the notion of PSMA PET being used for response assessment has gained interest in recent years as shown in multiple recent papers that have used PSMA PET/CT or PET/magnetic resonance imaging (MRI) for this purpose [15][16][17][18][19][20][21][22][23][24], in proposals for standardized PSMA PET progression criteria [7], and in the consensus statement by the European Association of Urology (EAU) and European Association of Nuclear Medicine (EANM) in 2020 [8]. Currently available literature on PSMA PET response mainly evaluates its concordance with PSA response, whereas only a few studies investigated its direct association with survival [15][16][17][18][19][20][21][22][23][24].…”