Deconvolution-based partial volume correction of PET images with parallel level set regularization.

The partial volume effect (PVE), caused by the limited spatial resolution of positron emission tomography (PET), degrades images both qualitatively and quantitatively. Anatomical information provided by magnetic resonance (MR) images has the potential to play an important role in partial volume correction (PVC) methods. Post-reconstruction MR-guided PVC methods typically use segmented MR tissue maps, and further, assume that PET activity distribution is uniform in each region, imposing considerable constraints through anatomical guidance.

In vivo hippocampal cornu ammonis 1-3 glutamatergic abnormalities are associated with temporal lobe epilepsy surgery outcomes.

Objective: Previous positron emission tomography (PET) studies using [ C]ABP688 show reduced metabotropic glutamate receptor type 5 (mGluR5) allosteric binding site availability in the epileptogenic hippocampus of mesial temporal lobe epilepsy (MTLE) patients. However, the link between mGluR5 abnormalities and postsurgical outcomes remains unclear. Here, we test whether reduced PET [ C]ABP688 binding in cornu ammonis (CA) sectors more vulnerable to glutamatergic excitotoxicity relates to surgical outcomes.

Large-scale mGluR5 network abnormalities linked to epilepsy duration in focal cortical dysplasia.

To determine the extent of metabotropic glutamate receptor type 5 (mGluR5) network abnormalities associated with focal cortical dysplasia (FCD), we performed graph theoretical analysis of [C]ABP688 PET binding potentials (BP), which allows for quantification of mGluR5 availability. Undirected graphs were constructed for the entire cortex in 17 FCD patients and 33 healthy controls using inter-regional similarity of [C]ABP688 BP. We assessed group differences in network integration between healthy controls and the ipsilateral and contralateral hemispheres of FCD patients.

Are dopamine receptor and transporter changes in Rett syndrome reflected in Mecp2-deficient mice?

We tested the claim that the dopaminergic dysfunction of Rett Syndrome (RTT) also occurs in Mecp2-deficient mice that serve as a model of the syndrome. We used positron emission tomography (PET) to image dopamine D receptors (DR) and transporters (DAT) in women with RTT and in Mecp2-deficient mice, and DR and DR density was measured in postmortem human tissue by autoradiography. Results showed 1) significantly reduced DR density in the striatum of women with RTT compared to control subjects.

Metabotropic Glutamate Receptor Type 5 (mGluR5) Cortical Abnormalities in Focal Cortical Dysplasia Identified In Vivo With [11C]ABP688 Positron-Emission Tomography (PET) Imaging.

Metabotropic glutamate receptor type 5 (mGluR5) abnormalities have been described in tissue resected from epilepsy patients with focal cortical dysplasia (FCD). To determine if these abnormalities could be identified in vivo, we investigated mGluR5 availability in 10 patients with focal epilepsy and an MRI diagnosis of FCD using positron-emission tomography (PET) and the radioligand [11C]ABP688. Partial volume corrected [11C]ABP688 binding potentials (BPND) were computed using the cerebellum as a reference region.

Characterization of age/sex and the regional distribution of mGluR5 availability in the healthy human brain measured by high-resolution [(11)C]ABP688 PET.

Purpose: Metabotropic glutamate receptor type 5 (mGluR5) is a G protein-coupled receptor that has been implicated in several psychiatric and neurological diseases. The radiopharmaceutical [(11)C]ABP688 allows for in vivo quantification of mGluR5 availability using positron emission tomography (PET). In this study, we aimed to detail the regional distribution of [(11)C]ABP688 binding potential (BPND) and the existence of age/sex effects in healthy individuals.

Mu Opioid Receptor Binding Correlates with Nicotine Dependence and Reward in Smokers.

The rewarding effects of nicotine are associated with activation of nicotine receptors. However, there is increasing evidence that the endogenous opioid system is involved in nicotine's rewarding effects. We employed PET imaging with [11C]carfentanil to test the hypotheses that acute cigarette smoking increases release of endogenous opioids in the human brain and that smokers have an upregulation of mu opioid receptors (MORs) when compared to nonsmokers.

An in vivo evaluation of cerebral cortical amyloid with [18F]flutemetamol using positron emission tomography compared with parietal biopsy samples in living normal pressure hydrocephalus patients.

Purpose: The primary objectives of this study were to assess the safety of [(18)F]flutemetamol injection and determine the level of association between the quantitative estimates of brain uptake of [(18)F]flutemetamol and the quantitative immunohistochemical (IHC) estimates of amyloid levels in cerebral cortex biopsies obtained during shunt placement in patients with normal pressure hydrocephalus (NPH).

Procedures: Parietal lobe biopsies were obtained from 12 subjects (mean (SD), 71 (8.1) years), during shunt placement for NPH.

Retrospective evaluation of the need of a redo surgery at the groin for the surgical treatment of varicose vein.

Background: Surgical treatment for varicose recurrence (STVR) involves removing all sources of reflux from the deep venous network to the superficial venous network. STVR is usually more complex and aggressive than first-line treatment by stripping, particularly for redo surgery at the groin (RSG). This retrospective study compared traditional STVR and a less aggressive surgical approach focusing on treatment of the varicose reservoir and avoiding RSG if possible.

Single photon emission computed tomography experience with (S)-5-[(123)I]iodo-3-(2-azetidinylmethoxy)pyridine in the living human brain of smokers and nonsmokers.

(S)-5-[(123)I]iodo-3-(2-azetidinylmethoxy)pyridine (5-[(123)I]IA), a novel potent radioligand for high-affinity alpha4beta2* neuronal nicotinic acetylcholine receptors (nAChRs), provides a means to evaluate the density and the distribution of nAChRs in the living human brain. We sought in healthy adult smokers and nonsmokers to (1) evaluate the safety, tolerability, and efficacy of 5-[(123)I]IA in an open nonblind trial and (2) to estimate the density and the distribution of alpha(4)beta(2)* nAChRs in the brain. Single photon emission computed tomography (SPECT) was performed for 5 h after the i.

Accurate event-driven motion compensation in high-resolution PET incorporating scattered and random events.

With continuing improvements in spatial resolution of positron emission tomography (PET) scanners, small patient movements during PET imaging become a significant source of resolution degradation. This work develops and investigates a comprehensive formalism for accurate motion-compensated reconstruction which at the same time is very feasible in the context of high-resolution PET. In particular, this paper proposes an effective method to incorporate presence of scattered and random coincidences in the context of motion (which is similarly applicable to various other motion correction schemes).

Design and implementation of an automated partial volume correction in PET: application to dopamine receptor quantification in the normal human striatum.

Unlabelled: The considerable effort and potential lack of reproducibility of human-driven PET quantification and partial volume correction (PVC) can be alleviated by use of atlas-based automatic analysis. The present study examined the application of a new algorithm designed to automatically define 3-dimensional regions of interest (ROIs) and their effect on dopamine receptor quantification in the normal human brain striatum, both without and with PVC.

Methods: A total of 90 healthy volunteers (age range, 18-46 y) received a single injection of (11)C-raclopride, and automatic segmentation of concomitant structural MR images was performed using a maximum-probability atlas in combination with a trained neural network.

System matrix modelling of externally tracked motion.

Background And Aim: In high-resolution emission tomography imaging, even small patient movements can considerably degrade image quality. The aim of this work was to develop a general approach to motion-corrected reconstruction of motion-contaminated data in the case of rigid motion (particularly brain imaging) which would be applicable to any PET scanner in the field, without specialized data-acquisition requirements.

Methods: Assuming the ability to externally track subject motion during scanning (e.

Mechanisms of dopaminergic and serotonergic neurotransmission in Tourette syndrome: clues from an in vivo neurochemistry study with PET.

Tourette syndrome (TS) is a neuropsychiatric disorder with childhood onset characterized by motor and phonic tics. Obsessive-compulsive disorder (OCD) is often concomitant with TS. Dysfunctional tonic and phasic dopamine (DA) and serotonin (5-HT) metabolism may play a role in the pathophysiology of TS.

Strategies for Motion Tracking and Correction in PET.

With the arrival of increasingly higher-resolution PET systems, small amounts of motion can cause significant blurring in the resulting images compared with the intrinsic resolution of the PET scanner. The authors review advanced correction methods for unwanted patient motion and for motion due to cardiac and respiratory cycles. A general theme in motion correction methods is the use of increasingly sophisticated software to make use of existing advanced hardware.

Partial Volume Correction Strategies in PET.

In the early days of PET, the partial volume effect (PVE) was identified as a serious factor affecting image quality and limiting the accuracy of quantitative analysis. Because of the limited spatial resolution of clinical PET systems, the images are blurred by the system response so that smaller objects appear larger. Although the total number of counts is preserved, they are distributed over a larger volume.

Increased occupancy of dopamine receptors in human striatum during cue-elicited cocaine craving.

In all, 19 research subjects, with current histories of frequent cocaine use, were exposed to cocaine-related cues to elicit drug craving. We measured the change of occupancy of dopamine at D2-like receptors with positron emission tomography (PET) and inferred a change of intrasynaptic dopamine (endogenous dopamine release), based on the displacement of radiotracer [(11)C]raclopride. Receptor occupancy by dopamine increased significantly in putamen of participants who reported cue-elicited craving compared to those who did not.

Positron emission tomography--a tool for identifying the effects of alcohol dependence on the brain.

To study alcohol's effects on the structure and function of the brain in living human beings, researchers can use various imaging techniques. Positron emission tomography (PET) is a functional imaging approach used to study the metabolism and physiology of the brain. PET studies have found that both acute and chronic alcohol ingestion alter blood flow and metabolism in various brain regions, including the frontal lobes and cerebellum.

Effect of partial volume correction on estimates of the influx and cerebral metabolism of 6-[(18)F]fluoro-L-dopa studied with PET in normal control and Parkinson's disease subjects.

The poor spatial resolution of positron emission tomography (PET) is a limiting factor in the accurate assay of physiological processes investigated by compartmental modeling of tracer uptake and metabolism in living human brain. The radioactivity concentration in a region-of-interest is consequently altered by loss of signal from that structure and contamination from adjacent brain regions, phenomena known as partial volume effects. We now apply an MRI-based algorithm to compensate for partial volume effects in the special case of compartmental modeling of the cerebral uptake of 6-[(18)F]fluoro-L-dopa (FDOPA), an exogenous substrate of dopa decarboxylase.

Correction for partial volume effects in PET: principle and validation.

Unlabelled: The accuracy of PET for measuring regional radiotracer concentrations in the human brain is limited by the finite resolution capability of the scanner and the resulting partial volume effects (PVEs). We designed a new algorithm to correct for PVEs by characterizing the geometric interaction between the PET system and the brain activity distribution.

Methods: The partial volume correction (PVC) algorithm uses high-resolution volumetric MR images correlated with the PET volume.

Dopamine transporters are markedly reduced in Lesch-Nyhan disease in vivo.

Dopamine (DA) deficiency has been implicated in Lesch-Nyhan disease (LND), a genetic disorder that is characterized by hyperuricemia, choreoathetosis, dystonia, and compulsive self-injury. To establish that DA deficiency is present in LND, the ligand WIN-35,428, which binds to DA transporters, was used to estimate the density of DA-containing neurons in the caudate and putamen of six patients with classic LND. Comparisons were made with 10 control subjects and 3 patients with Rett syndrome.

3D simulations of radiotracer uptake in deep nuclei of human brain.

The accuracy of Positron Emission Tomography (PET) for measuring in vivo concentrations of radiolabelled pharmaceuticals is affected by the limited tomograph resolution. Using computer simulations, we developed a model reproducing the distribution of the tracer [18F]fluoroDOPA which is specifically taken up in the normal human striatum. Validation of the model was performed by comparing the simulated images with real PET scans of the same brain.