scholarly journals Quantitative evaluation of PSMA PET imaging using a realistic anthropomorphic phantom and shell-less radioactive epoxy lesions

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Roberto Fedrigo ◽  
Dan J. Kadrmas ◽  
Patricia E. Edem ◽  
Lauren Fougner ◽  
Ivan S. Klyuzhin ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Pet Imaging ◽  
Cancer Metastasis ◽  
Segmentation Algorithm ◽  
Superior Performance ◽  
Metabolic Tumour Volume ◽  
Reconstruction Algorithms ◽  
Anthropomorphic Phantom ◽  
Focal Lesions ◽  
Psma Pet

Abstract Background Positron emission tomography (PET) with prostate specific membrane antigen (PSMA) have shown superior performance in detecting metastatic prostate cancers. Relative to [18F]fluorodeoxyglucose ([18F]FDG) PET images, PSMA PET images tend to visualize significantly higher-contrast focal lesions. We aim to evaluate segmentation and reconstruction algorithms in this emerging context. Specifically, Bayesian or maximum a posteriori (MAP) image reconstruction, compared to standard ordered subsets expectation maximization (OSEM) reconstruction, has received significant interest for its potential to reach convergence with minimal noise amplifications. However, few phantom studies have evaluated the quantitative accuracy of such reconstructions for high contrast, small lesions (sub-10 mm) that are typically observed in PSMA images. In this study, we cast 3 mm–16-mm spheres using epoxy resin infused with a long half-life positron emitter (sodium-22; 22Na) to simulate prostate cancer metastasis. The anthropomorphic Probe-IQ phantom, which features a liver, bladder, lungs, and ureters, was used to model relevant anatomy. Dynamic PET acquisitions were acquired and images were reconstructed with OSEM (varying subsets and iterations) and BSREM (varying β parameters), and the effects on lesion quantitation were evaluated. Results The 22Na lesions were scanned against an aqueous solution containing fluorine-18 (18F) as the background. Regions-of-interest were drawn with MIM Software using 40% fixed threshold (40% FT) and a gradient segmentation algorithm (MIM’s PET Edge+). Recovery coefficients (RCs) (max, mean, peak, and newly defined “apex”), metabolic tumour volume (MTV), and total tumour uptake (TTU) were calculated for each sphere. SUVpeak and SUVapex had the most consistent RCs for different lesion-to-background ratios and reconstruction parameters. The gradient-based segmentation algorithm was more accurate than 40% FT for determining MTV and TTU, particularly for lesions $$\le$$ ≤  6 mm in diameter (R2 = 0.979–0.996 vs. R2 = 0.115–0.527, respectively). Conclusion An anthropomorphic phantom was used to evaluate quantitation for PSMA PET imaging of metastatic prostate cancer lesions. BSREM with β = 200–400 and OSEM with 2–5 iterations resulted in the most accurate and robust measurements of SUVmean, MTV, and TTU for imaging conditions in 18F-PSMA PET/CT images. SUVapex, a hybrid metric of SUVmax and SUVpeak, was proposed for robust, accurate, and segmentation-free quantitation of lesions for PSMA PET.

scholarly journals Quantitative Evaluation of PSMA PET Imaging using a Realistic Anthropomorphic Phantom and Shell-less Radioactive Epoxy Lesions

2021 ◽  
Author(s):  
Roberto Fedrigo ◽  
Dan J. Kadrmas ◽  
Patricia E. Edem ◽  
Lauren Fougner ◽  
Ivan S. Klyuzhin ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Pet Imaging ◽  
Half Life ◽  
Cancer Metastasis ◽  
Segmentation Algorithm ◽  
Superior Performance ◽  
Metabolic Tumour Volume ◽  
Reconstruction Algorithms ◽  
Anthropomorphic Phantom ◽  
Psma Pet

Abstract Background Prostate specific membrane antigen (PSMA) PET images have shown superior performance in detecting metastatic prostate cancers. Relative to [18F]FDG PET images, PSMA PET images tend to visualize significantly higher-contrast focal lesions. We aim to evaluate segmentation and reconstruction algorithms in this emerging context. Specifically, Bayesian or maximum a posteriori (MAP) image reconstruction, compared to standard OSEM reconstruction, has received significant interest for its potential to reach convergence with minimal noise amplifications. However, few phantom studies have evaluated the quantitative accuracy of such reconstructions for high contrast, small lesions (sub-10mm) that are typically observed in PSMA images. In this study, we cast 3mm-16mm spheres using epoxy resin infused with a long half-life positron emitter (sodium-22; 22Na) to simulate prostate cancer metastasis. The anthropomorphic Probe-IQ phantom, which features a liver, bladder, lungs, and ureters, was used to model relevant anatomy. Dynamic PET acquisitions were acquired and images were reconstructed with OSEM (varying subsets and iterations) and BSREM (varying β parameters), and the effects on lesion quantitation were evaluated. Results The 22Na lesions were scanned against an aqueous solution containing fluorine-18 (18F) as the background. Due to the long half-life of 22Na compared to 18F, a separate scan with fully-decayed background was used to measure the ground truth radioactivity concentrations of the 22Na lesions. Regions-of-interest were drawn with MIM Software using 40% fixed threshold (40% FT) and a gradient segmentation algorithm (MIM’s PET Edge+). Recovery coefficients (RCs) (max, mean, peak, and newly defined “apex”) and metabolic tumour volume (MTV) were calculated for each sphere. SUVpeak and SUVapex had the most consistent RCs for different lesion-to-background ratios and reconstruction parameters. The gradient-based segmentation algorithm was more accurate than 40% FT for determining MTV, particularly for lesions \(\le\)6mm in diameter (R2 = 0.86–0.89 vs. R2 < 0.02, respectively). Conclusion An anthropomorphic phantom was used to evaluate quantitation for PSMA PET imaging of metastatic prostate cancer lesions. BSREM with β = 200–400 and OSEM with 1–2 iterations resulted in the most accurate SUV and MTV values for these imaging conditions. SUVapex, a hybrid metric of SUVmax and SUVpeak, was proposed for robust, accurate, and segmentation-free quantitation of lesions for PSMA PET.

scholarly journals Pattern of failure in prostate cancer previously treated with radical prostatectomy and post-operative radiotherapy: a secondary analysis of two prospective studies using novel molecular imaging techniques

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Lindsay S. Rowe ◽  
Stephanie Harmon ◽  
Adam Horn ◽  
Uma Shankavaram ◽  
Soumyajit Roy ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radical Prostatectomy ◽  
Pet Imaging ◽  
Biochemical Recurrence ◽  
Imaging Techniques ◽  
Specific Antigen ◽  
Definitive Treatment ◽  
Pattern Of Failure ◽  
Link Type ◽  
Psma Pet

Abstract Background Prostate Membrane Specific Antigen (PSMA) positron emission tomography (PET) and multiparametric MRI (mpMRI) have shown high accuracy in identifying recurrent lesions after definitive treatment in prostate cancer (PCa). In this study, we aimed to outline patterns of failure in a group of post-prostatectomy patients who received adjuvant or salvage radiation therapy (PORT) and subsequently experienced biochemical recurrence, using 18F-PSMA PET/CT and mpMRI. Methods PCa patients with biochemical failure post-prostatectomy, and no evident site of recurrence on conventional imaging, were enrolled on two prospective trials of first and second generation 18F-PSMA PET agents (18F-DCFBC and 18F-DCFPyL) in combination with MRI between October 2014 and December 2018. The primary aim of our study is to characterize these lesions with respect to their location relative to previous PORT field and received dose. Results A total of 34 participants underwent 18F-PSMA PET imaging for biochemical recurrence after radical prostatectomy and PORT, with 32/34 found to have 18F-PSMA avid lesions. On 18F-PSMA, 17/32 patients (53.1%) had metastatic disease, 8/32 (25.0%) patients had locoregional recurrences, and 7/32 (21.9%) had local failure in the prostate fossa. On further exploration, we noted 6/7 (86%) of prostate fossa recurrences were in-field and were encompassed by 100% isodose lines, receiving 64.8–72 Gy. One patient had marginal failure encompassed by the 49 Gy isodose. Conclusions 18F-PSMA PET imaging demonstrates promise in identifying occult PCa recurrence after PORT. Although distant recurrence was the predominant pattern of failure, in-field recurrence was noted in approximately 1/5th of patients. This should be considered in tailoring radiotherapy practice after prostatectomy. Trial registrationwww.clinicaltrials.gov, NCT02190279 and NCT03181867. Registered July 12, 2014, https://clinicaltrials.gov/ct2/show/NCT02190279 and June 8 2017, https://clinicaltrials.gov/ct2/show/NCT03181867.

64Cu-PSMA-BCH: A New Radiotracer for Delayed PET Imaging of Prostate Cancer

2021 ◽  
Author(s):  
Teli Liu ◽  
Chen Liu ◽  
Zhongyi Zhang ◽  
Ning Zhang ◽  
Xiaoyi Guo ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Pet Imaging ◽  
Radiation Dosimetry ◽  
Whole Body ◽  
Post Injection ◽  
Human Organ ◽  
Fine Needle ◽  
Fine Needle Aspirates ◽  
Psma Pet

Abstract PurposeDevelop a 64Cu labeled radiopharmaceutical targeting prostate specific membrane antigen (PSMA) and investigate its application for prostate cancer imaging. Methods64Cu-PSMA-BCH was prepared and investigated for stability, PSMA specificity and micro-PET imaging. With the approval of Ethics Committee of Beijing Cancer Hospital (No. 2017KT97), PET/CT imaging in 4 patients with suspected prostate cancer was performed and the radiation dosimetry was estimated. Then, PSMA PET-ultrasound image-guided biopsies were performed on 3 patients and the fine needle aspirates were further performed for autoradiography and immunohistochemistry analysis. Results64Cu-PSMA-BCH was prepared with high radiochemical yield and stability. In vivo study showed higher uptake in PSMA (+) 22Rv1 cells than PSMA (-) PC-3 cells (5.59±0.36 and 1.97±0.22 IA%/106 cells at 1 h). It accumulated in 22Rv1 tumor with increasing radioactivity uptake and T/N ratios from 1 h to 24 h post-injection. In patients with suspected prostate cancer, SUVmax and T/N ratios increased within 24 h post-injection. Compared with image at 1 h post-injection, more tumor lesions were detected at 4 h and 24 h post-injection. The human organ radiation dosimetry showed gallbladder wall was most critical, liver and kidneys were followed, and the whole-body effective dose was 0.0292 mSv/MBq. Two fine needle aspirates obtained by PET-ultrasound guided targeted biopsy showed high radioactive signal by autoradiography, with 100% PSMA expression in cytoplasm and 30% expression in nucleus. Conclusion64Cu-PSMA-BCH was PSMA specific and showed high stability in vivo with lower uptake in liver than 64Cu-PSMA-617. Biodistribution in mice and PCa patients showed similar profile compared with other PSMA ligands and it was safe with moderate effective dosimetry. The increased tumor uptake and T/N ratios by delayed imaging may facilitate the detection of small lesions and guiding targeted biopsies.

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

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.

Pictorial essay: normal variants, lesions, and pitfalls in 68Ga-PSMA PET imaging of prostate cancer

2018 ◽  
Vol 6 (3) ◽  
pp. 239-247 ◽  
Author(s):  
Alessandro Lambertini ◽  
Paolo Castellucci ◽  
Andrea Farolfi ◽  
Stefano Fanti
Keyword(s):  
Prostate Cancer ◽  
Pet Imaging ◽  
Normal Variants ◽  
Psma Pet ◽  
Pictorial Essay

scholarly journals Prostate-specific membrane antigen and fibroblast activation protein distribution in prostate cancer: preliminary data on immunohistochemistry and PET imaging

2021 ◽  
Author(s):  
Katharina Kessel ◽  
Robert Seifert ◽  
Matthias Weckesser ◽  
Martin Boegemann ◽  
Sebastian Huss ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Lymph Node ◽  
Pet Imaging ◽  
Fibroblast Activation Protein ◽  
Prostate Specific Membrane Antigen ◽  
Psma Pet ◽  
Node Metastases ◽  
Small Patient ◽  
Specific Membrane ◽  
Psma Expression

Abstract Introduction Fibroblast activation protein (FAP) has been recently presented as new imaging target for malignant diseases and offers high contrast to surrounding normal tissue. FAP tracer uptake has been reported in various tumor entities. The aim of this study was to compare FAP and Prostate-specific membrane antigen (PSMA) expression in primary prostate cancer employing histological analyses and PET imaging in two small patient collectives. Methods Two independent small patient collectives were included in this study. For cohort A, data of 5 prostate cancer patients and 3 patients with benign prostate hyperplasia were included. Patients with prostate cancer were initially referred for PSMA PET staging. Radical prostatectomy was performed in all patients and prostate specimen of patients and biopsies of healthy controls were available for further evaluation. Histological workup included HE and immunohistochemistry using PSMA Ab, FAP Ab. Cohort B consists of 6 Patients with diagnosed mCRPC and available PSMA as well as FAP PET. Results Patients with proven prostate cancer infiltration exhibited strong positivity for PSMA in both primary tumors and lymph node metastases while stainings for FAP were found positive in some cases, but not all (2/5). Controls with BPH presented moderate PSMA staining and in one case also with a positive FAP staining (1/3). PET imaging with FAP seemed to result in more precise results in case of low PSMA expression than PSMA-PET. Conclusions While PSMA staining intensity is a valid indicator of prostate cancer in both primary tumor and lymph node metastases, the expression of FAP seems to be heterogeneous but not necessarily linked to cancer-associated fibroblasts. It is also present in inflammation-associated myofibroblasts. Therefore, its ultimate role in prostate cancer diagnosis remains a subject of discussion.

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