Average Standardized Uptake Value Research Articles

Measurement of hepatic glucose (18F-fluorodeoxyglucose) uptake with positron emission tomography-magnetic resonance imaging in fumonisin B intoxicated rabbit bucks

Rabbit bucks (bodyweight 5 kg) underwent dietary intoxication with fumonisin B series mycotoxins (FB1 + FB2 + FB3, 15 mg/kg diet) for 14 days to test the applicability of positron emission tomography-magnetic resonance (PET MR) hybrid imaging in characterizing experimentally induced mild hepatotoxicosis. 18F-fluorodeoxyglucose (18F-FDG) radiotracer-aided imaging was performed before and after FBs administration on identical animals, and at both time points, blood was sampled for haematology and clinical chemistry. Kinetic PET image analysis revealed time-activity curves with uptake maxima below 1 min in the liver, renal cortex, portal vein, lung and coarctatio aortae. In the frame of static PET image analysis, based on the standardized uptake value (SUV), the so-called metabolic liver volume (MLV, liver volume defined by over 0.9 × average liver SUV) and the total liver glycolysis (TLG, MLV multiplied by the SUVmean) were calculated. Mycotoxicosis increased total liver glycolysis (p < 0.04) after 14 days and liver tissue TLG inhomogeneity was minimal. Pearson correlation between TLG and alkaline phosphatase (ALP) was positive (0.515), while negative with LDH and AST (− 0.721 and − 0.491, respectively). Results indicate a slight hepatic mycotoxin effect and significantly increased glucose uptake intensity, which has been sensitively detected with molecular imaging (18F-FDG PET MRI) in the rabbit model.

Preclinical evaluation of [18F]SYN1 and [18F]SYN2, novel radiotracers for PET myocardial perfusion imaging

BackgroundPositron emission tomography (PET) is now an established diagnostic method for myocardial perfusion imaging (MPI) in coronary artery disease, which is the main cause of death globally. The available tracers show several limitations, therefore, the 18F-labelled tracer is in high demand nowadays. The preclinical studies on normal Wistar rats aimed to characterise two potential, novel radiotracers, [18F]SYN1 and [18F]SYN2, to evaluate which is a better candidate for PET MPI cardiotracer.ResultsThe dynamic microPET images showed rapid myocardial uptake for both tracers. However, the uptake was higher and also stable for [18F]SYN2, with an average standardized uptake value of 3.8. The biodistribution studies confirmed that [18F]SYN2 uptake in the cardiac muscle was high and stable (3.02%ID/g at 15 min and 2.79%ID/g at 6 h) compared to [18F]SYN1 (1.84%ID/g at 15 min and 0.32%ID/g at 6 h). The critical organs determined in dosimetry studies were the small intestine and the kidneys. The estimated effective dose for humans was 0.00714 mSv/MBq for [18F]SYN1 and 0.0109 mSv/MBq for [18F]SYN2. The tested dose level of 2 mg/kg was considered to be the No Observed Adverse Effect Level (NOAEL) for both candidates. The better results were achieved for [18F]SYN2, therefore, further preclinical studies were conducted only for this tracer. Radioligand binding assays showed significant responses in 3 from 68 assays: muscarinic acetylcholine M1 and M2 receptors and potassium channel hERG. The compound was mostly metabolised via an oxidative N-dealkylation, while the fluor substituent was not separated from the molecule.Conclusion[18F]SYN2 showed a favourable pharmacodynamic and pharmacokinetic profile, which enabled a clear visualization of the heart in microPET. The compound was well-tolerated in studies in normal rats with moderate radiation exposure. The results encourage further exploration of [18F]SYN2 in clinical studies.

Quality metrics analysis in patients who received Lutetium-177 PSMA-617 (177Lu–PSMA) therapy in a real-world practice setting.

e17049 Background: 177Lu–PSMA is a radiolabeled small molecule that delivers β radiation to cells expressing prostate-specific membrane antigen (PSMA). It has been approved for use in metastatic castration-resistant prostate cancer (mCPRC) in 3/2022, based on VISION study. The Food and Drug Administration (FDA) label for 177Lu–PSMA requires prior therapy with an androgen receptor pathway inhibitor (ARPI) and taxane-based chemotherapy as well as presence of at least one PSMA-positive tumor with uptake greater than normal liver and no PSMA-negative lesions on a PSMA positron emission tomography (PET) scan. In the VISION study, PSMA PET was performed within 4 weeks of therapy start. Further, patient received either 177Lu–PSMA plus protocol permitted standard of care (SOC), including ARPI, or SOC alone. Given the relatively recent approval of this therapy, real-world familiarity with administration of this agent may not be optimal. Methods: A retrospective analysis of 25 patients with mCRPC who received 177Lu–PSMA therapy since 3/2022 at the University of California Irvine (24/25) and Hoag Hospital (1/25) was performed. Multiple variables were analyzed and compared to the FDA label for this agent as well as design of the VISION study. Results: All patients in this study had received an ARPI and at least one taxane chemotherapy prior to 177Lu–PSMA. A PSMA-PET scan was obtained prior to 177Lu–PSMA therapy in all patients. The timing of the scan was within 4 weeks of starting 177Lu–PSMA therapy in only 5/25 (20.0%) patients. The average time from PSMA PET scan to 177Lu–PSMA therapy start was 66 days [range: 18 - 326 days]. None of the PSMA PET scan reports included a baseline liver standardized uptake value (SUV) or mentioned whether any lesions were non PSMA-avid. All reports provided SUV values for some, but not all, PSMA-avid lesions. The average maximum SUV of the most PSMA-avid lesion noted on the reports was 34.7. All PSMA PET scans were retrospectively reviewed by a nuclear medicine specialist and the average maximum SUV of the most PSMA-avid lesion on re-review was 42.0 (p &lt;0.05). During 177Lu–PSMA therapy, co-administration of ARPI occurred in 10/24 (23.8%) of patients. Conclusions: This study highlights the differences in quality metrics between patients who received 177Lu–PSMA therapy in a real-world practice setting compared to the FDA label for this agent and VISION study design. Differences included lack of uniform PSMA PET scan reporting, timing of obtaining pre-treatment PSMA PET imaging, and co-administration of ARPI. Development of institutional algorithms around administration of 177Lu–PSMA therapy may be needed.

Diagnostic value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging in pediatric opsoclonus myoclonus ataxia syndrome presenting with neuroblastoma.

Early precision diagnosis and effective treatment of opsoclonus myoclonus ataxia syndrome (OMAS) patients presenting with neuroblastoma can prevent serious neurological outcomes. To assess the diagnostic value of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) imaging in pediatric OMAS with neuroblastoma. A retrospective evaluation of 45 patients diagnosed with OMAS who underwent 18F-FDG PET/CT was performed. A univariate analysis was performed to compare clinical characteristics between OMAS with and without neuroblastoma. Univariate and multivariate logistic regression analyses were applied to identify independent risk factors for OMAS with neuroblastoma and to develop the clinical model. Finally, independent risk factors and PET/CT were fitted to build the combined model for the diagnosis of OMAS with neuroblastoma and presented as a nomogram. Receiver operating characteristic curve, decision curve, and calibration curveanalyses were conducted to evaluate the performance of the models. Among 45 patients, 27 were PET/CT-positive, 23/27 lesions were neuroblastoma, and four were false positives. One of the false positive patients was confirmed to be adrenal reactive hyperplasia by postoperative pathology, and the symptoms of OMAS disappeared in the remaining three cases during clinical follow-up. The average maximal standardized uptake value of PET/CT-positive lesions was 2.6. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of PET/CT were 100%, 81.8%, 85.2%, 100%, and 91.1%, respectively. Age at diagnosis, lactate dehydrogenase, and neuron-specific enolase showed statistically significant differences between OMAS with and without neuroblastoma. Lactate dehydrogenase was identified as the independent risk factor to develop the clinical model, and the clinical model demonstrated an area under the curve (AUC) of 0.82 for the diagnosis of OMAS with neuroblastoma, with an AUC as high as 0.91 when combined with PET/CT. The decision curve analysis and calibration curve demonstrated that the nomogram had good consistency and clinical usefulness. In patients with OMAS, 18F-FDG PET/CT has a high diagnostic accuracy in detecting tumors of the neuroblastoma, especially when combined with the independent risk factor serum lactate dehydrogenase.

A Comparison of 68Ga-PSMA PET/CT-Based Split Renal Function with 99mTc-MAG3 Renography in Patients with Metastatic Castration-Resistant Prostate Carcinoma Treated with 177Lu-PSMA.

Physiological PSMA expression in the cells of the proximal renal tubules and consecutive radiopharmaceutical binding and retention could potentially lead to radioligand-therapy-induced nephrotoxicity. Thus, patients with metastatic castration-resistant prostate cancer undergo 99mTc-Mercaptoacetyltriglycine (MAG3) renal scintigraphy to assess kidney function and to exclude renal obstruction as part of their workup for PSMA-targeted radioligand therapy (RLT). 99mTc-MAG-3 renal scintigraphy often requires an additional visit to the nuclear medicine department and patients spend 30-90 min in the department, which is inconvenient and takes up camera time. In addition, the patients are subjected to a baseline 68Ga-PSMA PET/CT to assess for PSMA-positive disease prior to targeted radioligand therapy. The aim of this retrospective cross-sectional study was to compare 99mTc-MAG-3-based split renal function (SRF) with 68Ga-PSMA-derived SRF. This retrospective cross-sectional study included 28 patients with histologically proven metastatic castration-resistant prostate cancer (mCRPC) who received 177Lu-PSMA617. A comparison between the split renal function using 68Ga-PSMA PET/CT and the 99mTc-MAG-3-derived split renal function was carried out in 56 kidneys (n = 56). The SRF on 68Ga-PSMA was calculated using the volume and the average standard uptake value (SUVmean) within each VOI calculated as previously described by Roser et al.: SRF = (VOLUMEright) ∗ SUVmeanright/(VOLUMEright ∗ SUVmeanright + VOLUMEleft ∗ SUVmeanleft). Paired tests and correlation coefficients were used to compare 68Ga-PSMA and 99mTc-MAG-3. A visual comparison of kidney morphology on both studies was also performed. The median SRF of the right kidney was 49.9% (range: 3-91%) using 68Ga-PSMA PET/CT and 50.5% (range: 0-94%) with 99mTc-MAG3 scintigraphy. Notably, there was a strong correlation between SRF measurements obtained from PSMA and 99mTcMAG3, with a Pearson correlation coefficient of 0.957 (p < 0.001). Both 99mTc-MAG3 and 68Ga-PSMA PET/CT studies identified morphological renal abnormalities; there were nine hydronephrotic kidneys, four shrunken kidneys and one obstructed kidney, and there was a strong positive correlation between 68Ga-PSMA kidney morphology and 99mTcMAG3 renal scintigraphy kidney morphology, with a correlation coefficient of 0.93. PSMA-derived split function demonstrated a high correlation with renal function assessed on diuretic 99mTc-MAG3 renograms. PET-derived split renal function may, therefore, be considered an alternative to diuretic renogram-based split function. Furthermore, both 99mTc-MAG3 and 68Ga-PSMA PET/CT studies identified morphological renal abnormalities such as hydronephrosis, shrunken and obstructed kidneys. This correlation underscores the potential utility of 68Ga-PSMA imaging as a valuable tool for assessing kidney morphology as an alternative to renogram split function in clinical practice.

Combined average standard uptake value and rate constant can predict expression of EGFR in hypopharyngeal squamous cell carcinoma: A pilot study with integrated PET/MRI

PurposeTo investigate whether the quantitative multiparameters of 18F-FDG PET/MRI can predict expression of epidermal growth factor receptor (EGFR) of hypopharyngeal squamous cell carcinoma (HSCC). MethodsTwenty-one patients with HSCC confirmed by biopsy underwent neck integrated 18F-FDG PET/MRI and EGFR expression detection. Quantitative parameters derived from 18F-FDG PET, difusion-weighted imaging (DWI), and dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) were measured. The efficacies of quantitative multiparameters derived from 18F-FDG PET/MRI for predicting the expression of EGFR of HSCC were evaluated. ResultsThe patients were divided into positive expression group (PEG, n = 14) and negative expression group (NEG, n = 7). Mann-Whitney U nonparametric test showed that SUVmean and Kep had statistical difference between PEG and NPG, while other parameters had no statistical difference. Using 14.50 and 2.10 min−1 as the threshold values, areas under the curve (AUCs) for SUVmean and Kep were 0.786 with specificity of 92.9 % and sensitivity of 57.1 %. The combined use of SUVmean and Kep had better efficacy to evaluate the expression of EGFR with AUC of 0.980, sensitivity of 92.9 %, and specificity of 100.0 %. ConclusionCombined use of SUVmean and Kep showed good performance in predicting the expression of EGFR in HSCC. Integrated 18F-FDG PET/MRI enables simultaneous acquisition of SUVmean and Kep, so it represents as a powerful tool to noninvasively and repeatably evaluate the expression of EGFR during the management of HSCC.

Diagnostic value of [ 68 Ga]Ga-Pentixafor PET/CT in malignant melanoma: a pilot study.

To evaluate the diagnostic value of [ 68 Ga] Ga-Pentixafor in malignant melanoma patients. In this prospective study, patients with histology-proven melanoma were included and underwent [ 18 F]fluoro-D-glucose ([ 18 F]FDG) and [ 68 Ga] Ga-Pentixafor PET/computed tomography (CT) within a week. Suspicious lesions were interpreted as benign vs. malignant, and the corresponding semi-quantitative PET/CT parameters were recorded and compared. Twelve consecutive melanoma patients (mean age: 60 ± 6) were included. Two patients were referred for initial staging, two for detecting recurrence and eight for evaluating the extent of metastases. Overall, [ 18 F]FDG PET/CT showed 236 tumoral lesions, including two primary tumors, two recurrent lesions, 29 locoregional metastases and 203 distant metastases. In [ 68 Ga]Ga-Pentixafor PET/CT, 101 tumoral lesions were detected, including two primary tumors, one recurrence, 16 locoregional metastases and 82 distant metastases. Notably, a documented brain metastasis was only visualized on [ 68 Ga]Ga-Pentixafor PET/CT images. Compared with [ 18 F]FDG, [ 68 Ga]Ga-Pentixafor PET/CT provided a 42% detection rate. Regarding semi-quantitative measures, the intensity of uptake and tumor-to-background ratios were significantly lower on [ 68 Ga]Ga-Pentixafor PET/CT [average maximum standard uptake value (SUV max ) of 2.72 ± 1.33 vs. 11.41 ± 14.79; P value <0.001 and 1.17 ± 0.53 vs. 5.32 ± 7.34; P value <0.001, respectively]. When comparing [ 68 Ga]Ga-Pentixafor PET/CT with [ 18 F]FDG PET/CT, not only did [ 68 Ga]Ga-Pentixafor PET/CT detect fewer lesions, but the intensity of uptake and the TBRs were also lower on [ 68 Ga]Ga-Pentixafor PET/CT. Thus, our results may indicate a limited potential of this novel tracer in cutaneous melanoma patients compared to [ 18 F]FDG PET/CT. Given the lower TBRs, applying this radiotracer in radioligand therapies is also questionable.

Metabolic parameters of pretreatment 2-[18F]fluoro-D-glucose positron emission tomography for prognosis in patients with gallbladder adenocarcinoma: a cohort study.

The incidence of gallbladder adenocarcinoma (GBA) is relatively low, yet it exhibits a high degree of malignancy and a significantly low 5-year survival rate. The aim of this study was to investigate the prognostic value of pretreatment 2-[18F]fluoro-D-glucose positron emission tomography {2-[18F]FDG PET} parameters in predicting outcomes for patients with GBA. In total, 67 patients with GBA who underwent 2-[18F]FDG PET/computed tomography (CT) before treatment were retrospectively analyzed at Chinese PLA General Hospital from January 2012 to June 2022. All patients were diagnosed by pathology, and their baseline characteristics and clinical data were collected. The metabolic PET parameters of the primary and metastatic lesions were measured, including the maximum and average standardized uptake values (SUVs), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). The prognostic significance of metabolic parameters and other clinical variables was assessed using Cox proportional hazards regression models. Differences in progression-free survival (PFS) and overall survival (OS) in relation to metabolic parameters were examined using the Kaplan-Meier method. During a median follow-up period of 14.2 months, 43 patients (64.2%) experienced tumor recurrence or progression, and 38 patients (56.7%) died of cancer. In the univariate Cox regression analysis, liver parenchymal invasion (P=0.001), lymph node metastasis (P=0.007), distant metastases (P=0.049), tumor differentiation (P=0.028), surgery (P=0.014), carcinoembryonic antigen (CEA) level (P=0.030), carbohydrate antigen 19-9 (CA19-9) level (P=0.003), TLG (P=0.005), MTV (P<0.001), sum of the TLGs of the primary and metastatic lesions (total TLG, tTLG) (P=0.001), and sum of the MTVs of the primary and metastatic lesions (total MTV, tMTV) (P<0.001) were significant predictors of PFS. In multivariate analysis, MTV was an independent predictor of PFS [hazard ratio (HR) =2.785; 95% confidence interval (CI): 1.204-6.441; P=0.017]. In the univariate Cox regression analysis, liver parenchymal invasion (P=0.001), lymph node metastasis (P=0.027), distant metastases (P=0.036), tumor differentiation (P=0.047), surgery (P=0.002), neutrophil-to-lymphocyte ratio (NLR) (P=0.011), CEA level (P=0.036), CA19-9 level (P<0.001), TLG (P=0.007), MTV (P<0.001), tTLG (P=0.003), and tMTV (P<0.001) were significant predictors of OS. In the multivariate analysis, higher CA19-9 levels >37 U/mL and a greater tMTV (HR =2.961; 95% CI: 1.092-8.024; P=0.033) were predictive of OS. Our study results suggest that pretreatment 2-[18F]FDG PET parameters can not only assist in the diagnosis of patients with GBA but may also serve as predictive factors for the prognosis of these patients and should thus be applied in their treatment.

Comparative evaluation of 11C-methionine and 18F-fluorodeoxyglucose positron emission tomography for distinguishing between primary central nervous system lymphoma and isocitrate dehydrogenase-wildtype glioblastoma.

Distinguishing between primary central nervous system lymphoma (PCNSL) and isocitrate dehydrogenase (IDH)-wildtype glioblastoma is important for therapeutic decision-making. This study aimed to compare the performance of 11C-methionine (MET) and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for distinguishing between these two major malignant brain tumors. We retrospectively conducted qualitative and semiquantitative analyses of pre-treatment MET and FDG PET/computed tomography (CT) images of 22 patients with PCNSL and 64 patients with IDH-wildtype glioblastoma. For semiquantitative analysis, we calculated the tumor-to-normal tissue (T/N) ratio by dividing the maximum standardized uptake value (SUV) for the tumor (T) by the average SUV for the normal tissue (N). For performance evaluation, we employed receiver operating characteristic curve analysis and calculated the areas under the curve (AUC) values. In the qualitative analysis, all PCNSLs and IDH-wildtype glioblastomas were MET-positive, while 95% and 84% of PCNSLs and IDH-wildtype glioblastomas, respectively, were FDG-positive. Eleven patients were excluded from the FDG PET/CT semiquantitative analysis because of hyperglycemia. There was no difference in MET T/N ratio between PCNSL and IDH-wildtype glioblastoma (p = 0.37). FDG T/N ratio was significantly higher in PCNSL than in IDH-wildtype glioblastoma (p < 0.001). The AUC value for distinguishing PCNSL from IDH-wildtype glioblastoma was significantly higher for the FDG T/N ratio (0.871) than for the MET T/N ratio (0.565) (p = 0.0027). MET PET could detect both PCNSL and IDH-wildtype glioblastoma, but unlike FDG PET, it could not distinguish between these two major malignant brain tumors.

SFXN1 as a potential diagnostic and prognostic biomarker of LUAD is associated with 18F-FDG metabolic parameters

BackgroundSideroflexin 1 (SFXN1) has been discovered as a novel tumor marker for lung adenocarcinoma, but data on its importance in the development of lung adenocarcinoma is still limited. This study evaluated the correlation between SFXN1 and parameters related to 18F-flurodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT), and further explored the role of SFXN1 in the value-added and glycolytic processes of LUAD. MethodThe expression and prognostic value of SFXN1 mRNA in LUAD were analyzed using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) data base. Retrospective analysis of 18F-FDG PET imaging and metabolic parameters in 42 patients to explore the relationship between the expression of SFXN1 and glucose metabolism levels in lung adenocarcinoma and its clinical significance. H1975 cells were selected as the in vitro research object, and the biological effects of SFXN1 on LUAD were further elucidated through Edu proliferation assay, CCK8 activity assay, wound healing experiment, and cell flow cytometry. ResultSFXN1 is highly expressed in various tumors, including LUAD, and its high expression can serve as an independent predictor of overall survival in lung adenocarcinoma. In addition, the expression of SFXN1 in LUAD was significantly correlated with 18F-FDG PET/CT parameters: maximum and average standardized uptake values (SUVmax and SUVmean), as well as total lesion glycolysis (TLG) (rho = 0.574, 0.589, and 0.338, p < 0.05), which can predict the expression of SFXN1 with an accuracy of 0.934. In vitro functional experiments have shown that knocking down SFXN1 inhibits the proliferation and migration of LUAD cells, promotes cell apoptosis, and may inhibit tumor activity by regulating the expression of glycolytic related genes SLC2A1, HK2, GPI, ALDOA, GAPDH, ENO1, PKM, and LDHA. ConclusionThe overexpression of SFXN1 is closely related to FDG uptake, and SFXN1, as a promising prognostic biomarker, may mediate the development of LUAD through the glycolytic pathway.

Assessment of left atrial fibrosis by 18F-FDG PET/CT in persistent atrial fibrillation : comparison to electroanatomical mapping and cMR late gadolinium enhancement

Abstract A wide body of evidence suggests that left atrial (LA) interstitial fibrosis is a key contributor to persistent atrial fibrillation (peAF) and that its extent is predictive of the success of catheter ablation (CA) for this condition. Late gadolinium enhanced magnetic resonance imaging (LGE-cMR) has become increasingly popular for non-invasive detection and quantification of atrial fibrosis prior to CA. However, it is limited by a high rate of suboptimal scans and by large variability of quantification of fibrosis. We recently described the ability to obtain high quality 18- fluorodeoxyglucose (FDG) positron emission tomography (PET) of the atria after acipimox administration, and hypothesize that, similar to the left ventricle (LV), atrial metabolic activity could be a marker of cellular viability, indicating the absence of atrial fibrosis. The objective of our study was to investigate the potential utility of 18FDG uptake in the LA as an indicator of atrial scar and a predictor of CA success in patients with peAF. To this end, we compared the LA 18FDG uptake to LA voltage mapping during electrophysiological studies (EP) and cMR-LGE as a reference standard. Method 33 nondiabetic patients with nonvalvular peAF hospitalized for a first CA in our center prospectively underwent 18FDG-PET/CT, and LGE-CMR prior to EP and CA procedures. FDG-PET, LGE-cMR and electoanatomical maps were segmented and corregistrated in 3D surface models based on anatomical information from the contrast enhanced cMR angiograms. For 18FDG-PET/CT, maximum intensity projection of standardized uptake values (SUVs) along the surface was calculated and abnormal low metabolism was identified using a threshold of four standard deviations below the average SUV value of the atrial blood. Electrical scarring on EP voltage maps was defined as bipolar measurements of &amp;lt; 0.3 mV in AF, while fibrosis by LGE-CMR was evaluated using several thresholds of 2-5 standard deviations above the average blood signal intensity and the average intensity of the enhancement around the mitral valve. All three parameters of scar were expressed in percentage of the total LA area. Results Atrial hypometabolism by FDG-PET correlated strongly with electrical scaring by low voltage area during EP study (p&amp;lt;0.001, R² = 0.573). Atrial wall mean SUV standardized by LV uptake was also associated with low voltage, also the association's strength was mild (p =0.012, R²=0.22). There was good spatial corregistration of areas of low FDG metabolism with low voltage areas during EP study (Figure 2). By contrast there was no association between PET and LGE-cMR and association between atrial LGE by cMR and atrial voltage for all used thresholds. Conclusion Low 18FDG uptake by PET/CT showed a good correlation with atrial electrical scaring, while LGE-CMR did not. Our data suggest that atrial FDG PET could therefore be a valuable technique for non-invasive evaluation of atrial fibrosis prior to CA.Low metabolism versus low voltageMetabolic and voltage maps

Clinical Response to Tumor Necrosis Factor-α Inhibitor Therapy in the Management of Cardiac Sarcoidosis

Evidence that tumor necrosis factor-α (TNF-α) inhibitors may benefit patients with cardiac sarcoidosis (CS) is limited to small case series and both imaging and clinical outcomes in this population are not well known. This study aimed to evaluate the disease course of patients with CS treated with either infliximab or adalimumab therapy based on serial 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging and clinical outcomes. An institutional CS research database was queried for patients treated with TNF-α inhibitors between 2016 and 2021. Outcomes included (1) change in mean prednisone dose, (2) FDG-PET improvement, and (3) unplanned hospitalizations, advanced heart failure therapies, or death. Our query yielded 31 patients with CS. A total of 13 patients were on infliximab, 15 patients were on adalimumab, and 3 patients were on adalimumab before transitioning to infliximab. Mean prednisone dose decreased between FDG-PET immediately preceding TNF-α and second after TNF-α FDG-PET (18.6±15.7mg to 7.7±12.4mg, p=0.018). A significant decrease was seen in the mean number of segments demonstrating FDG uptake between most recent pre-TNF-α and first after TNF-α inhibitor FDG-PET (mean segments=4.2 vs 3.1, p=0.048). Between earliest pre-TNF-α and first after TNF-α FDG-PET there was a numerical decrease in average myocardial maximum standard uptake values (SUVmax) (4.4 vs 3.1, p=0.18), and the ratio of SUVmax myocardium:SUVmax blood pool (1.9 vs 1.5, p=0.26). Within 36months of initiating TNF-α inhibitor, 4 patients (13%) experienced unplanned cardiovascular hospitalization (median time to hospitalization=12.1months). In conclusion, in patients with CS, TNF-α inhibitor therapy is associated with decreased glucocorticoid use, numerical decrease in cardiac FDG uptake, and minimal cardiac morbidity.

Differentiating thymic epithelial tumors from mediastinal lymphomas: preoperative nomograms based on PET/CT radiomic features to minimize unnecessary anterior mediastinal surgery.

Clinical feasibility nomograms were developed to facilitate the differentiation between thymic epithelial tumors (TETs) and mediastinal lymphomas (MLs), aiming to minimize the occurrence of non-therapeutic thymectomy. A total of 255 patients diagnosed with TETs or MLs underwent pre-treatment 18F-FDG PET/CT. Comprehensive clinical and imaging data were collected, including age, gender, lactate dehydrogenase (LDH) level, pathological results, presence of myasthenia gravis symptoms, B symptoms, mass size, location, morphology, margins, density, and metabolic parameters derived from PET/CT. Radiomic features were extracted from the region of interest (ROI) of the primary lesion. Feature selection techniques were employed to identify the most discriminative subset of features. Machine learning methods were utilized to build candidate models, which were subsequently evaluated based on their area under the curve (AUC). Finally, nomograms were constructed using the optimal model to provide a clinical tool for improved diagnostic accuracy. The performance of the radiomic models was evaluated by their calibration, discrimination, and clinical utility. Several independent risk factors were identified for distinguishing TETs from MLs, including average standardized uptake value (SUVavg), LDH, age, mass size, and radiomic score (rad-score). Significance was observed in differentiating the two types of tumors based on these factors. The best clinical efficacy was demonstrated by the combined model, with an impressive AUC of 0.954. Decision curve analysis and calibration curves indicated that the combined model was clinically advantageous for discriminating TETs from MLs. Besides, the results of external validation showed a sensitivity of 0.8 and a specificity of 0.78. Preoperatively, the differentiation of TETs from MLs can be facilitated by the utilization of the combined clinical information and radiomics model. This approach holds promise in minimizing the occurrence of unnecessary anterior mediastinal surgeries.

Influence of Cirrhosis on 68Ga-FAPI PET/CT in Intrahepatic Tumors.

Background Gallium 68 (68Ga)-labeled fibroblast activation protein inhibitor (FAPI) is of great diagnostic value for intrahepatic tumors. However, cirrhosis may lead to increased 68Ga-FAPI uptake in background liver, affecting the diagnostic ability of 68Ga-FAPI. Purpose To assess the effect of cirrhosis on liver parenchyma and intrahepatic tumor uptake of 68Ga-FAPI and to compare the ability of 68Ga-FAPI and fluorine 18 (18F)-labeled fluorodeoxyglucose (FDG) PET/CT to depict intrahepatic tumors in patients with cirrhosis. Materials and Methods In this secondary analysis of a prospective trial, patients who underwent both 68Ga-FAPI and 18F-FDG PET/CT and those who underwent only 68Ga-FAPI PET/CT between August 2020 and May 2022 were considered for inclusion in the cirrhotic or noncirrhotic group, respectively. Patients with cirrhosis were chosen via a comprehensive assessment of imaging and clinical data, and patients without cirrhosis were randomly selected. 68Ga-FAPI and 18F-FDG PET/CT data were measured by two radiologists. Between-groups and within-group data were tested with the Mann-Whitney U test and the Wilcoxon signed-rank test, respectively. Results A total of 39 patients with cirrhosis (median age, 58 years [IQR, 50-68]; 29 male; 24 intrahepatic tumors) and 48 patients without cirrhosis (median age, 59 years [IQR, 51-67]; 30 male; 23 intrahepatic tumors) were evaluated. In patients without intrahepatic tumors, the liver 68Ga-FAPI average standardized uptake value (SUVavg) was higher in the cirrhotic group than in the noncirrhotic group (median SUVavg, 1.42 [IQR, 0.55-2.85] vs 0.45 [IQR, 0.41-0.72]; P = .002). However, no difference was observed in the diagnosis of intrahepatic tumor sensitivity (98% vs 93%, respectively). When compared with 18F-FDG, the sensitivity of 68Ga-FAPI PET/CT in the detection of intrahepatic tumors in patients with cirrhosis (41% vs 98%, respectively) and maximum standardized uptake value of tumors (median SUVmax, 2.60 [IQR, 2.14-4.49] vs 6.68 [IQR, 4.65-10.08]; P < .001) were higher. Conclusion The sensitivity of 68Ga-FAPI in the diagnosis of intrahepatic tumors was not affected by cirrhosis, and diagnostic accuracy of 68Ga-FAPI was higher than that of 18F-FDG in patients with cirrhosis. © RSNA, 2023 Supplemental material is available for this article.

Impact of Region-of-Interest Delineation on Stability and Reproducibility of Liver SNR Measurements in 68 Ga-PSMA PET/CT.

Objective This study aims to assess the impact of various regions of interest (ROIs) and volumes of interest (VOIs) delineations on the reproducibility of liver signal-to-noise-ratio (SNRliver) measurements, as well as to find the most reproducible way to estimate it in gallium-68 positron emission tomography ( 68 Ga-PET) imaging. We also investigated the SNRliver-weight relationship for these ROIs and VOIs delineations. Methods A cohort of 40 patients (40 males; mean weight: 76.5 kg [58-115 kg]) with prostate cancer were included. 68 Ga-PET/CT imaging (mean injected activity: 91.4 MBq [51.2 MBq to 134.1 MBq] was performed on a 5-ring bismuth germanium oxide-based Discovery IQ PET/CT using ordered subset expectation maximization image reconstruction algorithm. Afterward, circular ROIs and spherical VOIs with two different diameters of 30 and 40 mm were drawn on the right lobe of the livers. The performance of the various defined regions was evaluated by the average standardized uptake value (SUV mean ), standard deviation (SD) of the SUV (SUV SD ), SNR liver , and SD of the SNR liver metrics. Results There were no significant differences in SUV mean among the various ROIs and VOIs ( p > 0.05). On the other hand, the lower SUV SD was obtained by spherical VOI with diameter of 30 mm. The largest SNR liver was obtained by ROI (30 mm). The SD of SNR liver with ROI (30 mm) was also the largest, while the lowest SD of SNR liver was observed for VOI (40 mm). There is a higher correlation coefficient between the patient-dependent parameter of weight and the image quality parameter of SNRliver for both VOI (30 mm) and VOI (40 mm) compared to the ROIs. Conclusion Our results indicate that SNR liver measurements are affected by the size and shape of the respective ROIs and VOIs. The spherical VOI with a 40 mm diameter leads to more stable and reproducible SNR measurement in the liver.

The Use of F-18 FDG PET-Based Cognitive Reserve to Evaluate Cognitive Decline in Alzheimer's Disease, Independent of Educational Influence.

Background and Objectives: The optimal assessment of cognitive function, including the impact of education, is crucial in managing Alzheimer's disease (AD). This study aimed to evaluate the role of cognitive reserve (CR), represented by the metabolic status of regions of the cerebral cortex, to evaluate cognitive decline considering the educational attainment of patients with AD. Materials and Methods: We used data from the Alzheimer's Disease Neuroimaging Initiative database, and selected 124 patients who underwent both baseline F-18 fluorodeoxyglucose (FDG) and F-18 florbetaben (FBB) positron emission tomography (PET) scans. Demographics, cognitive function variables (Clinical Dementia Rating-Sum of Boxes [CDR]; AD Assessment Scale 11/13 [ADAS11/13] Mini-Mental State Examination [MMSE]), and the average standardized uptake value ratio (SUVR) of cerebral cortex regions to those of the cerebellum were obtained from the data. The participants' education level was divided into low and high education subgroups using four cut-offs of 12, 14, 16, and 18 years of educational attainment (G12, G14, G16, and G18, respectively). Demographic and cognitive function variables were compared between the two subgroups in each of the four groups, and their correlations with the SUVRs were evaluated. Results: There was no significant difference between the high and low education subgroups in each of the four groups, except for ADAS11/13 and MMSE in G14 and age in G16. The SUVRs of FDG PET (FDGSUVR) were significantly correlated with CDR, ADAS11/13, and MMSE scores. FDGSUVR showed different trajectories of neurodegeneration between the low and high education groups. Conclusions: FDGSUVR correlated moderately but significantly with neuropsychological test results, without being influenced by education level. Therefore, FDG PET may reflect CR independent of education level, and therefore could be a reliable tool to evaluate cognitive decline in AD.

Alteration of chronic inflammatory status by transarterial embolization in frozen shoulder evaluated by fluorine-18 fluorodeoxyglucose positron-emission tomography/computed tomography.

Frozen shoulder (FS) is speculated to have an inflammatory etiology. On angiography, abnormal angiogenesis is observed around the affected shoulder, suggesting a possible source of inflammation and pain. The effectiveness and safety of transarterial embolization (TAE) targeting abnormally proliferating blood vessels have been reported. This study investigated changes in chronic inflammatory and hypoxic status before and after TAE in FS by [18F]-fluoro-2-deoxyglucose (FDG) positron-emission tomography/computed tomography as a possible mechanism of the therapeutic response to TAE. Fifteen patients with unilateral FS, persistent for more than 6months, who were refractory to conservative treatments, underwent TAE using the temporary embolic agent imipenem/cilastatin. Patients underwent positron-emission tomography/computed tomography with FDG (as a biomarker of inflammation) before and 8weeks after TAE. Regional uptake was evaluated by the maximum standardized uptake value. The lesion-side-to-(contralateral-) normal-side uptake ratio was also calculated. Pain and functional scales, range-of-motion, and laboratory tests, including white blood cell, C-reactive protein, interleukin 6, vascular endothelial growth factor, and tumor necrosis factor α were evaluated. On FDG-PET, the average maximum standardized uptake value of the lesion-side was significantly greater than that of the normal-side (maximum standardized uptake value before TAE: 3.11±1.25 vs 1.95±1.15, P=.0001; 8-weeks post-TAE: 2.36±0.74 vs 1.78±0.69, P=.0002). The mean lesion-side-to-(contralateral-) normal-side uptake ratios before TAE (1.71±0.60) decreased after TAE (1.37±0.29, P=.011). The decrease of FDG uptake (-21.1±12.2%) showed a significant correlation with the change in the pain scale score (r=-0.56, P=.039) and extension score (r=-0.59, P=.026). Chronic inflammation in FS, as demonstrated by FDG uptake, was decreased after TAE. Thus, chronic inflammation is likely to be an underlying mechanism that should be targeted for symptomatic improvement of frozen shoulder.

Effectiveness of PET/CT and VATS for detecting and treating internal mammary lymph node metastasis: a case series.

We occasionally observed internal mammary lymph node metastases of breast cancer in a clinical setting. However, unlike a standard treatment in axillary metastasis, surgical resection for internal mammary lymph node metastasis is not prevalent because of unclear safety and benefits. Thus, we aimed to evaluate the diagnostic ability and clinical outcomes of positron emission tomography/computed tomography and video-assisted thoracoscopic surgery. We retrospectively investigated 34 patients with breast cancer with abnormal 18F-fluorodeoxyglucose uptake in internal mammary lymph nodes, at a single centre, between January 2015 and June 2022 and identified 11 female patients (mean age±SD, 51.5±12.9years) who underwent video-assisted thoracoscopic surgery resection. Positron emission tomography/computed tomography was used to determine the clinical stage. We reviewed the surgical pathology of eleven and two patients who underwent direct-view internal mammary lymph node resection to calculate the positive predictive value of positron emission tomography/computed tomography. Ipsilateral fluorodeoxyglucose accumulation was observed, with an average maximum standardized uptake value of 8.9 (range, 3.1-24.0). No perioperative complications occurred, and all patients who underwent video-assisted thoracoscopic surgery alone were discharged from the hospital on post-operative day 2 or 3. The estimated positive predictive value was 80%. All patients were alive, and seven of nine patients with metastasis were relapse-free, at a mean follow-up period of 17.9months (range, 1-51). However, two patients had recurrence at 16 and 14months after surgery for internal mammary lymph node relapse. Radiotherapy is the standard treatment for suspected internal mammary lymph node metastasis detected using positron emission tomography/computed tomography; however, we could safely perform minimally invasive video-assisted thoracoscopic surgery resection, leading to a definite pathological diagnosis.

A feasibility study for quantitative assessment of cerebrovascular malformations using flutriciclamide ([18F]GE-180) PET/MRI.

Neuroinflammation plays a key role in both the pathogenesis and the progression of cerebral cavernous malformations (CCM). Flutriciclamide ([18F]GE-180) is a translocator protein (TSPO) targeting positron emission tomography (PET) tracer, developed for imaging neuroinflammation. The objectives of this study were to describe characteristics of flutriciclamide uptake in different brain tissue regions in CCM patients compared to controls, and to evaluate flutriciclamide uptake and iron deposition within CCM lesions. Five patients with CCM and six controls underwent a 60 or 90 min continuous PET/MRI scan following 315 ± 68.9 MBq flutriciclamide administration. Standardized uptake value (SUV) and standardized uptake value ratio (SUVr) were obtained using the striatum as a pseudo-reference. Quantitative susceptibility maps (QSM) were used to define the location of the vascular malformation and calculate the amount of iron deposition in each lesion. Increased flutriciclamide uptake was observed in all CCM lesions. The temporal pole demonstrated the highest radiotracer uptake; the paracentral lobule, cuneus and hippocampus exhibited moderate uptake; while the striatum had the lowest uptake, with average SUVs of 0.66, 0.55, 0.63, 0.55, and 0.33 for patient with CCM and 0.57, 0.50, 0.48, 0.42, and 0.32 for controls, respectively. Regional SUVr showed similar trends. The average SUV and QSM values in CCM lesions were 0.58 ± 0.23 g/ml and 0.30 ± 0.10 ppm. SUVs and QSM were positively correlated in CCM lesions (r = 0.53, p = 0.03). The distribution of flutriciclamide ([18F]GE-180) in the human brain and CCM lesions demonstrated the potential of this TSPO PET tracer as a marker of neuroinflammation that may be relevant for characterizing CCM disease progression along with QSM.

A Comparative Study of 18F-FAPI-42 and 18F-FDG PET/CT for Evaluating Acute Kidney Injury in Cancer Patients.

Compare the value of imaging using positron 18F-labeled fibroblast activation protein inhibitor-42 (18F-FAPI-42) and 18F-labeled deoxyglucose (18F-FDG) for assessment of AKI. This study analyzed cancer patients who received 18F-FAPI-42 and 18F-FDG PET/CT imaging. Eight patients had AKI with bilateral ureteral obstruction (BUO), eight had BUO (CKD1-2) with no acute kidney disease (AKD), and eight had no ureteral obstruction (UO) with normal renal function. The average standardized uptake value (SUVave) of the renal parenchyma (RP-SUVave), the blood pool SUVave (B- SUVave), SUVave in the highest region of the renal collective system (RCS-SUVave), and the highest serum creatinine level (top SCr) were recorded. The 18F-FAPI-42 and 18F-FDG results showed that radiotracer of renal parenchyma was more concentrated in the AKI group than in the other two groups, whereas the RP-SUVave from 18F-FAPI-42 was higher than that from 18F-FDG in the AKI group (all P < 0.05). 18F-FAPI-42 imaging in the AKI group showed uptake by the renal parenchyma with a diffuse increase, but very little radiotracer in the renal collecting system, similar to a "super kidney scan." The renal parenchyma also had an increase of SUVave, with accumulation of radiotracer in the renal collecting system. AKI was more severe when a patient had a "super kidney scan" in both kidneys (P < 0.05). The B-SUVave level was higher in the AKI group than in the other two groups in 18F-FAPI-42 (both P < 0.05). 18F-FAPI-42 imaging had higher RP-SUVave than 18F-FDG imaging in cancer patients who had BUO with AKI. An increased renal parenchyma uptake in both kidneys and low radiotracer distribution in the collecting system suggest more severe AKI.