Suspected recurrence of brain metastases after focused high dose radiotherapy: can [F]FET- PET overcome diagnostic uncertainties?

Background: After focused high dose radiotherapy of brain metastases, differentiation between tumor recurrence and radiation-induced lesions by conventional MRI is challenging. This study investigates the usefulness of dynamic O-(2-F-Fluoroethyl)-L-Tyrosine positron emission tomography (F-FET PET) in patients with MRI-based suspicion of tumor recurrence after focused high dose radiotherapy of brain metastases.

Methods: Twenty-two patients with 34 brain metastases (median age 61.

Predicting Regional Pattern of Longitudinal β-Amyloid Accumulation by Baseline PET.

Knowledge about spatial and temporal patterns of β-amyloid (Aβ) accumulation is essential for understanding Alzheimer disease (AD) and for design of antiamyloid drug trials. Here, we tested whether the regional pattern of longitudinal Aβ accumulation can be predicted by baseline amyloid PET. Baseline and 2-y follow-up F-florbetapir PET data from 58 patients with incipient and manifest dementia due to AD were analyzed.

[F]FDG PET accurately differentiates infected and non-infected non-unions after fracture fixation.

Purpose: Complete fracture healing is crucial for good patient outcomes. A major complication in the treatment of fractures is non-union. The pathogenesis of non-unions is not always clear, although implant-associated infections play a significant role, especially after surgical treatment of open fractures.

Cerebral Glucose Metabolism and Dopaminergic Function in Patients with Corticobasal Syndrome.

Background And Purpose: The corticobasal syndrome (CBS) is a clinical diagnosis that comprises a group of rare neurodegenerative diseases manifesting in movement disorder and cognitive impairment. While diagnosis is based upon clinical criteria, there have been a number of molecular imaging studies, albeit in rather small cohorts. Therefore, we investigated the pattern of cerebral glucose metabolism, as well as dopamine transporter (DAT) availability in a large and clinically well-defined cohort.

Prevalence of Amyloid Positron Emission Tomographic Positivity in Poststroke Mild Cognitive Impairment.

Background And Purpose: Mild cognitive impairment (MCI) is common after stroke and associated with poor outcome. However, the mechanisms underlying poststroke MCI (PS-MCI) are insufficiently understood. We performed amyloid-β positron emission tomography (PET) in a prospective cohort of stroke survivors to determine the role of amyloid pathology in PS-MCI.

Applied multimodal diagnostics in a case of presenile dementia.

Background: Alzheimer's disease (AD) is the most common cause of dementia in the elderly. The possibility of disease-modifying strategies has evoked a need for early and accurate diagnosis. To improve the accuracy of the clinical diagnosis of AD, biomarkers like cerebrospinal fluid (CSF) and neuroimaging techniques like magnetic resonance imaging (MRI) and positron emission tomography (PET) have been incorporated into the diagnostic guidelines of AD.

Monitoring of Tumor Growth with [(18)F]-FET PET in a Mouse Model of Glioblastoma: SUV Measurements and Volumetric Approaches.

Noninvasive tumor growth monitoring is of particular interest for the evaluation of experimental glioma therapies. This study investigates the potential of positron emission tomography (PET) using O-(2-(18)F-fluoroethyl)-L-tyrosine ([(18)F]-FET) to determine tumor growth in a murine glioblastoma (GBM) model-including estimation of the biological tumor volume (BTV), which has hitherto not been investigated in the pre-clinical context. Fifteen GBM-bearing mice (GL261) and six control mice (shams) were investigated during 5 weeks by PET followed by autoradiographic and histological assessments.

Impact of MRI-based Segmentation Artifacts on Amyloid- and FDG-PET Quantitation.

Introduction: Magnet resonance image (MRI)-based segmentations are widely used for clinical brain research, especially in conjunction with positron-emission-tomography (PET). Although artifacts due to segmentation errors arise commonly, the impact of these artifacts on PET quantitation has not yet been investigated systematically. Therefore, the aim of this study was to assess the effect of segmentation errors on [(18)F]-AV45 and [(18)F]-FDG PET quantitation, with and without correction for partial volume effects (PVE).

Hypometabolism in Brain of Cognitively Normal Patients with Depressive Symptoms is Accompanied by Atrophy-Related Partial Volume Effects.

Late life depression (LLD) even in subsyndromal stages shows high conversion rates from cognitively normal (CN) to mild cognitive impairment (MCI). Results of [(18)F]-fluorodesoxyglucose positron-emission-tomography (FDG-PET) were inconsistent in LLD patients, whereas atrophy was repeatedly described. Therefore, we set out to investigate FDG metabolism and the effect of atrophy correction (PVEC) in geriatric CN patients with depressive symptoms.

sTREM2 cerebrospinal fluid levels are a potential biomarker for microglia activity in early-stage Alzheimer's disease and associate with neuronal injury markers.

TREM2 is an innate immune receptor expressed on the surface of microglia. Loss-of-function mutations of TREM2 are associated with increased risk of Alzheimer's disease (AD). TREM2 is a type-1 protein with an ectodomain that is proteolytically cleaved and released into the extracellular space as a soluble variant (sTREM2), which can be measured in the cerebrospinal fluid (CSF).

Small-Animal PET Imaging of Tau Pathology with 18F-THK5117 in 2 Transgenic Mouse Models.

Abnormal accumulation of tau aggregates in the brain is one of the hallmarks of Alzheimer disease neuropathology. We visualized tau deposition in vivo with the previously developed 2-arylquinoline derivative (18)F-THK5117 using small-animal PET in conjunction with autoradiography and immunohistochemistry gold standard assessment in 2 transgenic mouse models expressing hyperphosphorylated tau. Small-animal PET recordings were obtained in groups of P301S (n = 11) and biGT mice (n = 16) of different ages, with age-matched wild-type (WT) serving as controls.

Glial Activation and Glucose Metabolism in a Transgenic Amyloid Mouse Model: A Triple-Tracer PET Study.

Unlabelled: Amyloid imaging by small-animal PET in models of Alzheimer disease (AD) offers the possibility to track amyloidogenesis and brain energy metabolism. Because microglial activation is thought to contribute to AD pathology, we undertook a triple-tracer small-animal PET study to assess microglial activation and glucose metabolism in association with amyloid plaque load in a transgenic AD mouse model.

Methods: Groups of PS2APP and C57BL/6 wild-type mice of various ages were examined by small-animal PET.

Early static (18)F-FET-PET scans have a higher accuracy for glioma grading than the standard 20-40 min scans.

Purpose: Current guidelines for glioma imaging by positron emission tomography (PET) using the amino acid analogue O-(2-[(18)F]fluoroethyl)-L-tyrosine ((18)F-FET) recommend image acquisition from 20-40 min post injection (p.i.).

Mapping 3-year changes in gray matter and metabolism in Aβ-positive nondemented subjects.

Gray matter (GM) atrophy and brain glucose hypometabolism are already detected in the predementia stages of Alzheimer's disease (AD), but the regional and longitudinal associations between the two are not well understood. Here, we analyzed the patterns of longitudinal atrophy (magnetic resonance imaging [MRI]) and (18)F-Fluorodeoxyglucose-positron emission tomography ([18F]FDG-PET) metabolism decline in 40 cognitively healthy control (HC) and 52 mildly impaired (mild cognitive impairment [MCI]) subjects during 3 years. Based on cerebrospinal fluid and brain amyloid-PET, the subjects were divided into amyloid-beta (Aβ)- and Aβ+ subgroups.

Cross-sectional comparison of small animal [18F]-florbetaben amyloid-PET between transgenic AD mouse models.

We aimed to compare [18F]-florbetaben PET imaging in four transgenic mouse strains modelling Alzheimer's disease (AD), with the main focus on APPswe/PS2 mice and C57Bl/6 mice serving as controls (WT). A consistent PET protocol (N = 82 PET scans) was used, with cortical standardized uptake value ratio (SUVR) relative to cerebellum as the endpoint. We correlated methoxy-X04 staining of β-amyloid with PET results, and undertook ex vivo autoradiography for further validation of a partial volume effect correction (PVEC) of PET data.

Depressive symptoms accelerate cognitive decline in amyloid-positive MCI patients.

Purpose: Late-life depression even in subsyndromal stages is strongly associated with Alzheimer's disease (AD). Furthermore, brain amyloidosis is an early biomarker in subjects who subsequently suffer from AD and can be sensitively detected by amyloid PET. Therefore, we aimed to compare amyloid load and glucose metabolism in subsyndromally depressed subjects with mild cognitive impairment (MCI).

Improved longitudinal [(18)F]-AV45 amyloid PET by white matter reference and VOI-based partial volume effect correction.

Amyloid positron-emission-tomography (PET) offers an important research and diagnostic tool for investigating Alzheimer's disease (AD). The majority of amyloid PET studies have used the cerebellum as a reference region, and clinical studies have not accounted for atrophy-based partial volume effects (PVE). Longitudinal studies using cerebellum as reference tissue have revealed only small mean increases and high inter-subject variability in amyloid binding.

Bis-NHC chelate complexes of nickel(0) and platinum(0).

For a long time d(10)-ML2 fragments have been known for their potential to activate unreactive bonds by oxidative addition. In the development of more active species, two approaches have proven successful: the use of strong σ-donating ligands leading to electron-rich metal centers and the employment of chelating ligands resulting in a bent coordination geometry. Combining these two strategies, we synthesized bis-NHC chelate complexes of nickel(0) and platinum(0).

Reduced FDG-PET brain metabolism and executive function predict clinical progression in elderly healthy subjects.

Brain changes reminiscent of Alzheimer disease (AD) have been previously reported in a substantial portion of elderly cognitive healthy (HC) subjects. The major aim was to evaluate the accuracy of MRI assessed regional gray matter (GM) volume, 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), and neuropsychological test scores to identify those HC subjects who subsequently convert to mild cognitive impairment (MCI) or AD dementia. We obtained in 54 healthy control (HC) subjects a priori defined region of interest (ROI) values of medial temporal and parietal FDG-PET and medial temporal GM volume.

Impact of partial volume effect correction on cerebral β-amyloid imaging in APP-Swe mice using [(18)F]-florbetaben PET.

We previously investigated the progression of β-amyloid deposition in brain of mice over-expressing amyloid-precursor protein (APP-Swe), a model of Alzheimer's disease (AD), in a longitudinal PET study with the novel β-amyloid tracer [(18)F]-florbetaben. There were certain discrepancies between PET and autoradiographic findings, which seemed to arise from partial volume effects (PVE). Since this phenomenon can lead to bias, most especially in the quantitation of brain microPET studies of mice, we aimed in the present study to investigate the magnitude of PVE on [(18)F]-florbetaben quantitation in murine brain, and to establish and validate a useful correction method (PVEC).

Longitudinal assessment of cerebral β-amyloid deposition in mice overexpressing Swedish mutant β-amyloid precursor protein using 18F-florbetaben PET.

Unlabelled: The progression of β-amyloid deposition in the brains of mice overexpressing Swedish mutant β-amyloid precursor protein (APP-Swe), a model of Alzheimer disease (AD), was investigated in a longitudinal PET study using the novel β-amyloid tracer (18)F-florbetaben.

Methods: Groups of APP-Swe and age-matched wild-type (WT) mice (age range, 10-20 mo) were investigated. Dynamic emission recordings were acquired with a small-animal PET scanner during 90 min after the administration of (18)F-florbetaben (9 MBq, intravenously).