Dataset Information

False Positive Findings of [¹⁸F]PSMA-1007 PET/CT in Patients After Radical Prostatectomy with Undetectable Serum PSA Levels.

ABSTRACT:

Background

PET-CT using prostate-specific membrane antigen (PSMA)-targeting radiopharmaceuticals labeled with ⁶⁸Ga or ¹⁸F has emerged as the most sensitive staging tool in prostate cancer (PC). Nonetheless, the occurrence of false positive (FP) findings presents a major concern of this approach. In this prospective study, we investigated the frequency and pattern of false-positive findings of [¹⁸F]PSMA-1007 PET/CT in patients after radical prostatectomy with undetectable serum PSA levels. Any discrete non-physiological accumulation of [¹⁸F]PSMA-1007 in this population is by definition FP.

Methods

Seventeen men after radical prostatectomy, whose serum PSA levels were <0.05 ng/mL at 2-24 months after surgery were prospectively recruited. PET/CT was acquired at both 1 and 2 h after injection of [¹⁸F]PSMA-1007.

Findings

Three studies (18%) were interpreted as completely normal. Thirty-five foci of "non-physiological" uptake were observed in the remaining 14 (82%) patients, including a single skeletal focus in four patients, multiple skeletal foci in five patients and soft tissue uptake in eight, including in a desmoid tumor and in pelvic lymphocele. The SUV_max of all lesions was in the range of 1-7, except for the desmoid tumor which measured 12.7. All foci were visible in both the 1- and the 2 h studies, presenting a minor (<10%), statistically insignificant increase of SUV_max during this time-interval.

Interpretation

FP [¹⁸F]PSMA-1007-avid foci are found in about 80% of patients with undetectable serum PSA levels. Thus, focal uptake of [¹⁸F]PSMA-1007 outside its physiological distribution is not a categorical sign of metastasis and can arise from non-specific uptake of the ligand. The interpretation of [¹⁸F]PSMA-1007 PET/CT studies should always consider the clinical context, and lesions with SUV_max < 7 are suspicious for FP.

SUBMITTER: Orevi M

PROVIDER: S-EPMC9263625 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:18F-labeled prostate-specific membrane antigen (PSMA)-ligand PET has several principal advantages over 68Ga-PSMA-11. The purpose of this retrospective study was to evaluate the frequency of non-tumor-related uptake and the detection efficacy comparing 68Ga-PSMA-11 PET/CT and 18F-PSMA-1007 PET/CT in recurrent prostate cancer (PC) patients. Methods: The study included 102 patients with biochemically recurrent PC after radical prostatectomy undergoing 18F-PSMA-1007 PET/CT imaging. On the basis of various clinical variables, patients with corresponding 68Ga-PSMA-11 PET/CT scans were matched. All PET/CT scans (n = 204) were reviewed by 1 nuclear medicine physician. First, all PET-positive lesions were noted. Then, lesions suspected of being recurrent PC were differentiated from lesions attributed to a benign origin on the basis of known pitfalls and information from CT. For each region, the SUVmax of the lesion with the highest PSMA-ligand uptake was noted. Detection rates were determined, and SUVmax was compared separately for 68Ga-PSMA-11 and 18F-PSMA-1007. Results: In total, 18F-PSMA-1007 PET and 68Ga-PSMA-11 PET revealed 369 and 178 PSMA-ligand-positive lesions, respectively. 18F-PSMA-1007 PET revealed approximately 5 times more lesions attributed to a benign origin than did 68Ga-PSMA-11 PET (245 vs. 52 lesions, respectively). The benign lesions most frequently observed were ganglia, unspecific lymph node, and bone lesions, at a rate of 43%, 31%, and 24% for 18F-PSMA-1007 PET and 29%, 42%, and 27% for 68Ga-PSMA-11 PET, respectively. The SUVmax of lesions attributed to a benign origin was significantly higher (P < 0.0001) for 18F-PSMA-1007 PET. Further, a similar number of lesions was attributed to recurrent PC (124/369 for 18F-PSMA-1007 PET and 126/178 for 68Ga-PSMA-11 PET). Conclusion: The number of lesions with increased PSMA-ligand uptake attributed to a benign origin is considerably higher for 18F-PSMA-1007 PET than for 68Ga-PSMA-11 PET. This finding indicates the need for sophisticated reader training emphasizing known pitfalls and reporting within the clinical context.

Project description:AimDespite increasing use for the detection of biochemically recurrent prostate cancer (rPC), the diagnostic accuracy of positron emission tomography/computed tomography (PET/CT) with [18F]PSMA-1007 remains only partially investigated. The aim of this study was to determine the sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) for PC-local recurrence and metastases on a per region basis.Materials and methodsOne hundred seventy-seven consecutive patients undergoing [18F]PSMA-1007 PET/CT for rPC were retrospectively analysed. Six body regions were defined: prostate fossa, pelvic lymph nodes (LN), retroperitoneal LN, supradiaphragmatic LN, bones, and soft tissue. A region was counted positive if at least one PSMA-positive lesion suspicious for PC was observed. Confirmation of a true-positive PSMA-avid lesion was defined as positive by histopathology, fall in serum prostate-specific antigen (PSA) (> 50%) after targeted therapy or confirmatory further CT, MRI, PET/CT, or bone scan imaging. Regions where additional imaging was able to confirm the absence of suspicious PC lesions or regions outside exclusively targeted RT with serum PSA decline (> 50%) were counted as true-negative regions. SE, SP, PPV, and NPV were calculated for all six regions.ResultsThe overall PET-positivity rate was 91%. Conclusive follow-up for affirmation or refutation of a PSMA-positive lesion was available for 81/152 patients on a per region basis. In this subgroup, overall sensitivity, specificity, PPV, and NPV were 95% (CI: 0.90-0.98), 89% (CI: 0.83-0.93), 86% (0.80-0.90), and 96% (CI: 0.92-0.98), respectively. On a per region basis, PPV was 97% (CI: 0.83-0.99) for local recurrence, 93% (CI: 0.78-0.98) for pelvic LN, 87% (CI: 0.62-0.96) for retroperitoneal LN, 82% (CI: 0.52-0.95) for supradiaphragmatic LN, and 79% (0.65-0.89) for bone lesions. The number of solid organ metastases (n = 6) was too small for an accurate statistical analysis.ConclusionThe known high PET-positivity rate of [18F]PSMA-1007 PET/CT in rPC was confirmed, with corresponding high (> 90%) sensitivity and NPV on a per region basis. However, overall PPV was limited (86%), particularly for bone lesions (79%), which are a potential diagnostic weaknesses when using this tracer.

Project description:BackgroundAccurate prostate cancer imaging is critical for patient management. Multiple studies have demonstrated superior diagnostic accuracy of [68Ga]-PSMA-11 PET/CT over conventional imaging for disease detection, with validated clinical and biochemical predictors of disease detection. More recently [18F]PSMA-1007 offers theoretical imaging advantages, but there is limited evidence of clinical and biochemical predictors of scan findings in the staging population. This study investigates the association of clinical variables with imaging characteristics among patients who underwent [18F]PSMA-1007 PET/CT for primary staging of men with histopathologically confirmed prostate carcinoma. A retrospective review of 194 consecutive patients imaged between May 2019 to May 2020 was performed. Association between imaging variables (presence and distribution of metastatic disease, primary tumour SUVmax) and clinical variables (EAU risk criteria) were assessed using descriptive statistics, logistic regression model and ROC analysis.ResultsThe median age, PSA level and ISUP grade were 70 years, 10 ng/mL and ISUP grade 3, respectively. There were 36.6% of patients with intermediate-risk and 60.8% of patients with high-risk disease. ISUP grade was associated with the presence of metastasis overall (p = 0.008) as well as regional nodal (p = 0.003), non-regional nodal (p = 0.041) and bone (p = 0.006) metastases. PSA level was associated with metastatic disease overall (p = 0.001), regional (p = 0.001) and non-regional nodal metastases (p = 0.004), but not with bone metastases (p = 0.087). There were too few visceral metastases for meaningful analysis. SUVmax of the primary prostatic tumour was associated with ISUP grade (p = 0.004), PSA level (p < 0.001) and AJCC stage (p = 0.034). PSA > 20 ng/mL and ISUP grade > 3 had a specificity of 85% (95% CI 78-91%) and 60% (95% CI 50-68%) and a sensitivity of 36% (95% CI 25-49%) and 62% (95% CI 49-74%), respectively, for detection of metastatic disease.ConclusionMetastatic disease according to [18F]PSMA-1007 PET/CT was associated with ISUP grade and PSA level. This is the largest study using [18F]PSMA-1007 PET/CT to confirm a positive correlation of PSA level, ISUP grade and stage with primary prostate tumour SUVmax.

Project description:BackgroundDelineation of PSMA-positive tumor volume on PET using PSMA-ligands is of highest clinical interest as changes of PSMA-PET/CT-derived whole tumor volume (WTV) have shown to correlate with treatment response in metastatic prostate cancer patients. So far, WTV estimation was performed on PET using 68Ga-labeled ligands; nonetheless, 18F-labeled PET ligands are gaining increasing importance due to advantages over 68Ga-labeled compounds. However, standardized tumor delineation methods for 18F-labeled PET ligands have not been established so far. As correlation of PET-based information and morphological extent in osseous and visceral metastases is hampered by morphological delineation, low contrast in liver tissue and movement artefacts, we correlated CT-based volume of lymph node metastases (LNM) and different PET-based delineation approaches for thresholding on 18F-PSMA-1007 PET.MethodsFifty patients with metastatic prostate cancer, 18F-PSMA-1007 PET/CT and non-bulky LNM (short-axis diameter ≥10mm) were included. Fifty LNM were volumetrically assessed on contrast-enhanced CT (volumetric reference standard). Different approaches for tumor volume delineation were applied and correlated with the reference standard: I) fixed SUV threshold, II) isocontour thresholding relative to SUVmax (SUV%), and thresholds relative to III) liver (SUVliver), IV) parotis (SUVparotis) and V) spleen (SUVspleen).ResultsA fixed SUV of 4.0 (r=0.807, r2 = 0.651, p<0.001) showed the best overall association with the volumetric reference. 55% SUVmax (r=0.627, r2 = 0.393, p<0.001) showed highest association using an isocontour-based threshold. Best background-based approaches were 60% SUVliver (r=0.715, r2 = 0.511, p<0.001), 80% SUVparotis (r=0.762, r2 = 0.581, p<0.001) and 60% SUVspleen (r=0.645, r2 = 0.416, p<0.001). Background tissues SUVliver, SUVparotis & SUVspleen did not correlate (p>0.05 each). Recently reported cut-offs for intraprostatic tumor delineation (isocontour 44% SUVmax, 42% SUVmax and 20% SUVmax) revealed inferior association for LNM delineation.ConclusionsA threshold of SUV 4.0 for tumor delineation showed highest association with volumetric reference standard irrespective of potential changes in PSMA-avidity of background tissues (e. g. parotis). This approach is easily applicable in clinical routine without specific software requirements. Further studies applying this approach for total tumor volume delineation are initiated.

Project description:ObjectiveTo evaluate the prediction performance of 18F-PSMA-1007 PET/CT and clinicopathologic characteristics on prostate cancer (PCa) risk stratification and distant metastatic prediction.Materials and methodsA retrospective analysis was performed on 101 consecutively patients with biopsy or radical prostatectomy proved PCa who underwent 18F-PSMA-1007 PET/CT. The semi-quantitative analysis provided minimum, maximum and mean standardized uptake (SUVmin, SUVmax and SUVmean) of PCa. Association between clinicopathologic characteristics (total prostate-specific antigen, tPSA and Gleason Score, GS) and PET/CT indexes were analyzed. The diagnostic performance of distant metastatic on PET/CT parameters, tPSA and GS was evaluated using logistic regression analyses. A path analysis was conducted to evaluate the mediating effect of tPSA level on the relation between semi-quantitative parameters of primary tumors and metastatic lesions.ResultsThe PET/CT parameters were all higher in high risk stratification subgroups (tPSA>20 ng/mL, GS ≥ 8, and tPSA>20 ng/mL and/or GS ≥ 8, respectively) with high sensitivity (86.89%, 90.16% and 83.61%, respectively). The SUVmax, tPSA and GS could effectively predict distant metastatic with high sensitivity of SUVmax (90.50%) compared with tPSA (57.14%) and GS (55.61%). With a cutoff value of 29.01ng/mL for tPSA, the detection rate of distant metastasis between low and high prediction tPSA group had statistical differences (50.00% vs. 76.60%, respectively; P = 0.006) which was not found on guideline tPSA level (P>0.05). 6/15 (40%) patients tPSA between 20ng/mL to 29.01ng/mL without distant metastases may change the risk stratification. Finally, tPSA had a partial mediating effect on SUVmax of primary tumors and metastases lesions.ConclusionThe 18F-PSMA-1007 PET/CT SUVmax has a higher sensitivity and can be an "imaging biomarker" for primary PCa risk stratification. The prediction tPSA level (29.01 ng/mL) is more conducive to the assessment of distant metastasis and avoid unnecessary biopsy.

Dataset Information

False Positive Findings of [¹⁸F]PSMA-1007 PET/CT in Patients After Radical Prostatectomy with Undetectable Serum PSA Levels.

Background

Methods

Findings

Interpretation

Similar Datasets

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Tweets

Dataset Information

False Positive Findings of [18F]PSMA-1007 PET/CT in Patients After Radical Prostatectomy with Undetectable Serum PSA Levels.

Background

Methods

Findings

Interpretation

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

False Positive Findings of [¹⁸F]PSMA-1007 PET/CT in Patients After Radical Prostatectomy with Undetectable Serum PSA Levels.