Cannabis induced dopamine release: an in-vivo SPECT study.

In a research study aimed at examining the alterations in dopaminergic function in schizophrenia, the authors identified a surreptitious case scenario which provided new insights into the subjective and neurochemical effects of cannabis. A 38-year-old drug-free schizophrenic patient took part in a single photon emission computerized tomographic (SPECT) study of the brain, and smoked cannabis secretively during a pause in the course of an imaging session. Cannabis had an immediate calming effect, followed by a worsening of psychotic symptoms a few hours later.

Evaluation of linear registration algorithms for brain SPECT and the errors due to hypoperfusion lesions.

The semiquantitative analysis of perfusion single-photon emission computed tomography (SPECT) images requires a reproducible, objective method. Automated spatial standardization (registration) of images is a prerequisite to this goal. A source of registration error is the presence of hypoperfusion defects, which was evaluated in this study with simulated lesions.

Evaluation of voxel-based registration of 3-D power Doppler ultrasound and 3-D magnetic resonance angiographic images of carotid arteries.

Spatial registration and fusion of ultrasound (US) images with other modalities may aid clinical interpretation. We implemented and evaluated on patient data an automated retrospective registration of magnetic resonance angiography (MRA) carotid bifurcation images with 3-D power Doppler ultrasound (PD US) and indirectly with 3-D B-mode US. Volumes were initially thresholded to reduce the uncorrelated noise signals.

Variability and accuracy of measurements of prostate brachytherapy seed position in vitro using three-dimensional ultrasound: an intra- and inter-observer study.

This paper is a step in investigating whether three-dimensional (3D) ultrasound can be used intraoperatively to replace Computed Tomography (CT) for localization of brachytherapy seeds. In order to quantify the accuracy and variability of seed localization without introducing effects due to tissues, we first report our results with test phantoms. An inter- and intra-observer study was performed to assess the variability of 2 3D ultrasound scan acquisition methods: Tilt 3D scanning and pull-back 3D scanning.

Automated three-dimensional quantification of myocardial perfusion and brain SPECT.

To allow automated and objective reading of nuclear medicine tomography, we have developed a set of tools for clinical analysis of myocardial perfusion tomography (PERFIT) and Brain SPECT/PET (BRASS). We exploit algorithms for image registration and use three-dimensional (3D) "normal models" for individual patient comparisons to composite datasets on a "voxel-by-voxel basis" in order to automatically determine the statistically significant abnormalities. A multistage, 3D iterative inter-subject registration of patient images to normal templates is applied, including automated masking of the external activity before final fit.

Comparing the image quality of myocardial perfusion agents in the clinical laboratory: small test groups and large reference populations.

Myocardial perfusion studies have been performed for 6 years using technetium-99m (99Tcm)-sestamibi (MIBI). In this study we evaluated a newer agent, 99Tcm-tetrofosmin (TF), on a trial basis for 2 weeks, and compared the results from each week to those in an adjacent week of MIBI use. The routine protocol included weight-based dosing, frequent dipyridamole use, and separate-day rest and stress wherever possible.

[Multimodal SPECT and MRT imaging data analysis for an improvement in the diagnosis of idiopathic Parkinson's syndrome].

Parkinson's disease (PD) is characterized by a degeneration of nigrostriatal dopaminergic neurons, which can be imaged with 123I-labeled 2 beta-carbomethoxy-3 beta-(4-iodophenyl) tropane ([123I]beta-CIT) and single-photon emission computed tomography (SPECT). However, the quality of the region of interest (ROI) technique used for quantitative analysis of SPECT data is compromised by limited anatomical information in the images. We investigated whether the diagnosis of PD can be improved by combining the use of SPECT images with morphological image data from magnetic resonance imaging (MRI)/computed tomography (CT).

The carvedilol hibernation reversible ischaemia trial, marker of success (CHRISTMAS) study. Methodology of a randomised, placebo controlled, multicentre study of carvedilol in hibernation and heart failure.

Background: Carvedilol reduces mortality and improves symptoms and ejection fraction in ischemic heart failure, but its mode of action is not well defined and not all patients respond to treatment. The aim of the CHRISTMAS (Carvedilol Hibernation Reversible Ischaemia Trial, Marker of Success) study is to examine whether hibernation may be a significant factor determining this response. This paper describes the methodology and the rationale for the choice of the nuclear cardiology and echocardiography imaging techniques used in the study.

Optimization of automated quantification of 123I-IBZM uptake in the striatum applied to parkinsonism.

Unlabelled: Evaluation of therapies for parkinsonism by dopamine receptor SPECT requires a reproducible, optimized quantitation technique. This study presents a new, objective, automated technique for semiquantitative analysis of dopamine receptor density, as applied to the differential diagnosis of parkinsonism.

Methods: Dopamine receptor density measured by 123I-iodobenzamide (IBZM) SPECT was retrospectively analyzed in nonidiopathic parkinsonism (NIPS), in Parkinson's disease (PD), and in healthy volunteers (n = 19, 38, and 13, respectively).

Java-based remote viewing and processing of nuclear medicine images: toward "the imaging department without walls".

Unlabelled: In nuclear medicine practice, images often need to be reviewed and reports prepared from locations outside the department, usually in the form of hard copy. Although hard-copy images are simple and portable, they do not offer electronic data search and image manipulation capabilities. On the other hand, picture archiving and communication systems or dedicated workstations cannot be easily deployed at numerous locations.

Quantification and visualization of defects of the functional dopaminergic system using an automatic algorithm.

Unlabelled: In SPECT, the binding of radiotracers in brain areas is usually assessed by manual positioning of regions of interest (ROIs). The disadvantages of this method are that it is an observer-dependent procedure and that it may not be sensitive for assessing defects significantly smaller than the ROI. To circumvent these limitations, we developed a fully automatic three-dimensional technique that quantifies neuronal radiotracer binding on a voxel-by-voxel basis.

Automatic three-dimensional multimodality registration using radionuclide transmission CT attenuation maps: a phantom study.

Unlabelled: Coregistration of images from a single subject, acquired by different modalities, is important in clinical diagnosis, surgery and therapy planning. The purpose of this study was to evaluate, using a physical torso phantom, a novel, fully automated method for three-dimensional image registration of CT and SPECT, using radionuclide transmission (RNT) attenuation maps.

Methods: We obtained CT scans and SPECT scans paired with RNT maps of an anthropomorphic cardiac phantom.

Comparison of ordered subsets expectation maximization and Chang's attenuation correction method in quantitative cardiac SPET: a phantom study.

Photon attenuation is one of the primary causes of artifacts in cardiac single photon emission tomography (SPET). Several attenuation correction algorithms have been proposed. The aim of this study was to compare the effect of using the ordered subsets expectation maximization (OSEM) reconstruction algorithm and Chang's non-uniform attenuation correction method on quantitative cardiac SPET.

Pulmonary uptake of technetium-99m-sestamibi induced by dipyridamole-based stress or exercise.

Unlabelled: On poststress images with 99mTc-sestamibi (MIBI), increased lung uptake of the radiotracer may reflect severe or multivessel coronary artery disease.

Methods: We measured pulmonary/myocardial ratios of MIBI at standardized times on immediate poststress acquisitions and on delayed tomographic acquisitions. In 1500 sequential patients referred for rest and stress myocardial tomography, ancillary planar images were obtained 4 min postinjection at peak stress with exercise, either alone (exercise, n = 674), or after intravenous dipyridamole (dipyridamole, n = 826).

MRI-guided SPECT measurements of medial temporal lobe blood flow in Alzheimer's disease.

Unlabelled: In this study, we assessed the accuracy and reliability of MRI-guided SPECT measurements of medial temporal lobe blood flow in Alzheimer's disease (AD).

Methods: Interactively aligned three-dimensional MP-RAGE MRI and 99mTc-HMPAO SPECT images were used for MRI-guided measurement of medial temporal lobe CBF in eight control subjects and eight patients with probable AD. Intraoperator reliability was assessed by repeated alignment and measurement by one experienced operator.

The cortical representation of somatosensory evoked potentials of the phrenic nerve.

Respiratory electrophysiological studies are of essential value in diagnosing and managing patients with respiratory failure, but assessment of the sensory phrenic nerve fibres has been neglected. We recorded phrenic nerve somatosensory evoked potentials (SSEPs) by combining neurophysiological and neuroimaging techniques in three healthy subjects. Evoked potentials of the phrenic nerve showed the highest amplitude at CP3, determined by the modified 10-20 EEG system, and occurred at a constant latency, PI at 12.

Brain mapping of median nerve somatosensory evoked potentials with combined 99mTc-ECD single-photon emission tomography and magnetic resonance imaging.

Single-photon emission tomography (SPET) was performed during electrical median nerve stimulation and used to detect focal neuronal activation in the somatosensory pathways. Intravenously administered technetium-99m ethyl cysteinate dimer (ECD) was used as a blood flow tracer to obtain baseline and activated images in each of three subjects. After image registration, baseline images were compared voxel by voxel with the activation images.

Three-dimensional demarcation of perfusion zones corresponding to specific coronary arteries: application for automated interpretation of myocardial SPECT.

Unlabelled: In this study, three-dimensional maps of specific coronary artery territories were derived and combined with normal distribution maps as a reference for automated characterization of defects, including location and size.

Methods: One hundred sixty-eight 99mTc-sestamibi myocardial perfusion SPECT scans from normal patients and patients with single-vessel disease were selected according to angiographic data. Five separate groups were established for men and women: normal, proximal left anterior descending (PLAD), distal left anterior descending (DLAD), right coronary artery (RCA) and left circumflex (LCx).

Automated alignment and sizing of myocardial stress and rest scans to three-dimensional normal templates using an image registration algorithm.

Unlabelled: To optimize the interpretation of myocardial SPECT, we developed an automated method for alignment, sizing and quantification of images using three-dimensional reference templates.

Methods: Stress and rest reference templates were built using a hybrid three-dimensional image registration scheme based on principal-axes and simplex-minimization techniques. Normal patient studies were correlated to a common orientation, position and size.

Investigation of measures to reduce interfering abdominal activity on rest myocardial images with Tc-99m sestamibi.

With the new myocardial agent Tc-99m sestamibi, relatively high abdominal uptake represents a major limiting factor. The effect of a standard feeding (commercial milkshake taken immediately after injection), and posture (standing versus sitting for 10 minutes postinjection) on the resting biodistribution of sestamibi was investigated in patients receiving 3 to 5 MBq/kg injections as part of rest-stress tomography. Ancillary anterior 1-minute images of heart and abdomen were obtained at 15 minutes postinjection and 90 to 140 minutes postinjection in 32 patients, randomized to feeding and postural treatments.