Prognostic thresholds of fluorine-18 fluorodeoxyglucose-positron emission tomography mean and maximum standardized uptake values for survival and nodal involvement in lung neuroendocrine neoplasms.

OBJECTIVES: The mean standardized uptake value (SUVmean) and maximum standardized uptake value (SUVmax) on fluorine-18 fluorodeoxyglucose-positron emission tomography are prognostic biomarkers for survival and nodal involvement in non-small-cell lung cancer but their prognostic value in lung neuroendocrine neoplasms (NENs) remains unexplored. In this study, we aimed to examine whether they are also prognostic biomarkers for survival and nodal involvement in lung NENs. METHODS: We retrospectively studied patients with typical carcinoid, atypical carcinoid or large cell neuroendocrine carcinoma who had been radically resected at our institution between 2008 and 2020. We measured SUVmean and SUVmax on all primary tumours and lymph nodes that were clinically and/or pathologically involved. We dichotomized the patients into groups of high or low SUVmean and SUVmax of the primary tumour using time-dependent receiver operating characteristic curves and compared their overall survival using Kaplan-Meier curves and Cox models. Lastly, we predicted the patients' pathological nodal status with SUVmean and SUVmax of the lymph nodes using binomial logistic models. RESULTS: The study included 245 patients. Patients died earlier if their SUVmean of the primary tumour exceeded 3.9 [hazard ratio 1.97, 95% confidence interval (CI) 1.27-3.04, P = 0.002] or SUVmax exceeded 5.3 (hazard ratio 1.85, 95% CI 1.20-2.87, P = 0.006). Likewise, patients had a higher risk of pathological nodal involvement if their SUVmean of the lymph nodes exceeded 3.3 (odds ratio 10.00, 95% CI 2.59-51.01, P = 0.002) or SUVmax exceeded 4.2 (odds ratio 4.00, 95% CI 1.20-14.65, P = 0.028). CONCLUSIONS: The fluorine-18 fluorodeoxyglucose-positron emission tomography SUVmean and SUVmax are strong prognostic biomarkers for survival and nodal involvement in lung NENs and could be important guides for making treatment decisions.

Urokinase Plasminogen Activator Receptor: An Important Focal Player in Chronic Subdural Hematoma?

Chronic subdural hematoma (CSDH) development involves inflammatory, angiogenetic, and fibrinolytic mechanisms, several components of which are now unraveled through intensive research. The urokinase plasminogen activator receptor (uPAR) is part of the plasminogen activator system and possesses inflammatory, angiogenetic, and fibrinolytic capabilities. As a first, this study aims to identify uPAR in the hematoma fluid, hematoma membrane, dura mater, and systemic blood from patients with CSDH and, if present, to investigate if the uPAR level at the time of surgery may be a predictor for later developing recurrent CSDH. uPAR expression in the hematoma membrane and dura mater was analyzed using immunohistochemistry and presented as the H-score of the positive immunostaining. The uPAR levels in the hematoma fluid and systemic blood were determined using a multiplex antibody bead kit (Luminex). Samples were collected at the time of the first CSDH surgery, and in the case of recurrent CSDH within 90 days, the samples were again collected at reoperation. A comparison of uPAR expression between the hematoma membrane and dura mater, as well as uPAR levels in systemic blood and hematoma fluid, was performed using the Wilcoxon rank sum test. We included 112 patients, 26 of whom had recurrent CSDH. The median hematoma uPAR level was 22,125 (14,845-33,237) and significantly higher than the median systemic blood level of 789 pg/L (465-2,088) (p < 0.001). Similarly, the uPAR level of the hematoma membrane was 14.3 (7.54-44.8) and significantly higher than the dural uPAR level of 0.81 (0.3-1.98) (p < 0.001). For the first time, we identified uPAR in the subdural fluid, hematoma membrane, dura mater, and systemic blood from patients with CSDH. The high expression of uPAR in the subdural fluid and hematoma membrane indicates that the mechanisms of CSDH are predominantly in the subdural fluid collection and surrounding hematoma membrane.

Longitudinal imaging of murine atherosclerosis with 2-deoxy-2-[18F]fluoro-D-glucose and [18F]-sodium fluoride in genetically modified Apolipoprotein E knock-out and wild type mice.

In a longitudinal design, four arterial segments in mice were followed by positron emission tomography/computed tomography (PET/CT) imaging. We aimed to determine how the tracers reflected the development of atherosclerosis via the uptake of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) for imaging inflammation and [18F]-sodium fluoride (Na[18F]F) for imaging active microcalcification in a murine model of atherosclerosis. Apolipoprotein E knock-out (ApoE) mice and C57 BL/6NtaC (B6) mice were divided into four groups. They received either normal chow (N = 7, ApoE mice and N = 6, B6 mice) for 32 weeks or a high-fat diet (N = 6, ApoEHFD mice and N = 9, B6HFD mice) for 32 weeks. The mice were scanned with [18F]FDG and Na[18F]F using a dedicated small animal PET/CT scanner at three timepoints. The tracer uptakes in four aortic segments (abdominal aorta, aortic arch, ascending aorta, and thoracic aorta) were measured and reported as SUVmax values. The uptake of [18F]FDG (SUVmax: 5.7 ± 0.5 vs 1.9 ± 0.2, 230.3%, p = < 0.0001) and Na[18F]F (SUVmax: 9.6 ± 1.8 vs 4.0 ± 0.3, 175%, p = 0.007) was significantly increased in the abdominal aorta of ApoEHFD mice at Week 32 compared to baseline abdominal aorta values of ApoEHFD mice. [18F]FDG uptake in the aortic arch, ascending aorta and the thoracic aorta of B6HFD mice at Week 32 showed a robust resemblance to the abdominal aorta uptake whereas the Na[18F]F uptake only resembled in the thoracic aorta of B6HFD mice at Week 32 compared to the abdominal aorta. The uptake of both [18F]FDG and Na[18F]F increased as the disease progressed over time, and the abdominal aorta provided a robust measure across mouse strain and diet. Therefore, it seems to be the preferred region for image readout. For [18F]FDG-PET, both B6 and ApoE mice provide valuable information and either mouse strain may be used in preclinical cardiovascular studies, whereas for Na[18F]F -PET, ApoE mice should be preferred.

Urokinase-Type Plasminogen Activator Receptor (uPAR) Expression and [64Cu]Cu-DOTA-AE105 uPAR-PET/CT in Patient-Derived Xenograft Models of Oral Squamous Cell Carcinoma.

PURPOSE: [64Cu]Cu-DOTA-AE105 urokinase-type plasminogen activator receptor (uPAR)-PET/CT is a novel and promising imaging modality for cancer visualization, although it has not been tested in head and neck cancer patients nor in preclinical models that closely resemble these heterogenous tumors, i.e., patient-derived xenograft (PDX) models. The aim of the present study was to establish and validate oral squamous cell carcinoma (OSCC) PDX models and to evaluate [64Cu]Cu-uPAR-PET/CT for tumor imaging in these models. PROCEDURES: PDX flank tumor models were established by engrafting tumor tissue from three patients with locally advanced OSCC into immunodeficient mice. [64Cu]Cu-DOTA-AE105 was injected in passage 2 (P2) mice, and [64Cu]Cu-uPAR-PET/CT was performed 1 h and 24 h after injection. After the last PET scan, all animals were euthanized, and tumors dissected for autoradiography and immunohistochemical (IHC) staining. RESULTS: Three PDX models were established, and all of them showed histological stability and unchanged heterogenicity, uPAR expression, and Ki67 expression through passages. A significant correlation between uPAR expression and tumor growth was found. All tumors of all models (n=29) showed tumor uptake of [64Cu]Cu-DOTA-AE105. There was a clear visual concordance between the distribution of uPAR expression (IHC) and [64Cu]Cu-DOTA-AE105 uptake pattern in tumor tissue (autoradiography). No significant correlation was found between IHC (H-score) and PET-signal (SUVmax) (r=0.34; p=0.07). CONCLUSIONS: OSCC PDX models in early passages histologically mimic donor tumors and could serve as a valuable platform for the development of uPAR-targeted imaging and therapeutic modalities. Furthermore, [64Cu]Cu-uPAR-PET/CT showed target- and tumor-specific uptake in OSCC PDX models demonstrating the diagnostic potential of this modality for OSCC patients.

Imaging of atherosclerosis with [64Cu]Cu-DOTA-TATE in a translational head-to-head comparison study with [18F]FDG, and Na[18F]F in rabbits.

Atherosclerosis is a chronic inflammatory disease of the larger arteries that may lead to cardiovascular events. Identification of patients at highest risk of cardiovascular events is challenging, but molecular imaging using positron emission tomography (PET) may prove useful. The aim of this study was to evaluate and compare head-to-head three different PET tracers. Furthermore, tracer uptake is compared to gene expression alterations of the arterial vessel wall. Male New Zealand White rabbits (control group; n = 10, atherosclerotic group; n = 11) were used for the study. Vessel wall uptake was assessed with the three different PET tracers: [18F]FDG (inflammation), Na[18F]F (microcalcification), and [64Cu]Cu-DOTA-TATE (macrophages), using PET/computed tomography (CT). Tracer uptake was measured as standardized uptake value (SUV), and arteries from both groups were analyzed ex vivo by autoradiography, qPCR, histology, and immunohistochemistry. In rabbits, the atherosclerotic group showed significantly higher uptake of all three tracers compared to the control group [18F]FDG: SUVmean 1.50 ± 0.11 versus 1.23 ± 0.09, p = 0.025; Na[18F]F: SUVmean 1.54 ± 0.06 versus 1.18 ± 0.10, p = 0.006; and [64Cu]Cu-DOTA-TATE: SUVmean 2.30 ± 0.27 versus 1.65 ± 0.16; p = 0.047. Of the 102 genes analyzed, 52 were differentially expressed in the atherosclerotic group compared to the control group and several genes correlated with tracer uptake. In conclusion, we demonstrated the diagnostic value of [64Cu]Cu-DOTA-TATE and Na[18F]F for identifying atherosclerosis in rabbits. The two PET tracers provided information distinct from that obtained with [18F]FDG. None of the three tracers correlated significantly to each other, but [64Cu]Cu-DOTA-TATE and Na[18F]F uptake both correlated with markers of inflammation. [64Cu]Cu-DOTA-TATE was higher in atherosclerotic rabbits compared to [18F]FDG and Na[18F]F.

[68Ga]Ga-NODAGA-E[(cRGDyK)]2 angiogenesis PET following myocardial infarction in an experimental rat model predicts cardiac functional parameters and development of heart failure.

BACKGROUND: Angiogenesis has increasingly been a target for imaging and treatment over the last decade. The integrin αvß3 is highly expressed in cells during angiogenesis and are therefore a promising target for imaging. In this study, we aimed to investigate the PET tracer [68Ga]Ga-RGD as a marker of angiogenesis following MI and its ability to predict cardiac functional parameters. METHODS: First, the real-time interaction between [68Ga]Ga-RGD and integrin αvß3 was investigated using surface plasmon resonance (SPR). Second, an animal study was performed to investigate the [68Ga]Ga-RGD uptake in the infarcted area after one and four weeks following MI in a rat model (MI = 68, sham surgery = 36). Finally, the specificity of the [68Ga]Ga-RGD tracer was evaluated ex vivo using histology, autoradiography, gamma counting and flow cytometry. RESULTS: SPR showed that [68Ga]Ga-RGD has a high affinity for integrin αvß3, forming a strong and stable binding. PET/CT showed a significantly higher uptake of [68Ga]Ga-RGD in the infarcted area compared to sham one week (p < 0.001) and four weeks (p < 0.001) after MI. The uptake of [68Ga]Ga-RGD after one week correlated to end diastolic volume (r = 0.74, p < 0.001) and ejection fraction (r = - 0.71, p < 0.001) after four weeks. CONCLUSION: This study demonstrates that [68Ga]Ga-RGD has a high affinity for integrin αvß3, which enables the evaluation of angiogenesis and remodeling. The [68Ga]Ga-RGD uptake after one week indicates that [68Ga]Ga-RGD may be used as an early predictor of cardiac functional parameters and possible development of heart failure after MI. These encouraging data supports the clinical translation and future use in MI patients.

Subdural Levels of Interleukin 1-receptor Antagonist are Elevated in Patients with Recurrent Chronic Subdural Hematomas.

Anti-inflammatory treatment reduces the risk of recurrent chronic subdural hematoma (CSDH), but clinical implementation is improper due to side effects. Exact knowledge of subdural molecules involved in recurrent CSDH may lead to targeted medical treatment and possibly improve the prospect of a personalized approach by eliminating the broad use of anti-inflammatory drugs on the entire CSDH population. With this study, we aim to (1) describe the associations between cytokine levels at the primary surgery and the risk of subsequent recurrence and (2) describe the association between cytokines in patients with recurrent CSDH between the first and second operations. Systemic and subdural levels of pro- and anti-inflammatory cytokines were measured and compared between patients with the first-time CSDH and recurrent CSDH. Cytokine levels were analyzed using a multiplex antibody bead kit. In case of recurrent CSDH within 90 days of follow-up, the samples were re-collected and analyzed. We included 101 adult CSDH patients of which 20 had a recurrence. The levels of cytokines in the CSDH fluid from patients who were operated on for the first-time CSDH were not associated with the risk of later developing a recurrence. We found interleukin-1 receptor antagonist (IL-1ra) to be elevated in subdural fluid in patients with recurrent CSDH at the time of their second operation (p = 0.0005). This study provides knowledge on cytokine composition in the subdural fluid in patients with CSDH with and without recurrence. IL-1ra is elevated in subdural fluid in patients with recurrent CSDH at the time of the second operation, identifying a possible medical target.

[68Ga]Ga-NODAGA-E[(cRGDyK)]2 and [64Cu]Cu-DOTATATE PET Predict Improvement in Ischemic Cardiomyopathy.

An increasing number of patients are living with chronic ischemic cardiomyopathy (ICM) and/or heart failure. Treatment options and prognostic tools are lacking for many of these patients. Our aim was to investigate the prognostic value of imaging angiogenesis and macrophage activation via positron emission tomography (PET) in terms of functional improvement after cell therapy. Myocardial infarction was induced in rats. Animals were scanned with [18F]FDG PET and echocardiography after four weeks and randomized to allogeneic adipose tissue-derived stromal cells (ASCs, n = 18) or saline (n = 9). Angiogenesis and macrophage activation were assessed before and after treatment by [68Ga]Ga-RGD and [64Cu]Cu-DOTATATE. There was no overall effect of the treatment. Rats that improved left ventricular ejection fraction (LVEF) had higher uptake of both [68Ga]Ga-RGD and [64Cu]Cu-DOTATATE at follow-up (p = 0.006 and p = 0.008, respectively). The uptake of the two tracers correlated with each other (r = 0.683, p = 0.003 pre-treatment and r = 0.666, p = 0.004 post-treatment). SUVmax at follow-up could predict improvement in LVEF (p = 0.016 for [68Ga]Ga-RGD and p = 0.045 for [64Cu]Cu-DOTATATE). High uptake of [68Ga]Ga-RGD and [64Cu]Cu-DOTATATE PET after injection of ASCs or saline preceded improvement in LVEF. The use of these tracers could improve the monitoring of heart failure patients in treatment.

Urokinase-type plasminogen activator receptor (uPAR) assessed by liquid biopsies and PET/CT for prognostication in head and neck cancer patients.

Strong prognostic biomarkers are lacking regarding the stratification of treatment and surveillance regimens in head and neck squamous cell carcinoma (HNSCC). The study aimed to assess the prognostic value of soluble urokinase-type plasminogen activator receptor in plasma (suPAR) compared to evaluation by uPAR-positron-emission-tomography (PET) in HNSCC patients. Plasma from 19 controls and 49 HNSCC patients referred to curatively intended radiotherapy (2017-2021) was collected pre-treatment and post-treatment (n = 37). Information on uPAR-PET was available from previous evaluation. Patient median suPAR was significantly higher pre- and post-treatment compared to controls (p = 0.013, p = 0.003) and increased significantly during radiotherapy (p = 0.003). Pre-treatment suPAR did not predict survival outcomes. Post-treatment suPAR significantly predicted RFS (HR = 6.67 (95% CI 1.44-30.9) p = 0.015), but not OS (HR = 3.29 (95% CI 0.882-12.3) p = 0.076) in univariate analysis. RFS prediction was maintained for post-treatment suPAR in multivariate analysis, including TNM-stage (HR = 6.62 (95% CI 1.40-31.4) p = 0.017). Pre-treatment uPAR-PET/CT and post-treatment suPAR was available in 24 patients. High uPAR-estimates on both modalities was significantly associated with poor RFS compared to patients with low uPAR-estimates (log-rank, p = 0.008). Patients with discordant uPAR-estimates (one-low/one-high) were at intermediate risk, although non-significant (p = 0.131). In conclusion, pre-treatment suPAR did not predict RFS or OS. Pre-treatment uPAR-PET and post-treatment suPAR predicted RFS.

Semaglutide reduces vascular inflammation investigated by PET in a rabbit model of advanced atherosclerosis.

BACKGROUND AND AIMS: The objective of this study was to investigate the effects of semaglutide, a long acting glucagon-like peptide-1 receptor agonist, on atherosclerotic inflammation and calcification using a multimodality positron emission tomography and computed tomography (PET/CT) approach. METHODS: Atherosclerotic New Zealand White rabbits were randomized to an intervention- (n = 12) or placebo group (n = 11) receiving either semaglutide or saline-placebo. PET/CT imaging was done before and after 16-weeks of intervention. Three different radiotracers were used: [64Cu]Cu-DOTATATE for imaging of activated macrophages, [18F]FDG imaging cellular metabolism and [18F]NaF PET visualizing micro-calcifications. Tracer uptake was quantified by maximum standardized uptake value (SUVmax) and target-to-background-ratio (TBRmax). Animals were euthanized for autoradiographic imaging and histological analyses. RESULTS: A reduction in activated macrophage tracer-uptake was observed in the semaglutide group (SUVmax: p = 0.001 and TBRmax: p = 0.029). When imaging cellular metabolism, an attenuation of SUVmax and TBRmax was observed in the semaglutide group (p = 0.034 and p = 0.044). We found no difference in uptake of the micro-calcification tracer between the two groups (SUVmax: p = 0.62 and TBRmax: p = 0.36). Values of macrophage density in the vessel wall were significantly correlated with SUVmax values of the activated macrophage (r = 0.54, p = 0.0086) and cellular metabolism tracers (r = 0.51, p = 0.013). CONCLUSIONS: Semaglutide decreased vascular uptake of tracers imaging activated macrophages and cellular metabolism but not micro-calcifications compared to a saline placebo. This supports the hypothesis that semaglutide reduces atherosclerotic inflammation by means of decreased activated macrophage activity.

In vivo detection of urokinase-type plasminogen activator receptor (uPAR) expression in arterial atherogenesis using [64Cu]Cu-DOTA-AE105 positron emission tomography (PET).

BACKGROUND AND AIMS: Urokinase-type plasminogen activator receptor (uPAR) is associated with extracellular matrix (ECM) degradation and cancer aggressiveness. Its role in arterial atherogenesis as a molecular imaging target is not well-established. The aim of this study was to non-invasively visualize uPAR expression in atherosclerosis by a novel uPAR-targeting positron emission tomography (PET) tracer [64Cu]Cu-DOTA-AE105. METHODS: We used molecular biology to investigate uPAR expression by analyzing human atherosclerotic plaques and cultured cells. A retrospective analysis was performed on patients, who underwent combined PET/CT (n = 10) to measure [64Cu]Cu-DOTA-AE105 uptake in five large arteries, divided into a high and low-risk group based on coronary artery calcium score (CAC score). RESULTS: The in vitro assay for THP-1 monocytes displayed a significantly upregulated uPAR expression upon stimulation (5.2-fold upregulation, p < 0.0001 by a one-way ANOVA followed by Tukey's test) by single-cell flowcytometric analysis. Freshly excised human atherosclerotic plaques underwent flow cytometric and microarray analyses manifesting 73.9 ± 2.9% of mononuclear phagocyte system (MPS) cells expressing uPAR and had a greater than 7-fold higher gene expression of plasminogen activator urokinase receptor (PLAUR, p = 0.002), integrin subunit alpha X (ITGAX, p = 0.0008), and cluster of differentiation 163 (CD163, p < 0.0001). The tissue-to-background ratios (TBRmax) in five large arteries showed a higher [64Cu]Cu-DOTA-AE105 uptake in the group with high CAC score compared to the group with low CAC score (2.4 ± 0.1 vs 1.7 ± 0.1, p = 0.057), significantly higher in the ascending aorta (2.7 ± 0.1 vs 2.0 ± 0.1, p = 0.038) and the abdominal aorta (3.2 ± 0.2 vs 2.0 ± 0.2, p = 0.038) by a non-parametric Mann-Whitney test. CONCLUSIONS: uPAR is abundantly expressed by MPS cells in atherosclerotic plaques and can be visualized by the novel PET tracer [64Cu]Cu-DOTA-AE105 that may non-invasively detect extracellular matrix remodeling during atherogenesis.

Long-term outcomes after video-assisted thoracoscopic surgery in pulmonary large-cell neuroendocrine carcinoma.

BACKGROUND: Pulmonary large-cell neuroendocrine carcinoma (LCNEC) is a rare subtype of lung cancer with dismal prognosis. Long-term outcomes after primarily video-assisted thoracoscopic surgery (VATS) have not yet been described in LCNEC. This study aims to determine overall survival and recurrence-free survival after VATS as well as to identify prognostic factors for survival and recurrence. METHODS: Data were obtained from a prospective institutional database. Kaplan-Meier estimates of overall survival and recurrence-free survival were determined and compared across prognostic factors using log-rank analysis and the Cox proportional hazards model. RESULTS: Data from 82 consecutive patients undergoing surgical resection from 2009 to 2020 were included. All patients underwent surgical resection with curative intent, of whom 96.3% were by a VATS approach. Morbidity was low without any conversions or 30-day mortality. Lobectomy was performed in 87.8% of patients, followed by wedge resection in 4.9% and segmentectomy in 3.7%. No pneumonectomies were performed. Radical resection (R0) was achieved in 97.6%. Thirty-four patients (41.5%) had adjuvant platinum-based chemotherapy and high proportion completed at least four series (76.7%). The mean follow-up was 5.1 years. The 1-year, 3-year, and 5-year overall survival rates were 86%, 54%, and 45%, while the corresponding recurrence-free survival rates were 67%, 45%, and 35%. Advanced age was an independent predictor of poor overall survival (HR 2.08; 95% CI 1.04-4.17; p = 0.038). CONCLUSION: A 96.3% VATS rate was feasible in LCNEC and associated with a low morbidity rate and a high compliance with adjuvant chemotherapy. Overall survival and recurrence-free survival was comparable to previous series using thoracotomy.

Effect of Liraglutide on Arterial Inflammation Assessed as [18F]FDG Uptake in Patients With Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Trial.

BACKGROUND: The mechanism behind the cardiovascular protection observed with human GLP-1 RA (glucagon-like peptide-1 receptor agonists) in type 2 diabetes is unknown. We hypothesized that treatment with the GLP-1 RA liraglutide had a positive effect on vascular inflammation. METHODS: LIRAFLAME (Effect of liraglutide on vascular inflammation in type-2 diabetes: A randomized, placebocontrolled, double-blind, parallel clinical PET/CT trial) was a double-blind, randomized controlled trial performed at a single university hospital clinic in Denmark. Patients with type 2 diabetes were via computer-generated randomization list assigned (1:1) liraglutide up to 1.8 mg or placebo once daily for 26 weeks. The primary end point was change in vascular inflammation over 26 weeks assessed by [18F]-fluorodeoxyglucose positron emission tomography/computed tomography. Analyses were based on intention-to-treat. Key secondary outcomes included change in other indices of atherosclerosis. RESULTS: Between October 26, 2017, and August 16, 2019, 147 patients were screened and 102 were randomly assigned to liraglutide (n=51) or placebo (n=51) and 99 (97%) completed the trial. Change in the [18F]-fluorodeoxyglucose positron emission tomography measure of vascular inflammation (active-segment target-to-background ratio) did not differ between treatment groups: change from baseline to 26 weeks was -0.04 (95% CI, -0.17 to 0.08) in the liraglutide group compared with -0.09 (-0.19 to 0.01) in the placebo group (mean difference, 0.05 [95% CI, -0.11 to 0.21], P=0.53). Secondary analyses restricted to [18F]-fluorodeoxyglucose positron emission tomography of the carotid arteries as well as other indices of atherosclerosis confirmed the primary result. We performed an explorative analysis of interaction between treatment group and history of cardiovascular disease (P=0.052). CONCLUSIONS: In this low to moderate risk population with type 2 diabetes, liraglutide did not change vascular inflammation assessed as [18F]-fluorodeoxyglucose uptake compared with placebo. An explorative analysis indicated a possible effect in persons with history of cardiovascular disease, in line with current guidelines where liraglutide is recommended to patients with history of cardiovascular disease. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03449654.

Long-term survival and recurrence after resection of bronchopulmonary carcinoids: A single-center cohort study of 236 patients.

OBJECTIVE: The aim of this study was to determine overall survival and recurrence-free survival after resection of bronchopulmonary carcinoids by means of predominantly minimally invasive surgery and lung-sparing resections. In addition, we aimed to identify prognostic factors for overall survival. MATERIALS AND METHODS: Retrospective review of consecutive patients operated for bronchopulmonary carcinoids between January 2009 and October 2020 identified from a prospectively collected database. RESULTS: A total of 236 patients representing 240 cases of bronchopulmonary carcinoids were included. Of these, 212 (88.3 %) were typical carcinoids, while 28 (11.7 %) were atypical carcinoids. A Video-Assisted Thoracoscopic Surgery (VATS) approach was used in 75 % of cases. There was no 30-day mortality. The median follow-up was 5.6 years for overall survival and 4.7 years for recurrence-free survival. 5- and 10-year overall survival rates were 89 % and 71 %, while 5- and 10-year recurrence-free survival rates were 84 % and 71 %. Patients with atypical carcinoids had significantly reduced overall survival and recurrence-free survival rates (HR 3.4; 95 % CI 1.5-7.6; p = 0.003 and HR 5.4; 95 % CI 2.6-11.4; p < 0.001). Independent predictors of overall survival included atypical carcinoid (HR 2.7; 95 % CI 1.2-6.0; p = 0.018) and age > 60 years (HR 2.9; 95 % CI 1.2-7.3; p = 0.021). CONCLUSION: Surgery for bronchopulmonary carcinoids by means of predominantly VATS and lung-sparing resections provides favorable long-term survival. Atypical carcinoids and age > 60 years are independent predictors of poor overall survival.

64Cu-DOTATATE PET in Patients with Neuroendocrine Neoplasms: Prospective, Head-to-Head Comparison of Imaging at 1 Hour and 3 Hours After Injection.

64Cu-DOTATATE PET/CT imaging 1 h after injection is excellent for lesion detection in patients with neuroendocrine neoplasms (NENs). We hypothesized that the imaging time window can be extended up to 3 h after injection without significant differences in the number of lesions detected. Methods: From a prospective study, we compared, on a head-to-head basis, sets of 64Cu-DOTATATE PET/CT images from 35 patients with NENs scanned 1 and 3 h after injection of 200 MBq of 64Cu-DOTATATE. The number of lesions on both PET scans was counted and grouped according to organs or regions and compared with negative binomial regression. Discordant lesions (visible on only the 1-h images or only the 3-h 64Cu-DOTATATE PET images) were considered true if found on simultaneous CT or later MR, CT, or somatostatin receptor imaging. We measured lesion SUVmax, reference normal-organ or -tissue SUVmean, and tumor-to-normal-tissue ratios calculated from SUVmax and SUVmeanResults: We found 822 concordant lesions (visible on both 1-h and 3-h 64Cu-DOTATATE PET) and 5 discordant lesions, of which 4 were considered true. One discordant case in 1 patient involved a discordant organ system (lymph node) detected on 3-h but not 1-h 64Cu-DOTATATE PET that did not alter the patient's disease stage (stage IV) because the patient had 11 additional concordant liver lesions. We found no significant differences between the number of lesions detected on 1-h and 3-h 64Cu-DOTATATE PET. Throughout the 1- to 3-h imaging window, the mean tumor-to-normal-tissue ratio remained high in all key organs: liver (1 h: 12.6 [95% confidence interval (CI), 10.2-14.9]; 3 h: 11.0 [95%CI, 8.7-13.4]), intestines (1 h: 24.2 [95%CI, 14.9-33.4]; 3 h: 28.2 [95%CI, 16.5-40.0]), pancreas (1 h: 42.4 [95%CI, 12.3-72.5]; 3 h: 41.1 [95%CI, 8.7-73.4]), and bone (1 h: 103.0 [95%CI, 38.6-167.4]; 3 h: 124.2 [95%CI, 57.1-191.2]). Conclusion: The imaging time window of 64Cu-DOTATATE PET/CT for patients with NENs can be expanded from 1 h to 1-3 h without significant differences in the number of lesions detected.

18F-FDG PET is Superior to WHO Grading as a Prognostic Tool in Neuroendocrine Neoplasms and Useful in Guiding PRRT: A Prospective 10-Year Follow-up Study.

Accurate grading of patients with neuroendocrine neoplasms (NENs) is essential for risk stratification and optimal choice of therapy. Currently, grading is based on histologically assessed degree of tumor proliferation. The aim of the present study was to assess the long-term prognostic value of 18F-FDG PET imaging for risk stratification of NENs and compare it with tumor grading (World Health Organization 2010 classification). Methods: We conducted a prospective cohort study evaluating the prognostic value of 18F-FDG PET imaging and compared it with histologic grading. Enrolled were 166 patients of all grades and with histologically confirmed NENs of gastroenteropancreatic origin. The primary endpoint was overall survival (OS). Progression-free survival (PFS) was a secondary endpoint. In addition, OS in relation to peptide receptor radionuclide therapy (PRRT) was analyzed as an exploratory endpoint. The median follow-up time was 9.8 y. Results: Analysis of the whole cohort revealed that a positive 18F-FDG PET scan was associated with a shorter OS than a negative 18F-FDG PET scan (hazard ratio: 3.8; 95% CI: 2.4-5.9; P < 0.001). In G1 and G2 patients (n = 140), a positive 18F-FDG PET scan was the only identifier of high risk for death (hazard ratio: 3.6; 95% CI, 2.2-5.9; P < 0.001). In multivariate analysis, 18F-FDG PET, G3 tumor, ≥2 liver metastases, and ≥2 prior therapies were independent prognostic factors for OS, and 18F-FDG PET, G3 tumor, and ≥3 liver metastases were independent prognostic factors for PFS. For patients receiving PRRT, 18F-FDG-negative cases had a significantly longer survival than 18F-FDG-positive cases, whereas no difference was identified for tumor grading. 18F-FDG-positive patients receiving PRRT had a significantly longer median survival than patients not receiving PRRT (4.4 vs. 1.4 y, P = 0.001), whereas no difference was seen for 18F-FDG-negative patients. Conclusion:18F-FDG PET is useful for risk stratification of all NEN grades and is superior to histologic grading. 18F-FDG PET could differentiate G1 and G2 tumors into low- and high-risk groups. In the selection of therapy and for risk stratification of NEN patients, 18F-FDG PET status should be considered.

Pharmacokinetic analysis of [68Ga]Ga-DOTA-TOC PET in meningiomas for assessment of in vivo somatostatin receptor subtype 2.

PURPOSE: DOTA-D-Phe1-Tyr3-octreotide with gallium-68 ([68Ga]Ga-DOTA-TOC) is one of the PET tracers that forms the basis for peptide receptor radionuclide therapy based on somatostatin receptor subtype 2 (SSTR2) expression in meningiomas. Yet, the quantitative relationship between [68Ga]Ga-DOTA-TOC accumulation and SSTR2 is unknown. We conducted a correlative analysis of a range of [68Ga]Ga-DOTA-TOC PET metric(s) as imaging surrogate(s) of the receptor binding in meningiomas by correlating the PET results with SSTR2 expression from surgical specimens. We additionally investigated possible influences of secondary biological factors such as vascularization, inflammation and proliferation. METHODS: Fifteen patients with MRI-presumed or recurrent meningiomas underwent a 60-min dynamic [68Ga]Ga-DOTA-TOC PET/CT before surgery. The PET data comprised maximum and mean standardized uptake values (SUVmax, SUVmean) with and without normalization to reference regions, and quantitative measurements derived from kinetic modelling using a reversible two-tissue compartment model with the fractional blood volume (VB). Expressions of SSTR2 and proliferation (Ki-67, phosphohistone-H3, proliferating cell nuclear antigen) were determined by immunohistochemistry and/or quantitative polymerase chain reaction (qPCR), while biomarkers of vascularization (vascular endothelial growth factor A (VEGFA), endothelial marker CD34) and inflammation (cytokine interleukin-18, microglia/macrophage-specific marker CD68) by qPCR. RESULTS: Histopathology revealed 12 World Health Organization (WHO) grade I and three WHO grade II meningiomas showing no link to SSTR2. The majority of [68Ga]Ga-DOTA-TOC PET metrics showed significant associations with SSTR2 protein, while all PET metrics were positively correlated with SSTR2 mRNA with the best results for mean tumour-to-blood ratio (TBRmean) (r = 0.757, P = 0.001) and SUVmean (r = 0.714, P = 0.003). Significant positive correlations were also found between [68Ga]Ga-DOTA-TOC PET metrics, and VEGFA and VB. SSTR2 mRNA was moderately correlated with VEGFA (r = 0.539, P = 0.038). Neither [68Ga]Ga-DOTA-TOC PET metrics nor SSTR2 were correlated with proliferation or inflammation. CONCLUSION: [68Ga]Ga-DOTA-TOC accumulation in meningiomas is associated with SSTR2 binding and vascularization with TBRmean being the best PET metric for assessing SSTR2.

64Cu-DOTATATE PET/CT and Prediction of Overall and Progression-Free Survival in Patients with Neuroendocrine Neoplasms.

Overexpression of somatostatin receptors (SSTRs) in patients with neuroendocrine neoplasms (NENs) is used for both diagnosis and treatment. Receptor density may reflect tumor differentiation and thus be associated with prognosis. Noninvasive visualization and quantification of SSTR density is possible by SSTR imaging (SRI) using PET. Recently, we introduced 64Cu-DOTATATE for SRI, and we hypothesized that uptake of this tracer could be associated with overall survival (OS) and progression-free survival (PFS). Methods: We evaluated patients with NENs who underwent 64Cu-DOTATATE PET/CT SRI in 2 prospective studies. Tracer uptake was determined as the maximal SUV (SUVmax) for each patient. Kaplan-Meier analysis with log-rank was used to determine the predictive value of 64Cu-DOTATATE SUVmax for OS and PFS. Specificity, sensitivity, and accuracy were calculated for prediction of outcome at 24 mo after 64Cu-DOTATATE PET/CT. Results: In total, 128 patients with NENs were included and followed for a median of 73 mo (range, 1-112 mo). During follow-up, 112 experienced disease progression, and 69 died. The optimal cutoff for 64Cu-DOTATATE SUVmax was 43.3 for prediction of PFS, with a hazard ratio of 0.56 (95% confidence interval, 0.38-0.84) for patients with an SUVmax of more than 43.3. However, no significant cutoff was found for prediction of OS. In multiple Cox regression adjusted for age, sex, primary tumor site, and tumor grade, the SUVmax cutoff hazard ratio was 0.50 (range, 0.32-0.77) for PFS. The accuracy was moderate for predicting PFS (57%) at 24 mo after 64Cu-DOTATATE PET/CT. Conclusion: In this first study to report the association of 64Cu-DOTATATE PET/CT and outcome in patients with NENs, tumor SSTR density as visualized with 64Cu-DOTATATE PET/CT was prognostic for PFS but not OS. However, the accuracy of prediction of PFS at 24 mo after 64Cu-DOTATATE PET/CT SRI was moderate, limiting the value on an individual-patient basis.

In vivo imaging of cell proliferation in meningioma using 3'-deoxy-3'-[18F]fluorothymidine PET/MRI.

PURPOSE: Positron emission tomography (PET) with 3'-deoxy-3'-[18F]fluorothymidine ([18F]FLT) provides a noninvasive assessment of tumour proliferation in vivo and could be a valuable imaging modality for assessing malignancy in meningiomas. We investigated a range of static and dynamic [18F]FLT metrics by correlating the findings with cellular biomarkers of proliferation and angiogenesis. METHODS: Seventeen prospectively recruited adult patients with intracranial meningiomas underwent a 60-min dynamic [18F]FLT PET following surgery. Maximum and mean standardized uptake values (SUVmax, SUVmean) with and without normalization to healthy brain tissue and blood radioactivity obtained from 40 to 60 min summed dynamic images (PET40-60) and ~ 60-min blood samples were calculated. Kinetic modelling using a two-tissue reversible compartmental model with a fractioned blood volume (VB) was performed to determine the total distribution volume (VT). Expressions of proliferation and angiogenesis with key parameters including Ki-67 index, phosphohistone-H3 (phh3), MKI67, thymidine kinase 1 (TK1), proliferating cell nuclear antigen (PCNA), Kirsten RAt Sarcoma viral oncogene homolog (KRAS), TIMP metallopeptidase inhibitor 3 (TIMP3), and vascular endothelial growth factor A (VEGFA) were determined by immunohistochemistry and/or quantitative polymerase chain reaction. RESULTS: Immunohistochemistry revealed 13 World Health Organization (WHO) grade I and four WHO grade II meningiomas. SUVmax and SUVmean normalized to blood radioactivity from PET40-60 and blood sampling, and VT were able to significantly differentiate between WHO grades with the best results for maximum and mean tumour-to-whole-blood ratios (sensitivity 100%, specificity 94-95%, accuracy 99%; P = 0.003). Static [18F]FLT metrics were significantly correlated with proliferative biomarkers, especially Ki-67 index, phh3, and TK1, while no correlations were found with VEGFA or VB. Using Ki-67 index with a threshold > 4%, the majority of [18F]FLT metrics showed a high ability to identify aggressive meningiomas with SUVmean demonstrating the best performance (sensitivity 80%, specificity 81%, accuracy 80%; P = 0.024). CONCLUSION: [18F]FLT PET could be a useful imaging modality for assessing cellular proliferation in meningiomas.