FDG-PET Imaging Research Articles

Can FDG-PET Imaging Identify Cardiac Sarcoidosis Disease Phenotypes?

Despite the scarcity of data, most guidelines have advocated for the treatment of cardiac sarcoidosis with corticosteroids. However, there is heterogeneity in disease presentation and response to treatment, which can make treatment challenging. The ability to identify disease phenotypes to allow for tailored therapy is therefore highly desirable. This review will seek to outline the disease phenotypes of cardiac sarcoidosis and the role that FDG-PET imaging can play in identifying these phenotypes to optimize disease diagnosis and treatment management. FDG PET can identify cardiac sarcoidosis and is being increasingly used to monitor therapeutic response to immunosuppressive therapy, to follow treatment response after discontinuation of corticosteroid therapy, and to evaluate for disease relapse. Modern quantitative techniques using FDG PET imaging may allow for even better phenotypic disease characterization and the ability to track the response to immunosuppression more accurately. FDG PET currently plays an important role in cardiac sarcoidosis diagnosis. However, it also affords us the opportunity to offer insights into cardiac sarcoidosis disease phenotypes to better understand the underlying disease process and in the future may allows us to tailor therapies accordingly.

605. MITOCHONDRIAL METABOLISM IN UPPER GI ADENOCARCINOMA DETERMINES PATIENT SURVIVAL

Abstract Background Mitochondrial oxidative phosphorylation (OXPHOS) is responsible for meeting the vast majority of cellular energy demands. Ever since the description of aerobic glycolysis by Warburg in 1927, it has been recognised that cancers have dysfunctional metabolism. Clinically, this Warburg effect is the basis of FDG-PET imaging, increased FDG uptake represents increased tumour glycolysis and translates to worse upper GI adenocarcinoma outcomes. The cause of OXPHOS disruption in upper GI adenocarcinoma is poorly understood, its impact on potential therapeutic strategies is yet to be explored. This is particularly pertinent in upper GI adenocarcinomas as despite recent improvements, 5-year survival remains alarmingly low. Method Oesophageal and gastric adenocarcinoma samples collected in the UK from 175 patients (89 oesophageal adenocarcinoma, 86 gastric adenocarcinoma, 131 male, 44 female, median age=65, IQR=12) who underwent radical resection with curative intent between 1995 and 2009. Quantitative immunofluorescence were used to determine expressions of OXPHOS Complex I and IV at a single cell level. Patients were divided into high vs. low expressors of Complex I and IV using K-means clustering to allow for subsequent subgroup analysis. Result Survival analysis demonstrated significantly worse outcomes for low expressors as compared to high expressors of Complex I at 5 years post-op (5-year survival probability low expressors=0.440, 95%CI=0.358-0.539, high expressors=0.629, 95%CI=0.515-0.769, P-value=0.048). Similarly comparison of Complex IV expression also demonstrates disadvantageous survival for Complex IV low expressors (5-year survival probability low expressors=0.432, 95%CI=0.346-0.538, high expressors=0.603, 95%CI=0.499-0.729, P-value=0.042). The low expressors of Complex I and IV encompassed significantly more Stage III disease as per AJCC 7th edition. The low vs. high expression Complex I and IV groups are similarly matched for baseline patient characteristics. Conclusion These results demonstrate reduced capacity to carry out OXPHOS in oesophageal and gastric adenocarcinoma is characteristic of more advanced cancer and results in worse patient outcomes. Further work is needed to determine if OXPHOS status impacts on neo-adjuvant therapy response and how to exploit OXPHOS deficiency therapeutically in oesophageal and gastric adenocarcinomas. The limitations of this preliminary work include small sample size and tissue derived from historic patients over a long period of time, during which treatment and outcomes for upper GI cancer have significantly changed.

Correlation between dopaminergic and metabolic asymmetry in Lewy body disease – A dual-imaging study

IntroductionThe a-Synuclein Origin and Connectome (SOC) model of Lewy body diseases postulates that a-syuclein will be asymmetrically distributed in some patients with Lewy body diseases, potentially leading to asymmetric neuronal dysfunction and symptoms. MethodsWe included two patient groups: 19 non-demented Parkinson's disease (nPD) patients with [18F]FDG PET and motor symptoms assessed by UPDRS-III, and 65 Lewy body dementia (LBD) patients with [18F]FDG PET and dopamine radioisotope imaging. Asymmetry indices were calculated for [18F]FDG PET by including the cortex for each hemisphere, for dopamine radioisotope imaging by including the putamen and caudate separately, and for motor symptoms by using the difference between right-left UPDRS-III score. Correlations between these asymmetry indices were explored to test the predictions of the SOC model. To identify cases with a more typical LBD imaging profile, we calculated a Cingulate Island Sign (CIS) index on the [18F]FDG PET image. ResultsWe found a significant correlation between cortical interhemispheric [18F]FDG asymmetry and motor-symptom asymmetry in nPD patients (r = 0.62, P = 0.004). In patients with LBD, we found a significant correlation between cortical interhemispheric [18F]FDG asymmetry and dopamine transporter asymmetry in the caudate (r = 0.37, P = 0.0019), but not in the putamen (r = 0.15, P = 0.22). We observed that the correlation in the caudate was stronger in LBD subjects with the highest CIS index, i.e., with more typical LBD imaging profiles. ConclusionOur study partly supports the SOC model, but further investigations are needed – ideally of de novo, non-demented PD patients.

Head-to-Head Comparison of [18F]FDG PET Imaging and MRI for the Detection of Recurrence or Residual Tumor in Patients with Nasopharyngeal Carcinoma: A Meta-Analysis.

This meta-analysis compared the diagnostic performance of [18F] fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) or PET versus Magnetic resonance imaging (MRI) in detecting recurrence or residual tumors at the primary site in patients with nasopharyngeal carcinoma (NPC). A comprehensive literature search was conducted in the PubMed/MEDLINE and CENTRAL databases to find studies with at least 20 patients with NPC undergoing both [18F]FDG PET/CT (or [18F]FDG PET) and MRI for detecting recurrence or assessing residual disease at the primary site. The pooled sensitivity and specificity of PET/CT and MRI were calculated with 95% confidence intervals (CIs) and compared. Five studies, including 1908 patients (six patient groups), were included. PET imaging had higher sensitivity [93.3% (95% CI: 91.3-94.9%); I2 = 52.6%] compared to MRI [80.1% (95% CI: 77.2-82.8%); I2 = 68.3%], but the specificity of the two modalities was similar: 93.8% (95% CI: 92.2-95.2%; I2 = 0%) for PET/CT and 91.8% (95% CI: 90.1-93.4%; I2 = 94.3%) for MRI. The areas under the curve (AUCs) for PET/CT and MRI were 0.978 and 0.924, respectively, without significant difference (p = 0.23). This meta-analysis suggests that [18F]FDG PET imaging and MRI do not significantly differ in diagnostic performance. Nevertheless, [18F]FDG PET imaging shows higher sensitivity than MRI.

Large vessel vasculitis is a risk factor for relapse only in giant cell arteritis patients without polymyalgia rheumatica.

To evaluate differences in presentation and outcome of giant cell arteritis (GCA) patients with and without large vessel vasculitis (LVV) and according to the extent and severity of LVV. Consecutive patients diagnosed with GCA between 2003 and 2020 who have had FDG PET imaging at diagnosis ≤3 days after initiation of glucocorticoids and followed for ≥12 months at the University Hospitals Leuven (Belgium), were included retrospectively. PET scans were visually scored (0-3) in 7 vascular areas and a total vascular score (TVS) was calculated. LVV was defined as FDG uptake ≥2 in any large vessel. We included 238 GCA patients, of which 169 (71%) had LVV. LVV patients were younger (69 vs 74 years, p< 0.001) and more frequently female (72% vs 49%, p= 0.001). In patients without PMR symptoms, the presence of LVV was associated with relapse (aOR 3.05 [95%CI 1.32-7.43], p= 0.011) and with a lower probability of stopping glucocorticoids (aHR 0.59 [95%CI 0.37-0.94], p= 0.025). However, in those with PMR symptoms, there was no difference in relapse risk (aOR 1.20 [95%CI 0.53-2.66], p= 0.657) and in the probability of stopping glucocorticoids (aHR 1.25 [95%CI 0.75-2.09], p= 0.394) between patients with and without LVV. A higher TVS was associated with an increased risk of relapse (aOR 1.09 [95%CI 1.04-1.15], p= 0.001] in patients without PMR symptoms, but not in those with PMR symptoms (aOR 1.01 [95%CI 0.96-1.07], p= 0.693). LVV is a risk factor for relapse in GCA patients without PMR symptoms with a higher relapse risk in those with higher TVS.

Omics-derived biological modules reflect metabolic brain changes in Alzheimer's disease.

Brain glucose hypometabolism, indexed by the fluorodeoxyglucose positron emission tomography ([18F]FDG-PET) imaging, is a metabolic signature of Alzheimer's disease (AD). However, the underlying biological pathways involved in these metabolic changes remain elusive. Here, we integrated [18F]FDG-PET images with blood and hippocampal transcriptomic data from cognitively unimpaired (CU, n=445) and cognitively impaired (CI, n=749) individuals using modular dimension reduction techniques and voxel-wise linear regression analysis. Our results showed that multiple transcriptomic modules are associated with brain [18F]FDG-PET metabolism, with the top hits being a protein serine/threonine kinase activity gene cluster (peak-t(223)=4.86, P value<0.001) and zinc-finger-related regulatory units (peak-t(223)=3.90, P value<0.001). By integrating transcriptomics with PET imaging data, we identified that serine/threonine kinase activity-associated genes and zinc-finger-related regulatory units are highly associated with brain metabolic changes in AD. We conducted an integrated analysis of system-based transcriptomics and fluorodeoxyglucose positron emission tomography ([18F]FDG-PET) at the voxel level in Alzheimer's disease (AD). The biological process of serine/threonine kinase activity was the most associated with [18F]FDG-PET in the AD brain. Serine/threonine kinase activity alterations are associated with brain vulnerable regions in AD [18F]FDG-PET. Zinc-finger transcription factor targets were associated with AD brain [18F]FDG-PET metabolism.

Potential Utility of SGLT2i To Reduce Physiologic Cardiac Glucose Uptake During FDG PET Imaging

Potential Utility of SGLT2i To Reduce Physiologic Cardiac Glucose Uptake During FDG PET Imaging

Metabolic Tumor Volume on 18-Fluorodeoxyglucose Positron Emission Tomography as a Prognostic Marker of Survival in Patients With Locally Advanced or Metastatic Neuroendocrine Neoplasms Treated With 177Lutetium-DOTA-Octreotate Peptide Receptor Radionuclide Therapy.

We investigated metabolic tumor volume (MTV) and total lesion glycolysis (TLG) on pre-treatment FDG-PET as prognostic markers for survival in patients with metastatic neuroendocrine neoplasms (NENs) receiving peptide receptor radionuclide therapy (PRRT). A retrospective review of patients with metastatic NENs receiving PRRT was undertaken. Pre-treatment FDG-PET images were analyzed and variables collected included MTV and TLG (dichotomized by median into high vs low). Main Outcomes were overall survival (OS) and progression-free survival (PFS) by MTV and TLG (high vs low). One hundred five patients were included. Median age was 64 years (50% male). Main primary NEN sites were small bowel (43.8%) and pancreas (40.0%). Median MTV was 3.8 mL and median TLG was 19.9. Dichotomization formed identical cohorts regardless of whether MTV or TLG were used. Median OS was 72 months; OS did not differ based on MTV/TLG high versus low (47.4 months vs not reached; hazard ratio, 0.43; 95% confidence interval [CI], 0.18-1.04; P = 0.0594). Median PFS was 30.4 months; PFS differed based on MTV/TLG high versus low (21.6 months vs 45.7 months; hazard ratio, 0.35; 95% CI, 0.19-0.64; P = 0.007). Low MTV/TLG on pre-treatment FDG-PET was associated with longer PFS in metastatic NEN patients receiving PRRT.

Targeting Fn14 as a therapeutic target for cachexia reprograms the glycolytic pathway in tumour and brain in mice

PurposeCachexia is a complex syndrome characterized by unintentional weight loss, progressive muscle wasting and loss of appetite. Anti-Fn14 antibody (mAb 002) targets the TWEAK receptor (Fn14) in murine models of cancer cachexia and can extend the lifespan of mice by restoring the body weight of mice. Here, we investigated glucose metabolic changes in murine models of cachexia via [18F]FDG PET imaging, to explore whether Fn14 plays a role in the metabolic changes that occur during cancer cachexia.Methods[18F]FDG PET/MRI imaging was performed in cachexia-inducing tumour models versus models that do not induce cachexia. SUVaverage was calculated for all tumours via volume of interest (VOI) analysis of PET/MRI overlay images using PMOD software.Results[18F]FDG PET imaging demonstrated increased tumour and brain uptake in cachectic versus non-cachectic tumour-bearing mice. Therapy with mAb 002 was able to reduce [18F]FDG uptake in tumours (P < 0.05, n = 3). Fn14 KO tumours did not induce body weight loss and did not show an increase in [18F]FDG tumour and brain uptake over time. In non-cachectic mice bearing Fn14 KO tumours, [18F]FDG tumour uptake was significantly lower (P < 0.01) than in cachectic mice bearing Fn14 WT counterparts. As a by-product of glucose metabolism, l-lactate production was also increased in cachexia-inducing tumours expressing Fn14.ConclusionOur results demonstrate that Fn14 receptor activation is linked to glucose metabolism of cachexia-inducing tumours.Graphical

Nucleic Acids-Based Biomarkers for Alzheimer's Disease Diagnosis and Novel Molecules to Treat the Disease.

Alzheimer's disease (AD) represents the most common form of dementia and affects million people worldwide, with a high social burden and considerable economic costs. AD diagnosis benefits from a well-established panel of laboratory tests that allow ruling-in patients, along with FDG and amyloid PET imaging tools. The main laboratory tests used to identify AD patients are Aβ40, Aβ42, the Aβ42/Aβ40 ratio, phosphorylated Tau 181 (pTau181) and total Tau (tTau). Although they are measured preferentially in the cerebrospinal fluid (CSF), some evidence about the possibility for blood-based determination to enter clinical practice is growing up. Unfortunately, CSF biomarkers for AD and, even more, the blood-based ones, present a few flaws, and twenty years of research in this field did not overcome these pitfalls. The tale even worsens when the issue of treating AD is addressed due to the lack of effective strategies despite the many decades of attempts by pharmaceutic industries and scientists. Amyloid-based drugs failed to stop the disease, and no neuroinflammation-based drugs have been demonstrated to work so far. Hence, only symptomatic therapy is available, with no disease-modifying treatment on hand. Such a desolate situation fully justifies the active search for novel biomarkers to be used as reliable tests for AD diagnosis and molecular targets for treating patients. Recently, a novel group of molecules has been identified to be used for AD diagnosis and follow-up, the nuclei acid-based biomarkers. Nucleic acid-based biomarkers are a composite group of extracellular molecules consisting of DNA and RNA alone or in combination with other molecules, including proteins. This review article reports the main findings from the studies carried out on these biomarkers during AD, and highlights their advantages and limitations.

GWO+RuleFit: rule-based explainable machine-learning combined with heuristics to predict mid-treatment FDG PET response to chemoradiation for locally advanced non-small cell lung cancer.

Objective.Vital rules learned from fluorodeoxyglucose positron emission tomography (FDG-PET) radiomics of tumor subregional response can provide clinical decision support for precise treatment adaptation. We combined a rule-based machine learning (ML) model (RuleFit) with a heuristic algorithm (gray wolf optimizer, GWO) for mid-chemoradiation FDG-PET response prediction in patients with locally advanced non-small cell lung cancer.Approach.Tumors subregions were identified using K-means clustering. GWO+RuleFit consists of three main parts: (i) a random forest is constructed based on conventional features or radiomic features extracted from tumor regions or subregions in FDG-PET images, from which the initial rules are generated; (ii) GWO is used for iterative rule selection; (iii) the selected rules are fit to a linear model to make predictions about the target variable. Two target variables were considered: a binary response measure (ΔSUVmean ⩾ 20% decline) for classification and a continuous response measure (ΔSUVmean) for regression. GWO+RuleFit was benchmarked against common ML algorithms and RuleFit, with leave-one-out cross-validated performance evaluated by the area under the receiver operating characteristic curve (AUC) in classification and root-mean-square error (RMSE) in regression.Main results.GWO+RuleFit selected 15 rules from the radiomic feature dataset of 23 patients. For treatment response classification, GWO+RuleFit attained numerically better cross-validated performance than RuleFit across tumor regions and sets of features (AUC: 0.58-0.86 vs. 0.52-0.78,p= 0.170-0.925). GWO+Rulefit also had the best or second-best performance numerically compared to all other algorithms for all conditions. For treatment response regression prediction, GWO+RuleFit (RMSE: 0.162-0.192) performed better numerically for low-dimensional models (p= 0.097-0.614) and significantly better for high-dimensional models across all tumor regions except one (RMSE: 0.189-0.219,p< 0.004).Significance. The GWO+RuleFit selected rules were interpretable, highlighting distinct radiomic phenotypes that modulated treatment response. GWO+Rulefit achieved parsimonious models while maintaining utility for treatment response prediction, which can aid clinical decisions for patient risk stratification, treatment selection, and biologically driven adaptation. Clinical trial: NCT02773238.

Comparative Uptake Patterns of Radioactive Iodine and [18F]-Fluorodeoxyglucose (FDG) in Metastatic Differentiated Thyroid Cancers.

Background: Metastatic differentiated thyroid cancer (DTC) represents a molecularly heterogeneous group of cancers with varying radioactive iodine (RAI) and [18F]-fluorodeoxyglucose (FDG) uptake patterns potentially correlated with the degree of de-differentiation through the so-called "flip-flop" phenomenon. However, it is unknown if RAI and FDG uptake patterns correlate with molecular status or metastatic site. Materials and Methods: A retrospective analysis of metastatic DTC patients (n = 46) with radioactive 131-iodine whole body scan (WBS) and FDG-PET imaging between 2008 and 2022 was performed. The inclusion criteria included accessible FDG-PET and WBS studies within 1 year of each other. Studies were interpreted by two blinded radiologists for iodine or FDG uptake in extrathyroidal sites including lungs, lymph nodes, and bone. Cases were stratified by BRAF V600E mutation status, histology, and a combination of tumor genotype and histology. The data were analyzed by McNemar's Chi-square test. Results: Lung metastasis FDG uptake was significantly more common than iodine uptake (WBS: 52%, FDG: 84%, p = 0.04), but no significant differences were found for lymph or bone metastases. Lung metastasis FDG uptake was significantly more prevalent in the papillary pattern sub-cohort (WBS: 37%, FDG: 89%, p = 0.02) than the follicular pattern sub-cohort (WBS: 75%, FDG: 75%, p = 1.00). Similarly, BRAF V600E+ tumors with lung metastases also demonstrated a preponderance of FDG uptake (WBS: 29%, FDG: 93%, p = 0.02) than BRAF V600E- tumors (WBS: 83%, FDG: 83%, p = 1.00) with lung metastases. Papillary histology featured higher FDG uptake in lung metastasis (WBS: 39%, FDG: 89%, p = 0.03) compared with follicular histology (WBS: 69%, FDG: 77%, p = 1.00). Patients with papillary pattern disease, BRAF V600E+ mutation, or papillary histology had reduced agreement between both modalities in uptake at all metastatic sites compared with those with follicular pattern disease, BRAF V600E- mutation, or follicular histology. Low agreement in lymph node uptake was observed in all patients irrespective of molecular status or histology. Conclusions: The pattern of FDG-PET and radioiodine uptake is dependent on molecular status and metastatic site, with those with papillary histology or BRAF V600E+ mutation featuring increased FDG uptake in distant metastasis. Further study with an expanded cohort may identify which patients may benefit from specific imaging modalities to recognize and surveil metastases.

Evolving patterns of metastatic spread, treatment, and outcome for patients with oligometastatic colorectal cancer

IntroductionThe assessment and management of oligometastatic colorectal cancer has evolved over the last two decades. We aimed to examine trends in the presentation, management and outcomes of patients presenting with liver-only disease, given recent changed standards for baseline imaging, and evolving definitions of resectability. Patients with lung-only disease can provide a contemporaneous control group. MethodsProspectively maintained data from the multi-site Treatment of Recurrent and Advanced Colorectal Cancer Registry were reviewed over three consecutive periods; 2009–2013, 2014–2018, and 2019–2023. Survival outcomes were determined by Kaplan-Meier method. ResultsOf 4613 patients with metastatic colorectal cancer, median age was 66 years (interquartile range 56–76), and 2356 (51 %) patients had a single metastatic site. Compared to the earlier periods, patients diagnosed in 2019–2023, were younger, had better ECOG scores and were more likely to have three or more metastatic sites. The proportion of patients with liver-only metastases decreased over the three consecutive periods, from 32.0 % (n = 462), to 27.0 % (n = 498) to 25.9 % (n = 33), p < 0.001, however the proportion of liver-only metastases patients undergoing resection increased from 41.5 to 59.3 %, p < 0.001. The incidence and resection rate of lung-only metastases was unchanged over time. ConclusionThe increasing number of metastatic sites and reduced number of patients with liver-only metastases is potentially explained by the increased use of FDG-PET imaging at baseline. The increased proportion of patients with liver-only disease undergoing resection may be explained by advancement in surgical techniques, improvements in systemic therapies and the evolving definition of resectable disease. SynopsisThe pattern and treatment of metastatic colorectal cancer has evolved over the last two decades. This study examines the trends in presentation management and outcomes of patients with metastatic colorectal cancer using a multi-site database.

Establishment of a normal control model of children's brain 18-fluorodeoxyglucose positron emission tomography and analysis of the changing pattern in patients aged 0-14 years.

It is difficult to obtain 18-fluorodeoxyglucose positron emission tomography (18FDG-PET) data from normal children, and changes in brain metabolism in children due to growth and development are poorly understood. For the first time, we established a normal control model of brain 18FDG-PET in children and evaluated its feasibility. The association of PET with age in children aged 0-14 years was analyzed. This study aimed to establish a normal control model of brain 18FDG-PET in children for the first time and to verify its feasibility, and to analyze the trend of PET with age in children aged 0-14 years. In this retrospective cohort study, the 18FDG-PET imaging data of patients with no epileptiform discharge involvement contralateral to the epileptogenic zone were consecutively collected from January 2015 to June 2022 according to strictly defined screening criteria. For the normal control data, the hemisphere contralateral to the epileptogenic zone was mirrored and spliced to form an intact brain. The cohort of children aged 0-14 years was divided into 14 groups according age by year. Subsequently, patients who underwent lesionectomy with clear hypometabolism that roughly coincided with the extent of surgical resection were examined. The PET scan was compared with the control model, and the ratio of overlapping parts (hypometabolic areas ∩ surgical resection area) to hypometabolic parts (ROH) was calculated. Multiple regression analysis was performed on the normal control model for every 3- to 4-year age interval. A total of 159 normal control models were established. Five patients were randomly selected to verify the reliability of each yearly model. The average ROH was 0.968. Metabolism increasing with age in the different brain regions was observed at ages 0-2~, 3-5~, and 6-10 years. No age-related metabolic increase or decrease was found in the 10- to 14-year-old group. The metabolism in the 7- to 8-year-old group was higher than that in the 13- to 14-year-old group. With strict screening criteria, the method of mirroring the contralateral hemisphere of the epileptic zone and splicing it into a complete brain as a means of creating a normal control group is feasible. The method offers convenience to the studies that lack healthy pediatric controls. Children under 10 years of age (especially 0-6 years old) experience considerable metabolic changes year on year. After the age of 10 years, the changes in metabolism gradually decrease, and metabolism also slowly decreases. Our findings provide guidance the clinical interpretation of areas with hypometabolism and emphasize the importance of establishing a normal control model of the child's brain, which should not be replaced by an adult model.

Predictive Value of PERCIST for Locally Advanced Non-Small Cell Lung Cancer Treated with Preoperative Induction Therapy - A Multicenter Study in Japan.

Induction therapy followed by surgery is recommended as an alternative treatment strategy for locally advanced non-small cell lung cancer (NSCLC). Patients who achieve pathologic response after induction therapy have better outcomes than non-responders; therefore, therapeutic response must be evaluated. Recently, new approaches for monitoring therapeutic responses, which are based on 18F-Fluorodeoxyglucose positron emission tomography (FDG-PET), have been developed. In this study, we evaluated the predictive value of Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST), which uses standardized uptake values corrected for lean body mass (SUL) and total lesion glycolysis (TLG). A total of 130 patients in the Setouchi Lung Cancer Group who underwent FDG-PET imaging before and after induction therapy prior to a planned surgical resection for NSCLC between 2007 and 2016 were studied retrospectively. The pathologic responses of the primary lung tumors and metastatic lymph nodes were compared with their responses based on evaluation using PERCIST. Postoperative pathologic studies revealed pathologic complete response (pCR) in 42 (32.3%) patients. PERCIST was significantly correlated with pathologic response (p < 0.001). The sensitivity, specificity, and accuracy of PERCIST for predicting pCR were 16.7% (7/42), 88.6% (78/88), and 65.4% (85/130), respectively. Patients with pCR had significantly higher reduction rates in SULpeak for both primary lung tumors and metastatic lymph nodes and TLG for primary tumors than non-responders. In a multivariate Cox regression analysis, tumor site in upper lobes, reduction rate of TLG in primary tumor, and pathologic N0 were independent predictors of favorable recurrence-free survival (RFS). Our study suggested that PERCIST, especially the rate of TLG reduction rate, are useful to predict the pathological response and prognosis after induction therapy. Although improvement is necessary, PERCIST can be a promising method of the post-induction status in lung cancer. Further research is needed to confirm our findings.

Should new organ involvement be included in Response Evaluation Criteria in PSMA Imaging?

The current study is intended to investigate the effect of new organ involvement on overall survival (OS) and modify the Response Evaluation Criteria in PSMA Imaging (RECIP) by including new organ involvement to RECIP 1.0. This retrospective study includes 114 patients diagnosed with metastatic castration-resistant prostate cancer (mCRPC) between September 2017 and June 2022 who had received docetaxel treatment and had baseline and post-treatment prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) images. The inclusion criteria were patients with pre- and post-treatment [18F]FDG PET/CT images and whose [18F]FDG PET images were negative. Those whose data were unavailable, who had additional malignancy, or who received abiraterone, enzalutamide, or Lutetium (Lu)-177 treatment were excluded. Age, Gleason score (GS), TPSA (total prostate-specific antigen) levels, surgical history, and OS information were recorded for each patient. The 114 patients herein had a median age of 72.5 (51-91) years and a median GS of 8 (7-10). New lesions were observed in 59 patients (51.7%) and new organ PSMA uptake was observed in 14 patients (12.2%). In the multivariate Cox regression analysis, volume-based treatment response (vTR)-total lesion PSMA (TLP), RECIP PSMA-VOL, modified RECIP (mRECIP) PSMA-VOL, and mRECIP TLP were independent prognostic factors for mortality (p < 0.001, p = 0.006, p = 0.003, and p = 0.003, respectively). The median OS of patients with new organ involvement and new lesion with PSMA uptake was 9.3months (95% CI 2.1-16.5months) and 11.8months (95% CI 7.4-16.2months), respectively. The study concluded that new organ involvement had a shorter OS than new lesion involvement. In the mRECIP that we developed, unlike RECIP, we demonstrated that both PSMA-VOL and TLP value were independent prognostic factors for mortality.

Brain Glucose Metabolism as a Readout of the Central Nervous System Impact of Cigarette Smoke Exposure and Withdrawal and the Effects of NFL-101, as an Immune-Based Drug Candidate for Smoking Cessation Therapy.

Neuroimaging biomarkers are needed to investigate the impact of smoking withdrawal on brain function. NFL-101 is a denicotinized aqueous extract of tobacco leaves currently investigated as an immune-based smoking cessation therapy in humans. However, the immune response to NFL-101 and its ability to induce significant changes in brain function remain to be demonstrated. Brain glucose metabolism was investigated using [18F]fluoro-deoxy-glucose ([18F]FDG) PET imaging in a mouse model of cigarette smoke exposure (CSE, 4-week whole-body inhalation, twice daily). Compared with control animals, the relative uptake of [18F]FDG in CSE mice was decreased in the thalamus and brain stem (p < 0.001, n = 14 per group) and increased in the hippocampus, cortex, cerebellum, and olfactory bulb (p < 0.001). NFL-101 induced a humoral immune response (specific IgGs) in mice and activated human natural-killer lymphocytes in vitro. In CSE mice, but not in control mice, single-dose NFL-101 significantly increased [18F]FDG uptake in the thalamus (p < 0.01), thus restoring normal brain glucose metabolism after 2-day withdrawal in this nicotinic receptor-rich region. In tobacco research, [18F]FDG PET imaging provides a quantitative method to evaluate changes in the brain function associated with the withdrawal phase. This method also showed the CNS effects of NFL-101, with translational perspectives for future clinical evaluation in smokers.

ECAS correlation with metabolic alterations on FDG-PET imaging in ALS

Background: Cognitive impairment is observed in up to 50% of patients with amyotrophic lateral sclerosis (ALS). The Edinburgh Cognitive and Behavioral ALS Screen (ECAS) is an ALS-specific multi-domain screening tool. Few studies have examined the relationship between ECAS scores and [18F]fluorodeoxyglucose positron emission tomography ([18F]FDG-PET) findings. Objective: To assess the relationship between ECAS scores and glucose metabolism patterns on [18F]FDG -PET images in ALS. Methods: We collected [18F]FDG-PET images from 65 patients with ALS and 39 healthy controls. ECAS scores were collected on all patients and we calculated the correlation to [18F]FDG-PET in order to investigate the potential links between cognition and glucose metabolism. Results: We observed hypometabolism in the frontal cortex, insula, and limbic system, together with hypermetabolism in the cerebellum in patients with ALS compared to controls. A lower ECAS total score was associated with lower glucose metabolism in the right orbitofrontal gyrus and higher glucose metabolism in lateral occipital, medial occipital, and cerebellar regions, among patients with ALS. Similar results, although less widespread, were observed in the analyses of ECAS ALS-specific scores. Conclusions: The metabolic patterns in [18F]FDG -PET show that changes in the glucose metabolism of corresponding areas are related to cognitive dysfunction in ALS, and can be detected using the ECAS.

A PET/MRI study on the effect of obesity and NAFLD on hepatic [18F]FDG uptake

PurposeThe potential limitations of hepatic [18F]FDG-PET imaging for individuals with obesity and excessive liver fat (NAFLD) are being investigated. In this study, we aim to determine the reliability of standardized uptake values (SUVs) focusing on adjustment for liver fat content (LFC) derived from DIXON images and the effects of whole-body normalizations. MethodsLean and with obesity volunteers who underwent [18F]FDG-PET/MRI were reviewed retrospectively. DIXON fat images were used to determine LFC and for adjustment of SUVmean. The hepatic SUVs (mean, fat adjusted mean and max) were normalized to body weight, lean body mass and body surface area. Blood samples were analysed for glucose, serological liver enzymes and lipoproteins for further correlation of [18F]FDG uptake. ResultsOut of 11 volunteers with obesity (M:8, F:3, BMI:30–39 kg/m2), 9 confirmed the presence of NAFLD (>5.6 % fat). 22 age-matched lean volunteers (M:10, F:11, BMI:19–26 kg/m2) were used as control group. Both SUVmean, before and after adjustment to LFC, did not provide any difference between lean and with obesity groups under BW, LBM and BSA. SUVmax BW showed a difference between groups (p = 0.05). SUVs were independent of levels of GPT, GOT, gGT, insulin, HOMA-IR, triglycerides, cholesterol and LDL. Volunteers with low HDL were clustered with an increased hepatic [18F]FDG uptake. ConclusionOur method for adjustment of hepatic [18F]FDG-PET with DIXON fat images allows to achieve accurate results for individuals with NAFLD and obesity. For homogenic results, raw SUVmean should be combined with adjustment for liver fat, appropriate normalization and consideration of HDL levels.

Early FDG PET imaging and circulating T-cell repertoire biomarkers of response to chemotherapy and PD-1 checkpoint inhibitors in patients with stage IV NSCLC.

8622 Background: Chemotherapy and immune checkpoint inhibitors (chemoICI) for stage IV NSCLC without driver mutations produce variable response patterns and outcomes. Early assessment could establish selective benefit from treatment (de)escalation, consolidation, or adaptation. We evaluated FDG PET imaging and circulating T cell repertoire biomarkers of chemoICI response for clinical decision support. Methods: 35 patients with stage IV NSCLC prospectively enrolled on PET BRIGHT (NCT04151940) from 2019-2023 and received first-line carboplatin-pemetrexed-pembrolizumab. Synchronous FDG PET/CT and peripheral blood draws were performed prior to and after first dose of chemoICI at week 3. Imaging biomarkers included standardized uptake value (SUV) and total lesion glycolysis (TLG) metrics within the primary metabolic tumor volume and across lung lesions. Immunophenotyping included T cell receptor (TCR) sequencing from which TCR diversity metrics were extracted. Spearman correlation of FDG PET and TCR biomarkers with bi-dimensional size reduction after initial chemoICI was estimated. ROC analysis of PET and TCR biomarkers to discriminate chemoICI response status was benchmarked against PD-L1 testing, along with Mann-Whitney testing of groupwise differences. Results: The majority tested negative for PD-L1 (58% TPS&lt;1%). Most patients (63%) had partial response (PR) to initial chemoICI versus 33% with stable disease (SD) and 4% with progressive disease (PD). FDG PET primary tumor peak SUV decreased by a median of 15% [-82%, 63%] at week 3, while TLG decreased by 36% [-55%, 83%]. Higher baseline peak SUV and TLG, along with greater decline after first dose, were correlated with post-chemoICI size reduction (R 0.43-0.64, p=0.001-0.036). PR patients had higher baseline peak SUV (12 vs 6 g/mL, p=0.014) and greater week 3 decline in TLG (39% vs 7%, p=0.032) relative to SD/PD patients. Across lung lesions, PR-patient maximum SUV decreased while SD/PD-patient maximum SUV increased at week 3 (20% vs -19%, p=0.010). FDG PET biomarkers were stronger discriminators of chemoICI response status (AUC 0.75-0.82, p=0.009-0.046) than PD-L1 (AUC 0.60, p=0.42). Higher baseline blood TCR Simpson clonality was positively correlated with size reduction (R 0.70, p=0.004), whereas TCR Pielou evenness was negatively correlated (R -0.68, p=0.006). Higher baseline TCR clonality / lower TCR evenness discriminated chemoICI response status (AUC 0.80-0.84, p=0.028-0.049). TCR diversity changes were uncorrelated with response. Conclusions: FDG PET imaging prior to and after first dose chemoICI, along with baseline circulating T cell repertoire biomarkers, predict future response. Further investigation of these patient- and lesion-level biomarkers to guide personalized (de)escalation, consolidation, or adaptation of regimens for stage IV NSCLC is warranted. Clinical trial information: NCT04151940 .