Dataset Information

Optimization of Acquisition time of 68Ga-PSMA-Ligand PET/MRI in Patients with Local and Metastatic Prostate Cancer.

ABSTRACT: The aim of this optimization study was to minimize the acquisition time of 68Ga-HBED-CC-PSMA positron emission tomography/magnetic resonance imaging (PET/MRI) in patients with local and metastatic prostate cancer (PCa) to obtain a sufficient image quality and quantification accuracy without any appreciable loss.Twenty patients with PCa were administered intravenously with the 68Ga-HBED-CC-PSMA ligand (mean activity 99 MBq/patient, range 76-148 MBq) and subsequently underwent PET/MRI at, on average, 168 min (range 77-320 min) after injection. PET and MR imaging data were acquired simultaneously. PET acquisition was performed in list mode and PET images were reconstructed at different time intervals (1, 2, 4, 6, 8, and 10 min). Data were analyzed regarding radiotracer uptake in tumors and muscle tissue and PET image quality. Tumor uptake was quantified in terms of the maximum and mean standardized uptake value (SUVmax, SUVmean) within a spherical volume of interest (VOI). Reference VOIs were drawn in the gluteus maximus muscle on the right side. PET image quality was evaluated by experienced nuclear physicians/radiologists using a five-point ordinal scale from 5-1 (excellent-insufficient).Lesion detectability linearly increased with increasing acquisition times, reaching its maximum at PET acquisition times of 4 min. At this image acquisition time, tumor lesions in 19/20 (95%) patients were detected. PET image quality showed a positive correlation with increasing acquisition time, reaching a plateau at 4-6 min image acquisition. Both SUVmax and SUVmean correlated inversely with acquisition time and reached a plateau at acquisition times after 4 min.In the applied image acquisition settings, the optimal acquisition time of 68Ga-PSMA-ligand PET/MRI in patients with local and metastatic PCa was identified to be 4 min per bed position. At this acquisition time, PET image quality and lesion detectability reach a maximum while SUVmax and SUVmean do not change significantly beyond this time point.

SUBMITTER: Lutje S

PROVIDER: S-EPMC5068705 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Optimization of Acquisition time of 68Ga-PSMA-Ligand PET/MRI in Patients with Local and Metastatic Prostate Cancer.

Lütje Susanne S Blex Sebastian S Gomez Benedikt B Schaarschmidt Benedikt M BM Umutlu Lale L Forsting Michael M Jentzen Walter W Bockisch Andreas A Poeppel Thorsten D TD Wetter Axel A

PloS one 20161018 10

<h4>Objective</h4>The aim of this optimization study was to minimize the acquisition time of 68Ga-HBED-CC-PSMA positron emission tomography/magnetic resonance imaging (PET/MRI) in patients with local and metastatic prostate cancer (PCa) to obtain a sufficient image quality and quantification accuracy without any appreciable loss.<h4>Methods</h4>Twenty patients with PCa were administered intravenously with the 68Ga-HBED-CC-PSMA ligand (mean activity 99 MBq/patient, range 76-148 MBq) and subsequen ...[more]

PMID: 27755548

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Project description:PURPOSE:The first aim of this study was to evaluate 68Ga-PSMAHBED-CC conjugate 11 positron emission tomography (PSMA PET) parameters for assessment of response to 177Lu-PSMA-617 radioligand therapy (RLT) in patients with metastatic castration-resistant prostate cancer (mCRPC). The second aim was to investigate factors associated with overall survival (OS). METHODS:We retrospectively assessed mean standardized uptake values (SUVmean) and total tumor volumes (TTV) on PSMA PET in 38 of 55 mCRPC patients before and after RLT. PSA testing and PSMA PET/CT(MRI) imaging were performed during the 8 weeks before and the 6 weeks after RLT. PSMA PET and CT(MRI) images were reviewed separately according to the modified PET Response Criteria in Solid Tumors (mPERCIST) and RECIST1.1. The results were compared with PSA responses. Associations between OS and the RECIST evaluation and changes in SUVmean, TTV, and PSA, CRP, LDH, hemoglobin and ALP levels were determined in a univariable survival analysis. RESULTS:The median PSA level at the time of pretherapy PSMA PET/CT(MRI) was 60.8 ng/ml (IQR 15.4, 264.2 ng/ml). After RLT the median PSA level decreased by 44%, TTV by 45.1%, SUVmean by 25.8% and RECIST by 11.3%. A PSA response was seen in 18 patients (47.4%), stable disease in 12 (31.6%) and progressive disease in 8 (21.1%). Contrary to the changes in SUVmean and the RECIST evaluation, the change in TTV was significantly associated with PSA response (p?=?0.15, p?=?0.58, and p?<?0.001, respectively). After a median follow-up of 17 months (IQR 8.0, 24.2 months), 11 patients (28.9%) had died of their prostate cancer. The changes in both TTV and PSA levels were associated with OS (HR 1.001, 95% CI 1-1.003, p?=?0.04, and HR 1.004, 95% CI 1.001-1.008, p?=?0.01, respectively), while the changes in SUVmean and the RECIST evaluation were not. The pre-therapy CRP level was also associated with OS (HR 1.07, 95% CI 1.009-1.14, p?=?0.02). CONCLUSION:TTV on PSMA PET seems to be a reliable parameter for response assessment in mCRPC patients undergoing RLT and might overcome the limitations of RECIST in prostate cancer. Furthermore, the change in TTV was significantly associated with OS in our cohort.

Project description:Combined positron emission tomography (PET) and magnetic resonance imaging (MRI) targeting the prostate-specific membrane antigen (PSMA) with a 68Ga-labelled PSMA-analog (68Ga-PSMA-11) is discussed as a promising diagnostic method for patients with suspicion or history of prostate cancer. One potential drawback of this method are severe photopenic (halo-) artifacts surrounding the bladder and the kidneys in the scatter-corrected PET images, which have been reported to occur frequently in clinical practice. The goal of this work was to investigate the occurrence and impact of these artifacts and, secondly, to evaluate variants of the standard scatter correction method with regard to halo-artifact suppression.Experiments using a dedicated pelvis phantom were conducted to investigate whether the halo-artifact is modality-, tracer-, and/or concentration-dependent. Furthermore, 31 patients with history of prostate cancer were selected from an ongoing 68Ga-PSMA-11-PET/MRI study. For each patient, PET raw data were reconstructed employing six different variants of PET scatter correction: absolute scatter scaling, relative scatter scaling, and relative scatter scaling combined with prompt gamma correction, each of which was combined with a maximum scatter fraction (MaxSF) of MaxSF = 75% or MaxSF = 40%. Evaluation of the reconstructed images with regard to halo-artifact suppression was performed both quantitatively using statistical analysis and qualitatively by two independent readers.The phantom experiments did not reveal any modality-dependency (PET/MRI vs. PET/CT) or tracer-dependency (68Ga vs. 18F-FDG). Patient- and phantom-based data indicated that halo-artifacts derive from high organ-to-background activity ratios (OBR) between bladder/kidneys and surrounding soft tissue, with a positive correlation between OBR and halo size. Comparing different variants of scatter correction, reducing the maximum scatter fraction from the default value MaxSF = 75% to MaxSF = 40% was found to efficiently suppress halo-artifacts in both phantom and patient data. In 1 of 31 patients, reducing the maximum scatter fraction provided new PET-based information changing the patient's diagnosis.Halo-artifacts are particularly observed for 68Ga-PSMA-11-PET/MRI due to 1) the biodistribution of the PSMA-11-tracer resulting in large OBRs for bladder and kidneys and 2) inaccurate scatter correction methods currently used in clinical routine, which tend to overestimate the scatter contribution. If not compensated for, 68Ga-PSMA-11 uptake pathologies may be masked by halo-artifacts leading to false-negative diagnoses. Reducing the maximum scatter fraction was found to efficiently suppress halo-artifacts.

Project description:BackgroundAndrogen deprivation therapy (ADT) remains the standard therapy for patients with oligometastatic prostate cancer (OMPC). Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT)-based stereotactic body radiotherapy (SBRT) is emerging as an alternative option to postpone starting ADT and its associated side effects including the development of drug resistance. The aim of this study was to determine progression free-survival (PFS) and treatment failure free-survival (TFFS) after PSMA-PET/CT-based SBRT in OMPC patients. The efficacy and safety of single fraction radiosurgery (SFRS) and ADT delay were investigated.MethodsPatients with ≤5 metastases from OMPC, with/without ADT treated with PSMA-PET/CT-based SBRT were retrospectively analyzed. PFS and TFFS were primary endpoints. Secondary endpoints were local control (LC), overall survival (OS) and ADT-free survival (ADTFS).ResultsFifty patients with a total of 75 metastases detected by PSMA-PET/CT were analyzed. At the time of SBRT, 70% of patients were castration-sensitive. Overall, 80% of metastases were treated with SFRS (median dose 20 Gy, range: 16-25). After median follow-up of 34 months (range: 5-70) median PFS and TFFS were 12 months (range: 2-63) and 14 months (range: 2-70), respectively. Thirty-two (64%) patients had repeat oligometastatic disease. Twenty-four (48%) patients with progression underwent second SBRT course. Two-year LC after SFRS was 96%. Grade 1 and 2 toxicity occurred in 3 (6%) and 1 (2%) patients, respectively. ADTFS and OS rates at 2-years were 60.5% and 100%, respectively. In multivariate analysis, TFFS significantly improved in patients with time to first metastasis (TTM) >36 months (p = 0.01) and PSA before SBRT ≤1 ng/ml (p = 0.03).ConclusionFor patients with OMPC, SBRT might be used as an alternative to ADT. This way, the start/escalation of palliative ADT and its side effects can be deferred. Metastases treated with PSMA-PET/CT-based SFRS reached excellent LC with minimal toxicity. Low PSA levels and longer TTM predict elongated TFFS.

Project description:BACKGROUNDFocal radiation therapy has gained of interest in treatment of patients with primary prostate cancer (PCa). The question of how to define the intraprostatic boost volume is still open. Previous studies showed that multiparametric MRI (mpMRI) or PSMA PET alone could be used for boost volume definition. However, other studies proposed that the combined usage of both has the highest sensitivity in detection of intraprostatic lesions. The aim of this study was to demonstrate the feasibility and to evaluate the tumour control probability (TCP) and normal tissue complication probability (NTCP) of radiation therapy dose painting using 68Ga-HBED-CC PSMA PET/CT, mpMRI or the combination of both in primary PCa.METHODSTen patients underwent PSMA PET/CT and mpMRI followed by prostatectomy. Three gross tumour volumes (GTVs) were created based on PET (GTV-PET), mpMRI (GTV-MRI) and the union of both (GTV-union). Two plans were generated for each GTV. Plan95 consisted of whole-prostate IMRT to 77 Gy in 35 fractions and a simultaneous boost to 95 Gy (Plan95PET/Plan95MRI/Plan95union). Plan80 consisted of whole-prostate IMRT to 76 Gy in 38 fractions and a simultaneous boost to 80 Gy (Plan80PET/Plan80MRI/Plan80union). TCPs were calculated for GTV-histo (TCP-histo), which was delineated based on PCa distribution in co-registered histology slices. NTCPs were assessed for bladder and rectum.RESULTSDose constraints of published protocols were reached in every treatment plan. Mean TCP-histo were 99.7% (range: 97%-100%) and 75.5% (range: 33%-95%) for Plan95union and Plan80union, respectively. Plan95union had significantly higher TCP-histo values than Plan95MRI (p?=?0.008) and Plan95PET (p?=?0.008). Plan80union had significantly higher TCP-histo values than Plan80MRI (p?=?0.012), but not than Plan80PET (p?=?0.472). Plan95MRI had significantly lower NTCP-rectum than Plan95union (p?=?0.012). No significant differences in NTCP-rectum and NTCP-bladder were observed for all other plans (p?>?0.05).CONCLUSIONSIMRT dose escalation on GTVs based on mpMRI, PSMA PET/CT and the combination of both was feasible. Boosting GTV-union resulted in significantly higher TCP-histo with no or minimal increase of NTCPs compared to the other plans.

Project description:OBJECTIVES:The aim of this study was the validation of a recently established comprehensive and compact prediction model for 68Ga-PSMA-11-ligand positron-emission tomography (PET) positivity with an independent subsequent patient series. METHODS:A total of 292 consecutive patients with early biochemical recurrence after radical prostatectomy and PSA values between 0.2 and 1 ng/ml who underwent 68Ga-PSMA-11-ligand PET/computed tomography (CT) between January 2016 and June 2017 were retrospectively included. The cohort was divided into a very low PSA value (0.2-0.5 ng/ml, n = 151) and a low PSA value (> 0.5-1 ng/ml, n = 141) subgroup. First, pre-test positivity probabilities for each patient were calculated according to the previously published comprehensive prediction model using all clinical variables (PSA value, ISUP grade group, T- and N-stage, patient under androgen deprivation therapy (ADT), previous radiation therapy) and the compact model using just the most predictive factors PSA value, ADT, and grade group. Then, all 68Ga-PSMA-11-ligand PET/CTs were analysed by one experienced nuclear medicine physician, and the results were correlated to the calculated pre-test probabilities. RESULTS:In the very low PSA value subgroup, mean pre-test probability for positive findings in 68Ga-PSMA-11-ligand PET/CT was 57% (95% CI 55-60%) according to the compact model and 59% (95% CI 56-61%) according to the comprehensive model. In the low PSA value subgroup, mean pre-test probability was 72% (95% CI 70-74%) in the compact model and 74% (95% CI 72-76%) in the comprehensive model. After image analysis, 59% (89/151) of the patients in the very low PSA value subgroup revealed positive imaging findings. Seventy-nine percent (112/141) of the patients in the low PSA value subgroup presented with positive findings in the 68Ga-PSMA-11-ligand PET/CT. The accuracy (AUC) of the prediction models was 0.71 (95% CI 0.65-0.78) for the compact model and 0.74 (95% CI 0.68-0.80) for the comprehensive model. CONCLUSION:External validation of the recently proposed prediction models showed a high concordance of the calculated pre-test probabilities and actual 68Ga-PSMA-11-ligand PET/CT findings in the validation cohort confirming the prediction models' ability to determine the presence of a positive lesion at 68Ga-PSMA-11-ligand PET. However, the predictive accuracy of the nomogram itself is suboptimal and should be used with caution. Furthermore, the model's generalizability may be hampered due to the study design (in-house validation). Nevertheless, given the limited health resources and the costs of hybrid imaging techniques, prediction models might be a benefit in patient selection.

Dataset Information

Optimization of Acquisition time of 68Ga-PSMA-Ligand PET/MRI in Patients with Local and Metastatic Prostate Cancer.

Publications

Optimization of Acquisition time of 68Ga-PSMA-Ligand PET/MRI in Patients with Local and Metastatic Prostate Cancer.

Similar Datasets

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