Quantitative brain [F]FDG PET beyond normal blood glucose levels.

Introduction SUV measurements from static brain [F]FDG PET acquisitions are a commonly used tool in preclinical research, providing a simple alternative for kinetic modelling, which requires complex and time-consuming dynamic acquisitions. However, SUV can be severely affected by the animal handling and preconditioning protocols, primarily by those that may induce changes in blood glucose levels (BGL). Here, we aimed at developing and investigating the feasibility of SUV-based approaches for a wide range of BGL far beyond normal values, and consequently, to develop and validate a new model to generate standardized and reproducible SUV measurements for any BGL.

Partial volume correction in longitudinal tau PET studies: is it really needed?

Background: [F]flortaucipir (FTP) tau PET quantification is known to be affected by non-specific binding in off-target regions. Although partial volume correction (PVC) techniques partially account for this effect, their inclusion may also introduce noise and variability into the quantification process. While the impact of these effects has been studied in cross-sectional designs, the benefits and drawbacks of PVC on longitudinal FTP studies is still under scrutiny.

F-florbetapir PET as a marker of myelin integrity across the Alzheimer's disease spectrum.

Purpose: Recent evidence suggests that PET imaging with amyloid-β (Aβ) tracers can be used to assess myelin integrity in cerebral white matter (WM). Alzheimer's disease (AD) is characterized by myelin changes that are believed to occur early in the disease course. Nevertheless, the extent to which demyelination, as measured with Aβ PET, contributes to AD progression remains unexplored.

Quantification of internal dosimetry in PET patients II: Individualized Monte Carlo-based dosimetry for [18F]fluorocholine PET.

Purpose: To obtain individualized internal doses with a Monte Carlo (MC) method in patients undergoing diagnostic [18F]FCH-PET studies and to compare such doses with the MIRD method calculations.

Methods: A patient cohort of 17 males were imaged after intravenous administration of a mean [18F]FCH activity of 244.3 MBq.

SimPET-An open online platform for the Monte Carlo simulation of realistic brain PET data. Validation for F-FDG scans.

Purpose: SimPET (www.sim-pet.org) is a free cloud-based platform for the generation of realistic brain positron emission tomography (PET) data.

A Systematic Review of PET Textural Analysis and Radiomics in Cancer.

Background: Although many works have supported the utility of PET radiomics, several authors have raised concerns over the robustness and replicability of the results. This study aimed to perform a systematic review on the topic of PET radiomics and the used methodologies.

Methods: PubMed was searched up to 15 October 2020.

3D Printed Tacrolimus Rectal Formulations Ameliorate Colitis in an Experimental Animal Model of Inflammatory Bowel Disease.

The aim of this study was to fabricate novel self-supporting tacrolimus suppositories using semisolid extrusion 3-dimensional printing (3DP) and to investigate their efficacy in an experimental model of inflammatory bowel disease. Blends of Gelucire 44/14 and coconut oil were employed as lipid excipients to obtain suppository formulations with self-emulsifying properties, which were then tested in a TNBS (2,4,6-trinitrobenzenesulfonic acid) induced rat colitis model. Disease activity was monitored using PET/CT medical imaging; maximum standardized uptake values (SUV), a measure of tissue radiotracer accumulation rate, together with body weight changes and histological assessments, were used as inflammatory indices to monitor treatment efficacy.

Is FDG-PET texture analysis related to intratumor biological heterogeneity in lung cancer?

Objectives: We aimed at investigating the origin of the correlations between tumor volume and F-FDG-PET texture indices in lung cancer.

Methods: Eighty-five consecutive patients with newly diagnosed non-small cell lung cancer (NSCLC) underwent a F-FDG-PET/CT scan before treatment. Seven phantom spheres uniformly filled with F-FDG, and covering a range of activities and volumes similar to that found in lung tumors, were also scanned.

Feasibility of Longitudinal Brain PET with Real-Time Arterial Input Function in Rats.

Purpose: Preclinical dynamic brain PET studies remain hampered by the limitations related to the measurement of the arterial input function (AIF). In this regard, the use of an arterial-venous shunt is a promising method for the generation of real-time AIFs, but its application in longitudinal studies is still impeded by the cumbersome surgeries and high failure rates. We studied the feasibility and reproducibility of double arterial-venous shunt strategies for conducting longitudinal PET studies with real-time AIFs in rats.

[F]-FMISO PET/MRI Imaging Shows Ischemic Tissue around Hematoma in Intracerebral Hemorrhage.

Intracerebral hemorrhage (ICH), being the most severe cerebrovascular disease, accounts for 10-15% of all strokes. Hematoma expansion is one of the most important factors associated with poor outcome in intracerebral hemorrhage (ICH). Several studies have suggested that an "ischemic penumbra" might arise when the hematoma has a large expansion, but clinical studies are inconclusive.

Intensity normalization methods in brain FDG-PET quantification.

Background: The lack of standardization of intensity normalization methods and its unknown effect on the quantification output is recognized as a major drawback for the harmonization of brain FDG-PET quantification protocols. The aim of this work is the ground truth-based evaluation of different intensity normalization methods on brain FDG-PET quantification output.

Methods: Realistic FDG-PET images were generated using Monte Carlo simulation from activity and attenuation maps directly derived from 25 healthy subjects (adding theoretical relative hypometabolisms on 6 regions of interest and for 5 hypometabolism levels).

PET study of ocular and blood pharmacokinetics of intravitreal bevacizumab and aflibercept in rats.

Intravitreal injections are the standard procedure in the treatment of retinal pathologies, such as the administration of the anti-VEGF antibodies in age-related macular degeneration. The aim of this study is to evaluate the intraocular and blood pharmacokinetics after an intravitreal injection of Zr-labelled bevacizumab and Zr-labelled aflibercept in Sprague-Dawley rats using Positron Emission Tomography. First, both antibodies were radiolabelled to zirconium-89 with a maximum specific activity of 15 Mbq/mg for bevacizumab and 10 Mbq/mg for aflibercept.

Quantification of internal dosimetry in PET patients: individualized Monte Carlo vs generic phantom-based calculations.

Purpose: The purpose of this work is to calculate individualized dose distributions in patients undergoing F-FDG PET/CT studies through a methodology based on full Monte Carlo (MC) simulations and PET/CT patient images, and to compare such values with those obtained by employing nonindividualized phantom-based methods.

Methods: We developed a MC-based methodology for individualized internal dose calculations, which relies on CT images (for organ segmentation and dose deposition), PET images (for organ segmentation and distributions of activities), and a biokinetic model (which works with information provided by PET and CT images) to obtain cumulated activities. The software vGATE version 8.

White matter hyperintensities are associated with subthreshold amyloid accumulation.

The association between white matter hyperintensities (WMH) and amyloid accumulation over time in cognitively normal, amyloid-negative elderly people remains largely unexplored. In order to study whether baseline WMH were associated with longitudinal subthreshold amyloid accumulation, 159 cognitively normal participants from the Alzheimer's Disease Neuroimaging Initiative who were amyloid-negative at baseline were examined. All the participants underwent a T1 and a Fluid-Attenuated Inversion Recovery MRI scan at baseline.

Evaluation of the therapeutic activity of melatonin and resveratrol in Inflammatory Bowel Disease: A longitudinal PET/CT study in an animal model.

Inflammatory Bowel Disease (IBD) is a group of chronic disorders of the gastrointestinal tract, which two main types are Crohn's disease and ulcerative colitis. Although conventional therapeutic strategies have demonstrated to be effective in the IBD treatment, it is necessary to incorporate novel therapeutic agents that target other mechanisms involved in the pathogenesis of the disease, such as oxidative stress. For this reason, the efficacy in vivo of two antioxidant compounds, melatonin and resveratrol, has been investigated in an animal model of TNBS (2, 4, 6-trinitrobenzenesulfonic acid) induced colitis.

Staging the cognitive continuum in prodromal Alzheimer's disease with episodic memory.

It is unclear whether episodic memory is an appropriate descriptor of the cognitive continuum in mild cognitive impairment (MCI). Here, we investigated the ability of episodic memory to track cognitive changes in patients with MCI with biomarker evidence of Alzheimer's disease (AD). We examined 387 MCI amyloid-positive subjects, cognitively staged as "early" or "late" on the basis of episodic memory impairment.

Prediction of Alzheimer's disease dementia with MRI beyond the short-term: Implications for the design of predictive models.

Magnetic resonance imaging (MRI) volumetric measures have become a standard tool for the detection of incipient Alzheimer's Disease (AD) dementia in mild cognitive impairment (MCI). Focused on providing an earlier and more accurate diagnosis, sophisticated MRI machine learning algorithms have been developed over the recent years, most of them learning their non-disease patterns from MCI that remained stable over 2-3 years. In this work, we analyzed whether these stable MCI over short-term periods are actually appropriate training examples of non-disease patterns.

Celia's encephalopathy and c.974dupG in BSCL2 gene: a hidden change in a known variant.

Celia's encephalopathy (progressive encephalopathy with/without lipodystrophy (PELD)) is a childhood neurodegenerative disorder with a fatal prognosis before the age of 10, due to the variant c.985C>T in the BSCL2 gene that causes a cryptic splicing site leading to skipping of exon 7. For years, different authors have reported cases of congenital generalized lipodystrophy due to the variant c.

Federalism, two-level games and the politics of abortion rights implementation in subnational Argentina.

The implementation of the 2012 Argentinean Supreme Court landmark ruling, which declared abortion legal in all cases of rape and established standards of implementation of lawful abortions at all levels of government, shows an uneven pattern of compliance by subnational governments throughout the country. Based on a case-study of the implementation of the Court's decision in the province of Salta, this article advances an explanation of mechanisms that can affect the definition and enforcement of abortion rights at the local level, in a federation. Drawing on Putnam's concept of two-level games, it argues that, at critical junctures, local authorities and especially strong governors with presidential aspirations, may have electoral incentives at the national level to comply at least partially with national laws and judicial decisions which are contrary to their own ideological preferences and their local political allegiances.

Dedicated breast PET value to evaluate BI-RADS 4 breast lesions.

Purpose: To evaluate the diagnostic value of dedicated breast PET (dbPET) parallel imaging in mammographically or sonographically detected BI-RADS 4 (Breast Imaging Reporting And Data Systems) lesions.

Materials And Methods: After institutional review board and patient approvals, 50 consecutive women with 60 BI-RADS 4 breast lesions were prospectively included in the study. All patients underwent Magnetic Resonance Imaging (MRI) and dbPET before biopsy and fusion of both MRI and dbPET images was performed to better locate corresponding lesions.

Longitudinal PET/CT evaluation of TNBS-induced inflammatory bowel disease rat model.

Inflammatory bowel disease (IBD) is a group of chronic disorders of the gastrointestinal tract, which two main types are Crohn's disease and ulcerative colitis. It has multifactorial etiologies, being essential the use of animal models and disease activity measures to develop new therapies. With this aim, the use of animal models in combination with non-invasive molecular imaging can play an important role in the development of new treatments.

Association of metreleptin treatment and dietary intervention with neurological outcomes in Celia's encephalopathy.

Celia's encephalopathy (progressive encephalopathy with/without lipodystrophy, PELD) is a recessive neurodegenerative disease that is fatal in childhood. It is caused by a c.985C>T variant in the BSCL2/seipin gene that results in an aberrant seipin protein.

Texture analysis of high-resolution dedicated breast F-FDG PET images correlates with immunohistochemical factors and subtype of breast cancer.

Purpose: This study aims to determine whether PET textural features measured with a new dedicated breast PET scanner reflect biological characteristics of breast tumors.

Methods: One hundred and thirty-nine breast tumors from 127 consecutive patients were included in this analysis. All of them underwent a F-FDG PET scan before treatment.

Preclinical PET Study of Intravitreal Injections.

Purpose: This work aimed at describing the time course of vitreous clearance through the use of positron emission tomography (PET) as a noninvasive tool for pharmacokinetic studies of intravitreal injection.

Methods: The pharmacokinetic profile of intravitreal injections of molecules labeled with 18Fluorine (18F) was evaluated in adult Sprague Dawley rats by using a dedicated small-animal PET/computed tomography scanner. Different conditions were studied: three molecules radiolabeled with 18F (18F-FDG, 18F-NaF, and 18F-Choline), three volumes of intravitreal injections (7, 4, and 2 μL), and absence or presence of eye inflammation (uveitis).