Increasing striatal dopamine release through repeated bouts of theta burst transcranial magnetic stimulation of the left dorsolateral prefrontal cortex. A 18F-desmethoxyfallypride positron emission tomography study.

Introduction: Transcranial Magnetic Stimulation (TMS) can modulate fronto-striatal connectivity in the human brain. Here Positron Emission Tomography (PET) and neuro-navigated TMS were combined to investigate the dynamics of the fronto-striatal connectivity in the human brain. Employing 18F-DesmethoxyFallypride (DMFP) - a Dopamine receptor-antagonist - the release of endogenous dopamine in the striatum in response to time-spaced repeated bouts of excitatory, intermittent theta burst stimulation (iTBS) of the Left-Dorsolateral Prefrontal Cortex (L-DLPFC) was measured.

Tc‑labeled single-domain antibody for SPECT/CT assessment of HER2 expression in diverse cancer types.

Unlabelled: The expression status of human epidermal growth factor receptor 2 (HER2) in cancer predicts response to HER2-targeted therapy. Therefore, its accurate determination is of utmost importance. In recent years, there has been an increase in research on noninvasive techniques for molecular imaging, as this method offers the advantages of a more accurate determination of HER2 status without the need for multiple biopsies.

Sodium [F]Fluoride PET Can Efficiently Monitor In Vivo Atherosclerotic Plaque Calcification Progression and Treatment.

Given the high sensitivity and specificity of sodium [F]Fluoride (Na[F]F) for vascular calcifications and positive emerging data of vitamin K on vascular health, the aim of this study is to assess the ability of Na[F]F to monitor therapy and disease progression in a unitary atherosclerotic mouse model. ApoE mice were placed on a Western-type diet for 12-weeks and then split into four groups. The early stage atherosclerosis group received a chow diet for an additional 12-weeks, while the advanced atherosclerosis group continued the Western-type diet.

Evaluation of a Pretargeting Strategy for Molecular Imaging of the Prostate Stem Cell Antigen with a Single Chain Antibody.

In pretargeted radio-immunotherapy, the gradual administration of a non-radioactive tumor antigen-addressing antibody-construct and the subsequent application of a radioactive labeled, low molecular weight substance enable a highly effective and selective targeting of tumor tissue. We evaluated this concept in prostate stem cell antigen (PSCA)-positive cancers using the antigen-specific, biotinylated single chain antibody scFv(AM1)-P-BAP conjugated with tetrameric neutravidin. To visualize the systemic biodistribution, a radiolabeled biotin was injected to interact with scFv(AM1)-P-BAP/neutravidin conjugate.

Impact of Glutathione Modulation on Stability and Pharmacokinetic Profile of Redox-Sensitive Nanogels.

Nanoparticles degradable upon external stimuli combine pharmacokinetic features of both small molecules as well as large nanoparticles. However, despite promising preclinical results, several redox responsive disulphide-linked nanoparticles failed in clinical translation, mainly due to their unexpected in vivo behavior. Glutathione (GSH) is one of the most evaluated antioxidants responsible for disulfide degradation.

Multistage Passive and Active Delivery of Radiolabeled Nanogels for Superior Tumor Penetration Efficiency.

Development of nanosized drug delivery systems in cancer therapy is directed toward improving tumor selectivity and minimizing damages of healthy tissue. We introduce a delivery system with synergistic optimization and combination of passive and active targeting strategies. The approach is based on radiopeptide labeled redox sensitive hydrophilic nanogels, which exploit passive targeting by the enhanced permeability and retention effect while avoiding elimination by the mononuclear phagocyte system and fast hepatic and renal clearance.

The reconstruction algorithm used for [Ga]PSMA-HBED-CC PET/CT reconstruction significantly influences the number of detected lymph node metastases and coeliac ganglia.

Purpose: To investigate whether the numbers of lymph node metastases and coeliac ganglia delineated on [Ga]PSMA-HBED-CC PET/CT scans differ among datasets generated using different reconstruction algorithms.

Methods: Data were constructed using the BLOB-OS-TF, BLOB-OS and 3D-RAMLA algorithms. All reconstructions were assessed by two nuclear medicine physicians for the number of pelvic/paraaortal lymph node metastases as well the number of coeliac ganglia.

Metabolic tumour volume of anal carcinoma on (18)FDG PET/CT before combined radiochemotherapy is the only independant determinant of recurrence free survival.

Aim: to determine whether [(18)F]2-fluoro-2-deoxyglucose (FDG) positron emission tomography and X-ray computed tomography (PET/CT) findings and metabolic parameters before combined chemo- and radiotherapy (CRT) have a prognostic value in patients with anal carcinoma.

Materials And Methods: 45 patients with anal cancer who underwent pre-treatment FDG-PET/CT were included. Metabolic parameters, recurrence and anal carcinoma specific survival were analyzed.

Comparison of automatic versus manual procedures for the quantification of dopamine D2 receptor availability using I-123-IBZM-SPECT.

Introduction: I-123-IBZM-SPECT is often used to differentiate between idiopathic Parkinson's syndrome and atypical parkinsonian syndromes. The aim of this study was to compare three different procedures to quantify the receptor availability of striatal dopamine D2 receptors. (a) Manual quantification performed using individually adjusted volume of interests sets (mVoi).

Simulation-based partial volume correction for dopaminergic PET imaging: Impact of segmentation accuracy.

Aim: Partial volume correction (PVC) is an essential step for quantitative positron emission tomography (PET). In the present study, PVELab, a freely available software, is evaluated for PVC in (18)F-FDOPA brain-PET, with a special focus on the accuracy degradation introduced by various MR-based segmentation approaches.

Methods: Four PVC algorithms (M-PVC; MG-PVC; mMG-PVC; and R-PVC) were analyzed on simulated (18)F-FDOPA brain-PET images.

123I-iodobenzamide SPECT is not an independent predictor of dopaminergic responsiveness in patients with suspected atypical parkinsonian syndromes.

Unlabelled: The prediction of dopaminergic responsiveness in patients with parkinsonism is desirable for effective treatment strategies. We investigated whether striatal dopamine D2/D3 receptor (D2R) binding assessed by (123)I-iodobenzamide SPECT is an independent predictor of dopaminergic responsiveness in patients with parkinsonism.

Methods: Seventy-eight patients with clinically suspected atypical parkinsonian syndrome (APS) were prospectively recruited for imaging.

Quantitative myocardial perfusion-SPECT: algorithm-specific influence of reorientation on calculation of summed stress score.

Purpose: Myocardial perfusion SPECT (MPS) with software-assisted determination of summed stress score (SSS) is of established importance for diagnosis/therapy planning in coronary artery disease. Differences in contour finding suggest algorithm-specific influence on quantification if heart axes are chosen incorrectly. Thus, this study quantified the influence of heart-axis tilt on SSS calculation using Quantitative Perfusion SPECT and 4D-MSPECT.

Caffeine occupancy of human cerebral A1 adenosine receptors: in vivo quantification with 18F-CPFPX and PET.

Unlabelled: Caffeine is the neuroactive agent in coffee and tea and is a broadly consumed stimulant. It is a nonselective antagonist of the neuromodulator adenosine and, if applied in commonly consumed doses, evokes its stimulating effects through the blockade of adenosine receptors. (18)F-8-cyclopentyl-3-(3-fluoropropyl)-1-propylxanthine ((18)F-CPFPX) has been established as a highly selective and affine PET ligand for the A(1) adenosine receptor (A(1)AR).

[¹⁸F]FDG-PET is superior to [¹²³I]IBZM-SPECT for the differential diagnosis of parkinsonism.

Objective: Imaging of regional cerebral glucose metabolism with PET and striatal dopamine D2/D3 receptors (D2R) with SPECT improves the differential diagnosis of parkinsonism. We prospectively investigated 1) the diagnostic merits of these approaches in differentiating between Lewy body diseases (LBD; majority Parkinson disease [PD]) and atypical parkinsonian syndromes (APS); 2) the diagnostic value of [¹⁸F]fluorodeoxyglucose (FDG)-PET to differentiate among APS subgroups.

Methods: Ninety-five of 107 consecutive patients with clinically suspected APS referred for imaging were recruited.

Image quality and data quantification in dopamine transporter SPECT: advantage of 3-dimensional OSEM reconstruction?

Purpose: Reconstruction of striatal dopamine transporter (DAT) SPECT is commonly done by filtered back projection (FBP). We investigated if image reconstruction by 3-dimensional ordered-subset expectation maximization (3D-OSEM) with resolution recovery, which has recently become available for clinical routine, provides a relevant improvement.

Methods: I-FP-CIT SPECT studies of 18 patients with normal to severely decreased DAT binding were reconstructed by FBP, 2D-OSEM (without resolution recovery), and 3D-OSEM, each with 2 different filter settings, yielding 3 data set pairs of relatively low and high resolution and noise: FBP with seventh-order Butterworth filter [cutoff frequency, 0.

A phantom assessment of portable imaging and radio-guided surgery systems with technetium-99m and fluorine-18.

Aim: To perform a detailed analysis of the performance of mobile intraoperative imaging systems and gamma probes in a phantom set-up, and compare this with a conventional gamma camera.

Methods: Two separate experiments were performed. In the first, a modified Jaszczak phantom equipped with five (99m)Tc-filled hot spheres (0.

Dose-escalation using intensity-modulated radiotherapy for prostate cancer - evaluation of quality of life with and without (18)F-choline PET-CT detected simultaneous integrated boost.

Background: In comparison to the conventional whole-prostate dose escalation, an integrated boost to the macroscopic malignant lesion might potentially improve tumor control rates without increasing toxicity. Quality of life after radiotherapy (RT) with vs. without (18)F-choline PET-CT detected simultaneous integrated boost (SIB) was prospectively evaluated in this study.

Mesolimbic functional magnetic resonance imaging activations during reward anticipation correlate with reward-related ventral striatal dopamine release.

The dopaminergic mechanisms that control reward-motivated behavior are the subject of intense study, but it is yet unclear how, in humans, neural activity in mesolimbic reward-circuitry and its functional neuroimaging correlates are related to dopamine release. To address this question, we obtained functional magnetic resonance imaging (fMRI) measures of reward-related neural activity and [(11)C]raclopride positron emission tomography measures of dopamine release in the same human participants, while they performed a delayed monetary incentive task. Across the cohort, a positive correlation emerged between neural activity of the substantia nigra/ventral tegmental area (SN/VTA), the main origin of dopaminergic neurotransmission, during reward anticipation and reward-related [(11)C]raclopride displacement as an index of dopamine release in the ventral striatum, major target of SN/VTA dopamine neurons.

Quantification of left ventricular volumes and ejection fraction from gated 99mTc-MIBI SPECT: MRI validation of the EXINI heart software package.

Unlabelled: The aim of the study was to validate the accuracy of the EXINI heart software (EXINI) package in assessing left ventricular end-diastolic/systolic volumes (EDV, ESV) and ejection fraction (LVEF) from gated (99m)Tc-MIBI single-photon emission tomography (SPECT). Cardiac magnetic resonance imaging (cMRI) was used as reference. Furthermore, effects of perfusion defects and image quality in SPECT on correlation between gated SPECT and magnetic resonance imaging were investigated.

Gated myocardial perfusion SPECT: algorithm-specific influence of reorientation on calculation of left ventricular volumes and ejection fraction.

Unlabelled: Gated myocardial perfusion SPECT allows calculation of end-diastolic and end-systolic volumes (EDV and ESV, respectively) and left ventricular ejection fraction (LVEF). The quantification algorithms QGS (quantitative gated SPECT), 4D-MSPECT, and CARE heart show a good correlation with cardiac MRI. Nevertheless, differences in contour finding suggest algorithm-specific effects if heart axes vary.

Kinetic analyses of [123I]IBZM SPECT for quantification of striatal dopamine D2 receptor binding: a critical evaluation of the single-scan approach.

Background: Dopamine-D2 receptor imaging with single-photon emission computed tomography (SPECT) and [(123)I]IBZM is of great interest for basic and applied neurosciences. However, the use of kinetic analyses for quantification of dynamic [(123)I]IBZM SPECT and the validity of the commonly employed single-scan pseudo-equilibrium analysis (PsEA) have not been appropriately investigated. The present study addresses these shortcomings.

Sleep deprivation increases A1 adenosine receptor binding in the human brain: a positron emission tomography study.

It is currently hypothesized that adenosine is involved in the induction of sleep after prolonged wakefulness. This effect is partially reversed by the application of caffeine, which is a nonselective blocker of adenosine receptors. Here, we report that the most abundant and highly concentrated A1 subtype of cerebral adenosine receptors is upregulated after 24 h of sleep deprivation.

Test-retest stability of cerebral A1 adenosine receptor quantification using [18F]CPFPX and PET.

Purpose: The goal of the present study was to evaluate the reproducibility of cerebral A1 adenosine receptor (A1AR) quantification using [18F]CPFPX and PET in a test-retest design.

Methods: Eleven healthy volunteers were studied twice. Eight brain regions ranging from high to low receptor binding were examined.

Metabolism of the A1 adenosine receptor PET ligand [18F]CPFPX by CYP1A2: implications for bolus/infusion PET studies.

The A1 adenosine receptor positron emission tomography (PET) ligand 8-cyclopentyl-3-(3-[18F]fluoropropyl)-1-propylxanthine ([18F]CPFPX, ) undergoes a fast hepatic metabolism. An optimal design of PET quantitation approaches (e.g.