18F-fluorodeoxyglucose Uptake Research Articles

#2460 Haemodialysis-related periarticular calcifications as cause of recurrent severe inflammatory state

Abstract Background and Aims End stage chronic kidney disease (CKD) and haemodialysis (HD) are associated with disturbances in mineral and bone turnover ultimately leading to chronic kidney disease–mineral and bone disorder (CKD-MBD), which affects more than 90 % of patients with stage 5D CKD. The primary changes observed in CKD–MBD involve elevated phosphorus levels, decreased calcium levels, insufficient serum vitamin D, and heightened release of parathyroid hormone from the parathyroid glands, leading to secondary hyperparathyroidism. CKD-MBD leads to vascular calcification, increasing cardiovascular risk. There is also a correlation between abnormal bone remodeling activity in CKD-MBD and the likelihood of calcification in soft tissues. In rare instances, profound calcification occurs in periarticular tissues, resulting in severe inflammation and manifesting as systemic disease with articular involvement clinically. The objective of this case report is to demonstrate a recurrent inflammatory condition caused by severe periarticular calcification in a patient on HD. Case report We present a case of a middle-aged white male diagnosed with hypertension, hypercholesterolemia, chronic obstructive pulmonary disease, hepatitis C, and end-stage renal disease caused by hydronephrosis. He was undergoing HD since July 2020. From summer 2021 the patient experienced recurrent fever and arthralgias in the hips, elbows, and shoulders. Frequent acute hospitalizations were needed due to recurring fevers and severe inflammatory response with markedly elevated acute phase reactants (CRP was repeatedly >200 mg/l), raising suspicion of infection. Laboratory and imaging tests however showed no clear signs of infection, and antibiotic therapy was ineffective. An x-ray of the right AC-joint showed multiple periarticular calcifications dorsally from the AC-joint. Later, due to severe pain and swelling an MRI-scan of right elbow joint was conducted, revealing an osteomyelitis-suspect finding of the olecranon, and olecranon bursitis. No bacteria were detected in the punctate of olecranon bursa. X-ray scans of the elbows revealed bilateral soft tissue calcification dorsally from the proximal ulna. The x-ray scan of the right shoulder revealed calcific expansion in the AC-joint area, leading to total destruction of the lateral part of the clavicle. MRI and CT scans showed severe periarticular calcification around AC- and glenohumeral joints without inflammatory involvement of the synovium. Bony erosions were observed due to the pressure of calcified tissue on the bone. Whole-body CT-scan showed no sites of infection but there was a periarticular calcification observed around the hip joints. A PET-CT scan of the whole body, neck, and upper extremities revealed no signs of malignancy or infections, but there was an increased uptake of 18F-fluorodeoxyglucose detected in several periarticular sites, indicating a multi-site inflammatory process resulting from severe periarticular calcifications. A dual-energy CT-scan of upper extremities was performed, excluding the accumulation of monosodium urate crystals. The cycle of multiple hospitalizations and antibacterial therapies was broken with the diagnosis of CKD and HD-related inflammatory periarticular calcification. Initially, the inflammation was addressed with high-dose glucocorticoids. However, the dose was successfully tapered during the first month of treatment, and the patient continued to do well on a maintenance dose of 5 mg/day of prednisolone. Subsequently, hospitalizations, antibiotics, or surgical procedures were no longer required. Conclusion Severe CKD and HD cause disturbances in mineral and bone metabolism, that can lead to periarticular calcification. Like in our presented case, multi-site calcifications may mimic infection or autoimmune rheumatoid conditions making the way to correct diagnosis cumbersome and costly. Imaging techniques help us distinguish periarticular deposits from inflammatory and infectious arthritis. In our case low-dose prednisolone effectively reduced inflammation, obviating hospitalizations and minimizing healthcare burden.

Fine needle aspiration diagnosis of benign oncocytic lesions of the head and neck associated with false positive 18F-fluorodeoxyglucose uptake on positron emission tomography scan.

18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography/computed tomography (PET/CT) has become the mainstay for staging and post-therapy surveillance of cancer as malignant neoplasms generally demonstrate higher FDG uptake that benign entities. However, there are certain benign lesions, most notably oncocytic tumors, that can display very high uptake and fine needle aspiration (FNA) is usually done to confirm malignancy. Therefore, it is important to recognize that benign oncocytic lesions of the head and neck may also present as FDG-avid lesions to avoid a diagnostic pitfall. Electronic search of institutional surgical and cytopathology archives was conducted to identify cases of benign oncocytic lesions involving the head and neck region diagnosed by FNA from January 2012 to April 2022. Chart review was used to assess whether lesions were initially discovered via PET scanning. One hundred and twenty-five cases of oncocytic lesions were identified; 12 (9%) PET positive lesions were identified in the head and neck region from patients being evaluated for metastasis or for suspicion of malignancy. Cytopathology of all 12 cases demonstrated benign oncocytic lesions; eight (67%) of these cases were consistent with Warthin tumor, one (8.3%) was a benign oncocytic lesion, and one (8.3%) was consistent wit a parathyroid adenoma. Most (58%) of the PET-positive lesions were in parotid region, two from thyroid gland (17%), one from submandibular gland (8%), one from paratracheal area (8%). The PET scan SUVs ranged from 3.3 to 19.5 g mL-1. Oncocytic lesions including Warthin tumors can result in false-positive FDG uptake on PET scans. Clinicians and cytopathologists should be aware of PET-positive benign oncocytic head and neck lesions.

FDG uptake in the cervical muscles after neck dissection: imaging features and postoperative natural course on 18F‑FDG‑PET/CT.

This study aimed to assess the imaging features and postoperative natural course of 18F-fluorodeoxyglucose (FDG) uptake in the cervical muscles after neck dissection. This study included 83 patients who underwent preoperative and postoperative 18F-FDG-PET/CT and were diagnosed with head and neck malignancy after neck dissection. Postoperative 18F-FDG-PET/CT was performed within 5years after neck dissection. Preoperative and postoperative FDG uptake of the trapezius, sternocleidomastoid, scalene, pectoralis major, and deltoid muscles was visually assessed. Increased postoperative uptake was visually defined as higher postoperative FDG uptake than the preoperative one in the corresponding muscle. The maximum standardized uptake value (SUVmax) was measured in cases with increased postoperative uptakes. Increased postoperative uptakes were observed in 43 patients (52%). The trapezius (31/83, 37%), sternocleidomastoid (19/83, 23%), and scalene (12/83, 14%) muscles were involved, as opposed to the pectoralis major and deltoid muscles were not. Increased postoperative uptakes were observed on the dissected side in all 43 patients. Significant differences between SUVmax estimated from the mixed-effects model and postoperative months were observed in the trapezius muscle (Coefficient (β) = -0.038; 95% confidence interval (CI): [-0.047, -0.028]; p < 0.001) and sternocleidomastoid muscle (β = -0.015; 95% CI: [-0.029, -0.001]; p = 0.046). Increased postoperative uptakes in the cervical muscles were observed on the dissected side in approximately half of the patients after neck dissection. The SUVmax in the trapezius and sternocleidomastoid muscles decreased after surgery over time.

18F-fluorodeoxyglucose uptake patterns in positron emission tomography/computed tomography caused by inflammation and/or infection after graft surgery for thoracic aortic dissection

BackgroundTo identify 18F-fluorodeoxyglucose (FDG) uptake patterns in positron emission tomography/computed tomography (PET/CT) caused by infection, inflammation, surgical material, and/or graft coating. Methods and resultsOf 610 consecutive patients with thoracic aortic graft surgery, 60 patients with 187 PET/CT were retrospectively included. We quantified FDG uptake in all grafts using maximum standardized uptake value (SUVmax) alone and in relation to liver background (SUVratio) and determined the uptake pattern. Mixed linear regression models with random slope and intercept were applied for the analysis of SUVratio over time and generalized estimating equations to analyze the associations with anastomosis uptake.FDG uptake was frequently focal (90%), higher in infected than in noninfected grafts (mean SUVratio 2.19; 95% CI 2.05–2.32 vs. 1.63; 1.46–1.79, P < 0.001), and decreasing slowly over time (SUVratio per year since surgery −0.048; 95% CI -0.15- 0.051, P = 0.34), without a difference in slope between infected and noninfected grafts (P = 0.52). There was no evidence of an interaction between SUVratio and use of BioGlue® surgical adhesive (intercept P = 0.73, slope P = 0.71), or graft coating (gelatin and collagen, all P > 0.7). FDG uptake at the anastomosis was more frequent in noninfected grafts than in infected grafts (66% vs. 21%, odds ratio (OR) 11.34; 95% CI 3.61–35.66, P < 0.001). This effect was attenuated by the use of BioGlue® (OR 5.05; 95% CI 0.45–56.9, P = 0.19). ConclusionsFDG uptake in PET/CT after thoracic aortic graft surgery is higher in infected grafts than in noninfected grafts. In noninfected grafts, focal uptake is also frequent, mostly anastomosis-associated, not associated with graft coating, and possibly affected by the use of BioGlue®.

(18)F-fluorodeoxyglucose uptake by positron emission tomography in patients with IPAH and CTEPH.

Pulmonary arterial hypertension (PAH) is driven by pathologies associated with increased metabolism such as pulmonary revascularization, vasoconstriction and smooth muscle cell proliferation in pulmonary artery wall. 18-fluorodeoxyglucose positron emission tomography (18FDG-PET) is an imaging technique sensitive to glucose metabolism and might be considered as a non-invasive method for diagnosis due to significant role of inflammation in idiopathic pulmonary artery hypertension (IPAH) and chronic thromboembolic pulmonary hypertension (CTEPH). The present study aimed to investigate the role of PET/CT imaging of patients with IPAH and CTEPH as an alternative diagnosis method. Demographic characteristics, FDG uptake in lungs, pulmonary artery and right ventricle (RV) of 17 patients (10 IPAH, 7 CTEPH), and 30 controls were evaluated. PET scanning, 6-min walk test, pro-BNP level, right heart catheterization of patients were performed both at the onsert and after 6-month PAH specific treatment. IPAH and CTEPH patients had significantly higher left lung FDG (p = 0.006), right lung FDG (p = 0.004), right atrial (RA) FDG (p < 0.001) and RV FDG (p < 0.001) uptakes than controls. Positive correlation was detected between the RV FDG uptake and the mean pulmonary artery pressure (mPAP) (r = 0.7, p = 0.012) and between the RA FDG uptake and the right atrial pressure (RAP) (r = 0.5, p = 0.02). Increased RV FDG and RA FDG uptakes predicts the presence of pulmonary hypertension and correlates with mPAP and RAP, respectively, which are important indicators in the prognosis of PAH. Further studies are required whether FDG PET imaging can be used to diagnose or predict the prognosis of pulmonary hypertension.

Prognostic value of bone marrow and tumor 18 F-FDG uptake on PET/CT in patients with oropharyngeal cancer and the interplay between inflammation and FDG uptake.

To examine the prognostic value of F-18 fluorodeoxyglucose (FDG) uptake in the bone marrow (BM) for disease recurrence and survival in patients with oropharyngeal squamous cell carcinoma (OP-SCC). The secondary aims were to evaluate the prognostic value of PET/CT parameters for the primary oropharyngeal tumor and total tumor burden, and to assess the correlation between FDG uptake variables and serum inflammatory markers. This was an observational study of 91 patients with OP-SCC who underwent pretreatment FDG-PET/CT. The patients' blood samples were collected before treatment, and treatment was administered with the intention to cure. The median follow-up time was 40 months. The PET parameters measured were SUVmean BM for the assessment of BM FDG uptake, SUVmean , SUVmax , total lesion glycolysis (TLG), and metabolic tumor volume (MTV) for the evaluation of primary oropharyngeal tumor and total tumor burden. Blood samples were analyzed to determine each patient's white cell, red cell, and platelet cell counts, hemoglobin, and C-reactive protein level. In a subgroup of 33 patients, blood serum was analyzed to evaluate the expression of serum immune proteins using a proximity extension assay (Olink Proteomics). The univariate analysis revealed that SUVmean BM and tumor-specific parameters (SUVmax tumor, SUVmean total, SUVmax total, MTVtotal, TLGtotal) were significantly associated with recurrence-free survival (RFS). After adjusting for age, sex, and stage only SUVmean BM remained significantly associated with RFS. Spearman's correlation identified several correlations between PET parameters and inflammatory markers. Our results show that several FDG-PET/CT parameters may have a prognostic value of treatment outcome in patients with OP-SCC. However, SUVmean BM was the only independent PET parameter that showed a prognostic value for RFS in the study cohort. Moreover, the study findings might suggest an association between systemic inflammation and the metabolic activity in the BM.

Nuclear imaging to visualize periodontal inflammation: Findings of a randomized controlled trial.

To investigate non-surgical periodontal therapy by 18F-fluorodeoxyglucose (2-[18 F]FDG) uptake using positron emission tomography (PET) integrated with computed tomography (CT). Eighty-five patients with peripheral artery disease and severe periodontitis-randomized into three groups receiving therapy with (PT1; n = 29) or without (PT2; n = 28) systemic antibiotics or no treatment (controls: n = 28)-underwent nuclear imaging at baseline and at 3 months. Clinical inflammation (periodontal inflamed surface area; PISA) did not significantly differ across the groups at baseline (p = 0.395) but was significantly reduced at 3 months (p < 0.001), and significantly more so in the PT1/PT2 groups than in the control group (p < 0.001/=0.025) and in the PT1 than in the P2 group (p = 0.001). Radiotracer uptake was measured in both jaws using maximum and mean 'standardized uptake values' (SUVmax , SUVmean ) and 'target-to-background ratios' (TBRmax , TBRmean ). At 3 months, reductions were relatively small in absolute numbers and fell short of revealing correlations with PISA or significant differences across the groups. Still, they were very consistent in both treatment groups, whereas reductions were not consistently seen in the control group. 2-[18 F]FDG PET/CT scans did reflect the clinical effects of periodontal treatment very consistently but, for reasons yet to be clarified, less closely than expected.

Exploration of tumor size measurement methods in preoperative breast cancer assessment using whole-body silicon photomultiplier PET: feasibility and first results.

Whole-body silicon photomultiplier positron emission tomography (WB SiPM PET) could be used to diagnose breast cancer spread before lumpectomy. We aimed to investigate the method of measuring the tumor size by WB SiPM PET as a basis for diagnosing breast cancer spread in the breast. We retrospectively reviewed 35 breast cancer lesions in 32 patients who underwent WB SiPM PET/CT in the prone position as preoperative breast cancer examinations from September 2020 to March 2022. In all cases, a 20-mm spherical VOI was placed in the normal mammary gland to measure the mean standardised uptake value (SUVmean) and the standard deviation (SD) of 18F-fluorodeoxyglucose (FDG) uptake. We prepared four types of candidates (SUVmean + 2 SD, SUVmean + 3 SD, 1.5 SUVmean + 2 SD, 1.5 SUVmean + 3 SD) for thresholds for delineating tumor contours on PET images. On the semiautomatic viewer soft, the maximum tumor sizes were measured at each of the four thresholds and compared with the pathological tumor sizes, including the extensive intraductal component (EIC). The lesion detection sensitivity was 97% for WB SiPM PET. PET detected 34 lesions, excluding 4-mm ductal carcinomas in situ (DCIS). PET measurements at the '1.5 SUVmean + 2 SD' threshold demonstrated values closest to the pathological tumor sizes, including EIC. Moreover, '1.5 SUVmean + 2 SD' had the highest concordance (63%). The study demonstrated that among various PET thresholds, the '1.5 SUVmean + 2 SD' threshold exhibited the best performance. However, even with this threshold, the concordance rate was limited to only 63%.

Hepatic arterial infusion chemotherapy combined with bevacizumab plus a PD-1 inhibitor for gallbladder cancer with hepatic oligometastasis: a real-world study.

Gallbladder cancer (GBC) is different from other biliary tract cancers in terms of molecular phenotype and microenvironment. Specific treatments for GBC need to be urgently explored. This study preliminarily investigated the clinical value of hepatic artery infusion chemotherapy (HAIC) combined with bevacizumab plus a programmed death receptor-1 (PD-1) inhibitor for treatment of GBC with hepatic oligometastasis. We retrospectively collected data on GBC patients with hepatic oligometastasis, who received this combination therapy. The clinical data, conversion rate, treatment response, adverse events (AEs), and short-term survival were summarized. The responses of primary gallbladder lesions and hepatic metastasis, and their effect on prognosis, were investigated. A total of 27 patients were included in the analysis. No grade 4 AEs were observed. The overall objective response rate (ORR) was 55.6% and the disease control rate (DCR) was 85.2%. Median overall survival (OS) time was 15.0 months and the 1-year survival rate was 64.0%. Median progression-free survival (PFS) time was 7.0 months and the 1-year PFS rate was 16.2%. Six patients (22.2%) were successfully converted to resection. Compared with primary gallbladder lesions, it appeared more difficult for patients with hepatic metastasis to achieve remission (ORR: 40.7% vs. 77.8%; P=0.012), but its response appeared to be closely related to the prognosis [median OS: 16.0 months in the complete response (CR) or partial response (PR) group vs. 11.0 months in the stable disease (SD) or progressive disease (PD) group, P=0.070; median PFS: 12.0 months in the CR or PR group vs. 6.5 months in the SD or PD group, P<0.001]. Preoperative CA19-9 of >1,900 U/mL and >5 cm metastatic lesions were associated with an unsatisfactory response, whereas a significant decrease of 18F-fluorodeoxyglucose (18F-FDG) uptake may be a marker of tumor remission. The combination of HAIC, a PD-1 inhibitor, and bevacizumab shows potential for advanced GBC with hepatic oligometastasis. The therapeutic response of hepatic metastasis had a greater influence on prognosis than that of primary gallbladder lesions.

Cold exposure modulates potential brown adipokines in humans, but only FGF21 is associated with brown adipose tissue volume.

The study objective was to investigate the effect of cold exposure on the plasma levels of five potential human brown adipokines (chemokine ligand 14 [CXCL14], growth differentiation factor 15 [GDF15], fibroblast growth factor 21 [FGF21], interleukin 6 [IL6], and bone morphogenic protein 8b [BMP8b])and to study whether such cold-induced effects are related to brown adipose tissue (BAT) volume, activity, or radiodensityin young humans. Plasma levels of brown adipokines were measured before and 1 h and 2 h after starting an individualized cold exposure in 30 young adults (60% women, 21.9 ± 2.3 y; 24.9 ± 5.1 kg/m2 ). BAT volume, 18 F-fluorodeoxyglucose uptake, and radiodensity were assessed by a static positron emission tomography-computerized tomography scan after cold exposure. Cold exposure increased the concentration of CXCL14 (Δ2h = 0.58 ± 0.98 ng/mL; p = 0.007), GDF15 (Δ2h = 19.63 ± 46.2 pg/mL; p = 0.013), FGF21 (Δ2h = 33.72 ± 55.13 pg/mL; p = 0.003), and IL6 (Δ1h = 1.98 ± 3.56 pg/mL; p = 0.048) and reduced BMP8b (Δ2h = -37.12 ± 83.53 pg/mL; p = 0.022). The cold-induced increase in plasma FGF21 was positively associated with BAT volume (Δ2h: β = 0.456; R2 = 0.307; p = 0.001), but not with 18 F-fluorodeoxyglucose uptake or radiodensity. None of the changes in the other studied brown adipokines was related to BAT volume, activity, or radiodensity. Cold exposure modulates plasma levels of several potential brown adipokines in humans, whereas only cold-induced changes in FGF21 levels are associated with BAT volume. These findings suggest that human BAT might contribute to the circulatory pool of FGF21.

Physiological myocardial 18F-FDG uptake pattern in oncologic PET/CT: comparison with findings in cardiac sarcoidosis.

Physiological myocardial 18F-fluorodeoxyglucose (18F-FDG) uptake in oncologic positron emission tomography (PET)/computed tomography (CT) is commonly observed with multiple variations under clinical fasting conditions. The purpose of the present study was to evaluate physiological myocardial 18F-FDG uptake pattern by comparing with the results in cardiac sarcoidosis. A total of 174 examinations in 174 patients without cardiac disease and 27 examinations in 17 patients with cardiac sarcoidosis were performed. The polar map images generated from 18F-FDG PET/CT data were visually assessed as "basal-ring," "focal," and "focal on diffuse" patterns. Semi-quantitative analysis was also performed using the regional relative 18F-FDG uptake (% uptake). On visual analysis, the "focal on diffuse" pattern was the most common in both examinations (43% and 59%, respectively). The physiological % uptake in the lateral and basal septal walls tended to be higher. Subgroup analysis showed significantly higher uptake in the mid-wall and left circumflex territory. In cardiac sarcoidosis patients, there was a significant difference only between segments 2 and 15 (p=0.04). No significant differences were observed between the base-mid-apical territory and coronary artery branch territory. High 18F-FDG uptake in the basal septal walls is likely to be observed as both physiological uptake in patients without cardiac disease and pathological uptake in patients with cardiac sarcoidosis.

Visualization of small brain nuclei with a high-spatial resolution, clinically available whole-body PET scanner

ObjectiveTo verify the visibility of physiological 18F-fluorodeoxyglucose (18F-FDG) uptake in nuclei in and around the brainstem by a whole-body (WB) silicon photomultiplier positron emission tomography (SiPM-PET) scanner with point-spread function (PSF) reconstruction using various iteration numbers.MethodsTen healthy subjects (5 men, 5 women; mean age, 56.0 ± 5.0 years) who underwent 18F-FDG PET/CT using a WB SiPM-PET scanner and magnetic resonance imaging (MRI) of the brain including a spin-echo three-dimensional sampling perfection with application-optimized contrasts using different flip angle evolutions fluid-attenuated inversion recovery (3D-FLAIR) and a 3D-T1 magnetization-prepared rapid gradient-echo (T1-MPRAGE) images were enrolled. Each acquired PET image was reconstructed using ordered-subset expectation maximization (OSEM) with iteration numbers of 4, 16, 64, and 256 (subset 5 fixed) + time-of-flight (TOF) + PSF. The reconstructed PET images and 3D-FLAIR images for each subject were registered to individual T1-MPRAGE volumes using normalized mutual information criteria. For each MR-coregistered individual PET image, the pattern of FDG uptake in the inferior olivary nuclei (ION), dentate nuclei (DN), midbrain raphe nuclei (MRN), inferior colliculi (IC), mammillary bodies (MB), red nuclei (RN), subthalamic nuclei (STN), lateral geniculate nuclei (LGN), medial geniculate nuclei (MGN), and superior colliculi (SC) was visually classified into the following three categories: good, clearly distinguishable FDG accumulation; fair, obscure contour of FDG accumulation; poor, FDG accumulation indistinguishable from surrounding uptake.ResultsAmong individual 18F-FDG PET images with OSEM iterations of 4, 16, 64, and 256 + TOF + PSF, the iteration numbers that showed the best visibility in each structure were as follows: ION, MRN, LGN, MGN, and SC, iteration 64; DN, iteration 16; IC, iterations 16, 64, and 256; MB, iterations 64 and 256; and RN and STN, iterations 16 and 64, respectively. Of the four iterations, the 18F-FDG PET image of iteration 64 visualized FDG accumulation in small structures in and around the brainstem most clearly (good, 98 structures; fair, 2 structures).ConclusionsA clinically available WB SiPM-PET scanner is useful for visualizing physiological FDG uptake in small brain nuclei, using a sufficiently high number of iterations for OSEM with TOF and PSF reconstructions.

Asymmetry of thalamic hypometabolism on FDG-PET/CT in neurofibromatosis type 1: Association with peripheral tumor burden.

Thalamic hypometabolism is a consistent finding in brain PET with F-18 fluorodeoxyglucose (FDG) in patients with neurofibromatosis type 1 (NF1). However, the pathophysiology of this metabolic alteration is unknown. We hypothesized that it might be secondary to disturbance of peripheral input to the thalamus by NF1-characteristic peripheral nerve sheath tumors (PNSTs). To test this hypothesis, we investigated the relationship between thalamic FDG uptake and the number, volume, and localization of PNSTs. This retrospective study included 22 adult NF1 patients (41% women, 36.2±13.0years) referred to whole-body FDG-PET/contrast-enhanced CT for suspected malignant transformation of PNSTs and 22 sex- and age-matched controls. Brain FDG uptake was scaled voxelwise to the individual median uptake in cerebellar gray matter. Bilateral mean and left-right asymmetry of thalamic FDG uptake were determined using a left-right symmetric anatomical thalamus mask. PNSTs were manually segmented in contrast-enhanced CT. Thalamic FDG uptake was reduced in NF1 patients by 2.0 standard deviations (p<.0005) compared to controls. Left-right asymmetry was increased by 1.3 standard deviations (p=.013). Thalamic hypometabolism was higher in NF1 patients with ≥3 PNSTs than in patients with ≤2 PNSTs (2.6 vs. 1.6 standard deviations, p=.032). The impact of the occurrence of paraspinal/paravertebral PNSTs and of the mean PNST volume on thalamic FDG uptake did not reach statistical significance (p=.098 and p=.189). Left-right asymmetry of thalamic FDG uptake was not associated with left-right asymmetry of PNST burden (p=.658). This study provides first evidence of left-right asymmetry of thalamic hypometabolism in NF1 and that it might be mediated by NF1-associated peripheral tumors.

Predictive value of 18 F-FDG PET/CT and serum tumor markers for tumor mutational burden in patients with non-small cell lung cancer.

To investigate the correlations between metabolic parameters (MPs) of 18 F-fluorodeoxyglucose (FDG) uptake on positron emission tomography/computed tomography (PET/CT), serum tumor markers (STMs), and tumor mutational burden (TMB) in patients with non-small cell lung cancer (NSCLC). In this retrospective study, we enrolled 129 patients with NSCLC (males, 78; females, 51) who underwent baseline TMB and STM tests and 18 F-FDG PET/CT scans before treatment between March 2018 and September 2022. Patients were categorized into TMB-high (TMB ≥10 mutations/Mb; n = 27 [20.9%]) and non-TMB-high (TMB <10 mutations/Mb; n = 102 [79.1%]) groups. Binary logistic regression analyses were performed to determine independent predictors of TMB-high. Univariate and multivariate linear regression analyses were performed to determine independent predictors of TMB level on a log scale. Subgroup analyses for adenocarcinoma (ADC), ADC with EGFR+, ADC with EGFR-, and squamous cell carcinoma (SCC) were performed. For ADC, all MPs (SULpeak , SULmax , SULmean , MTV, and TLG) were significantly higher in the TMB-high group than the non-TMB-high group; smoker (odds ratio [OR] = 27.08, p = 0.018), EGFR+ (OR = 0.03, p = 0.033), KRAS+ (OR = 7.98, p = 0.083), high CEA (OR = 33.56, p = 0.029), and high CA125 (OR = 13.68, p = 0.030) were independent predictors of TMB-high; and all MPs showed significant positive linear correlations with TMB on a log scale, with SULpeak as an independent predictor. However, no significant correlation was observed for SCC. MPs and STMs can predict the TMB level for patients with ADC, and may serve as potential substitutes for TMB with increased value and easy implementation in guiding immunotherapy through noninvasive methods.

Dynamic 18F-FDG-PET kinetic parameters for epileptogenic zone localization in drug-resistant epilepsy

Objective: Precisely localizing the seizure onset zone remains a challenging task in drug-resistant epilepsy (DRE) patients especially given its critical role in successful surgery and effective management. This study aimed to investigate the kinetic parameters of regional 18F-fluorodeoxyglucose (FDG) uptake in DRE patients, aiming to identify the kinetic parameters best enabling the identification of the epileptogenic region.Methods: Consecutive DRE patients with clinically mandated interictal 18F-FDG PET/CT were recruited from October 2019 to September 2020 for pre-surgical evaluation. Immediately after injecting 18F-FDG of 112–179 MBq, dynamic data were acquired for 90 min. The motion correction and resampling to the Montreal atlas was performed in order to generate a transformation matrix. 116 volume of interests (VOIs) and regional time-activity curves (TACs) were generated by employing the automated anatomical labeling (AAL) template using PMOD software. Kinetic parameters of FDG unidirectional blood-brain clearance (K1), efflux (k2), phosphorylation (k3), and net metabolic flux (Ki) were derived using irreversible 2-tissue-compartment model with an image-derived input function (IDIF). The kinetic parameters values obtained from all regions were ranked and compared with the presumed epileptogenic zone (EZ).Results: Eleven DRE patients (5 males, 6 females, mean age 35.1 ± 10.2 years) were analyzed. We found that the region with the lowest values of Ki provided correct lateralization in 7/7 (100%) of patient with temporal lobe epilepsy (TLE) and the region with the lowest Ki and k3 parameters showed concordance with the EZ in 100% and 71.4% of patients, respectively.Conclusion: The present parametric approach to the evaluation of FDG-PET may be more sensitive than semi-quantitative approaches for the detection of pathophysiology in the EZ of patients with medically unresponsive TLE in addition to the routine clinical investigations.

Association Between Vascular 18F-Fluorodeoxyglucose Uptake at Diagnosis and Change in Aortic Dimensions in Giant Cell Arteritis : A Cohort Study.

Previous studies have shown that patients with giant cell arteritis (GCA) who have vascular 18F-fluorodeoxyglucose (FDG) uptake at diagnosis are at increased risk for thoracic aortic complications. To measure the association between vascular FDG uptake at diagnosis and the change in aortic dimensions. Prospective cohort study. University Hospitals Leuven. 106 patients with GCA and FDG positron emission tomography (PET) imaging 3 days or less after initiation of glucocorticoids. Patients had PET and computed tomography (CT) imaging at diagnosis and CT imaging yearly for a maximum of 10 years. The PET scans were scored 0 to 3 in 7 vascular areas and summed to a total vascular score (TVS). The PET scan results were positive when FDG uptake was grade 2 or greater in any large vessel. The association between vascular FDG uptake and aortic dimensions was estimated by linear mixed-effects models with random intercept and slope. When compared with patients with a negative PET scan result, those with a positive scan result had a greater increase in the diameter of the ascending aorta (difference in 5-year progression, 1.58 mm [95% CI, 0.41 to 2.74 mm]), the diameter of the descending aorta (1.32 mm [CI, 0.38 to 2.26 mm]), and the volume of the thoracic aorta (20.5 cm³ [CI, 4.5 to 36.5 cm³]). These thoracic aortic dimensions were also positively associated with TVS. Patients with a positive PET scan result had a higher risk for thoracic aortic aneurysms (adjusted hazard ratio, 10.21 [CI, 1.25 to 83.3]). The lengthy inclusion and follow-up period resulted in missing data and the use of different PET machines. Higher TVS was associated with greater yearly increase in thoracic aortic dimensions. Performing PET imaging at diagnosis may help to estimate the risk for aortic aneurysm formation. None.

Alterations in 18F-FDG Uptake Patterns may Limit Cross-sectional Evaluation of Adrenal Adenomas Using Single 18F-FDG PET/CT Imaging.

Adrenal adenomas are observed in up to 7% of the population and are predominantly non-functional, increased 18F-fluorodeoxyglucose (FDG) uptake is seen in only a small portion of them on 18F-FDG positron emission tomography/computed tomography (PET/CT) imaging. In this report, we present the sequential 18F-FDG PET/CT imaging findings of 2 patients with radiologically or pathologically confirmed adrenal adenomas who had severely altered 18F-FDG uptake patterns in adrenal lesions in different imaging studies of the same patient. In light of these findings, we wanted to highlight that evaluating adrenal adenomas as cross-sectional with semi-quantitative PET/CT parameters obtained from single imaging may cause misinterpretation.

Similarity between structural and proxy estimates of brain connectivity

Functional magnetic resonance and diffusion weighted imaging have so far made a major contribution to delineation of the brain connectome at the macroscale. While functional connectivity (FC) was shown to be related to structural connectivity (SC) to a certain degree, their spatial overlap is unknown. Even less clear are relations of SC with estimates of connectivity from inter-subject covariance of regional F18-fluorodeoxyglucose uptake (FDGcov) and grey matter volume (GMVcov). Here, we asked to what extent SC underlies three proxy estimates of brain connectivity: FC, FDGcov and GMVcov. Simultaneous PET/MR acquisitions were performed in 56 healthy middle-aged individuals. Similarity between four networks was assessed using Spearman correlation and convergence ratio (CR), a measure of spatial overlap. Spearman correlation coefficient was 0.27 for SC-FC, 0.40 for SC-FDGcov, and 0.15 for SC-GMVcov. Mean CRs were 51% for SC-FC, 48% for SC-FDGcov, and 37% for SC-GMVcov. These results proved to be reproducible and robust against image processing steps. In sum, we found a relevant similarity of SC with FC and FDGcov, while GMVcov consistently showed the weakest similarity. These findings indicate that white matter tracts underlie FDGcov to a similar degree as FC, supporting FDGcov as estimate of functional brain connectivity.

Positron Emission Computed Tomography Spectrum of Large Vessel Vasculitis in a Tertiary Center: Differences in 18F-fluorodeoxyglucose Uptake between Large Vessel Vasculitis with Predominant Cranial and Extracranial Giant Cell Arteritis Phenotypes.

(1) Objective:To assess the spectrum of PET-CT-related large vessel vasculitis (LVV) in a Spanish tertiary center and to determine whether FDG uptake by PET-CT differs between giant cell arteritis (GCA) with predominant cranial or extracranial phenotypes. (2) Methods: The spectrum of patients diagnosed with LVV by PET-CT in a tertiary referral hospital that cares for 450,000 people over a period of two years was reviewed. Moreover, differences in FDG uptake between LVV-GCA with predominantly cranial and extracranial phenotype were analyzed. (3) Results: Eighty patients were diagnosed with LVV by PET-CT. Most were due to systemic vasculitis (n = 64; 80%), especially GCA (n = 54; 67.5%). Other conditions included the presence of rheumatic diseases (n = 4; 3.2%), tumors (n = 9; 7.2%) and infections (n = 3; 2.4%). LVV-GCA patients with predominant extracranial GCA phenotype were younger (mean ± SD: 68.07 ± 9.91 vs. 75.46 ± 7.64 years; p = 0.017) and had a longer delay to the diagnosis (median [interquartile range] 12 [4-18] vs. 4 [3-8]; p = 0.006), but had polymyalgia rheumatica symptoms more frequently than those with predominantly cranial GCA phenotype (46.3% vs. 15.4%, p = 0.057). When FDG uptake was compared according to the two different disease patterns, no statistically significant differences were observed. However, patients with extracranial LVV-GCA showed a non-significantly higher frequency of vasculitic involvement of lower-extremity arteries. (4) Conclusions: Regardless of the predominant phenotype, LVV identified by PET-CT is more commonly due to GCA in the Spanish population. In these GCA patients, younger age, PMR, and a higher frequency of lower-extremity artery vasculitis suggest the presence of LVV.

In-vivo detection of white adipose tissue browning: a multimodality imaging approach

Detection and differentiation of brown fat in humans poses several challenges, as this tissue is sparse and often mixed with white adipose tissue. Non-invasive detection of beige fat represents an even greater challenge as this tissue is structurally and functionally more like white fat than brown fat. Here we used positron emission tomography with 18F-fluorodeoxyglucose, computed tomography, xenon-enhanced computed tomography, and dynamic contrast-enhanced ultrasound, to non-invasively detect functional and structural changes associated with the browning process of inguinal white fat, induced in mice by chronic stimulation with the β3-adrenergic receptor agonist CL-316243. These studies reveal a very heterogeneous increase in baseline tissue radiodensity and xenon-enhanced radiodensity, indicative of both an increase in adipocytes water and protein content as well as tissue perfusion, mostly in regions that showed enhanced norepinephrine-stimulated perfusion before CL-316243 treatment. No statistically significant increase in 18F-fluorodeoxyglucose uptake or norepinephrine-stimulated tissue perfusion were observed in the mice after the CL-316243 treatment. The increase in tissue-water content and perfusion, along with the negligible increase in the tissue glucose uptake and norepinephrine-stimulated perfusion deserve more attention, especially considering the potential metabolic role that this tissue may play in whole body metabolism.