Evaluation of Quantitative Ga-68 PSMA PET/CT Repeatability of Recurrent Prostate Cancer Lesions Using Both OSEM and Bayesian Penalized Likelihood Reconstruction Algorithms

Rationale: To formally determine the repeatability of Ga-68 PSMA lesion uptake in both relapsing and metastatic tumor. In addition, it was hypothesized that the BPL algorithm Q. Clear has the ability to lower SUV signal variability in the small lesions typically encountered in Ga-68 PSMA PET imaging of prostate cancer. Methods: Patients with biochemical recurrence of prostate cancer were prospectively enrolled in this single center pilot test-retest study and underwent two Ga-68 PSMA PET/CT scans within 7.9 days on average. Lesions were classified as suspected local recurrence, lymph node metastases or bone metastases. Two datasets were generated: one standard PSF + OSEM and one with PSF + BPL reconstruction algorithm. For tumor lesions, SUVmax was determined. Repeatability was formally assessed using Bland–Altman analysis for both BPL and standard reconstruction. Results: A total number of 65 PSMA-positive tumor lesions were found in 23 patients (range 1 to 12 lesions a patient). Overall repeatability in the 65 lesions was −1.5% ± 22.7% (SD) on standard reconstructions and −2.1% ± 29.1% (SD) on BPL reconstructions. Ga-68 PSMA SUVmax had upper and lower limits of agreement of +42.9% and −45.9% for standard reconstructions and +55.0% and −59.1% for BPL reconstructions, respectively (NS). Tumor SUVmax repeatability was dependent on lesion area, with smaller lesions exhibiting poorer repeatability on both standard and BPL reconstructions (F-test, p < 0.0001). Conclusion: A minimum response of 50% seems appropriate in this clinical situation. This is more than the recommended 30% for other radiotracers and clinical situations (PERCIST response criteria). BPL does not seem to lower signal variability in these cases.

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Evaluation of 68Ga-PSMA PET/CT Images Acquired with a Reduced Scan Time Duration in Prostate Cancer Patients using the Digital Biograph Vision

10.21203/rs.3.rs-30754/v1 ◽

2020 ◽

Author(s):

Manuel Weber ◽

Regina Hofferber ◽

Ken Herrmann ◽

Wolfgang Peter Fendler ◽

Maurizio Conti ◽

...

Keyword(s):

Prostate Cancer ◽

Image Reconstruction ◽

Diagnostic Performance ◽

Reconstruction Algorithm ◽

Reconstruction Algorithms ◽

Time Duration ◽

Acquisition Protocol ◽

Scan Time ◽

Psma Pet ◽

Pet Ct

Abstract Aim 68Ga-PSMA PET/CT allows for a superior detection of prostate cancer (PC) tissue, especially in context of a low tumor burden. Digital PET/CT bears the potential of reducing scan time duration / administered tracer activity due to, for instance, its higher sensitivity and improved time coincidence resolution. It might thereby expand 68Ga-PSMA PET/CT that is currently limited by 68Ge/68Ga-generator yield. Our aim was to clinically evaluate the influence of a reduced scan time duration in combination with different image reconstruction algorithms on the diagnostic performance. Methods Twenty PC patients (11 for biochemical recurrence, 5 for initial staging, 4 for metastatic disease) sequentially underwent 68Ga-PSMA PET/CT on a digital Siemens Biograph Vision. PET data were collected in continuous-bed-motion mode with a scan time duration of approximately 17 min (reference acquisition protocol) and 5 min (reduced acquisition protocol). 4 iterative reconstruction algorithms were applied using a time-of-flight (TOF) approach alone or combined with point-spread-function (PSF) correction, each with 2 or 4 iterations. To evaluate the diagnostic performance, the following metrics were chosen: (a) per-region detectability, (b) the tumor maximum and peak standardized uptake values (SUVmax and SUVpeak) and (c) image noise using the liver’s activity distribution. Results Overall, 98% of regions (91% of affected regions) were correctly classified in the reduced acquisition protocol independent of the image reconstruction algorithm. Two nodal lesions (each ≤ 4 mm) were not identified (leading to downstaging in 1/20 cases). Mean absolute percentage deviation of SUVmax (SUVpeak) was approximately 9% (6%) for each reconstruction algorithm. The mean image noise increased from 13–21% (4 iterations) and from 10–15% (2 iterations) for PSF + TOF and TOF images. Conclusions High agreement at 3.5-fold reduction of scan time in terms of per-region detection (98% of regions) and image quantification (mean deviation ≤ 10%) was demonstrated; however, small lesions can be missed in about 10% of patients leading to downstaging (T1N0M0 instead of T1N1M0) in 5% of patients. Our results suggest that a reduction of scan time duration or administered 68Ga-PSMA activities can be considered in metastatic patients, where missing small lesions would not impact patient management.

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Evaluation of Quantitative 68Ga-PSMA PET/CT Repeatability of Recurrent Prostate Cancer Lesions Using Both Standard and Bayesian Penalized Likelihood Reconstruction Algorithms

10.21203/rs.3.rs-68827/v1 ◽

2020 ◽

Author(s):

Mark J Roef ◽

Sjoerd Rijnsdorp ◽

Christel Brouwer ◽

Dirk Wyndaele ◽

Albert J. Arends

Keyword(s):

Prostate Cancer ◽

Metastatic Disease ◽

Penalized Likelihood ◽

Standardized Uptake Value ◽

Limits Of Agreement ◽

Early Relapse ◽

Psma Pet ◽

Pet Ct ◽

Lower Limits ◽

Signal Variability

Abstract Purpose To formally determine the repeatability of 68Ga-PSMA lesion uptake in both relapsing and metastatic tumour. In addition, it was hypothesized that the Bayesian penalized likelihood algorithm Q.Clear has the ability to lower SUV signal variability in the small lesions typically encountered in PET images of early relapse or early metastatic disease of prostate cancer.Methods Patients with biochemical recurrence of prostate cancer were prospectively enrolled in this pilot test-retest study and underwent two 68Ga-PSMA PET/CT scans within on average 7.9 days. Lesions were classified by two independent readers as suspected local recurrence, lymph node metastases or bone metastases. Two datasets were generated: one standard ordered subset expectation maximization (OSEM) reconstruction incorporating both time-of-flight (TOF) and point spread function (PSF) modelling, and one with the Bayesian penalized likelihood (BPL) reconstruction algorithm, called Q.Clear. For tumour lesions the maximum standardized uptake value (SUVmax) were determined. Repeatability was formally assessed using Bland-Altman analysis for both BPL and standard reconstruction. Results A total number of 65 PSMA-positive tumour lesions were found in 23 patients (range 1 to 12 lesions a patient). Another 7 patients had no detectable lesions and were therefore excluded. Overall repeatability in the 65 lesions was -1.5% ± 22.7% (SD) on standard reconstructions and -2.1% ± 29.1% (SD) on BPL reconstructions. The difference was not statistically significant. 68Ga-PSMA SUVmax had upper and lower limits of agreement of +42.9% and -45.9% for standard reconstructions and +55.0% and -59.1% for BPL reconstructions, respectively. Tumour SUVmax repeatability was dependent on lesion area, with smaller lesions exhibiting poorer repeatability on both standard and BPL reconstructions (F-test, p < 0.0001).Conclusion 68Ga-PSMA SUVmax has relatively high upper and lower limits of agreement for both standard and BPL reconstructions in the small lesions typical for early relapse or early metastatic disease of prostate cancer. BPL does not seem to lower signal variability in these cases.

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Evaluation of 68Ga-PSMA PET/CT Images Acquired with a Reduced Scan Time Duration in Prostate Cancer Patients using the Digital Biograph Vision

10.21203/rs.3.rs-30754/v2 ◽

2020 ◽

Author(s):

Manuel Weber ◽

Regina Hofferber ◽

Ken Herrmann ◽

Wolfgang Peter Fendler ◽

Maurizio Conti ◽

...

Keyword(s):

Prostate Cancer ◽

Cancer Patients ◽

Diagnostic Performance ◽

Reconstruction Algorithm ◽

Reconstruction Algorithms ◽

Time Duration ◽

Acquisition Protocol ◽

Scan Time ◽

Psma Pet ◽

Pet Ct

Abstract Aim: 68Ga-PSMA PET/CT allows for a superior detection of prostate cancer tissue, especially in the context of a low tumor burden. Digital PET/CT bears the potential of reducing scan time duration / administered tracer activity due to, for instance, its higher sensitivity and improved time coincidence resolution. It might thereby expand 68Ga-PSMA PET/CT that is currently limited by 68Ge/68Ga-generator yield. Our aim was to clinically evaluate the influence of a reduced scan time duration in combination with different image reconstruction algorithms on the diagnostic performance.Methods: Twenty prostate cancer patients (11 for biochemical recurrence, 5 for initial staging, 4 for metastatic disease) sequentially underwent 68Ga-PSMA PET/CT on a digital Siemens Biograph Vision. PET data were collected in continuous-bed-motion mode with a mean scan time duration of 16.7 min (reference acquisition protocol) and 4.6 min (reduced acquisition protocol). 4 iterative reconstruction algorithms were applied using a time-of-flight (TOF) approach alone or combined with point-spread-function (PSF) correction, each with 2 or 4 iterations. To evaluate the diagnostic performance, the following metrics were chosen: (a) per-region detectability, (b) the tumor maximum and peak standardized uptake values (SUVmax and SUVpeak) and (c) image noise using the liver’s activity distribution.Results: Overall, 98% of regions (91% of affected regions) were correctly classified in the reduced acquisition protocol independent of the image reconstruction algorithm. Two nodal lesions (each ≤4 mm) were not identified (leading to downstaging in 1/20 cases). Mean absolute percentage deviation of SUVmax (SUVpeak) was approximately 9% (6%) for each reconstruction algorithm. The mean image noise increased from 13% to 21% (4 iterations) and from 10% to 15% (2 iterations) for PSF+TOF and TOF images.Conclusions: High agreement at 3.5-fold reduction of scan time in terms of per-region detection (98 % of regions) and image quantification (mean deviation ≤ 10 %) was demonstrated; however, small lesions can be missed in about 10% of patients leading to downstaging (T1N0M0 instead of T1N1M0) in 5 % of patients. Our results suggest that a reduction of scan time duration or administered 68Ga-PSMA activities can be considered in metastatic patients, where missing small lesions would not impact patient management. Limitations include the small and heterogeneous sample size and the lack of follow-up.

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Detection of Lymph Node Metastases in Patients With Prostate Cancer: Comparing Conventional and Digital [18F]-fluorocholine PET-CT Using Histopathology as Reference

10.21203/rs.3.rs-552089/v1 ◽

2021 ◽

Author(s):

Mimmi Bjöersdorff ◽

Christopher Puterman ◽

Jenny Oddstig ◽

Jennifer Amidi ◽

Sophia Zackrisson ◽

...

Keyword(s):

Prostate Cancer ◽

Lymph Node ◽

High Risk ◽

Lymph Nodes ◽

Lymph Node Metastases ◽

Reconstruction Algorithms ◽

High Risk Prostate Cancer ◽

Pet Ct ◽

Risk Prostate Cancer ◽

Node Metastases

Abstract Background: Positron emission tomography-computed tomography (PET-CT) can be used to detect and stage metastatic lymph nodes in intermediate to high-risk prostate cancer. Improvements to hardware, such as digital technology, and to software, such as reconstruction algorithms, have recently been made. We compared the capability of detecting regional lymph node metastases using conventional and digital silicon photomultiplier (SiPM)-based PET-CT technology for [18F]-fluorocholine (FCH). Extended pelvic lymph node dissection (ePLND) histopathology was used as the reference method.Methods: Retrospectively, a consecutive series of patients with prostate cancer who had undergone staging with FCH PET-CT before ePLND were included. Images were obtained with either a conventional or a SiPM-based PET-CT and compared. FCH uptake in pelvic lymph nodes beyond the uptake in the mediastinal blood pool was considered to be abnormal.Results: One hundred eighty patients with intermediate or high-risk prostate cancer were examined using a conventional Philips Gemini PET-CT (n = 93) between 2015 and 2017 or a digital GE Discovery MI PET-CT (n = 87) from 2017 to 2018. Images that were obtained using the Philips Gemini PET-CT system showed 19 patients (20%) with suspected lymph node metastases compared with 40 patients (46%) using the GE Discovery MI PET-CT. Sensitivity, specificity, and positive and negative predictive value (PPV and NPV) were 0.30, 0.84, 0.47, and 0.72, respectively, for the Philips Gemini and 0.60, 0.58, 0.30, and 0.83, respectively for GE Discovery MI. Area under the curve (AUC) in a receiver operating characteristics (ROC) analysis was similar between the two PET-CT systems (0.58 and 0.58, P = 0.8).Conclusions: A marked difference in sensitivity and specificity was found for the different PET-CT systems, although similar overall diagnostic performance. This is probably due to differences in both hard- and software, including reconstruction algorithms, and should be considered when new technology is introduced.

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Evaluation of [68Ga]Ga-PSMA PET/CT Images Acquired with a Reduced Scan Time Duration in Prostate Cancer Patients using the Digital Biograph Vision

10.21203/rs.3.rs-30754/v3 ◽

2020 ◽

Author(s):

Manuel Weber ◽

Walter Jentzen ◽

Regina Hofferber ◽

Ken Herrmann ◽

Wolfgang Peter Fendler ◽

...

Keyword(s):

Prostate Cancer ◽

Image Reconstruction ◽

Cancer Patients ◽

Diagnostic Performance ◽

Reconstruction Algorithm ◽

Reconstruction Algorithms ◽

Time Duration ◽

Acquisition Protocol ◽

Scan Time ◽

Pet Ct

Abstract Aim: [68Ga]Ga-PSMA-11 PET/CT allows for a superior detection of prostate cancer tissue, especially in the context of a low tumor burden. Digital PET/CT bears the potential of reducing scan time duration / administered tracer activity due to, for instance, its higher sensitivity and improved time coincidence resolution. It might thereby expand [68Ga]Ga-PSMA-11 PET/CT that is currently limited by 68Ge/68Ga-generator yield. Our aim was to clinically evaluate the influence of a reduced scan time duration in combination with different image reconstruction algorithms on the diagnostic performance.Methods: Twenty prostate cancer patients (11 for biochemical recurrence, 5 for initial staging, 4 for metastatic disease) sequentially underwent [68Ga]Ga-PSMA-11 PET/CT on a digital Siemens Biograph Vision. PET data were collected in continuous-bed-motion mode with a mean scan time duration of 16.7 min (reference acquisition protocol) and 4.6 min (reduced acquisition protocol). 4 iterative reconstruction algorithms were applied using a time-of-flight (TOF) approach alone or combined with point-spread-function (PSF) correction, each with 2 or 4 iterations. To evaluate the diagnostic performance, the following metrics were chosen: (a) per-region detectability, (b) the tumor maximum and peak standardized uptake values (SUVmax and SUVpeak) and (c) image noise using the liver’s activity distribution.Results: Overall, 98% of regions (91% of affected regions) were correctly classified in the reduced acquisition protocol independent of the image reconstruction algorithm. Two nodal lesions (each ≤4 mm) were not identified (leading to downstaging in 1/20 cases). Mean absolute percentage deviation of SUVmax (SUVpeak) was approximately 9% (6%) for each reconstruction algorithm. The mean image noise increased from 13% to 21% (4 iterations) and from 10% to 15% (2 iterations) for PSF+TOF and TOF images.Conclusions: High agreement at 3.5-fold reduction of scan time in terms of per-region detection (98 % of regions) and image quantification (mean deviation ≤ 10 %) was demonstrated; however, small lesions can be missed in about 10% of patients leading to downstaging (T1N0M0 instead of T1N1M0) in 5 % of patients. Our results suggest that a reduction of scan time duration or administered [68Ga]Ga-PSMA-11 activities can be considered in metastatic patients, where missing small lesions would not impact patient management. Limitations include the small and heterogeneous sample size and the lack of follow-up.

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High negative predictive value of 68Ga PSMA PET-CT for local lymph node metastases in high risk primary prostate cancer with histopathological correlation

Cancer Imaging ◽

10.1186/s40644-019-0273-x ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 3

Author(s):

Labib Ataur Rahman ◽

Damacent Rutagengwa ◽

Peter Lin ◽

Michael Lin ◽

June Yap ◽

...

Keyword(s):

Prostate Cancer ◽

Lymph Node ◽

High Risk ◽

Radical Prostatectomy ◽

Lymph Node Metastases ◽

Pelvic Lymph Node Dissection ◽

Primary Prostate Cancer ◽

Psma Pet ◽

Pet Ct ◽

Node Metastases

Abstract Background Current guidelines highlight the importance of accurate staging in the management and prognostication of high risk primary prostate cancer. Conventional radiologic imaging techniques are insufficient to reliably detect lymph node metastases in prostate cancer. Despite promising results, there is limited published data on the diagnostic accuracy of PSMA PET-CT to assess local nodal metastases prior to radical prostatectomy. This study aims to assess the diagnostic efficacy of 68Ga PSMA PET-CT in local lymph node staging of high risk primary prostate cancer when compared to histopathological findings following radical prostatectomy with pelvic lymph node dissection. Methods We retrospectively analysed consecutive patients with high risk primary prostate cancer referred by urologists for primary staging PSMA PET-CT using a 68Ga-labeled PSMA ligand, Glu-NH-CO-NHLys-(Ahx)-[HBEDD-CC], from October 2015 to October 2017. The scans of patients who underwent radical prostatectomy with pelvic lymph node dissection were interpreted by the consensus reading of two experienced nuclear medicine physicians blinded to clinical and histopathological data. The contemporaneous records of the referring urologists were retrospectively reviewed for noteworthy unexpected PET findings that altered their personal preference for surgical management. Results Seventy-one patients were recruited and analysed. PSMA PET-CT showed findings compatible with local disease in 47 patients (66.2%), lymph node metastases in 10 patients (14.1%) and distant metastases in 14 patients (19.7%). Twenty-eight patients (twenty-seven of whom had local disease only) underwent surgery yielding 214 lymph nodes, all of which were negative on histopathological analysis. On a node-based analysis, 213 of 214 lymph nodes were accurately identified as negative for disease with a negative predictive value of 100%. 11 patients had unexpected PET findings contemporaneously documented by urologists to alter their preference for surgical management. Conclusions PSMA PET-CT appears to have a high negative predictive value for local lymph node metastases in high risk primary prostate cancer when compared to histopathological findings following radical prostatectomy with pelvic lymph node dissection.

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Evaluation of [68Ga]Ga-PSMA PET/CT images acquired with a reduced scan time duration in prostate cancer patients using the digital biograph vision

EJNMMI Research ◽

10.1186/s13550-021-00765-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Manuel Weber ◽

Walter Jentzen ◽

Regina Hofferber ◽

Ken Herrmann ◽

Wolfgang Peter Fendler ◽

...

Keyword(s):

Prostate Cancer ◽

Image Reconstruction ◽

Cancer Patients ◽

Diagnostic Performance ◽

Reconstruction Algorithm ◽

Reconstruction Algorithms ◽

Time Duration ◽

Acquisition Protocol ◽

Scan Time ◽

Pet Ct

Abstract Aim [68Ga]Ga-PSMA-11 PET/CT allows for a superior detection of prostate cancer tissue, especially in the context of a low tumor burden. Digital PET/CT bears the potential of reducing scan time duration/administered tracer activity due to, for instance, its higher sensitivity and improved time coincidence resolution. It might thereby expand [68Ga]Ga-PSMA-11 PET/CT that is currently limited by 68Ge/68Ga-generator yield. Our aim was to clinically evaluate the influence of a reduced scan time duration in combination with different image reconstruction algorithms on the diagnostic performance. Methods Twenty prostate cancer patients (11 for biochemical recurrence, 5 for initial staging, 4 for metastatic disease) sequentially underwent [68Ga]Ga-PSMA-11 PET/CT on a digital Siemens Biograph Vision. PET data were collected in continuous-bed-motion mode with a mean scan time duration of 16.7 min (reference acquisition protocol) and 4.6 min (reduced acquisition protocol). Four iterative reconstruction algorithms were applied using a time-of-flight (TOF) approach alone or combined with point-spread-function (PSF) correction, each with 2 or 4 iterations. To evaluate the diagnostic performance, the following metrics were chosen: (a) per-region detectability, (b) the tumor maximum and peak standardized uptake values (SUVmax and SUVpeak), and (c) image noise using the liver’s activity distribution. Results Overall, 98% of regions (91% of affected regions) were correctly classified in the reduced acquisition protocol independent of the image reconstruction algorithm. Two nodal lesions (each ≤ 4 mm) were not identified (leading to downstaging in 1/20 cases). Mean absolute percentage deviation of SUVmax (SUVpeak) was approximately 9% (6%) for each reconstruction algorithm. The mean image noise increased from 13 to 21% (4 iterations) and from 10 to 15% (2 iterations) for PSF + TOF and TOF images. Conclusions High agreement at 3.5-fold reduction of scan time in terms of per-region detection (98% of regions) and image quantification (mean deviation ≤ 10%) was demonstrated; however, small lesions can be missed in about 10% of patients leading to downstaging (T1N0M0 instead of T1N1M0) in 5% of patients. Our results suggest that a reduction of scan time duration or administered [68Ga]Ga-PSMA-11 activities can be considered in metastatic patients, where missing small lesions would not impact patient management. Limitations include the small and heterogeneous sample size and the lack of follow-up.

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