Effects of escitalopram on synaptic density in the healthy human brain: a randomized controlled trial.

Selective serotonin reuptake inhibitors (SSRIs) are widely used for treating neuropsychiatric disorders. However, the exact mechanism of action and why effects can take several weeks to manifest is not clear. The hypothesis of neuroplasticity is supported by preclinical studies, but the evidence in humans is limited.

Stress Hormone Dynamics Are Coupled to Brain Serotonin 4 Receptor Availability in Unmedicated Patients With Major Depressive Disorder: A NeuroPharm Study.

Background: A prominent finding in major depressive disorder (MDD) is distorted stress hormone dynamics, which is regulated by serotonergic brain signaling. An interesting feature of the cerebral serotonin system is the serotonin 4 receptor (5-HT4R), which is lower in depressed relative to healthy individuals and also has been highlighted as a promising novel antidepressant target. Here, we test the novel hypothesis that brain 5-HT4R availability in untreated patients with MDD is correlated with cortisol dynamics, indexed by the cortisol awakening response (CAR).

Association of apolipoprotein M and sphingosine-1-phosphate with brown adipose tissue after cold exposure in humans.

The HDL-associated apolipoprotein M (apoM) and its ligand sphingosine-1-phosphate (S1P) may control energy metabolism. ApoM deficiency in mice is associated with increased vascular permeability, brown adipose tissue (BAT) mass and activity, and protection against obesity. In the current study, we explored the connection between plasma apoM/S1P levels and parameters of BAT as measured via F-FDG PET/CT after cold exposure in humans.

Four weeks treatment with the GLP-1 receptor analogue liraglutide lowers liver fat and concomitantly circulating glucagon in individuals with overweight.

We investigated the effect of pharmacologically induced weight loss on markers of glucagon resistance in individuals with overweight during treatment with the glucagon-like peptide-1 receptor agonist liraglutide. We performed an open-label study in 14 men with overweight (age 38 ± 11 years, BMI 32 ± 4 kg/m) without simultaneously diabetes. Subjects were treated with liraglutide, initiated and titrated with 0.

Correction: Christensen et al. Impact of [F]FDG-PET and [F]FLT-PET-Parameters in Patients with Suspected Relapse of Irradiated Lung Cancer. 2021, , 279.

In the original publication [...

Characterisation of Children's Head Motion for Magnetic Resonance Imaging With and Without General Anaesthesia.

Head motion is one of the major reasons for artefacts in Magnetic Resonance Imaging (MRI), which is especially challenging for children who are often intimidated by the dimensions of the MR scanner. In order to optimise the MRI acquisition for children in the clinical setting, insights into children's motion patterns are essential. In this work, we analyse motion data from 61 paediatric patients.

Dorsal striatal dopamine induces fronto-cortical hypoactivity and attenuates anxiety and compulsive behaviors in rats.

Dorsal striatal dopamine transmission engages the cortico-striato-thalamo-cortical (CSTC) circuit, which is implicated in many neuropsychiatric diseases, including obsessive-compulsive disorder (OCD). Yet it is unknown if dorsal striatal dopamine hyperactivity is the cause or consequence of changes elsewhere in the CSTC circuit. Classical pharmacological and neurotoxic manipulations of the CSTC and other brain circuits suffer from various drawbacks related to off-target effects and adaptive changes.

Impact of [F]FDG-PET and [F]FLT-PET-Parameters in Patients with Suspected Relapse of Irradiated Lung Cancer.

Radiation-induced changes may cause a non-malignant high 2-deoxy-2-[F]fluoro-d-glucose (FDG)-uptake. The 3'-deoxy-3'-[F]fluorothymidine (FLT)-PET/CT performs better in the differential diagnosis of inflammatory changes and lung lesions with a higher specificity than FDG-PET/CT. We investigated the association between post-radiotherapy FDG-PET-parameters, FLT-PET-parameters, and outcome.

A high-resolution in vivo atlas of the human brain's benzodiazepine binding site of GABA receptors.

Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human brain and plays a key role in several brain functions and neuropsychiatric disorders such as anxiety, epilepsy, and depression. For decades, several in vivo and ex vivo techniques have been used to highlight the mechanisms of the GABA system, however, no studies have currently combined the techniques to create a high-resolution multimodal view of the GABA system. Here, we present a quantitative high-resolution in vivo atlas of the human brain benzodiazepine receptor sites (BZR) located on postsynaptic ionotropic GABA receptors (GABARs), generated on the basis of in vivo [C]flumazenil Positron Emission Tomography (PET) data.

Parkinson patients have a presynaptic serotonergic deficit: A dynamic deep brain stimulation PET study.

Patients with Parkinson's disease (PD) often suffer from non-motor symptoms, which may be caused by serotonergic dysfunction. Apart from alleviating the motor symptoms, Deep Brain Stimulation (DBS) in the subthalamic nucleus (STN) may also influence non-motor symptoms. The aim of this study is to investigate how turning DBS off affects the serotonergic system.

F-FLT PET/CT Adds Value to F-FDG PET/CT for Diagnosing Relapse After Definitive Radiotherapy in Patients with Lung Cancer: Results of a Prospective Clinical Trial.

Diagnosing relapse after radiotherapy for lung cancer is challenging. The specificity of both CT and F-FDG PET/CT is low because of radiation-induced changes. 3'-deoxy-3'-F-fluorothymidine (F-FLT) PET has previously demonstrated higher specificity for malignancy than F-FDG PET.

Visual stimuli induce serotonin release in occipital cortex: A simultaneous positron emission tomography/magnetic resonance imaging study.

Endogenous serotonin (5-HT) release can be measured noninvasively using positron emission tomography (PET) imaging in combination with certain serotonergic radiotracers. This allows us to investigate effects of pharmacological and nonpharmacological interventions on brain 5-HT levels in living humans. Here, we study the neural responses to a visual stimulus using simultaneous PET/MRI.

No effects of a 6-week intervention with a glucagon-like peptide-1 receptor agonist on pancreatic volume and oedema in obese men without diabetes.

Aim: To investigate the effect of a glucagon-like peptide-1 receptor agonist (GLP-1RA), liraglutide, on pancreatic volume, oedema, cellularity and DNA synthesis in humans.

Materials And Methods: We performed an open-label study in 14 obese men (age 38 ± 11 years, body mass index 32 ± 4 kg/m ) without diabetes. Subjects were examined at baseline, during titration (week 4) of liraglutide towards 3.

Guidelines for the content and format of PET brain data in publications and archives: A consensus paper.

It is a growing concern that outcomes of neuroimaging studies often cannot be replicated. To counteract this, the magnetic resonance (MR) neuroimaging community has promoted acquisition standards and created data sharing platforms, based on a consensus on how to organize and share MR neuroimaging data. Here, we take a similar approach to positron emission tomography (PET) data.

F-fluorothymidine (FLT)-PET and diffusion-weighted MRI for early response evaluation in patients with small cell lung cancer: a pilot study.

Background: Small cell lung cancer (SCLC) is an aggressive cancer often presenting in an advanced stage and prognosis is poor. Early response evaluation may have impact on the treatment strategy.

Aim: We evaluated F-fluorothymidine-(FLT)-PET/diffusion-weighted-(DW)-MRI early after treatment start to describe biological changes during therapy, the potential of early response evaluation, and the added value of FLT-PET/DW-MRI.

Human biodistribution and radiation dosimetry of the 5-HT receptor agonist Cimbi-36 labeled with carbon-11 in two positions.

Background: Cimbi-36 can be C-labeled to form an agonist radioligand used for positron emission tomography (PET) imaging of the 5-HT receptor in the brain. In its non-labeled form (25B-NBOMe), it is used as a recreational drug that can lead to severe adverse effects, in some cases, with fatal outcome. We investigated human biodistribution and radiation dosimetry of the radioligand with two different radiolabeling positions.

Automatic delineation of brain regions on MRI and PET images from the pig.

Background: The increasing use of the pig as a research model in neuroimaging requires standardized processing tools. For example, extraction of regional dynamic time series from brain PET images requires parcellation procedures that benefit from being automated.

Comparison With Existing Methods: Manual inter-modality spatial normalization to a MRI atlas is operator-dependent, time-consuming, and can be inaccurate with lack of cortical radiotracer binding or skull uptake.

Reproducibility of MR-Based Attenuation Maps in PET/MRI and the Impact on PET Quantification in Lung Cancer.

Quantitative PET/MRI is dependent on reliable and reproducible MR-based attenuation correction (MR-AC). In this study, we evaluated the quality of current vendor-provided thoracic MR-AC maps and further investigated the reproducibility of their impact on F-FDG PET quantification in patients with non-small cell lung cancer. Eleven patients with inoperable non-small cell lung cancer underwent 2-5 thoracic PET/MRI scan-rescan examinations within 22 d.

Low 5-HT receptor binding in the migraine brain: A PET study.

Background The pathophysiology of migraine may involve dysfunction of serotonergic signaling. In particular, the 5-HT receptor is considered a key player due to the efficacy of 5-HT receptor agonists for treatment of migraine attacks. Aim To examine the cerebral 5-HT receptor binding in interictal migraine patients without aura compared to controls.

Cerebral serotonin release correlates with [C]AZ10419369 PET measures of 5-HT receptor binding in the pig brain.

Positron emission tomography (PET) can, when used with appropriate radioligands, non-invasively capture temporal and spatial information about acute changes in brain neurotransmitter systems. We here evaluate the 5-HT receptor partial agonist PET radioligand, [C]AZ10419369, for its sensitivity to detect changes in endogenous cerebral serotonin levels, as induced by different pharmacological challenges. To enable a direct translation of PET imaging data to changes in brain serotonin levels, we compared the [C]AZ10419369 PET signal in the pig brain to simultaneous measurements of extracellular serotonin levels with microdialysis after various acute interventions (saline, escitalopram, fenfluramine).

Testosterone levels in healthy men correlate negatively with serotonin 4 receptor binding.

The serotonergic system integrates sex steroid information and plays a central role in mood and stress regulation, cognition, appetite and sleep. This interplay may be critical for likelihood of developing depressive episodes, at least in a subgroup of sensitive individuals. The serotonin 4 receptor (5-HTR) indexes central serotonergic tonus, which may be related to endogenous sex-steroid levels in the mentally healthy state even though this remains elusive.

Optimized MLAA for quantitative non-TOF PET/MR of the brain.

For quantitative tracer distribution in positron emission tomography, attenuation correction is essential. In a hybrid PET/CT system the CT images serve as a basis for generation of the attenuation map, but in PET/MR, the MR images do not have a similarly simple relationship with the attenuation map. Hence attenuation correction in PET/MR systems is more challenging.

Cross-calibration of the Siemens mMR: easily acquired accurate PET phantom measurements, long-term stability and reproducibility.

Background: We present a quick and easy method to perform quantitatively accurate PET scans of typical water-filled PET plastic shell phantoms on the Siemens Biograph mMR PET/MR system. We perform regular cross-calibrations (Xcal) of our PET systems, including the PET/MR, using a Siemens mCT water phantom.

Long-term Stability: The mMR calibration stability was evaluated over a 3-year period where 54 cross-calibrations were acquired, showing that the mMR on average underestimated the concentration by 16 %, consistently due to the use of MR-based μ-maps.