Clinical application of autologous technetium-99m-labelled eosinophils to detect focal eosinophilic inflammation in the lung.

The detection of focal eosinophilic inflammation by non-invasive means may aid the diagnosis and follow-up of a variety of pulmonary pathologies. All current methods of detection involve invasive sampling, which may be contraindicated or too high-risk to be performed safely. The use of injected autologous technetium-99m (Tc-99m)-labelled eosinophils coupled to single-photon emission computed tomography (SPECT) has been demonstrated to localise eosinophilic inflammation in the lungs of a patient with antineutrophil cytoplasmic antibody-positive vasculitis.

Experimental results from a prototype slit-slat collimator with mixed multiplexed and non-multiplexed data.

We have previously shown with simulations that a gain in signal-to-noise ratio (SNR) can be obtained by using mixed multiplexed (MX) and non-MX data in a slit-slat SPECT system as compared to using non-MX data only. We have now developed a prototype slit-slat collimator for a conventional gamma camera in order to validate these simulation results. The prototype collimator consists of seven slits and multiple parallel slats.

Performance evaluation of a pixellated Ge Compton camera.

An ongoing project is being carried out to develop a high purity germanium (HPGe) Compton camera for medical applications. The Compton camera offers many potential advantages over the conventional gamma camera. The camera reported in this paper comprises two pixellated germanium detector planes housed 9.

The potential for mixed multiplexed and non-multiplexed data to improve the reconstruction quality of a multi-slit-slat collimator SPECT system.

Multiplexing is a way of increasing the sensitivity in a multi-slit-slat SPECT system by allowing the overlap of projections from neighboring apertures. The fundamental objective of multiplexing is to increase the signal-to-noise ratio for a given system resolution. Multiplexing may therefore lead to an improved tradeoff between resolution and sensitivity.

Vascular inflammation imaging with 18F-FDG PET/CT: when to image?

Unlabelled: We prospectively investigated the ideal imaging time to measure vascular uptake after injection of (18)F-FDG.

Methods: A total of 17 patients with atherosclerotic abdominal aortic aneurysm underwent dynamic abdominal PET/CT using 2-min frames between 45 and 53, 57 and 65, 115 and 123, and 175 and 183 min after injection of (18)F-FDG. For each period of dynamic imaging, vessel wall and lumen uptake were measured using the maximum standardized uptake value (SUV(max)) and target-to-background ratio (TBR).

Design of a novel slit-slat collimator system for SPECT imaging of the human brain.

We present three novel multi-slit-slat (MSS) system designs which allow for the acquisition of data with variable multiplexing in order to optimize the use of a high intrinsic resolution detector for clinical brain SPECT. In this paper we first study the relationship between the geometric parameters of a MSS collimator system and the resulting resolution and sensitivity for an on-axis point at the centre of the field-of-view (FOV), assuming a continuous cylindrical detector model. The model predicts that for optimal system sensitivity and resolution, the ratio of the detector radius to slit collimator radius should be 1.

Fusion of metabolic function and morphology: sequential [18F]fluorodeoxyglucose positron-emission tomography/computed tomography studies yield new insights into the natural history of bone metastases in breast cancer.

Purpose: By monitoring bone metastases with sequential [(18)F]fluorodeoxyglucose positron-emission tomography/computed tomography ([(18)F]FDG-PET/CT) imaging, this study investigates the clinical relevance of [(18)F]FDG uptake features of bone metastases with various radiographic appearances.

Patients And Methods: Bone metastases were found in 67 of 408 consecutive patients with known/suspected recurrent breast cancer on [(18)F]FDG-PET/CT, characterized by CT morphology changes and/or bony [(18)F]FDG uptake. Twenty-five of the patients had sequential [(18)F]FDG-PET/CT examinations (86 studies) over an average follow-up period of 23 months.

How often do patients undergo repeat PET or PET/CT examinations? Experience from a UK institution.

Background And Aim: According to the report of the Intercollegiate Standing Committee on Nuclear Medicine, the UK requires 40-60 positron emission tomography (PET) machines in the next decade (Intercollegiate Standing Committee on Nuclear Medicine). Positron Emission Tomography: a Strategy for Provision in the UK. London: Royal College of Physicians of London; 2003, pp.

A bolus/infusion paradigm for the novel NMDA receptor SPET tracer [123I]CNS 1261.

We have previously performed quantitative kinetic modeling of [(123)I]CNS 1261, a new SPET ligand for the MK801 intrachannel site of the NMDA receptor. We now report a bolus-infusion protocol, which eliminates the need for arterial blood sampling. Dynamic SPET scanning and venous blood sampling were performed in 7 healthy volunteers.

Cross-calibration of a fan-beam X-ray densitometer with a pencil-beam system.

This study describes the cross-calibration of two Hologic bone densitometers, one using a fan-beam X-ray source (QDR4500/A) and the other a pencil-beam source (QDR1000/W). The QDR4500/A allows spine and hip measurements to be made at three principal speeds. Results from two spine phantoms and 154 patients showed no significant difference in the absolute values or precision between speeds.

Clinical outcome after one year following samarium-153 particulate hydroxyapatite radiation synovectomy.

The clinical outcome and tolerability following treatment with samarium-153 particulate hydroxyapatite was evaluated in patients with persistent rheumatoid knee synovitis. The clinical review of 18 patients treated with intra-articular samarium-153 particulate hydroxyapatite combined with triamcinolone hexacetonide who had failed to obtain more than 4 weeks symptom relief from a prior intra-articular glucocorticoid injection was undertaken. No unwanted effects from the treatment were observed.

Samarium-153-particulate hydroxyapatite radiation synovectomy: biodistribution data for chronic knee synovitis.

Unlabelled: Biodistribution data for the radiation synovectomy agent samarium-153-particulate hydroxyapatite (153Sm-PHYP) are reported.

Methods: Mean extra-articular activity accumulation calculated from serial whole-body scans in 13 patients treated for chronic knee synovitis was 0.74% of injected activity (range 0%-3%).

Collimator design for single photon emission tomography.

We discuss recent trends in collimator design and technology, with emphasis on theoretical and practical issues of importance for single photon emission tomography (SPET). The well-known imaging performance parameters of parallel-hole collimators are compared with those of fan-beam collimators, which have enjoyed considerable success in recent years, particularly for brain SPET. We review a simplistic approach to the collimator optimization problem, as well as more sophisticated "task-dependent" treatments and important considerations for SPET collimator design.

The investigation of osteoradionecrosis of the mandible by 99mTc-methylene diphosphonate radionuclide bone scans.

The need for a reliable non-invasive investigation in osteoradionecrosis (ORN) of the mandible is discussed. The results of 99mTc-methylene diphosphonate bone scans using single photon emission tomography, and measuring dynamic uptake in 13 patients are presented. These suggest that sites of osteoradionecrosis may be defined by a paradoxically increased uptake of 99mTc-methylene diphosphonate.

The range of bone density in normal British women.

A study to determine the range of bone density in British females was carried out on a group of 165 normal women. The results showed an increase in mineral content with peak values occurring in the fourth decade (mean 1.06 g/cm2; 95% confidence limits 0.

In vivo characterisation of 3-iodo-6-methoxybenzamide 123I in humans.

3-Iodo-6-methoxybenzamide (123I-IBZM), a new Dopamine D2 receptor ligand, was used in conjunction with SME 810 brain tomography to study six subjects (one normal volunteer, four schizophrenics and one DAT patient). Initial Dynamic SPET was followed by multislice SPET. High-resolution images of the D2 receptor distribution in the basal ganglia were obtained.

X-ray dual-photon absorptiometry: a new method for the measurement of bone density.

A recently introduced method (dual-photon X-ray absorptiometry, DEXA) capable of measuring skeletal density in man (at present in the spine and hips, but ultimately for the whole body) has been evaluated in terms of its ability to perform long-term assessment of bone density changes. The method, which uses X rays rather than gamma rays as its photon source, represents a significant improvement over present systems both in image quality and precision (reproducibility) of results, which is better than 1% in vivo. Scanning time is approximately halved compared with present techniques and the radiation dose is reduced by 25%.

Functional imaging of the brain.

The radionuclide tracer method is unique amongst all other imaging methodologies in its ability to trace organ or tissue function and metabolism. It derives this advantage from the nature of the signal used for image generation, and its single interaction with the organ or system under examination. Physical processes such as electron or proton density assessment or resonance, edge identification, electrical or ultrasonic impedence, do not pertain to the image generation process in nuclear medicine, and if so, only in a rather secondary manner.

The in vivo distribution of 99Tcm-HM-PAO in normal man.

The distribution of 99Tcm-HM-PAO is described in normal man. Since our initial report on the clinical potential of this new radiopharmaceutical in 1984, a number of clinical trials are in progress worldwide. As the tracer has been designed to enable the in vivo assessment of the distribution of cerebral blood flow in man, significant interest in this new 99Tcm-labelled compound can be detected not only in the nuclear medicine practice in general, but in the more specialist areas of medicine such as neurology and psychiatry.

A 99Tcm-labelled radiotracer for the investigation of cerebral vascular disease.

The first clinical data is given on 99Tcm-hexamethylpropyleneamine oxime (HM-PAO) in normal subjects and patients with established stroke. Regional cerebral blood flow maps (rCBF) have been recorded and displayed in tomographic mode with this new radiopharmaceutical. Good images were obtained, comparable to those achieved with 123I-isopropylamphetamine (IMP).

Cerebral blood flow studies with 123iodine-labelled amines.

The cerebral distribution of a new class of 123I radiopharmaceuticals was determined by emission tomography after the isotope had been injected intravenously into 20 patients with a variety of neurological disorders. Regional cerebral blood flow images of diagnostic quality were obtained in all cases. Early and late ischaemic stroke showed up as areas of impaired perfusion, and gliomas and secondary deposits as areas of increased or reduced blood flow.