In the study, we report an in situ corrosion and mass transport monitoring method developed using a radionuclide tracing technique for the corrosion study of 316L stainless steel (316L SS) in a NaCl-MgCl2 eutectic molten salt natural circulation loop. This method involves cyclotron irradiation of a small tube section with 16 MeV protons, later welds at the hot leg of the molten salt flow loop, generating radionuclides 51Cr, 52Mn, and 56Co at the salt-alloy interface. By measuring the activity variations of these radionuclides at different sections along the loop, both the in situ monitoring of the corrosion attack depth of 316L SS and corrosion product transport and its precipitation in flowing NaCl-MgCl2 molten salt are achieved. While 316L SS is the focus of this study, the technique reported herein can be extended to other structural materials being used in a wide range of industrial applications.In situ corrosion monitoring is essential to unveil corrosion mechanisms and safeguard materials' health. Here, the authors develop a radionuclide tracing based in situ corrosion monitoring technique that can monitor corrosion attack depth and corrosion product transport in flowing molten salts.

Targeted Meitner-Auger Therapy (TMAT) has potential for personalized treatment thanks to its subcellular dosimetric selectivity, which is distinct from the dosimetry of & beta;- and & alpha; particle emission based Targeted Radionuclide Therapy (TRT). To date, most clinical and preclinical TMAT studies have used commercially available radionuclides. These studies showed promising results despite using radionuclides with theoretically suboptimal photon to electron ratios, decay kinetics, and electron emission spectra. Studies using radionuclides whose decay characteristics are considered more optimal are therefore important for evaluation of the full potential of Meitner-Auger therapy; 119Sb is among the best such candidates. In the present work, we develop radiochemical purification of 120Sb from irradiated natural tin targets for TMAT studies with 119Sb.

The therapeutic potential of the Meitner-Auger- and conversion-electron emitting radionuclide Sb-119 remains unexplored because of the difficulty of incorporating it into biologically targeted compounds. To address this challenge, we report the development of Sb-119 production from electroplated tin cyclotron targets and its complexation by a novel trithiol chelate. The chelation reaction occurs in harsh solvent conditions even in the presence of large quantities of tin, which are necessary for production on small, low energy (16 MeV) cyclotrons. The Sb-119-trithiol complex has high stability and can be purified by HPLC. The third generation trithiol chelate and the analogous stable Sb-nat-trithiol compound were synthesized and characterized, including by single-crystal X-ray diffraction analyses.

The therapeutic potential of the Meitner-Auger- and conversion-electron emitting radionuclide Sb-119 remains unexplored because of the difficulty of incorporating it into biologically targeted compounds. To address this challenge, we report the development of Sb-119 production from electroplated tin cyclotron targets and its complexation by a novel trithiol chelate. The chelation reaction occurs in harsh solvent conditions even in the presence of large quantities of tin, which are necessary for production on small, low energy (16 MeV) cyclotrons. The Sb-119-trithiol complex has high stability and can be purified by HPLC. The third generation trithiol chelate and the analogous stable Sb-nat-trithiol compound were synthesized and characterized, including by single-crystal X-ray diffraction analyses.

Natural killer (NK) cell therapies are being increasingly used as an adoptive cell therapy for cancer because they can recognize tumor cells in an antigen-independent manner. While promising, the understanding of NK cell persistence, particularly within a harsh tumor microenvironment, is limited. Fluorine-19 (F-19) MRI is a noninvasive imaging modality that has shown promise in longitudinally tracking cell populations in vivo; however, it has not been studied on murine NK cells. In this study, the impact of F-19 labeling on murine NK cell viability and function was assessed in vitro and then used to quantify NK cell persistence in vivo. While there was no noticeable impact on viability, labeling NK cells with F-19 did attenuate cytotoxicity against lymphoma cells in vitro. Fluorescent microscopy verified F-19 labeling in both the cytoplasm and nucleus of NK cells. Lymphoma-bearing mice were given intratumoral injections of F-19-labeled NK cells in which signal was detectable across the 6 day observation period via F-19 MRI. Quantification from the composite images detected 78-94% of the initially injected NK cells across 6 days, with a significant decrease between Days 3 and 6. Postmortem flow cytometry demonstrated retention of F-19 intracellularly within adoptively transferred NK cells with less than 1% of F-19-containing cells identified as tumor-associated macrophages that presumably ingested nonviable NK cells. This work demonstrates that F-19 MRI offers a specific imaging platform to track and quantify murine NK cells within tumors noninvasively.

Background Nearly all persons with Down syndrome will show pathology of Alzheimer's disease in their 40s. There is a critical need for studies to identify early biomarkers of these various pathological changes of Alzheimer's disease in the Down syndrome population and understand the relationship of these biomarkers to cognitive symptoms in order to inform clinical trials. Although Alzheimer's disease is often considered a disease of gray matter, white matter degeneration has been documented during the preclinical stage of Alzheimer's disease. The current study examined the association between diffusion tensor imaging (DTI) measures of white matter microstructure and episodic memory performance in 52 adults with Down syndrome. Methods Seventy (N = 70) participants (M = 40.13, SD = 7.77 years) received baseline scans as part of the Neurodegeneration in Aging Down Syndrome (NiAD) study at two imaging facilities (36 at the University of Wisconsin-Madison [UW-Madison] and 34 at the University of Pittsburgh Medical Center [UPMC]). All participants had genetically confirmed trisomy 21. Fifty-two (N = 52) participants remained after QC. The DTI measures, fractional anisotropy (FA) and mean diffusivity (MD), were calculated for each participant. A combined measure of episodic memory was generated by summing the z-scores of (1) Free and Cued Recall test and (2) Rivermead Behavioural Memory Test for Children Picture Recognition. The DTI data were projected onto a population-derived FA skeleton and tract-based spatial statistics analysis was conducted using the FSL tool PALM to calculate Pearson's r values between FA and MD with episodic memory. Results A positive correlation of episodic memory with FA and a negative correlation of episodic memory and MD in the major association white matter tracts were observed. Results were significant (p < 0.05) after correction for chronological age, imaging site, and premorbid cognitive ability. Conclusion These findings suggest that white matter degeneration may be implicated in early episodic memory declines prior to the onset of dementia in adults with Down syndrome. Further, our findings suggest a coupling of episodic memory and white matter microstructure independent of chronological age.

We report an extraction chromatography-based method via Actinide Resin for the isolation of radio-manganese from both natural chromium and isotopically enriched iron targets for cyclotron production of (52)gMn and Mn-51. For the separation of (52)gMn from n(at)Cr, a decay-corrected radiochemical yield of 83.7 +/- 8.4% was achieved. For Mn-51 from Fe-54, a decay-corrected radiochemical yield of 78 +/- 11% was achieved. This automatable method efficiently isolates both radionuclides from accelerator target material. (C) 2021 Elsevier Inc. All rights reserved.

Deep learning (DL) approaches to medical image analysis tasks have recently become popular; however, they suffer from a lack of human interpretability critical for both increasing understanding of the methods' operation and enabling clinical translation. This review summarizes currently available methods for performing image model interpretation and critically evaluates published uses of these methods for medical imaging applications. We divide model interpretation in two categories: (1) understanding model structure and function and (2) understanding model output. Understanding model structure and function summarizes ways to inspect the learned features of the model and how those features act on an image. We discuss techniques for reducing the dimensionality of high-dimensional data and cover autoencoders, both of which can also be leveraged for model interpretation. Understanding model output covers attribution-based methods, such as saliency maps and class activation maps, which produce heatmaps describing the importance of different parts of an image to the model prediction. We describe the mathematics behind these methods, give examples of their use in medical imaging, and compare them against one another. We summarize several published toolkits for model interpretation specific to medical imaging applications, cover limitations of current model interpretation methods, provide recommendations for DL practitioners looking to incorporate model interpretation into their task, and offer general discussion on the importance of model interpretation in medical imaging contexts.

High-frequency quantitative ultrasound is a potential non-invasive source of imaging cell-tissue scale biomarkers for major diseases such as heart disease, cancer, and preterm birth. However, one of the barriers to developing such biomarkers is that it is labor-intensive to compare quantitative ultrasound images to optical images of the tissue structure. We have previously developed a multiscale imaging system that can obtain registered qualitative ultrasound and optical images, but there are further technical challenges to obtaining quantitative data: System-specific details of obtaining and processing data with Verasonics high-frequency transducers; the need for high-frequency reference phantoms; and off-axis clutter from imaging above a glass coverslip. This paper provides a characterization of the Verasonics ultrasound system with the 18.5 MHz L22-14v and 28.5 MHz L38-22v transducers, describes the construction of high-frequency reference phantoms, and details methods for reducing off-axis clutter. The paper features a demonstration multiscale image of a wild type mouse mammary gland that incorporates quantitative ultrasound with both transducers and second harmonic generation microscopy. These advances demonstrate a way to obtain, on a single system with a cohesive and integrated pipeline, quantitative ultrasound data that is correlated with optical imaging without the need for extensive sample preparation.

Infants admitted to the neonatal intensive care unit (NICU) often suffer from multifaceted pulmonary morbidities that are not well understood. Ultrashort echo time (UTE) magnetic resonance imaging (MRI) is a promising technique for pulmonary imaging in this population without requiring exposure to ionizing radiation. The aims of this study were to investigate the effect of neonatal pulmonary disease on R-2* and tissue density and to utilize numerical simulations to evaluate the effect of different alveolar structures on predicted R-2*.This was a prospective study, in which 17 neonatal human subjects (five control, seven with bronchopulmonary dysplasia [BPD], five with congenital diaphragmatic hernia [CDH]) were enrolled. Twelve subjects were male and five were female, with postmenstrual age (PMA) at MRI of 39.7 +/- 4.7 weeks. A 1.5T/multiecho three-dimensional UTE MRI was used. Pulmonary R-2* and tissue density were compared across disease groups over the whole lung and regionally. A spherical shell alveolar model was used to predict the expected R-2* over a range of tissue densities and tissue susceptibilities. Tests for significantly different mean R-2* and tissue densities across disease groups were evaluated using analysis of variance, with subsequent pairwise group comparisons performed using t tests. Lung tissue density was lower in the ipsilateral lung in CDH compared to both controls and BPD patients (both p < 0.05), while only the contralateral lung in CDH (CDHc) had higher whole-lung R-2* than both controls and BPD (both p < 0.05). R-2* differences were significant between controls and CDHc within all tissue density ranges (all p < 0.05) with the exception of the 80%-90% range (p = 0.17). Simulations predicted an inverse relationship between alveolar tissue density and R-2* that matches empirical human data. Alveolar wall thickness had no effect on R-2* independent of density (p = 1). The inverse relationship between R-2* and tissue density is influenced by the presence of disease globally and regionally in neonates with BPD and CDH in the NICU.Level of Evidence 2.Technical Efficacy Stage 2.