Performance Of Positron Emission Tomography Research Articles

Subject-aware PET Denoising with Contrastive Adversarial Domain Generalization.

Recent advances in deep learning (DL) have greatly improved the performance of positron emission tomography (PET) denoising performance. However, DL model performance can vary a lot across subjects, due to the large variability of the count levels and spatial distributions. A generalizable DL model that mitigates the subject-wise variations is highly expected toward a reliable and trustworthy system for clinical application. In this work, we propose a contrastive adversarial learning framework for subject-wise domain generalization (DG). Specifically, we configure a contrastive discriminator in addition to the UNet-based denoising module to check the subject-related information in the bottleneck feature, while the denoising module is adversarially trained to enforce the extraction of subject-invariant features. The sampled low-count realizations from the list-mode data are used as anchor-positive pairs to be close to each other, while the other subjects are used as negative samples to be distributed far away. We evaluated on 97 18F-MK6240 tau PET studies, each having 20 noise realizations with 25% fractions of events. Training, validation, and testing were implemented using 1400, 120, and 420 pairs of 3D image volumes in a subject-independent manner. The proposed contrastive adversarial DG demonstrated superior denoising performance than conventional UNet without subject-wise DG and cross-entropy-based adversarial DG.

Performance of Positron Emission Tomography at Diagnosis and Response Assessment in Low and Intermediate-Risk Nodular Lymphocyte Predominant Hodgkin Lymphoma

Background: Nodular lymphocyte predominant Hodgkin lymphoma (nLPHL) has different histology, clinical presentation, and outcomes than classical Hodgkin Lymphoma (cHL). Positron Emission Tomography (PET) plays an important role in staging and response assessment in cHL, but little is published about the use of PET to guide treatment in nLPHL. A better understanding of the clinical significance of PET response in nLPHL is critical for incorporating PET into prospective trials. Methods: Children's Oncology Group study AHOD03P1 (NCT00107198) enrolled patients with low-risk nLPHL and AHOD0031 (NCT00025259) enrolled patients with intermediate-risk cHL and nLPHL <22 years of age. AHOD03P1 patients with stage IA and >1 lymph node or stage IIA nLPHL were treated with 3 cycles of doxorubicin, vincristine, prednisone, and cyclophosphamide (AV-PC) chemotherapy, given every 21 days. Patients with a complete response (CR) based on anatomic response and qualitative reading (<mediastinal blood pool) of negative PET on central review did not receive radiation therapy while patients with <CR received 21-Gy involved field radiation therapy (IFRT). AHOD0031 patients with stages IB, IAE, IIB, IIAE, IIIA, IVA with or without bulk disease, and IA or IIA with bulk disease received 2 cycles of doxorubicin, bleomycin, vincristine, etoposide, prednisone and cyclophosphamide (ABVE-PC) followed by response evaluation. Slow early responders were randomized to an additional 2 cycles of ABVE-PC with or without 2 cycles of dexamethasone, etoposide, cisplatin and cytarabine (DECA) and all received IFRT. Rapid early responders (RERs) received 2 additional cycles of ABVE-PC. RERs with CR were randomized to IFRT or no further therapy. RER/non-CRs were non-randomly assigned to IFRT. PET scans from both trials available in the Imaging and Radiation Oncology Core (IROC) were retrospectively reviewed and assigned a score of 1-5 on the Deauville 5-point scale (5PS). Patients who did not have evaluable imaging due to either scans not performed, on CD-ROM and inaccessible, or poor quality, were excluded from this analysis. Three-year event-free survival (EFS) was analyzed by 5PS at end of therapy using the Kaplan Meier method. Results: AHOD03P1 enrolled 135 patients with low-risk nLPHL who received chemotherapy and AHOD0031 enrolled 96 patients with intermediate-risk nLPHL. PET imaging available for review at diagnosis in 99 low-risk patients, 92% 5PS=5, and 55 intermediate-risk patients, 98% 5PS=5. Median age 13.4 years (range 16.5), 84.9% male, 29.9% Stage I, 49.8% Stage II, 18.6% Stage III, and 1.7% Stage IV. After 3 cycles of chemotherapy, 106 low-risk patients had available PET scans, 5PS 1 n=50, 5PS 2 n=35, 5PS 3 n=11, 5PS 4 n=7, and 5PS 5 n=3. Three-year EFS for patients with end of chemotherapy 5PS was: 5PS 1 89.9% (95% CI 77.3-95.7%), 5PS 2 97.1% (95% CI 81.4-99.6%), 5PS 3 90.9% (95% CI 50.8-98.7%), 5PS 4 28.6% (95% CI 1.0-71.1%), 5PS 5 66.7% (95% CI 5.4-94.5%) p=0.0081. When categorized as PET negative (5PS 1-3) and PET positive (5PS 4-5), 3-year EFS was 92.6% (95% CI 85.2-96.4%) for PET negative and 45.0% (95% CI 10.6-75.3%) for PET positive patients, p=0.0036 (Figure 1A). Forty-nine intermediate-risk patients had available PET scans after 2 cycles of chemotherapy, 5PS 1 n=9, 5PS 2 n=26, 5PS 3 n=10, 5PS 4 n=3, and 5PS 5 n=1. Three-year EFS by interim response was: 5PS 1 88.9% (95% CI 43.3-98.4%), 5PS 2 96.0% (95% CI 74.8-99.4%), 5PS 3 100%, 5PS 4 100%, 5PS 5 0%, p<0.0001. Thirty-six patients had available PET scans after 4 cycles of chemotherapy, 5PS 1 n=20, 5PS 2 n=11, 5PS 3 n=3, 5PS 4 n=1, and 5PS 5 n=1. Three-year EFS by response after 4 cycles of chemotherapy: 5PS 1 95.0% (95% CI 69.5-99.3%), 5PS 2 100%, 5PS 3 100%, 5PS 4 100%, 5PS 5 0% p<0.0001. When divided into PET negative (5PS 1-3) and PET positive (5PS 4-5), 3-year EFS 97.0% (95% CI 80.4-99.6%) for PET negative and 50.0% (95% CI 0.6-91.0%) for PET positive patients after 4 cycles of chemotherapy, p=0.1449 (Figure 1B). Conclusions: At diagnosis, low and intermediate-risk nLPHL lesions are almost always PET avid with 5PS=5. PET response following 3 cycles of AV-PC chemotherapy is highly predictive of outcome in pediatric patients with low-risk nLPHL when considering 5PS=3 as PET negative. Intermediate-risk patients with negative PET following ABVE-PC achieved excellent outcomes. Whether PET maintains prognostic significance in patients with nLPHL treated with rituximab needs to be studied.

Diagnostic Performance of Positron Emission Tomography with Fibroblast-Activating Protein Inhibitors in Gastric Cancer: A Systematic Review and Meta-Analysis.

Various papers have introduced the use of positron emission tomography (PET) with [68Ga]Ga-radiolabeled fibroblast-activation protein inhibitor (FAPi) radiopharmaceuticals in different subtypes of gastric cancer (GC). Our aim was to assess the diagnostic performance of this novel molecular imaging technique in GC with a systematic review and meta-analysis. A straightforward literature search of papers concerning the diagnostic performance of FAP-targeted PET imaging was performed. Original articles evaluating this novel molecular imaging examination in both newly diagnosed GC patients and GC patients with disease relapse were included. The systematic review included nine original studies, and eight of them were also eligible for meta-analysis. The quantitative synthesis provided pooled detection rates of 95% and 97% for the assessment of primary tumor and distant metastases, respectively, and a pooled sensitivity and specificity of 74% and 89%, respectively, for regional lymph node metastases. Significant statistical heterogeneity among the included studies was found only in the analysis of the primary tumor detection rate (I2 = 64%). Conclusions: Beyond the limitations of this systematic review and meta-analysis (i.e., all the included studies were conducted in Asia, and using [18F]FDG PET/CT as a comparator of the index test), the quantitative data provided demonstrate the promising diagnostic performance of FAP-targeted PET imaging in GC. Nevertheless, more prospective multicentric studies are needed to confirm the excellent performances of FAP-targeted PET in this cluster of patients.

Diagnostic performance of positron emission tomography combined with computed tomography with 18F-PSMA-1007 for detecting local recurrence of prostate cancer after radical prostatectomy

In the situation of biochemical recurrence (BCR) of prostate cancer (PCa) it is important to distinguish between local recurrence in the prostate bed and systemic disease progression. Conventional imaging modalities have a limited role, especially in patients with low prostate specific antigen (PSA) levels. In recent years, the role of positron emission tomography combined with computed tomography (PET/CT) with PSMA-labeled ligands has grown, but there is currently no consensus on the role and effectiveness of the method in detecting local recurrence of the disease. The aim of the study was to analyze the diagnostic performance of 18F-PSMA‐1007 PET/CT in detecting local recurrence of prostate cancer. The study included 57 patients with BCR after radical prostatectomy, who underwent PET/CT with 18F-PSMA-1007 and according to its results there were no distant and/or regional metastases. Local recurrence was clinically verified in 53 (93.0%) patients. The sensitivity of PET/CT in detecting local recurrence was 58.5 %, specificity ‒ 75.0, positive predictive value ‒ 96.9, negative predictive value ‒ 12.0 %. According to multivariate analysis, only PSA level was significantly associated with truepositive PET/CT findings (p = 0.02). According to multivariate analysis, PSA level is an independent predictive factor of 18F-PSMA‐1007 PET/CT sensitivity in detecting local recurrence (p < 0.05). In the subgroup of patients with a low PSA level sensitivity was only 20.0 %. Therefore, a negative PET/CT scan at PSA level <0.5 ng/ml is not a reason for delay the initiation of salvage radiation therapy.

Evaluation of the Diagnostic Performance of Positron Emission Tomography/Magnetic Resonance for the Diagnosis of Liver Metastases.

The aim of this study was to compare the performance of positron emission tomography (PET)/magnetic resonance (MR) versus stand-alone PET and stand-alone magnetic resonance imaging (MRI) in the detection and characterization of suspected liver metastases. This multi-institutional retrospective performance study was approved by the institutional review boards and was Health Insurance Portability and Accountability Act compliant, with waiver of informed consent. Seventy-nine patients with confirmed solid extrahepatic malignancies who underwent upper abdominal PET/MR between February 2017 and June 2018 were included. Where focal hepatic lesions were identified, the likelihood of a diagnosis of a liver metastasis was defined on an ordinal scale for MRI, PET, and PET/MRI by 3 readers: 1 nuclear medicine physician and 2 radiologists. The number of lesions per patient, lesion size, and involved hepatic segments were recorded. Proof of metastases was based on histopathologic correlation or clinical/imaging follow-up. Diagnostic performance was assessed using sensitivity, specificity, positive and negative predictive values, and receiver operator characteristic curve analysis. A total of 79 patients (53 years, interquartile range, 50-68; 43 men) were included. PET/MR had a sensitivity of 95%, specificity of 97%, positive predictive value of 97%, and negative predictive value of 95%. The sensitivity, specificity, positive predictive value, and negative predictive value of MRI were 88%, 98%, 98%, and 90% and for PET were 83%, 97%, 97%, and 86%, respectively. The areas under the curve for PET/MRI, MRI, and PET were 95%, 92%, and 92%, respectively. Contrast-enhanced PET/MR has a higher sensitivity and negative predictive value than either PET or MRI alone in the setting of suspected liver metastases. Fewer lesions were characterized as indeterminate by PET/MR in comparison with PET and MRI. This superior performance could potentially impact treatment and management decisions for patients with suspected liver metastases.

Diagnostic Performance of PET Imaging Using Different Radiopharmaceuticals in Prostate Cancer According to Published Meta-Analyses.

A significant number of meta-analyses reporting data on the diagnostic performance of positron emission tomography (PET) in prostate cancer (PCa) is currently available in the literature. In particular, different PET radiopharmaceuticals were used for this purpose. The aim of this review is to summarize information retrieved by published meta-analyses on this topic. The first step included a systematic search of the literature (last search date: June 2020), screening two databases (PubMed/MEDLINE and Cochrane Library). This combination of key words was used: (A) “PET” OR “positron emission tomography” AND (B) “prostate” OR “prostatic” AND (C) meta-analysis. Only meta-analyses on Positron Emission Tomography/Computed Tomography (PET/CT) or Positron Emission Tomography/Magnetic Resonance (PET/MR) in PCa were selected. We have summarized the diagnostic performance of PET imaging in PCa, taking into account 39 meta-analyses published in the literature. Evidence-based data showed the good diagnostic performance of PET/CT with several radiopharmaceuticals, including prostate-specific membrane antigen (PSMA)-targeted agents, radiolabeled choline, fluciclovine, and fluoride in restaging and staging settings. Less evidence-based data were available for PET/MR with different radiotracers. More prospective multicentric studies and cost-effectiveness analyses are warranted.

Diagnostic Performance of PET or PET/CT with Different Radiotracers in Patients with Suspicious Lung Cancer or Pleural Tumours according to Published Meta-Analyses

Purpose Several meta-analyses have reported data about the diagnostic performance of positron emission tomography or positron emission tomography/computed tomography (PET or PET/CT) with different radiotracers in patients with suspicious lung cancer (LC) or pleural tumours (PT). This review article aims at providing an overview on the recent evidence-based data in this setting. Methods A comprehensive literature search of meta-analyses published in PubMed/MEDLINE and Cochrane Library database from January 2010 through March 2020 about the diagnostic performance of PET or PET/CT with different radiotracers in patients with suspicious LC or PT was performed. This combination of keywords was used: (A) “PET” OR “positron emission tomography” AND (B) “lung” OR “pulmonary” OR “pleur∗” AND (C) meta-analysis. Only meta-analyses on PET or PET/CT in patients with suspicious LC or PT were selected. Results We have summarized the diagnostic performance of PET or PET/CT with fluorine-18 fluorodeoxyglucose (18F-FDG) and other radiotracers taking into account 17 meta-analyses. Evidence-based data demonstrated a good diagnostic performance of 18F-FDG PET or PET/CT for the characterization of solitary pulmonary nodules (SPNs) or pleural lesions with overall higher sensitivity than specificity. Evidence-based data do not support the routine use of dual time point (DTP) 18F-FDG PET/CT or fluorine-18 fluorothymidine (18F-FLT) PET/CT in the differential diagnosis of SPNs. Even if 18F-FDG PET/CT has high sensitivity and specificity as a selective screening modality for LC, its role in this setting remains unknown. Conclusions Evidence-based data about the diagnostic performance of PET/CT with different radiotracers for suspicious LC or PT are increasing, with good diagnostic performance of 18F-FDG PET/CT. More prospective multicenter studies and cost-effectiveness analyses are warranted.

Comparison between The Diagnostic Performance of Positron Emission Tomography and Diffusion-Weighted MRI in Detecting Recurrence of Head and Neck Squamous Cell Carcinoma during Post Treatment Follow-up

Abstract Background Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide. (16) Despite aggressive combined-modality treatment regimens, there remains a high percentage (15-50%) of locoregional recurrences.(7) This problem make the clinician to rely on the functional imaging modalities such as Diffusion weighted MRI and Positron Emission Tomography to detect recurrence. Objective To perform a meta-analytical study on the comparison between the diagnostic role of DW/MRI and PET/CT scan in detecting recurrence of HNSCC during post-treatment follow-up. Methods This meta-analysis was conducted from 1/1/ 1998 to 31/3/2018 . Literature search on PubMed and Google scholar was done to identify randomised controlled trials and comparative studies either prospective or retrospective. MedCalc ver. 18.2 (MedCalc, Ostend, Belgium) was used for data analysis. Results Of the eight articles included, The meta-analysis was based on a total of 199 patients. All of them used DW/MRI and 186 of them used PET/CT. Comparative study between the two groups regarding sensitivity, specificity and accuracy revealed; highly significant difference in sensitivity in favor of PET/CT (p < 0.009), significant increase in specificity in favor of DW/MRI (p = 0.048) and no significant difference in accuracy between the two group. Conclusion PET/CT scan was found to be more sensitive than DW/MRI while DW/MRI was found to be more specific than PET/CT. Yet both have the same degree of accuracy.

Performance characteristic evaluation of a bismuth germanate-based high-sensitivity 5-ring discovery image quality positron emission tomography/computed tomography system as per National Electrical Manufacturers Association NU 2-2012.

National Electrical Manufacturers Association (NEMA) provides guidelines to assess the performance of Positron Emission Tomography (PET). A PET/CT scanner, Discovery IQ, GE Medical systems, Milwaukee, USA was installed in our department which has high a sensitivity PET component. We have performed the NEMA NU-2 2012 quality control tests to evaluate this system on site before clinical use. Performance measurements of the PET scanner were made using the NEMA NU2-2012 procedures for spatial resolution, scatter fraction, sensitivity, count rate loss and random coincidence estimation, Noise Equivalent Count Rate (NECR) and image quality. As per NU2 2012, spatial resolution was measured at 1 cm, 10 cm and 20 cm vertically from the centre and at each of these points resolution was measured at tangential, radial and axial directions. Sensitivity was measured at centre and 10 cm off center vertically from the center. The system sensitivity is reported as an average of the two measured values. Scatter fraction and NECR measurements, Image quality test was also performed. The tangential, radial and axial FWHM were 4.99 mm, 4.20 mm and 4.79 mm at 1 cm off centre, 5.49 mm, 4.69 mm and 4.81 mm at 10 cm off centre and 7.99 mm, 5.07 mm and 4.95 mm at 20 cm off centre respectively. The absolute sensitivity of this scanner was found to be 20.1 cps/kBq. The scatter fraction calculated from the decay method was 37.94% and NECR was 125 kcps. The peak NECR was achieved at activity concentration of 8.7 KBq/ml and the count loss below the peak NECR was found to be 0.68%. Image quality test for, contrast recovery, background variability and lung error residual mean met all specifications. Overall PET performance of Discovery IQ whole-body scanner was satisfactory and the scanner met all the performance specifications required by NEMA 2012.

Diagnostic Performance of PET or PET/CT Using 18F-FDG Labeled White Blood Cells in Infectious Diseases: A Systematic Review and a Bivariate Meta-Analysis.

Background: Diagnostic performance of positron emission tomography using white blood cells labeled with fluorine-18-fluorodeoxyglucose (18F-FDG-WBC PET or PET/CT) in patients with suspicious infectious diseases has been evaluated in several studies; however, there is no consensus about the diagnostic accuracy of this method. Therefore, a systematic review and meta-analysis was carried out on this topic. Methods: A comprehensive computer literature search screening PubMed/MEDLINE, Embase and Cochrane library databases through March 2019 was performed. Pooled sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR−), and diagnostic odds ratio (DOR) of 18F-FDG-WBC PET or PET/CT in patients with infectious diseases were calculated. Results: Eight studies on the use of 18F-FDG-WBC PET or PET/CT in suspicious infectious diseases were discussed in the systematic review. The meta-analysis of seven studies (236 patients) provided these pooled results on a per patient-based analysis: sensitivity was 86.3% [95% confidence interval (95%CI) 75–92.9%], specificity 92% (95%CI 79.8–97.1%), LR+ 6.6 (95%CI: 3.1–14.1), LR− 0.2 (95%CI: 0.12–0.33), DOR 43.5 (95%CI: 12.2–155). A statistically significant heterogeneity was not detected. Conclusions: Despite limited literature data, 18F-FDG-WBC PET or PET/CT demonstrated a good diagnostic accuracy for the diagnosis of infectious diseases; nevertheless, larger studies are needed.

Comparison of PET/MRI with multiparametric MRI in diagnosis of primary prostate cancer: A meta-analysis

ObjectiveThis meta-analysis aimed to compare the diagnostic performance of positron emission tomography (PET)/MRI using various radiotracers with multiparametric (mp) MRI for detection of primary prostate cancer (PCa). MethodsA systematic literature search up to January 2019 was performed to identify studies that evaluated the diagnostic value of PET/MRI and mpMRI for detection of PCa in the same patient cohorts and had sufficient data to construct 2 × 2 contingency tables for true-positive (TP), false-positive (FP), false-negative (FN), and true-negative (TN) results. The quality of each study was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, and pooled sensitivity (SEN) and specificity (SPE) were calculated. Summary receiver operating characteristic (ROC) curves and area under the curves (AUCs) were used to compare the performances of PET/MRI and mpMRI. ResultsWe identified 9 eligible studies that included a total of 353 patients. PET/MRI had a SEN of 0.783 (95% CI, 0.758–0.807) and a SPE of 0.899 (95% CI, 0.879–0.917), and mpMRI had a SEN of 0.603 (95% CI, 0.574–0.631) and a SPE of 0.887 (95% CI, 0.866–0.906). PET/MRI had a higher AUC than mpMRI (0.9311, 95% CI, 0.8990–0.9632 vs. 0.8403, 95% CI, 0.7864–0.8942; P = 0.0036). There was no notable publication bias, but there was medium heterogeneity in outcomes. The meta-regression analysis showed the major potential cause of heterogeneity was the use of region-based rather than lesion-based analysis. ConclusionPET/MRI has very good diagnostic performance and outperforms mpMRI for the diagnosis of primary PCa.

Evaluation of PET Scanner Performance in PET/MR and PET/CT Systems: NEMA Tests.

Objective:The aim of the present study was to compare the performance of positron emission tomography (PET) component of PET/computed tomography (CT) with new emerging PET/magnetic resonance (MR) of the same vendor.Methods:According to National Electrical Manufacturers Association NU2-07, five separate experimental tests were performed to evaluate the performance of PET scanner of General Electric GE company; SIGNATM model PET/MR and GE Discovery 710 model PET/CT. The main investigated aspects were spatial resolution, sensitivity, scatter fraction, count rate performance, image quality, count loss and random events correction accuracy.Results:The findings of this study demonstrated superior sensitivity (~ 4 folds) of PET scanner in PET/MR compared to PET/CT system. Image quality test exhibited higher contrast in PET/MR (~ 9%) compared with PET/CT. The scatter fraction of PET/MR was 43.4% at noise equivalent count rate (NECR) peak of 218 kcps and the corresponding activity concentration was 17.7 kBq/cc. Whereas the scatter fraction of PET/CT was found as 39.2% at NECR peak of 72 kcps and activity concentration of 24.3 kBq/cc. The percentage error of the random event correction accuracy was 3.4% and 3.1% in PET/MR and PET/CT, respectively.Conclusion:It was concluded that PET/MR system is about 4 times more sensitive than PET/CT, and the contrast of hot lesions in PET/MR was ~ 9% higher than PET/CT. These outcomes also emphasize the possibility to achieve excellent clinical PET images with low administered dose and/or a short acquisition time in PET/MR.

18F-FDG PET for diagnosing painful arthroplasty/prosthetic joint infection

Up to now, there were some studies about the role of 18F-FDG PET or PET/CT in the diagnosis of prosthetic joint infection after arthroplasty with different values of sensitivity and specificity. The purpose of this study was to systematically review the published data regarding the diagnostic performance of positron emission tomography (PET) or PET/computed tomography (PET/CT) in prosthetic infection after arthroplasty. A comprehensive computer literature search of studies published regarding PET or PET/CT in patients suspicious of prosthetic infection was performed. Pooled sensitivity, specificity and area under the receiver operating characteristic (ROC) curve of PET or PET/CT in patients suspicious of prosthetic infection on a per prosthesis-based analysis were calculated. Sixteen studies comprising 1101 prosthesis with suspicious of prosthetic infection after arthroplasty were included in this meta-analysis. The pooled sensitivity of PET or PET/CT in detecting prosthetic infection was 87% [95% confidence interval (CI) 83–90%] on a per prosthesis-based analysis. The pooled specificity of PET or PET/CT in detecting prosthetic infection was 87% (95% CI 85–89%) on a per prosthesis-based analysis. The area under the ROC curve was 0.94 on a per prosthesis-based analysis. 18F-FDG PET or PET/CT demonstrated high sensitivity and specificity in subjects suspicious of prosthetic infection. However, various degrees of uptake in the asymptomatic patients are very common. Physicians should recognize these characteristics, and then 18F-FDG PET or PET/CT can act as an effective method in the diagnosis of prosthetic infection.

Simulation study of a D-shape PET scanner for improved sensitivity and reduced cost in whole-body imaging

Much research effort is being made to increase the sensitivity and improve the imaging performance of positron emission tomography (PET) scanners. Conventionally, sensitivity can be increased by increasing the number of detector rings in the axial direction (but at high cost) or reducing the diameter of the scanner (with the disadvantages of reducing the space for patients and degrading the spatial resolution due to the parallax error). In this study, we proposed a PET scanner with a truncated ring and an array of detectors that can be arranged in a straight line below the bed. We called this system ‘D-PET’ as it resembles the letter ‘D’ when it is rotated by 90° in the counterclockwise direction. The basic design idea was to cut the unused space under the patient’s bed; this area is usually not in use in clinical diagnosis. We conducted Monte Carlo simulations of the D-PET scanner and compared its performance with a cylindrical PET scanner. The scanners were constructed from 4-layer depth-of-interaction detectors which consisted of a 16 × 16 × 4 LYSO crystal array with dimensions of 2.85 × 2.85 × 5 mm3. The results showed that the D-PET had an increase in sensitivity and peak-NECR of 30% and 18%, respectively. The D-PET had low noise in the reconstructed images throughout the field-of-view compared to the cylindrical PET. These were achieved while keeping sufficient space for the patient, and also without a severe effect on the spatial resolution. Furthermore, the number of detectors (and hence the cost) of the D-PET scanner was reduced by 12% compared to the cylindrical PET scanner.

Diagnostic performance of different imaging modalities in the assessment of distant metastasis and local recurrence of tumor in patients with non-small cell lung cancer.

To compare the diagnostic performance of positron emission tomography with [18F] fluoro-2-deoxy-glucose (FDG-PET) coregistered with magnetic resonance imaging (FDG-PET/MRI), MRI with and without diffusion-weighted imaging (DWI), FDG-PET fused with computed tomography (FDG-PET/CT) with brain contrast-enhanced (CE-) MRI, and routine radiological examination for assessment of postoperative recurrence in nonsmall-cell lung cancer (NSCLC) patients. 96 consecutive postoperative NSCLC patients (52 men, 44 women; mean age 72 years) prospectively underwent whole-body 3T MRI with and without DWI; PET/CTs and routine radiological examinations consisted of CE-brain MRI, whole-body CE-CT, and bone scintigraphy. The patients were divided into a recurrence (n = 17) and a nonrecurrence (n = 79) group based on pathological and follow-up examinations. All coregistered PET/MRIs were generated by proprietary software. The probability of recurrence was visually assessed on a per-patient basis. Receiver operating characteristic analyses were used to compare the diagnostic performance of all methods. Finally, diagnostic capabilities were compared by means of McNemar's test. Areas under the curves (Azs) were significantly larger for PET/MRI and whole-body MRI with DWI (Az = 0.99) than for PET/CT (Az = 0.92, P < 0.05) and conventional radiological examination (Az = 0.91, P < 0.05). Specificity and accuracy of PET/MRI and MRI with and without DWI were significantly higher than those of PET/CT (P < 0.05) and routine radiological examination (P < 0.05). Whole-body FDG-PET/MRI and MRI with DWI were found to be more specific and accurate than FDG-PET/CT and routine radiological examinations for assessment of recurrence in NSCLC patients, although MRI with and without DWI demonstrated slightly lower sensitivity than PET/CT. 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1707-1717.

Prognostic value of normal positron emission tomography myocardial perfusion imaging in patients with known or suspected coronary artery disease: a meta-analysis.

Several studies have confirmed high diagnostic performance of positron emission tomography (PET) myocardial perfusion imaging (MPI) in patients with known or suspected coronary artery disease. However, whether the superior diagnostic accuracy could translate into improved mortality outcomes remains unknown. The aim of this study was to define the prognostic value of normal PET MPI. PubMed and EMBASE were searched to identify related studies up to June 2016. All studies using PET MPI to evaluate subjects with known or suspected coronary artery disease and providing absolute number of patients with a negative test and primary data on clinical outcomes with a follow-up time ≥3 months were included for analysis. The search yielded 11 studies comprising 20,471 patients for final analysis. The negative-predictive value (NPV) for cardiac death, all-cause death and major adverse cardiovascular events (MACE) were 98.80% [95% confidence interval (CI), 97.64%-99.39%], 94.89% (95% CI: 92.99-96.30%) and 90.26% (95% CI: 78.01-96.03%), over 36.9 months of follow-up for cardiac death, over 26.8 months for all-cause death and 35.7 months for MACE. The corresponding annualized event rates were 0.39%, 2.29% and 3.27%, respectively. In subgroup analyses of different imaging analysis methods for PET MPI, studies using perfusion abnormity had a similar NPV as compared with those using coronary flow reserve (98.46% vs 98.86%, p-value = NS), with a corresponding annualized event rate after negative tests (equal to 1 - NPV) as 0.45% and 0.42%, respectively. Normal PET has a high NPV for cardiac death, MACE and all-cause mortality. Different indexes used for PET imaging analysis have a comparable prognostic value. Advances in knowledge: A normal PET MPI conferred a very low risk of cardiac death of 0.39% per year, which is close to that of a normal aged-matched population.

Brain uptake and safety of Flutemetamol F 18 injection in Japanese subjects with probable Alzheimer\u2019s disease, subjects with amnestic mild cognitive impairment and healthy volunteers

ObjectiveThis Phase 2 study assessed the performance of positron emission tomography (PET) brain images made with Flutemetamol F 18 Injection in detecting β-amyloid neuritic plaques in Japanese subjects.MethodsSeventy subjects (25 with probable Alzheimer’s disease (pAD), 20 with amnestic mild cognitive impairment (aMCI), and 25 cognitively normal healthy volunteers[HVs]) underwent PET brain imaging after intravenous Flutemetamol F 18 Injection (185 MBq). Images were interpreted as normal or abnormal for neuritic plaque density by each of five non-Japanese and five Japanese readers who were blinded to clinical data. The primary efficacy analysis (based on HV and pAD data) was the agreement of the non-Japanese readers’ image interpretations with the clinical diagnosis, resulting in estimates of positive percent agreement (PPA; based on AD subjects; similar to sensitivity) and negative percent agreement (NPA; based on HVs; similar to specificity). Secondary analyses included PPA and NPA for the Japanese readers; inter-reader agreement (IRA); intra-reader reproducibility (IRR); quantitative image interpretations (standardized uptake value ratios [SUVRs]) by diagnostic subgroup; test–retest variability in five pAD subjects; and safety.ResultsPPA was 92% for all non-Japanese readers and ranged from 88 to 92% for the Japanese readers. NPA ranged from 96 to 100% for both the non-Japanese readers and the Japanese readers. The majority image interpretations (the interpretations made independently by ≥3 of 5 readers) resulted in PPA values of 92 and 92% and NPA values of 100 and 96% for the non-Japanese and Japanese readers, respectively. IRA and IRR were strong. Composite SUVR values (mean of multiple regional values) allowed clear differentiation between pAD subjects and HVs. Test–retest variability ranged from 1.14 to 2.27%, and test–retest agreement of the blinded visual interpretations was 100% for all readers. Flutemetamol F 18 Injection was generally well tolerated.ConclusionsThe detection of brain neuritic plaques in Japanese subjects using [18F]Flutemetamol PET images gave results highly consistent with clinical diagnosis, with non-Japanese and Japanese readers giving similar results. Inter-reader agreement and intra-reader reproducibility were high for both sets of readers. Visual delineation of abnormal and normal scans was corroborated by quantitative assessment, with low test–retest variability.Trial registrationClinicaltrials.gov registration number NCT02813070.

Diagnostic Performance and Safety of Positron Emission Tomography Using 18F-Fluciclovine in Patients with Clinically Suspected High- or Low-grade Gliomas: A Multicenter Phase IIb Trial.

Objective(s):The study objective was to assess the diagnostic performance of positron emission tomography (PET) for gliomas using the novel tracer 18F-fluciclovine (anti-[18F]FACBC) and to evaluate the safety of this tracer in patients with clinically suspected gliomas.Methods:Anti-[18F]FACBC was administered to 40 patients with clinically suspected high- or low-grade gliomas, followed by PET imaging. T1-weighted, contrast-enhanced T1-weighted, and fluid-attenuated inversion recovery (or T2-weighted) magnetic resonance imaging (MRI) scans were obtained to plan for the tissue collection. Tissues were collected from either “areas visualized using anti-[18F]FACBC PET imaging but not using contrast-enhanced T1-weighted imaging” or “areas visualized using both anti-[18F]FACBC-PET imaging and contrast-enhanced T1-weighted imaging” and were histopathologically examined to assess the diagnostic accuracy of anti-[18F]FACBC-PET for gliomas.Results:The positive predictive value of anti-[18F]FACBC-PET imaging for glioma in areas visualized using anti-[18F]FACBC-PET imaging, but not visualized using contrast-enhanced T1-weighted images, was 100.0% (26/26), and the value in areas visualized using both contrast-enhanced T1-weighted imaging and anti-[18F]FACBC-PET imaging was 87.5% (7/8). Twelve adverse events occurred in 7 (17.5%) of the 40 patients who received anti-[18F]FACBC. Five events in five patients were considered to be adverse drug reactions; however, none of the events were serious, and all except one resolved spontaneously without treatment.Conclusion:This Phase IIb trial showed that anti-[18F]FACBC-PET imaging was effective for the detection of gliomas in areas not visualized using contrast-enhanced T1-weighted MRI and the tracer was well tolerated.

Accuracy of a new diagnostic tool in deep infiltrating endometriosis: pET-CT with [18F]-FES

Background: Diagnosis of deep infiltrating endometriosis (DIE) remains a challenge. The preoperative workup is generally limited especially in the evaluation of extra-genital and extra-pelvic disease and in distinguishing between previous surgical scar and active lesion so that the laparoscopy and histology verification is still considered to be the gold standard for the diagnosis of the disease. We proposed to evaluate the performance of positron emission tomography (PET-CT) with a sperimental tracer of estrogen receptor (16α-[18F]fluoro-17β-estradiol-[18F]-FES-) for the non-invasive diagnosis and staging of this ubiquitous, estrogen-dependent disease. Primary endpoint of the study was to evaluate the feasibility of this tool comparing its accuracy with the histology. Secondary endpoint was to compare the accuracy of [18F]-FES PET-CT with that of magnetic resonance imaging (MRI). Methods: Four eligible patients with extra-genital DIE without hormonal treatment for at least 2 spontaneous mestrual cycles were enrolled in this sperimental study. On “Step 1” (third menstrual day of the second spontaneous cycle), patient underwent an abdominal-pelvic MRI with contrast agent after a blood sampling with dosage of hormonal profile. On “Step 2” (after menstruation and before the 15th day of the second cycle) the same eligible patient underwent an abdominal-pelvic [18F]-FES PET-CT scan. On “Step 3” (within 30 days from the [18F]-FES PET-CT) patient underwent nerve-sparing laparoscopic complete excision of endometriosis. During surgery, 9 anatomical areas were systematically assessed for each patient. Findings of [18F]-FES PET-CT and RMI were compared by a region-by-region analysis to surgical histological biopsies obtained from laparoscopy, standard of reference in our study. Results: In total 40 anatomical regions were examined; 8 were positive on [18F]-FES PET-CT, 4 were positive on RMI and 9 were positive on histology. A total of 10 regions were discordant on [18F]-FES PET-CT and RMI. Nine out of 10 (90%) discrepant findings demonstrated agreement between [18F]-FES PET-CT and histology. Conclusion: Preliminary data of this pilot sperimental study indicated that [18F]-FES PET-CT might be superior to RMI and other current diagnostic tools in detecting endometriosis. [18F]-FES PET-CT showed greater accuracy not only for the extra-genital and extra-pelvic regions but also for genital ones, mainly in patients with previous surgery in which it is difficult to discriminate surgical scar from an active endometriotic lesion. Further studies are needed to investigate its role in case of endometriosis of bowel in different sites than recto-sigmoid, nervous localizations, subcentimetrical disease and endometriomas. If such data will be confirmed on large series, we maybe could think to avoid surgery only for diagnostic purposes; or unnecessary surgery in patients [18F]-FES negative; or simply we will be able to better plan the surgery.

PET block detector calibration using subtractive clustering algorithm and comparison with hough transform algorithm

Detector calibration plays an important role in improving of image quality and increasing performance of positron emission tomography (PET) systems. To achieve this aim, raw data coordinate event-byevent are mapped to the index of the crystal in which the particle is absorbed. We proposed and tested subtractive clustering and Hough transform algorithms to determine crystal peak position and generate an appropriate look-up table. The results show superiority of Hough transform to the subtractive clustering and other methods because this algorithm determines position of all peaks, even in irregular and unclear data. The acquired results can be beneficial for all of the medical imaging instruments such as PET and single-photon emission computed tomography detectors based on pixilated scintillators.