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01 februari 2023, Item does not contain fulltext, PURPOSE: As bone formation is associated with psoriatic arthritis (PsA), positron emission tomography (PET) using a (18)F-Fluoride tracer may enable sensitive detection of disease activity. Our primary aim was to determine the feasibility of whole-body (18)F-sodium fluoride PET-CT in clinically active PsA patients to depict new bone formation (as a reflection of disease activity) at peripheral joints and entheses. Our secondary aim was to describe (18)F-sodium fluoride findings in the axial skeleton. METHODS: Sixteen patients (female 10/16, age 50.6 ± 8.9 years) with PsA fulfilling CASPAR criteria or with a clinical diagnosis of PsA according to the treating rheumatologist and with ≥ 1 clinically active enthesitis site were included. Of each patient, a whole-body (18)F-sodium fluoride PET-CT scan was performed. All scans were scored for PET-positive lesions at peripheral joints, enthesis sites and the spine. Clinical disease activity was assessed by swollen/tender joint count 44, enthesitis according to MASES and SPARCC scores. RESULTS: Out of 1088 evaluated joints, 109 joints showed PET enhancement, mainly in the interphalangeal and metatarsal joints of the feet (14/109, 12.9%) and the distal interphalangeal joints of the hands (14/109, 12.9%). PET positivity was found at 44/464 enthesis sites, mainly at the patella tendon insertion (11/44, 25%) and quadriceps tendon insertion (10/44, 22.7%). Of the PET-positive joints and enthesis sites, respectively 18.2% and 29.5% were clinically positive; 81.8% and 70.5% of the PET-positive joints and entheses respectively were clinically asymptomatic. In 11 patients, ≥ 1 axial PET-positive lesion was observed, mainly in the cervical spine. CONCLUSIONS: New molecular bone formation was observed on (18)F-sodium fluoride PET-CT scans, in all domains in which PsA disease activity can be observed, with a substantial part showing no clinical symptoms. CLINICAL TRIAL REGISTRATION: EudraCT: 2017-004,850-40, registered on 13 December 2

01 april 2023, Item does not contain fulltext, PURPOSE: To relate [(18)F]fluoride uptake on PET with abnormalities on magnetic resonance imaging (MRI) and conventional radiography (CR) in ankylosing spondylitis (AS) patients. METHODS: Ten clinically active AS patients (female 6/10, age 38 ± 11 years) were included, and both spine and SI-joints were examined. PET scans were dichotomously scored for enhanced [(18)F]fluoride uptake, MRI scans were scored for fatty lesions, erosions, ankylosis, and bone marrow edema (BME), and CR was scored for erosions, syndesmophytes, and ankylosis. The overlap of lesions across all modalities was evaluated through univariate and multivariate analyses using a generalized mixed model. RESULTS: In the spine, 69 lesions with enhanced [(18)F]fluoride uptake, 257 MRI lesions, and 88 CR lesions were observed. PET lesions were mostly located in costovertebral and facet joints, outside the field of view (FOV) of the MRI and CR. However, PET lesions inside the FOV of MRI and CR partially showed no abnormality on MRI and CR. In lesions with abnormalities on multiple modalities, both univariate and multivariate analysis showed that PET activity had the strongest association with BME on MRI and ankylosis on CR. In the SI joints, 15 lesions (75%) with PET uptake were found, with 87% showing abnormalities on MRI and CR. CONCLUSION: [(18)F]fluoride PET lesions are often found outside the scope of MRI and CR, and even in the same location show only partial overlap with abnormalities on MRI (especially BME) and CR (especially ankylosis). This suggests that [(18)F]fluoride PET partially visualizes aspects of AS separate from MRI and CR, providing novel information. CLINICAL TRIAL REGISTRATION: NL43223.029.13 registered at 02-05-2013. https://www.toetsingonline.nl/to/ccmo_search.nsf/fABRpop?readform&unids=C1257BA2002CC066C1257B4E0049A65A.

Item does not contain fulltext, Upregulation of prostate-specific membrane antigen (PSMA) in neovasculature has been described in glioblastoma multiforme (GBM), whereas vasculature in nonaffected brain shows hardly any expression of PSMA. It is unclear whether PSMA-targeting tracer uptake on PET is based on PSMA-specific binding to neovasculature or aspecific uptake in tumor. Here, we quantified uptake of various PSMA-targeting tracers in GBM and correlated this with PSMA expression in tumor biopsy samples from the same patients. Methods: Fourteen patients diagnosed with de novo (n = 8) or recurrent (n = 6) GBM underwent a preoperative PET scan after injection of 1.5 MBq/kg [(68)Ga]Ga-PSMA-11 (n = 7), 200 MBq of [(18)F]DCFpyl (n = 3), or 200 MBq of [(18)F]PSMA-1007 (n = 4). Uptake in tumor and tumor-to-background ratios, with contralateral nonaffected brain as background, were determined. In a subset of patients, PSMA expression levels from different regions in the tumor tissue samples (n = 40), determined using immunohistochemistry (n = 35) or RNA sequencing (n = 13), were correlated with tracer uptake on PET. Results: Moderate to high (SUV(max), 1.3-20.0) heterogeneous uptake was found in all tumors irrespective of the tracer type used. Uptake in nonaffected brain was low, resulting in high tumor-to-background ratios (6.1-359.0) calculated by dividing SUV(max) of tumor by SUV(max) of background. Immunohistochemistry showed variable PSMA expression on endothelial cells of tumor microvasculature, as well as on dispersed individual cells (of unknown origin), and granular staining of the neuropil. No correlation was found between in vivo uptake and PSMA expression levels (for immunohistochemistry, r = -0.173, P = 0.320; for RNA, r = -0.033, P = 0.915). Conclusion: Our results indicate the potential use of various PSMA-targeting tracers in GBM. However, we found no correlation between PSMA expression levels on immunohistochemistry and uptake intensity on PET. Whether this may be explained by methodol

Practical testing for observing the failure modes is expensive, time consuming and often limits the pace of research progress. Moreover, because of the limitations of equipment, the existing structures cannot be tested at ultimate failure and scale effect is not observed on large scale experimentally. Thus, numerical modeling and statistical analysis is required for prediction of the behavior of fire damaged and fire-damaged repaired structures. This Paper explores the regression models and Finite element studies to predict the load-deformation response of bolstered concrete columns, damaged through exposure to heat at 300 °C, 500 °C and 900 °C, strengthened using smart materials and confined by carbon fiber reinforced polymers. Using software ABAQUS, a numerical model was developed, capable of predicting the axial load-deformation performance of undamaged, fire damaged and fire-damaged reinforced columns repaired by employing various confinement techniques. SPSS Software was used for Regression modeling (Linear, multiple, and Quadratic). The obtained results showed that regression equations and numerical modeling offered a better alternative to the experimental methods. High correlation coefficient r and coefficient of determination r2, more than 90%, for all developed equations, confirmed it as an excellent fit statistical model for prediction of axial load capacity and axial deformation. Similarly, the response predicted by numerical modeling showed minor difference i-e less than 10% with that of experimental. Thus, it can be concluded that, the numerical modeling and prediction formulae agree quite with the experimental results and can be used as alternatives for prediction of loads and deformations.

This paper presents numerical and regression modeling of 21 undamaged, fire-damaged, and repaired fire-damaged reinforced circular concrete (RC) columns. The columns were exposed to three different temperatures of 300°C, 500°C, and 900°C and tested for axial residual capacity. It was found that concrete loses its strength after exposure to a temperature of 300°C or above. Fire-damaged columns were then repaired using various composite confinement techniques. Strength was regained when CFRP confinement was applied to fire-damaged columns but it increased the deformation as well and thus reduced the stiffness which is not desirable. To overcome this challenge, steel wire mesh, filled with cement sand mortar and wrapped with CFRP was employed. Further, a numerical model was developed that could precisely predict the residual capacity of these columns. The paper briefly reviewed and summarised the development of numerical techniques, including material properties, geometry, elements, loading, boundary conditions, and contact algorithm for undamaged, fire-damaged, and repaired fire-damaged columns. Moreover, analytical equations were developed using linear, multiple, and quadratic regression modeling. The results obtained using the proposed model and regression equations showed that these models offered a better alternative to the experimental testing for the prediction of the post-fire performance of damaged and repaired RC columns.