Effects of dietary tryptophan and phenylalanine-tyrosine depletion on phasic alertness in healthy adults - A pilot study.

Background: The synthesis of the neurotransmitters serotonin (5-HT) and dopamine (DA) in the brain can be directly altered by dietary manipulation of their relevant precursor amino acids (AA). There is evidence that altered serotonergic and dopaminergic neurotransmission are both associated with impaired attentional control. Specifically, phasic alertness is one specific aspect of attention that has been linked to changes in 5-HT and DA availability in different neurocircuitries related to attentional processes.

Volumetric assessment of recurrent or progressive gliomas: comparison between F-DOPA PET and perfusion-weighted MRI.

Purpose: To compare the diagnostic information obtained with 6-[(18)F]-fluoro-L-3,4-dihydroxyphenylalanine (F-DOPA) PET and relative cerebral blood volume (rCBV) maps in recurrent or progressive glioma.

Methods: All patients with recurrent or progressive glioma referred for F-DOPA imaging at our institution between May 2010 and May 2014 were retrospectively included, provided that macroscopic disease was visible on conventional MRI images and that rCBV maps were available for comparison. The final analysis included 50 paired studies (44 patients).

Improved nTMS- and DTI-derived CST tractography through anatomical ROI seeding on anterior pontine level compared to internal capsule.

Imaging of the course of the corticospinal tract (CST) by diffusion tensor imaging (DTI) is useful for function-preserving tumour surgery. The integration of functional localizer data into tracking algorithms offers to establish a direct structure-function relationship in DTI data. However, alterations of MRI signals in and adjacent to brain tumours often lead to spurious tracking results.

The usefulness of dynamic O-(2-18F-fluoroethyl)-L-tyrosine PET in the clinical evaluation of brain tumors in children and adolescents.

Unlabelled: Experience regarding O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) PET in children and adolescents with brain tumors is limited.

Methods: Sixty-nine (18)F-FET PET scans of 48 children and adolescents (median age, 13 y; range, 1-18 y) were analyzed retrospectively. Twenty-six scans to assess newly diagnosed cerebral lesions, 24 scans for diagnosing tumor progression or recurrence, 8 scans for monitoring of chemotherapy effects, and 11 scans for the detection of residual tumor after resection were obtained.

Applications of PET imaging of neurological tumors with radiolabeled amino acids.

Routine diagnostics and treatment monitoring of brain tumors is usually based on contrast-enhanced magnetic resonance imaging (MRI). However, the capacity of structural MRI to differentiate neoplastic tissue from non-specific treatment changes may be limited especially after therapeutic interventions such as neurosurgical resection, radio- and chemotherapy. Metabolic imaging using PET may provide relevant additional information on tumor metabolism, which allows for more accurate diagnostics especially in clinically equivocal situations.

Diagnosis of pseudoprogression in patients with glioblastoma using O-(2-[18F]fluoroethyl)-L-tyrosine PET.

Purpose: The follow-up of glioblastoma patients after radiochemotherapy with conventional MRI can be difficult since reactive alterations to the blood-brain barrier with contrast enhancement may mimic tumour progression (i.e. pseudoprogression, PsP).

Uptake and tracer kinetics of O-(2-(18)F-fluoroethyl)-L-tyrosine in meningiomas: preliminary results.

Purpose: O-(2-[(18)F]Fluoroethyl)-L-tyrosine ((18)F-FET) is a well-established PET tracer for the imaging of cerebral gliomas, but little is known about (18)F-FET uptake in meningiomas. The aim of this study was to explore (18)F-FET kinetics and tumour-to-background contrast in meningiomas of various histologies.

Methods: A group of 24 patients with suspected cerebral meningioma on MRI/CT had an additional dynamic (18)F-FET PET scan prior to surgery.

Isomers of 4-[18F]fluoro-proline: radiosynthesis, biological evaluation and results in humans using PET.

Proline and hydroxyproline represent major constituents of mammalian structural proteins, especially of collagen. An efficient radiosynthesis of the (18)F-labeled proline derivatives cis-/trans-4-[(18)F]fluoro-L-proline was developed two decades ago with the aim to investigate various diseases with altered collagen synthesis using Positron-Emission- Tomography (PET). A number of studies have explored cis-4-[(18)F]fluoro-L-proline uptake in various pathologies associated with increased collagen formation and in neoplastic lesions, but so far the results have not been very promising.

(68)Ga-DOTATATE-positron emission tomography imaging in spinal meningioma.

Imaging with positron emission tomography (PET) and (68)Ga-DOTA peptides is a promising method in intracranial meningiomas. Especially in recurrent meningioma discrimination between scar tissue and recurrent tumor tissue in magnetic resonance imaging (MRI) is often difficult. We report the first case of (68)Ga-DOTATATE-PET/computed tomography (PET/CT) imaging in recurrent spinal meningioma.

Comparison of 18F-FET PET and perfusion-weighted MR imaging: a PET/MR imaging hybrid study in patients with brain tumors.

Unlabelled: PET using O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) provides important diagnostic information in addition to that from conventional MR imaging on tumor extent and activity of cerebral gliomas. Recent studies suggest that perfusion-weighted MR imaging (PWI), especially maps of regional cerebral blood volume (rCBV), may provide similar diagnostic information. In this study, we directly compared (18)F-FET PET and PWI in patients with brain tumors.

A margin-based analysis of the dosimetric impact of motion on step-and-shoot IMRT lung plans.

Purpose: Intrafraction motion during step-and-shoot (SNS) IMRT is known to affect the target dosimetry by a combination of dose blurring and interplay effects. These effects are typically managed by adding a margin around the target. A quantitative analysis was performed, assessing the relationship between target motion, margin size, and target dosimetry with the goal of introducing new margin recipes.

5-Aminolevulinic Acid and (18)F-FET-PET as Metabolic Imaging Tools for Surgery of a Recurrent Skull Base Meningioma.

Background Metabolic imaging technologies such as 5-aminolevulinic acid (ALA) fluorescence-guided resection and positron-emission tomography (PET) imaging have improved glioma surgery within the last decade. At present, these tools are not routinely used in meningioma surgery. Objective We present a case of a complex-shaped, recurrent skull base meningioma where 5-ALA fluorescence-guidance and (18)F-fluoroethyltyrosine (FET)-PET-imaging facilitated surgical resection.

No experimental evidence for sneaking in a west african cichlid fish with extremely long sperm.

Alternative reproductive tactics are widespread in fishes, increasing the potential for sperm competition. Sperm competition has enormous impact on both variation in sperm numbers and sperm size. In cichlids, the sperm competition risk is very divergent and longer sperm are usually interpreted as adaptation to sperm competition.

A virtual phantom library for the quantification of deformable image registration uncertainties in patients with cancers of the head and neck.

Purpose: Deformable image registration (DIR) is being used increasingly in various clinical applications. However, the underlying uncertainties of DIR are not well-understood and a comprehensive methodology has not been developed for assessing a range of interfraction anatomic changes during head and neck cancer radiotherapy. This study describes the development of a library of clinically relevant virtual phantoms for the purpose of aiding clinicians in the QA of DIR software.

Relationship of regional cerebral blood flow and kinetic behaviour of O-(2-(18)F-fluoroethyl)-L-tyrosine uptake in cerebral gliomas.

Objectives: O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) is an established tracer for brain tumour imaging. (18)F-FET kinetics in gliomas appear to have potential for tumour grading, but the mechanisms remain unclear. The aim of this study was to explore the relationship between regional cerebral blood flow (rCBF) as measured by arterial spin labelling MRI and the kinetic behaviour of (18)F-FET PET in cerebral gliomas.

Safety considerations for IGRT: Executive summary.

Radiation therapy is an effective cancer treatment that is constantly being transformed by technological innovation. Dedicated devices for fraction-by-fraction imaging and guidance within the treatment room have enabled image guided radiation therapy (IGRT) allowing clinicians to pursue highly conformal dose distributions, higher dose prescriptions, and shorter fractionation schedules. Capitalizing on IGRT-enabled accuracy and precision requires a strong link between IGRT practices and planning target volume (PTV) design.

Role of O-(2-18F-fluoroethyl)-L-tyrosine PET as a diagnostic tool for detection of malignant progression in patients with low-grade glioma.

Unlabelled: In patients with low-grade glioma (LGG) of World Health Organization (WHO) grade II, early detection of progression to WHO grade III or IV is of high clinical importance because the initiation of a specific treatment depends mainly on the WHO grade. In a significant number of patients with LGG, however, information on tumor activity and malignant progression cannot be obtained on the basis of clinical or conventional MR imaging findings only. We here investigated the potential of O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) PET to noninvasively detect malignant progression in patients with LGG.

Monitoring of radiochemotherapy in patients with glioblastoma using O-(2-¹⁸Fluoroethyl)-L-tyrosine positron emission tomography: is dynamic imaging helpful?

Monitoring of radiochemotherapy (RCX) in patients with glioblastoma is difficult because unspecific alterations in magnetic resonance imaging with contrast enhancement can mimic tumor progression. Changes in tumor to brain ratios (TBRs) in positron emission tomography (PET) using O-(2-¹⁸fluoroethyl)-l-tyrosine (¹⁸F-FET) after RCX with temozolomide of patients with glioblastoma have been shown to be valuable parameters to predict survival. The kinetic behavior of ¹⁸F-FET in the tumors is another promising parameter to analyze tumor metabolism.