Detection Efficacy of Hybrid <sup>68</sup>Ga-PSMA Ligand PET/CT in Prostate Cancer Patients with Biochemical Recurrence After Primary Radiation Therapy Defined by Phoenix Criteria

Molecular Imaging, a paper entitled: " 68 Ga-PSMA PET/CT in patients with recurrent prostate cancer after radical treatment: prospective results in 314 patients" was published by Caroli et al. [1]. The study was based on a prospective analysis performed in 314 patients affected by prostate cancer who underwent 68 Ga-PSMA PET/CT for the biochemical recurrence of disease. Patients with a very early biochemical recurrence (PSA > 0.2 ng/mL) and with a negative/doubtful Choline PET/CT were included. By analyzing the characteristics of the tumor (i.e T-stage, N-stage, PSA value and Gleason score), the authors found that 68 Ga-PSMA PET/CT positivity was correlated only with the PSA level, without showing any relationship with the other known biological characteristics of aggressiveness. However, the authors confirmed that 68 Ga-PSMA PET/CT is more accurate for PCa restaging than other currently used PET radiotracers. The correlations among 68 Ga-PSMA PET/CT, Choline PET/CT, clinical tumor variables and hormonal therapy are extremely important in order to understand the appropriateness of these imaging modalities in prostate cancer patients. Clinical features, such as clinical stage, PSA level and Gleason score are usually used for the stratification of the prognosis and therapeutic management of prostate cancer patients. Advanced clinical stage and high Gleason score are

supporting

confidence: 80%

“…Conversely, Giovacchini et al [3] did not find any correlation between 11 C-Choline positivity and Gleason score, at multivariate analysis. Similarly, any correlation between the tumor differentiation and 68 Ga-PSMA has been demonstrated [4,5].…”

mentioning

confidence: 95%

Prostate cancer imaging: when the game gets tough, the hard one gets done!

Evangelista

Sepulcri

Maruzzo

2018

“…Afshar-Oromieh et al used two different protocols: in the first protocol, first two nuclear medicine physicians evaluated the data separately and afterwards together [29], and another protocol where two nuclear medicine physicians together with an assistant radiology physician supervised by a board-certified radiology physician evaluated the image series and a board-certified nuclear medicine physician reevaluated the patients PSMA PET/CT [10]. In two separate studies, authors have evaluated the interreader variability of a nuclear medicine physician and a radiologist and compared the results with consensus finding [9,30]. A detailed description of the differences in reading between the physicians is not documented in the studies cited here.…”

Section: Interobserver Variabilitymentioning

confidence: 99%

Interobserver variability, detection rate, and lesion patterns of 68Ga-PSMA-11-PET/CT in early-stage biochemical recurrence of prostate cancer after radical prostatectomy

Miksch

Bottke

Krohn

et al. 2020

Purpose 68 Ga-PSMA-11-PET/CT is increasingly used in early-stage biochemical recurrence of prostate cancer to detect potential lesions for an individualized radiotherapy concept. However, subtle findings especially concerning small local recurrences can still be challenging to interpret and are prone to variability between different readers. Thus, we analyzed interobserver variability, detection rate, and lesion patterns systematically in a homogeneous patient population with low-level biochemical recurrence. Methods We analyzed 68 Ga-PSMA-11-PET/CTs in 116 patients with status post-prostatectomy and PSA levels up to 0.6 ng/ml. None of them received ADT or radiotherapy beforehand. Images were interpreted and blinded by two nuclear medicine physicians (R1 and R2). Findings were rated using a 5-point scale concerning local recurrence, lymph nodes, bone lesions, and other findings (1: definitely benign, 2: probably benign, 3: equivocal, 4: probably malignant, 5: definitely malignant). In findings with substantial discrepancies of 2 or more categories and/or potentially leading to differences in further patient management, a consensus reading was done with a third reader (R3). Interobserver agreement was measured by Cohens Kappa analysis after sub-categorizing our classification system to benign (1 + 2), equivocal (3), and malignant (4 + 5). Time course of PSA levels after salvage treatment of patients rated as positive (4 + 5) was analyzed. Results The overall detection rate (categories 4 and 5) was 50% (R1/R2, 49%/51%) and in the PSA subgroups 0-0.2 ng/ml, 0.21-0.3 ng/ml, and 0.31-0.6 ng/ml 24%/27%, 57%/57%, and 65%/68%, respectively. Local recurrence was the most common lesion manifestation followed by lymphatic and bone metastases. The overall agreement in the Cohens Kappa analysis was 0.74 between R1 and R2. For local, lymphatic, and bone sites, the agreement was 0.76, 0.73, and 0.58, respectively. PSA levels of PSMA PET/CT-positive patients after salvage treatment decreased in 75% (27/36) and increased in 25% (9/36). A decrease of PSA, although more frequent in patients with imaging suggesting only local tumor recurrence (86%, 18/21), was also observed in 67% (10/15) of patients with findings of metastatic disease. Conclusions In a highly homogeneous group of prostate cancer patients with early-stage biochemical recurrence after radical prostatectomy, we could show that 68 Ga-PSMA-11-PET/CT has a good detection rate of 50% which is in accordance with literature, with clinically relevant findings even in patients with PSA < 0.21 ng/ml. The interobserver variability is low, particularly concerning assessment of local recurrences and lymph nodes. Therefore, PSMA-PET/CT is a robust diagnostic modality in this patient group for therapy planning.Jonathan Miksch and Dirk Bottke are shared first authors.

“…A variety of closely related compounds are under investigation [29]. Retrospective studies have suggested a high sensitivity of PET using 68 Ga-PSMA ligands in early restaging of prostate cancer but, as with other PET tracers, their value in primary tumour staging is yet to be determined, especially in patients with high-risk disease [30, 31]. Moreover, large prospective studies are required to confirm their imaging performance and clinical impact.…”

Section: Psma and Somatostatin Receptor Imaging And Therapy: High Thrmentioning

confidence: 99%

Highlights lecture EANM 2016: “Embracing molecular imaging and multi-modal imaging: a smart move for nuclear medicine towards personalized medicine”

Aboagye

Kraeber-Bodéré

2017

The 2016 EANM Congress took place in Barcelona, Spain, from 15 to 19 October under the leadership of Prof. Wim Oyen, chair of the EANM Scientific Committee. With more than 6,000 participants, this congress was the most important European event in nuclear medicine, bringing together a multidisciplinary community involved in the different fields of nuclear medicine. There were over 600 oral and 1,200 poster or e-Poster presentations with an overwhelming focus on development and application of imaging for personalized care, which is timely for the community. Beyond FDG PET, major highlights included progress in the use of PSMA and SSTR receptor-targeted radiopharmaceuticals and associated theranostics in oncology. Innovations in radiopharmaceuticals for imaging pathologies of the brain and cardiovascular system, as well as infection and inflammation, were also highlighted. In the areas of physics and instrumentation, multimodality imaging and radiomics were highlighted as promising areas of research.