Accuracy Of Positron Emission Tomography Research Articles

Diagnostic Accuracy of PET with 18F-Fluciclovine ([18F]FACBC) in Detecting High-Grade Gliomas: A Systematic Review and Meta-Analysis.

18F-Fluciclovine ([18F]FACBC) has been recently proposed as a synthetic radiolabeled amino acid for positron emission tomography (PET) imaging in patients with brain neoplasms. Our aim is to evaluate the diagnostic performance of [18F]FACBC PET in high-grade glioma (HGG) patients, taking into account the literature data. A comprehensive literature search was performed. We included original articles evaluating [18F]FACBC PET in the detection of HGG before therapy and for the suspicion of tumor recurrence. Pooled sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR-), and diagnostic odds ratios (DOR), including 95% confidence intervals (95% CI), were measured. Statistical heterogeneity and publication bias were also assessed. ten studies were included in the review and eight in the meta-analysis (113 patients). Regarding the identification of HGG, the sensitivity of [18F]FACBC PET ranged between 85.7% and 100%, with a pooled estimate of 92.9% (95% CI: 84.4-96.9%), while the specificity ranged from 50% to 100%, with a pooled estimate of 70.7% (95% CI: 47.5-86.5%). The pooled LR+, LR-, and DOR of [18F]FACBC PET were 2.5, 0.14, and 37, respectively. No significant statistical heterogeneity or publication bias were found. evidence-based data demonstrate the good diagnostic accuracy of [18F]FACBC PET for HGG detection. Due to the still limited data, further studies are warranted to confirm the promising role of [18F]FACBC PET in this context.

Rationale and design of the RAPID-WATER-FLOW trial: Radiolabeled perfusion to identify coronary artery disease using water to evaluate responses of myocardial FLOW

ObjectivesThe objective of this study was to determine the diagnostic performance of 15O-water positron emission tomography (PET) myocardial perfusion imaging to detect coronary artery disease (CAD) using the truth-standard of invasive coronary angiography (ICA) with fractional flow reserve (FFR) or instantaneous wave-Free Ratio (iFR) or coronary computed tomography angiogram (CCTA). Background15O-water has a very high first-pass extraction that allows accurate quantification of myocardial blood flow and detection of flow-limiting CAD. However, the need for an on-site cyclotron and lack of automated production at the point of care and relatively complex image analysis protocol has limited its clinical use to date. MethodsThe RAPID WATER FLOW study is an open-label, multicenter, prospective investigation of the accuracy of 15O-water PET to detect obstructive angiographic and physiologically significant stenosis in patients with suspected CAD. The study will include the use of an automated system for producing, dosing, and injecting 15O-water and enrolling approximately 215 individuals with suspected CAD at approximately 10 study sites in North America and Europe. The primary endpoint of the study is the diagnostic sensitivity and specificity of the 15O-water PET study using the truth-standard of ICA with FFR or iFR to determine flow-limiting stenosis, or CCTA to rule out CAD and incorporating a quantitative analytic platform developed for the 15O-water PET acquisitions. Sensitivity and specificity are to be considered positive if the lower bound of the 95% confidence interval is superior to the threshold of 60% for both, consistent with prior registration studies.Subgroup analyses include assessments of diagnostic sensitivity, specificity, and accuracy in female, obese, and diabetic individuals, as well as in those with multivessel disease. All enrolled individuals will be followed for adverse and serious adverse events for up to 32 hours after the index PET scan.The study will have >90% power (one-sided test, α = 0.025) to test the hypothesis that sensitivity and specificity of 15O-water PET are both >60%. ConclusionsThe RAPID WATER FLOW study is a prospective, multicenter study to determine the diagnostic sensitivity and specificity of 15O-water PET as compared to ICA with FFR/iFR or CCTA. This study will introduce several novel aspects to imaging registration studies, including a more relevant truth standard incorporating invasive physiologic indexes, coronary CTA to qualify normal individuals for eligibility, and a more quantitative approach to image analysis than has been done in prior pivotal studies. Clinical trial registration informationClinical-Trials.gov (#NCT05134012).

MCP-Net: Introducing Patlak Loss Optimization to Whole-body Dynamic PET Inter-frame Motion Correction.

In whole-body dynamic positron emission tomography (PET), inter-frame subject motion causes spatial misalignment and affects parametric imaging. Many of the current deep learning inter-frame motion correction techniques focus solely on the anatomy-based registration problem, neglecting the tracer kinetics that contains functional information. To directly reduce the Patlak fitting error for 18F-FDG and further improve model performance, we propose an interframe motion correction framework with Patlak loss optimization integrated into the neural network (MCP-Net). The MCP-Net consists of a multiple-frame motion estimation block, an image-warping block, and an analytical Patlak block that estimates Patlak fitting using motion-corrected frames and the input function. A novel Patlak loss penalty component utilizing mean squared percentage fitting error is added to the loss function to reinforce the motion correction. The parametric images were generated using standard Patlak analysis following motion correction. Our framework enhanced the spatial alignment in both dynamic frames and parametric images and lowered normalized fitting error when compared to both conventional and deep learning benchmarks. MCP-Net also achieved the lowest motion prediction error and showed the best generalization capability. The potential of enhancing network performance and improving the quantitative accuracy of dynamic PET by directly utilizing tracer kinetics is suggested.

Recent topics in fibroblast activation protein inhibitor-PET/CT: clinical and pharmacological aspects.

Recently, positron emission tomography (PET) with fibroblast activation protein inhibitor (FAPI) has gained significant attention as an advanced tumor diagnostic imaging tool. FAPI PET has a promising potential owing to its ability to accurately depict most malignant tumors. It has an accuracy that is comparable to or surpassing the diagnostic accuracy of PET using 18F-fluorodeoxyglucose (FDG). Moreover, FAPI PET can identify malignant lesions that may be inconclusive on FDG PET. Beyond its application in neoplastic disorders, there have been encouraging reports suggesting the utility of FAPI PET in non-neoplastic conditions such as respiratory or cardiac diseases. This article aimed to provide a comprehensive overview of the recently published articles investigating FAPI and discuss its clinical utility with an emphasis on its application in tumor diagnostics. Numerous radiopharmaceutical FAPIs, including 18F- and 68Ga-labeled compounds, have been developed, and they offer various advantages and applications. With the progress in the FAPI PET synthesis to enhance accumulation and retention in pathological lesions, future studies are expected to provide valuable data on its therapeutic efficacy.

Diagnostic accuracy of glioma pseudoprogression identification with positron emission tomography imaging: a systematic review and meta-analysis.

Positron emission tomography (PET) imaging is a promising molecular neuroimaging technique and has been proposed as one of the criteria for glioma management. However, there is some controversy concerning the diagnostic accuracy of PET using different radiotracers to differentiate between glioma pseudoprogression (PsP) and true progression (TPR). The purpose of this meta-analysis was to systematically evaluate the methodological quality and clinical value of original studies for distinguishing PsP from TPR in glioma. The Medline, Web of Science, Embase, Cochrane Library, and ClinicalTrials.gov were searched from inception until September 1, 2022. Retrieved clinical studies only investigated the PsP cases but did not include the cases of radiation necrosis or other treatment-related changes. Eligible studies were screened for data extraction and evaluated by 2 independent reviewers using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. A random effects model was used to describe summary receiver operating characteristics. Meta-regression and subgroup analyses were applied to identify any sources of heterogeneity. The meta-analysis included 20 studies, comprising 317 (30.9%) patients with PsP and 708 (69.1%) with TPR. The summary sensitivity and specificity of general PET for identifying PsP were 0.86 [95% confidence interval (CI): 0.77-0.91] and 0.84 (95% CI: 0.79-0.88), respectively. The statistical heterogeneity was explained by sample size, study design, World Health Organization (WHO) grade, gold standard, and radiotracer type. The summary sensitivity and specificity of O-(2-18F-fluoroethyl)-L-tyrosine (18F-FET PET) were 0.80 (95% CI: 0.68-0.88) and 0.81 (95% CI: 0.75-0.85), respectively. The maximum tumor-to-brain ratio (TBRmax) and the mean tumor-to-brain ratio (TBRmean) both showed excellent diagnostic performance in 18F-FET studies, the summary sensitivity was 0.83 (95% CI: 0.72-0.91) and 0.79 (95% CI: 0.65-0.98), respectively, and the specificity was 0.76 (95% CI: 0.68-0.84) and 0.78 (95% CI: 0.64-0.88), respectively. PET imaging is generally accurate in identifying glioma PsP. Considering the credibility of meta-evidence and the practicability of using radiotracer, 18F-FET PET holds the highest clinical value, while TBRmax and TBRmean should be regarded as reliable parameters. PET used with the radiotracers and multiple-parameter combinations of PET with magnetic resonance imaging (MRI) and radiomics analysis have broad research and application prospects, whose diagnostic values for identifying glioma PsP warrant further investigation.

PET-MRI for evaluation of response to radiochemotherapy in patients with locally advanced cervical cancer

ObjectiveWe aimed to analyze the diagnostic test accuracy of positron emission tomography and a magnetic resonance imaging scan (PET-MRI) fusion in evaluating tumor response after radiochemotherapy in patients with locally...

Meningioma grading based on positron emission tomography: A systematic review and meta-analysis

IntroductionMeningiomas are the most common central nervous system tumor in adults. Knowledge of the tumor grade can guide optimal treatment timing and shape personalized follow-up strategies. Positron emission tomography (PET) has been utilized for the metabolic assessment of various intracranial space-occupying lesions. Herewith, we set out to evaluate the diagnostic accuracy of PET for the noninvasive assessment of meningioma's grade. Materials and methodsThe Medline, Scopus and Cochrane databases were systematically searched in March 2022 for studies that evaluated the sensitivity and specificity of PET compared to the gold standard of histological diagnosis in the grading of meningiomas. Summary statistics will be calculated and scatter plots, summary curve from the HSROC model and posterior predictions by empirical Bayes estimates will be presented. ResultsFive studies consisting of 242 patients with a total of 196 low-grade (Grade 1) and 46 high grade (Grade 2/3) meningiomas were included in our analysis. Three of the included studies used 18F-FDG, one study used 18F-FLT and one used(Whiting et al., 2011) 18 F-FET as PET tracers. The pooled sensitivity was 76% (95% CI: 52%–91%) and the pooled specificity was 89% (95% CI: 83%–93%). The diagnostic odds ratio was 27.17 (95% CI: 9.22–80.06), the positive likelihood ratio was 7.18 (95% CI: 4.54–11.34) and the negative likelihood ratio was 0.26 (95% CI: 0.11–0.61). ConclusionPET is a promising and viable option as a noninvasive imaging tool to differentiate the meningioma grades. However, currently it cannot overtake the gold standard of histological grade confirmation. More studies are required for further validation and refinement of this imaging technique and assessment of other radiotracers as well.

Dedicated phantom tools using traceable 68Ge/68Ga point-like sources for dedicated-breast PET and positron emission mammography scanners.

Since the early 2000s, many types of positron emission tomography (PET) scanners dedicated to breast imaging for the diagnosis of breast cancer have been introduced. However, conventional performance evaluation methods developed for whole-body PET scanners cannot be used for such devices. In this study, we developed phantom tools for evaluating the quantitative accuracy of positron emission mammography (PEM) and dedicated-breast PET (dbPET) scanners using novel traceable point-like 68Ge/68Ga sources. The PEM phantom consisted of an acrylic cube (100 × 100 × 40mm) and three point-like sources. The dbPET phantom comprised an acrylic cylinder (ø100 × 100mm) and five point-like sources. These phantoms were used for evaluating the fundamental responses of clinical PEM and dbPET scanners to point-like inputs in a medium. The results showed that reasonable recovery values were obtained based on region-of-interest analyses of the reconstructed images. The developed phantoms using traceable 68Ge/68Ga point-like sources were useful for evaluating the physical characteristics of PEM and dbPET scanners. Thus, they offer a practical, reliable, and universal measurement scheme for evaluating various types of PET scanners using common sets of sealed sources.

High tau PET binding reveals a constellation of beta‐amyloid positivity and fast cognitive decline

AbstractBackgroundBeta‐amyloid Positron Emission Tomography (PET) efficiently detects beta‐amyloid plaques supporting the presence of a pathophysiological landmark of Alzheimer’s disease (AD) continuum, but lacks specificity regarding the prediction of future cognitive status. The increasing validation of tau PET tracers raises questions about whether a tau PET biomarker could predict clinically relevant cognitive decline and its potentially beneficial role in the assessment of individuals who belong to the AD continuum.MethodWe identified 335 subjects [cognitive normal (CN; n=217), mild cognitive impairment (MCI; n=99), dementia (n=19)] with baseline beta‐amyloid and tau PET scans that have completed a follow‐up of at least two years, from the Alzheimer’s Disease Neuroimaging Initiative dataset. First, we assessed the accuracy of tau PET to discriminate the MCI patients that will convert to AD. Based on Alzheimer’s Disease Assessment Scale–Cognitive Subscale, we used linear mixed‐effects models to define the annual rate of cognitive change of all individuals and Gaussian mixture modelling to cluster them as either fast or slow decliners. Next, group comparisons and the accuracy of tau PET to discriminate between them were tested. Finally, the association between baseline tau PET SUVR and cognitive rate of change was assessed with linear modelsResultThe individuals with beta‐amyloid positivity and fast cognitive decline showed the highest tau PET binding values independently of baseline cognitive status, compared to the other groups (beta‐amyloid negative with fast or slow decline and beta‐amyloid positive with slow decline). Baseline tau PET binding could determine fast decliners with a beta‐amyloid positive scan with an accuracy of 85% (composite temporal region of interest). Similarly, tau PET binding accuracy was high in determining MCI patients that would be both beta‐amyloid positive and show progress in their diagnosis. Linear models showed that baseline tau PET binding is related to the annual rate of cognitive decline in beta‐amyloid positive individuals.ConclusionHigh baseline tau load is coupled with both beta‐amyloid pathology and an accelerated profile of cognitive decline. Tau PET imaging could offer substantial advantages over beta‐amyloid PET imaging since it provides important information about both the underlying pathophysiology and the prognosis of the disease.

Comparison of second-line on-site computed quantitative flow ratio from coronary computed tomography angiography to PET perfusion imaging for detecting obstructive coronary artery disease

Abstract Introduction In patients with suspected obstructive coronary artery disease (CAD) on coronary computed tomography (CTA), guidelines endorse second-line selective testing for hemodynamic evaluation of suspected CAD. A variety of non-invasive modalities are available, and myocardial perfusion imaging with Rubidium-82 positron emission tomography (PET) is an established method with high diagnostic performance. Recently, an on-site method estimating computed tomography-derived quantitative flow ratio (CT-QFR) showed promising results for discriminating obstructive CAD. However, no study has compared the diagnostic performances of PET and CT-QFR. Purpose To assess a possible non-inferiority of CT-QFR compared to PET in patients with suspected obstructive CAD at CTA using invasive coronary angiography (ICA) with fractional flow reserve (FFR) as reference. Methods Patients (n=1732, 57% males, age 59±9.5) referred on a clinical indication with symptoms suggestive of obstructive CAD underwent routine CTA. Patients with ≥50% diameter stenosis (DS) on CTA were referred for PET and subsequent ICA with FFR. CT-QFR was analyzed post-hoc blinded to PET and ICA results. Abnormal CT-QFR was defined as CT-QFR ≤0.80 in any vessel with a diameter ≥1.5mm. An independent core-lab evaluated PET scans as abnormal/normal with optional analyst-dependent application of pre-specified criteria; summed stress score of ≥4 in ≥2 contiguous segments, vessel-specific myocardial blood flow (MBF) <2.00 ml/g/min, global myocardial blood flow reserve ≤1.8, and/or transient ischemic dilatation ratio >1.13. Obstructive CAD was defined as ICA with FFR ≤0.80 or high-grade stenosis (≥90% DS). Results In total, 445/1732 patients (25%) had suspected obstructive CAD on CTA of whom 400/445 patients (90%) underwent subsequent PET and ICA. CT-QFR was successfully analysed in 383/400 (96%) patients classifying 174/383 (45%) patients as having disease. In comparison, PET classified 130/383 (34%) patients as having disease. In total, obstructive CAD by ICA with FFR was identified in 162 (42%) patients. There was no significant difference in area under the receiver-operating characteristic curves for CT-QFR compared to the best performing PET metric (lowest vessel-specific MBF); 0.84 (95% CI 0.80–0.89) vs. 0.81 (0.77–0.85), p=0.19)) (Fig. 1). Overall diagnostic accuracy of CT-QFR versus PET was similar (78% (95% CI 74–82) vs. 77% (72–81), p=0.70. Sensitivities for CT-QFR and PET were 78% (71–84) and 63% (55–70), p<0.01, respectively, and specificities 78% (72–84) and 87% (82–91), p=0.01, respectively (Fig. 2). Three-vessel or left main disease on ICA was correctly identified in 30/31 patients by both CT-QFR and PET. Conclusion In patients with suspected obstructive CAD by CTA, second-line CT-QFR was non-inferior to PET for discriminating obstructive CAD by invasive FFR; Although diagnostic accuracy was similar, CT-QFR demonstrated higher sensitivity while PET showed higher specificity Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Aarhus University PhD fellowshipRegion Mid Health Research Foundation

Diagnosis of left ventricular hypertrophy using non-ECG-gated 15O-water PET

AimTo develop a method for diagnosing left ventricular (LV) hypertrophy from cardiac perfusion 15O-water positron emission tomography (PET). MethodsWe retrospectively pooled data from 139 subjects in four research cohorts. LV remodeling patterns ranged from normal to severe eccentric and concentric hypertrophy. 15O-water PET scans (n = 197) were performed with three different PET devices. A low-end scanner (66 scans) was used for method development, and remaining scans with newer devices for a blinded evaluation. Dynamic data were converted into parametric images of perfusable tissue fraction for semi-automatic delineation of the LV wall and calculation of LV mass (LVM) and septal wall thickness (WT). LVM and WT from PET were compared to cardiac magnetic resonance (CMR, n = 47) and WT to 2D-echocardiography (2DE, n = 36). PET accuracy was tested using linear regression, Bland–Altman plots, and ROC curves. Observer reproducibility were evaluated using intraclass correlation coefficients. ResultsHigh correlations were found in the blinded analyses (r ≥ 0.87, P < 0.0001 for all). AUC for detecting increased LVM and WT (> 12 mm and > 15 mm) was ≥ 0.95 (P < 0.0001 for all). Reproducibility was excellent (ICC ≥ 0.93, P < 0.0001). Conclusion15O-water PET might detect LV hypertrophy with high accuracy and precision.

Diagnostic Accuracy of Positron Emission Tomography-Computed Tomography (PET-CT Scan) In Detecting Bone Marrow Involvement in Patients with Diffuse Large B cell Lymphoma

Objective: To evaluate the diagnostic accuracy of positron emission tomography combined with CT scan (PET-CT Scan) in detecting bone marrow involvement in patients with diffuse large B-cell lymphoma, keeping bone marrow biopsy as gold standard. Methodology: From November 2017 to May 2018, a cross sectional validation study was carried out at the Aga Khan University in Karachi Department of Oncology's Section of Clinical Hematology. The study comprised a total of 112 patients who were identified as having diffuse large B cell lymphoma after a lymph node was implicated was histopathologically examined. All patients had a PET-CT scan and bone marrow biopsy technique as part of the staging workup. With bone marrow biopsy acting as the gold standard, the diagnostic efficacy of a PET-CT scan for identifying bone marrow involvement was evaluated. Results: Of 112 patients, there were 71(63.39%) males and 41(36.61%) females. The mean age was 45.09±17.36 years. The mean duration of diagnosis was 17.19±6.02 days. Through biopsy, bone marrow involvement was identified in 40 (35.7%) cases. Through a PET-CT scan, bone marrow involvement was identified in 47 (41.9%) cases. The PET- CT scan in comparison with bone marrow biopsy for detecting bone marrow involvement in patients with DLBCL had a sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of 95%, 87.7%, 80.85%, 96.92% and 90.18% respectively. Conclusion: PET-CT scan can accurately detect bone marrow involvement in patients with DLBCL so it can be used in most patients instead of invasive bone marrow biopsy procedure for staging of DLBCL patients.

68Ga-PSMA-11 PET/MRI versus multiparametric MRI in men referred for prostate biopsy: primary tumour localization and interreader agreement

BackgroundMagnetic resonance imaging (MRI) is recommended by the European Urology Association guidelines as the standard modality for imaging-guided biopsy. Recently positron emission tomography with prostate-specific membrane antigen (PSMA PET) has shown promising results as a tool for this purpose. The aim of this study was to compare the accuracy of positron emission tomography with prostate-specific membrane antigen/magnetic resonance imaging (PET/MRI) using the gallium-labeled prostate-specific membrane antigen (68Ga-PSMA-11) and multiparametric MRI (mpMRI) for pre-biopsy tumour localization and interreader agreement for visual and semiquantitative analysis. Semiquantitative parameters included apparent diffusion coefficient (ADC) and maximum lesion diameter for mpMRI and standardized uptake value (SUVmax) and PSMA-positive volume (PSMAvol) for PSMA PET/MRI.ResultsSensitivity and specificity were 61.4% and 92.9% for mpMRI and 66.7% and 92.9% for PSMA PET/MRI for reader one, respectively. RPE was available in 23 patients and 41 of 47 quadrants with discrepant findings. Based on RPE results, the specificity for both imaging modalities increased to 98% and 99%, and the sensitivity improved to 63.9% and 72.1% for mpMRI and PSMA PET/MRI, respectively. Both modalities yielded a substantial interreader agreement for primary tumour localization (mpMRI kappa = 0.65 (0.52–0.79), PSMA PET/MRI kappa = 0.73 (0.61–0.84)). ICC for SUVmax, PSMAvol and lesion diameter were almost perfect (≥ 0.90) while for ADC it was only moderate (ICC = 0.54 (0.04–0.78)). ADC and lesion diameter did not correlate significantly with Gleason score (ρ = 0.26 and ρ = 0.16) while SUVmax and PSMAvol did (ρ = − 0.474 and ρ = − 0.468).ConclusionsPSMA PET/MRI has similar accuracy and reliability to mpMRI regarding primary prostate cancer (PCa) localization. In our cohort, semiquantitative parameters from PSMA PET/MRI correlated with tumour grade and were more reliable than the ones from mpMRI.

Functional stress imaging to predict abnormal coronary fractional flow reserve: the PACIFIC 2 study.

AimsThe diagnostic performance of non-invasive imaging in patients with prior coronary artery disease (CAD) has not been tested in prospective head-to-head comparative studies. The aim of this study was to compare the diagnostic performance of qualitative single-photon emission computed tomography (SPECT), quantitative positron emission tomography (PET), and qualitative magnetic resonance imaging (MRI) in patients with a prior myocardial infarction (MI) or percutaneous coronary intervention (PCI).Methods and resultsIn this prospective clinical study, all patients with prior MI and/or PCI and new symptoms of ischaemic CAD underwent 99mTc-tetrofosmin SPECT, [15O]H2O PET, and MRI, followed by invasive coronary angiography with fractional flow reserve (FFR) in all coronary arteries. All modalities were interpreted by core laboratories. Haemodynamically significant CAD was defined by at least one coronary artery with an FFR ≤0.80. Among the 189 enrolled patients, 63% had significant CAD. Sensitivity was 67% (95% confidence interval 58–76%) for SPECT, 81% (72–87%) for PET, and 66% (56–75%) for MRI. Specificity was 61% (48–72%) for SPECT, 65% (53–76%) for PET, and 62% (49–74%) for MRI. Sensitivity of PET was higher than SPECT (P = 0.016) and MRI (P = 0.014), whereas specificity did not differ among the modalities. Diagnostic accuracy for PET (75%, 68–81%) did not statistically differ from SPECT (65%, 58–72%, P = 0.03) and MRI (64%, 57–72%, P = 0.052). Using FFR < 0.75 as a reference, accuracies increased to 69% (SPECT), 79% (PET), and 71% (MRI).ConclusionIn this prospective head-to-head comparative study, SPECT, PET, and MRI did not show a significantly different accuracy for diagnosing FFR defined significant CAD in patients with prior PCI and/or MI. Overall diagnostic performances, however, were discouraging and the additive value of non-invasive imaging in this high-risk population is questionable.

Data-driven gated CT: An automated respiratory gating method to enable data-driven gated PET/CT.

The accuracy of positron emission tomography (PET) quantification and localization can be compromised if a misregistered computed tomography (CT) is used for attenuation correction (AC) in PET/CT. As data-driven gating (DDG) continues to grow in clinical use, these issues are becoming more relevant with respect to solutions for gated CT. In this work, a new automated DDG CT method was developed to provide average CT and DDG CT for AC of PET and DDG PET, respectively. An automatic DDG CT was developed to provide the end-expiratory (EE) and end-inspiratory (EI) phases of images from low-dose cine CT images, with all phases being averaged to generate an average CT. The respiratory phases of EE and EI were determined according to lung region Hounsfield unit (HU) values and body outline contours. The average CT was used for AC of baseline PET and DDG CT at EE phase was used for AC of DDG PET at the quiescent or EE phase. The EI and EE phases obtained with DDG CT were used for assessing the magnitude of respiratory motion. The proposed DDG CT was compared to two commercial CT gating methods: (1) 4D CT (external device based) and (2) D4D CT (DDG based) in 38 patient datasets with respect to respiratory phase image selection, lung HU, lung volume, and image artifacts. In a separate set of twenty consecutive PET/CT studies containing a mix of 18 F-FDG, 68 Ga-Dotatate, and 64 Cu-Dotatate scans, the proposed DDG CT was compared with D4D CT for impacts on registration and quantification in DDG PET/CT. In the EE phase, the images selected by DDG CT and 4D CT were identical 62.5% ± 21.6% of the time, whereas DDG CT and D4D CT were 6.5% ± 9.7%, and 4D CT and D4D CT were 8.6% ± 12.2%. These differences in EE phase image selection were significant (p < 0.0001). In the EI phase, the images selected by DDG CT and 4D CT were identical 68.2% ± 18.9% of the time, DDG CT and D4D CT were 63.9% ± 18.8%, and 4D CT and D4D CT were 61.2% ± 19.8%. These differences were not significant. The mean lung HU and volumes were not statistically different (p > 0.1) among the three methods. In some studies, DDG CT was better than D4D or 4D CT in the appropriate selection of the EE and EI phases, and D4D CT was found to reverse the EE and EI phases or not select the correct images by visual inspection. A statistically significant improvement of DDG CT over D4D CT for AC of DDG PET was also demonstrated with PET quantification analysis. When irregular breath cycles were present in the cine CT, DDG CT could be used to replace average CT for the improved AC of baseline PET. A new automatic DDG CT was developed to tackle the issues of misregistration and tumor motion in PET/CT imaging. DDG CT was significantly more consistent than D4D CT in selecting the EE phase images as the clinical standard of 4D CT. When compared to both commercial gated CT methods of 4D CT and D4D CT, DDG CT appeared to be more robust in the lower lung and upper diaphragm regions where misregistration and tumor motion often occur. DDG CT offered improved AC for DDG PET relative to D4D CT. In cases with irregular respiratory motion, DDG CT improved AC over average CT for baseline PET. The new DDG CT provides the benefits of 4D CT without the need for external device gating.

MCP-Net: Inter-frame Motion Correction with Patlak Regularization for Whole-body Dynamic PET.

Inter-frame patient motion introduces spatial misalignment and degrades parametric imaging in whole-body dynamic positron emission tomography (PET). Most current deep learning inter-frame motion correction works consider only the image registration problem, ignoring tracer kinetics. We propose an inter-frame Motion Correction framework with Patlak regularization (MCP-Net) to directly optimize the Patlak fitting error and further improve model performance. The MCP-Net contains three modules: a motion estimation module consisting of a multiple-frame 3-D U-Net with a convolutional long short-term memory layer combined at the bottleneck; an image warping module that performs spatial transformation; and an analytical Patlak module that estimates Patlak fitting with the motion-corrected frames and the individual input function. A Patlak loss penalization term using mean squared percentage fitting error is introduced to the loss function in addition to image similarity measurement and displacement gradient loss. Following motion correction, the parametric images were generated by standard Patlak analysis. Compared with both traditional and deep learning benchmarks, our network further corrected the residual spatial mismatch in the dynamic frames, improved the spatial alignment of Patlak Ki/Vb images, and reduced normalized fitting error. With the utilization of tracer dynamics and enhanced network performance, MCP-Net has the potential for further improving the quantitative accuracy of dynamic PET. Our code is released at https://github.com/gxq1998/MCP-Net.

Positron Emission Tomography (PET) for Molecular Plant Imaging.

Positron emission tomography (PET) is an imaging technology that measures 3D spatial distribution and kinetics of radio-tagged biomolecules in a living subject quantitatively and nondestructively. Commonly used positron-emitting radionuclides include 11C, 13N, and 15O, which are essential elements for plant growth. Combining radiotracer techniques with PET, this in vivo molecular imaging capability offers plant biologists a powerful tool for molecular phenotyping research. While PET is widely used clinically for cancer diagnosis and pre-clinically for drug development, it is an unfamiliar imaging tool for plant biologists. This chapter introduces the basic principles of PET, factors that affect the quantitative accuracy of PET when imaging plants, and techniques for administering radiotracers to plants for a variety of molecular plant imaging applications.

Prognostic value of high-frequency oscillations combined with multimodal imaging methods for epilepsy surgery.

Background:The combination of high-frequency oscillations (HFOs) with single-mode imaging methods has been proved useful in identifying epileptogenic zones, whereas few studies have examined HFOs combined with multimodal imaging methods. The aim of this study was to evaluate the prognostic value of ripples, an HFO subtype with a frequency of 80 to 200 Hz is combined with multimodal imaging methods in predicting epilepsy surgery outcome.Methods:HFOs were analyzed in 21 consecutive medically refractory epilepsy patients who underwent epilepsy surgery. All patients underwent positron emission tomography (PET) and deep electrode implantation for stereo-electroencephalography (SEEG); 11 patients underwent magnetoencephalography (MEG). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in predicting surgical outcome were calculated for ripples combined with PET, MEG, both PET and MEG, and PET combined with MEG. Kaplan-Meier survival analyses were conducted in each group to estimate prognostic value.Results:The study included 13 men and 8 women. Accuracy for ripples, PET, and MEG alone in predicting surgical outcome was 42.9%, 42.9%, and 81.8%, respectively. Accuracy for ripples combined with PET and MEG was the highest. Resection of regions identified by ripples, MEG dipoles, and combined PET findings was significantly associated with better surgical outcome (P < 0.05).Conclusions:Intracranial electrodes are essential to detect regions which generate ripples and to remove these areas which indicate good surgical outcome for medically intractable epilepsy. With the assistance of presurgical noninvasive imaging examinations, PET and MEG, for example, the SEEG electrodes would identify epileptogenic regions more effectively.

Tumor-Specificity Growth Factor Combined with Tumor Markers in Nuclear Medicine Imaging to Identify Prostate Cancer Osteonosus.

Objective This study has explored the application value of malignant tumor SPE growth factor (TSGF) combined with tumor markers (TM) (TSGF + TM) in nuclear medicine imaging to identify prostate cancer osteonosus (PCO). Methods A retrospective analysis for 70 patients with prostate cancer and bone disease admitted to our hospital was performed, 30 healthy persons in the same period were selected as the control group, and the advantages and disadvantages of various examinations were analyzed. All patients were diagnosed with PET whole body bone imaging. Suspicious lesions could be examined by MRI or CT. According to the results of imaging examination, patients were divided into 40 cases of malignant prostate cancer and 30 cases of benign prostate cancer. All the patients underwent 18F-FDG-PET imaging, alpha-fetoprotein (AFP), and TSGF + TM determination. The case diagnosis results were compared and analyzed, and the sensitivity (SEN), specificity (SPE), and accuracy (ACC) of various detection methods were calculated. The SEN, SPE, and ACC of positron emission tomography (PET) were 90.9%, 57.8%, and 81.2%, respectively; those of TM were 79.2%, 94.6%, and 69.8%, respectively; and those of TSGF + TM were 95.9%, 100%, and 97.3%, respectively. The accuracy of combined diagnosis of tumors can reach 100%. The AFP and TSGF levels of serum TM were compared and analyzed, and it was found that the benign lesion group and the malignant lesion group showed significant increases compared with the control group, and the difference between the malignant lesion group and the control group was obvious (P < 0.05). SGF combined with TM could obtain a more definite diagnosis in PCO. Conclusion TSGF + TM combined with 18F-FDG-PET imaging showed important clinical value to diagnose the PCO. The imaging accuracy of TSGF + TM combined with 18F-FDG-PET is 97.3%, and the specificity of tumor diagnosis is 100%. Therefore, the TSGF + TM applied in medical imaging and identification of PCO was worthy of clinical promotion.

Assessment of MicroPET Image Quality Based on Reconstruction Methods and Post-Filtering

The accuracy of positron emission tomography (PET) imaging is hampered by the partial volume effect (PVE), which causes image blurring and sampling. The PVE produces spillover phenomena, making PET analysis difficult. Generally, the PVE values vary based on reconstruction methods and filtering. Thus, selection of the proper reconstruction and filtering method can ensure accurate and high-quality PET images. This study compared the values of factors (recovery coefficient (RC), uniformity, and spillover ratio (SOR)) associated with different reconstruction and post-filtering methods using a mouse image quality phantom (NEMA NU 4), and we present an effective approach for microPET images. The PET images were obtained using a microPET scanner (Inveon, Siemens Medical Solutions, Malvern, PA, USA). PET data were reconstructed and/or post-filtered. For tumors smaller than 3 mm, iterative reconstruction methods provided better image quality. For tumor sizes bigger than 3 mm, reconstruction methods without post-filtering showed better results.