Anger Gamma Camera Research Articles

Radiation exposure after myocardial perfusion imaging with Cadmium-Zinc-Telluride camera versus conventional camera

BackgroundPatient exposure to radiation during the management of coronary heart disease (CHD) can be reduced with more efficient technologies in nuclear medicine, such as the Cadmium-Zinc-Telluride (CZT) gamma-camera for myocardial perfusion imaging (MPI) studies. However, it has been suggested that CZT has lower specificity, which might lead to more downstream radiological procedures, particularly among obese individuals. Methods and ResultsWe evaluated 244 patients with suspected CHD who underwent CZT-SPECT and matched 1:1 according to sex, age, and body mass index (BMI) with those undergoing MPI study with the Anger gamma-camera (Anger-SPECT). The outcome was the total radiation exposure from the MPI study added to the radiation exposure from all subsequent cardiac examinations during a 90-day follow-up. The total radiation dose after 90 days was significantly lower in the CZT-SPECT group (6.4 ± 4.8 vs 9.5±4.9 mSv, P < .001). After adjusting for potential confounders, CZT-SPECT remained associated with lower total radiation dose, but it significantly attenuated among obese individuals (Beta coefficient − 3.73 ± 0.86 for BMI < 30 vs − 2.30 ± 0.92 for BMI ≥ 30 Kg/m2, P for interaction < 0.032). ConclusionsCZT-SPECT was associated with lower total radiation doses compared to Anger-SPECT, albeit this benefit may be attenuated in obese individuals.

Differences in polar-map patterns using the novel technologies for myocardial perfusion imaging

BackgroundNew technologies are available in MPI. Our aim was to evaluate their impact on the uniformity of normal myocardial uptake in the polar-map representation, over different count statistics, with and without the attenuation (AC) and scatter corrections (SC). MethodsA phantom study was performed using 5 Anger gamma cameras with filtered back projection or iterative reconstruction with resolution recovery (IRR), with or without SCAC; a D530c, with or without AC; and a D-SPECT. Count statistics ranged up to a quarter of the reference for the conventional gamma cameras and up to one half for the advanced scanners. Using polar maps, the segmental uptakes and their uncertainties, the ‘global uniformity’ of polar maps expressed as the coefficient of variation (COV) among the segmental uptakes and the anterior/inferior (ANT/INF) ratio were calculated. ResultsBoth segmental uptakes and their uncertainties did not depend on the count statistics in the range studied. An increase in the segmental uptakes was found from IRR to IRR + SCAC (78.0% ± 13.5% vs 86.1% ± 9.4%; P < .0001). COV was lower for D-SPECT (10.1% ± 0.5%) and after SCAC for both conventional (9.9% ± 3.0%) and advanced systems (8.9% ± 1.7%). The ANT/INF ratio was above 1 for IRR (1.12 ± 0.07) and fell slightly below 1 for IRR + SCAC (0.97 ± 0.05). ConclusionsTo compare data from the analysis of polar maps across different systems will require the adoption of specific normality databases, developed for each system and reconstruction method employed.

Measurement of myocardial perfusion reserve with Anger gamma-camera

Measurement of myocardial perfusion reserve with Anger gamma-camera

Iterative reconstruction of detector response of an Anger gamma camera

Statistical event reconstruction techniques can give better results for gamma cameras than the traditional centroid method. However, implementation of such techniques requires detailed knowledge of the photomultiplier tube light-response functions. Here we describe an iterative method which allows one to obtain the response functions from flood irradiation data without imposing strict requirements on the spatial uniformity of the event distribution. A successful application of the method for medical gamma cameras is demonstrated using both simulated and experimental data. An implementation of the iterative reconstruction technique capable of operating in real time is presented. We show that this technique can also be used for monitoring photomultiplier gain variations.

The Nuclear Imaging Uncertainty Principle. Do Nuclear Cameras Really Work?

AbstractThe introduction of the Heisenberg Uncertainty principle and Nuclear Cardiology occurred simultaneously in 1925-1927. Thirty years later the Anger gamma camera would allow for a more sophisticated radioactive isotope counting to determine the presence or absence of disease. When employed with technetium-99m isotopes, ischemic heart disease can be inferred by differences in visual appearance of cardiac images. These gestalts of imaging results have been separated from the quantitative information recorded by the cameras computer. We investigated whether current camera and computer systems are sophisticated enough to quantify differences between images to be clinically relevant. Our study demonstrated that efforts to &amp;quot;sharpen&amp;quot; image appearance does so at a reduction in &amp;quot;accuracy&amp;quot;. Like Heisenberg, this work shows that one cannot know the exact location AND the amount of activity simultaneously and that a decision must be made for accuracy over image sharpness if one is to truly quantify differences in isotope concentration between images.

A New Architecture for Pixellated Solid State Gamma Camera Used in Nuclear Medicine

The purpose of this paper is to introduce a novel technique for acquiring and reconstructing planar or tomographic images obtained using a gamma camera. The aim is to overcome the sensitivity-spatial resolution tradeoff for conventional Anger gamma cameras. The future generation of solid state gamma cameras will benefit from the recent advances in CdZnTe (CZT) detector performances. Previous studies have shown that pixellated CZT detectors have a high energy resolution, good detection efficiency and a high intrinsic spatial resolution. Moreover, these detectors provide important additional information: the depth of interaction (DOI). In this paper, we introduce the HiSens (High Sensitivity) architecture: an original collimator architecture associated with a CZT pixellated detector that takes advantage of such performances, particularly in terms of DOI information and an adapted method of iterative reconstruction. We explain about the ability of our CZT detector, associated with specific electronic processing, to obtain accurate DOI information on a 5 mm-thick CZT detector. We have used SINDBAD simulation tool to evaluate the performance of the HiSens architecture. We describe an adapted iterative reconstruction using the CZT DOI information in order to improve image quality. Then we show preliminary simulation results of the HiSens architecture performances.

Breast scintigraphy today: indications and limitations.

Breast carcinoma is the most common neoplasm found among women in the Western world. Mammography (MM) is the most widely used diagnostic imaging method for screening and diagnosing breast cancer. However, despite technical improvements in recent years, MM has known diagnostic limits; consequently not all breast carcinomas are identified on mammograms, especially if the breast is dense, there is a breast prosthesis or the patient has previously undergone radiation, surgery or biopsy. In addition, the mammographic images of benign and malignant lesions can be similar. Therefore, abnormalities detected on MM frequently result in negative biopsies. Scintimammography (SM) is the functional imaging study of the breast using primarily the radiopharmaceuticals (99m)Tc-sestamibi and (99m)Tc-tetrofosmin. The main advantage of SM is that its functional basis makes this technique a useful complement to MM. SM resolves some of the main limitations of MM as it is not affected by changes in breast morphology. Several single-site and multi-centre studies have demonstrated that SM has an improved specificity compared with MM, because it is better able to distinguish malignant from benign breast lesions. Interestingly, except in smaller lesions, a higher sensitivity has been recorded for SM than for MM in most of these studies as well. Adjunctive use of SM when MM is equivocal can reduce the number of unnecessary breast biopsies and identify previously unexpected sites of breast cancer. SM appears unaffected by the anatomical changes seen following chemotherapy and radiotherapy, and so this technique can be particularly useful in monitoring the treatment of breast cancer patients, especially when breast-conserving treatment is given. The main limitation to SM has been the sub-optimal resolution of the standard Anger gamma camera, which makes it difficult to detect lesions of less than 10 mm; however, the development of high-resolution breast-dedicated gamma cameras may offer improvements in this respect. This review will look at the evidence for SM and show how it can become part of the clinical care algorithm in breast cancer.

Imaging probe for breast cancer localization

High spatial resolution, small Field Of View (FOV), fully portable scintillation cameras are lower cost and obviously lower weight than large FOV, not transportable Anger gamma cameras. Portable cameras allow easy transfer of the detector, thus of radioisotope imaging, where the bioptical procedure takes place. In this paper we describe a preliminary experience on radionuclide Breast Cancer (BC) imaging with a 22.8×22.8 mm2 FOV minicamera, already used by our group for sentinel node detection with the name of Imaging Probe (IP). In this work IP BC detection was performed with the aim of guiding biopsy, in particular open biopsy, or to help or modify fine needle or needle addressing when main driving method was echography or digital radiography. The IP prototype weight was about 1 kg. This small scintillation camera is based on the compact Position Sensitive Photomultiplier Tube Hamamatsu R7600-00-C8, coupled to a CsI(Tl) scintillation array 2.6×2.6×5.0 mm3 crystal-pixel size. Spatial resolution of the IP was 2.5 mm Full-Width at Half-Maximum at laboratory tests. IP was provided with acquisition software allowing quick change of pixels number on the computer acquisition frame and an on-line image-smoothing program. Both these programs were developed in order to allow nuclear physicians to quickly get target source when the patient was anesthetized in the operator room, with sterile conditions. 99mTc Sestamibi (MIBI) was injected at the dose of 740 MBq 1 h before imaging and biopsy to 14 patients with suspicious or known BC. Scintigraphic images were acquired before and after biopsy in each patient. Operator was allowed to take into account scintigraphic images as well as previously performed X-ray mammograms and echographies. High-resolution IP images were able to guide biopsy toward cancer or washout zones of the cancer, that are thought to be chemoresistant in 7 patients out of 10. Four patients, in whom IP and MIBI were not able to guide biopsy, did not show cancer. Two patients in whom biopsy was performed in the high washout zone, did show Multi Drug Resistance (MDR) gene product at immunohistochemistry on bioptical samples. Specific radioactivity was measured on biopsy specimens and measurement confirmed the etherogeneous distribution of MIBI within cancers. Our study confirms the ability of IP to guide breast biopsy even when our mini-camera has to be manually handled by trained physicians during operation.

Results of clinical trials with SPEM

Abstract X-ray mammography represents the principal tool for breast cancer screening, but has several limitations. Due to the low specificity of X-ray mammography, many more biopsies are performed than are necessary. More than 60% of breast biopsies performed because of suspicious X-ray mammograms yield a diagnosis other than cancer. In women with X-ray dense breast tissue, X-ray mammography can miss as many as 20% of cancers. Several studies suggest that combining 99mTc Sestamibi Scintimammography (SM) with X-ray mammography can increase the accuracy of breast imaging in selected populations. The principal limitation of prone-position scintimammography (PSM) using a standard Anger gamma camera is low sensitivity for subcentimeter cancers (i.e., stages T1a and T1b). Detecting these small cancers is extremely important clinically, since removal of the cancers at these early stages is thought to represent the best opportunity for cure. Our group constructed a high spatial resolution detector specifically dedicated to SM, the Single Photon Emission Mammography (SPEM) camera. Unlike conventional Anger gamma cameras, the SPEM camera incorporates a high spatial resolution position-sensitive photomultiplier tube, coupled to an array of scintillating crystals. The compactness of the SPEM camera allows breast compression to be implemented in a cranio-caudal view, facilitating comparison to X-ray mammograms taken in the same position. Clinical results so obtained have demonstrated increased diagnostic sensitivity in sub-centimeter tumors (80% for SPEM vs 50% with PSM). Factors contributing to this increased sensitivity include improved signal-to-noise ratio (SNR). For sub-centimeter cancers, SPEM SNR values were consistently much higher than those of PSM. Classic detectability studies have demonstrated that an SNR value >5 is required for reliable detection of cancers. For subcentimeter cancers, only the SPEM attained or exceeded this minimum threshold. The results showed that compression, which optimizes resolution by reducing lesion-to-collimator distance, and increases planar image contrast by reducing signal and attenuation from interposed normal breast tissue, plays a fundamental role in the visualization of subcentimeter breast cancers.

Glomerular targeting of acidic fibroblast growth factor-1 in renal transplanted rats.

Acidic fibroblast growth factor (FGF-1) functions as a potent hormonal inducer of wound repair mechanisms in vivo. In addition, the involvement of FGF-1 in a number of pathophysiological conditions, including chronic human renal allograft rejection, has been described. Consequently, there is an increasing need to monitor FGF-1 pharmacokinetics and distribution for both therapeutic and diagnostic opportunities. We now describe in vivo imaging and targeting of FGF-1 in renal transplanted rats. Sham-operated, syngeneic renal transplanted, and allogeneic renal transplanted rats were imaged using an Anger gamma camera. Renal function was evaluated first by dynamic 99mTc-MAG3 imaging, and subsequently, 99mTc-labeled FGF-1 (99mTc-FGF-1) was imaged after i.v. injection. Microautoradiography of harvested kidneys determined the compartmental localization of 99mTc-FGF-1. 99mTc-MAG3 renal scans were grossly abnormal in the allogeneic renal transplanted rats. In this group, a significant reduction in 99mTc-FGF-1 renal binding was measured by imaging analyses, as compared with renal binding in the sham-operated and syngeneic renal transplanted groups, which were not significantly different. Both groups of renal transplanted rats showed a redistribution of FGF-1 to the glomerular compartment. 99mTc-FGF-1 serves as a new radiotracer to measure in vivo targeting of the growth factor. Reduced renal binding of 99mTc-FGF-1 in the allogeneic transplanted kidney was consistent with decreased blood flow. Unique glomerular targeting of 99mTc-FGF-1 in the transplanted kidney provides additional evidence supporting a role for this growth factor in the pathogenesis of chronic rejection.

PET imaging using gamma cameras

This paper will review the recent advances and future developments in the field of coincidence imaging of positron emitters with a conventional Anger-type gamma camera. FDG imaging has shown high clinical importance in cardiology, neurology and especially oncology. Since access to full ring PET is mainly limited to university hospitals, there have been new developments allowing PET imaging on the standard Anger gamma camera. First the principles of coincidence imaging on a gamma camera will be reviewed. We will discuss the limitations of this technique, and the techniques used to partly overcome these limitations. The different configurations of the gamma camera operating in coincidence mode are pointed out. Different corrections for image degrading effects and reconstruction methods are evaluated in the final part.

Imaging and tissue biodistribution of 99mTc-labeled adenovirus knob (serotype 5).

Hepatic sequestration of systemically administered adenoviral vectors reduces the number of viral particles available for delivery to other tissues. The biological basis of this phenomenon was investigated using a new in vivo technique which permitted imaging in real time. Recombinant adenovirus serotype 5 knob (Ad5K) was radiolabeled with the gamma-emitter 99mTc (half-life = 6 h). Scatchard analysis of the 99mTc-Ad5K showed specific, high-affinity binding to U293 cells (Kd = 1.4 +/- 0.5 nM), demonstrating that the radiolabeling process had no effect on receptor binding. In vivo dynamic imaging with an Anger gamma camera revealed that the liver binding followed an exponential rise to maximum, with a measured 100% extraction efficiency. Initially, the liver binding capacity was 3.1 +/- 0.4 micrograms Ad5K, equivalent to approximately 17,000 Ad5K molecules per liver cell. Liver binding was blocked by preincubation of Ad5K with neutralizing anti-Ad5K antibody; a 50% reduction in liver uptake was demonstrated by imaging. Unlabeled Ad5K was more effective in blocking liver uptake of 99mTc-Ad5K, whereas irrelevant unlabeled Ad3K had no effect. Imaging data for the liver uptake studies were in agreement with biodistribution determined by removing and measuring tissues. These data demonstrated that in vivo imaging is a sensitive tool for measuring changes to liver tropism. Similar imaging techniques can be applied to adenovirus vectors to measure specific targeting for gene therapy.

PET imaging using gamma camera systems: a review.

Optimized positron emission tomographs have begun to demonstrate an ever widening range of clinical applications for positron labelled pharmaceuticals. This potential has led to a renewed interest in the use of the more widely available Anger gamma camera detectors for imaging the 511 keV photons from the positron decay process. Two forms of detection can be considered: either the detection of the 511 keV photons as single events or the detection of coincidence events from the opposed pair annihilation photons. The widespread availability of dual, opposed-pair, large field-of-view detectors has promoted the development of coincidence detection without collimation. With detector rotation, positron emission tomography (PET) can be performed. An alternative and lower cost option has been the universal development of ultra high-energy collimators to perform single photon emission tomography (SPET) with 511 keV photons. This review outlines the currently available performance characteristics of these two approaches and compares them with those from two- and three-dimensional PET optimized systems. The limitations on the development of these systems is discussed through the analysis of the principles underlying both single photon and coincidence detection. Preliminary clinical experience indicates that limitations in the performance characteristics of these systems has implications for their potential role, although applications in cardiology and oncology are being pursued.

Radiation safety in the central radiopharmacy

The currently increasing number of new radiopharmaceuticals and the increase in individual patient-dose activity, particularly for single photon emission computer tomography imaging, coupled with the switch toward unit doses probably contribute to an increase in the radiation burden to radiopharmacy personnel. To meet this increased need of the nuclear medicine community, a medium-sized radiopharmacy may order seven to eight 3-Ci molybdenum-99/technetium-99M generators per week and may perform 10 to 15 elutions per day. The maximum radiation exposure to radiopharmacy personnel occurs during the generator elutions, compounding (kit preparation), and unit-dose dispensing. Additional sources of radiation exposure can occur during receipt of radioactive packages, transport of prepared doses, and the process of storage and disposal of radioactive waste. Recent reports have shown extremity radiation doses to the fingers and hands at 14 to 21 rem/year. Radiation exposure can be monitored by film badges, thermoluminescent detectors, or one of the analog or digital self-reading dosimeters. Each monitoring device has advantages and the choice depends upon the personnel involved (eg, visitors) and the particular needs of the radiopharmacy. Extremity dose reductions during radiopharmacy procedures can be achieved by a number of techniques, some as simple as the use of 8- to 9-inch forceps during transfers of radioactive vials and syringes and the use of a dose-drawing syringe shield during unit-dose dispensing procedures. In preparation of unsealed doses or capsules of radioactive iodine, there is a potential for a high internal dose because of inhalation of the volitile solution. Frequent monitoring in the form of bioassays and the use of strict threshold levels will ensure early detection of exposure to radioactive iodine and quick corrective action. In pharmacies and nuclear medicine departments handling fluorine-18 for use with Anger gamma cameras, the high levels of both beta and gamma radiation present an additional set of radiation safety problems.

Fluorine 18-labeled fluorodeoxyglucose myocardial scintigraphy with Anger gamma cameras for assessing myocardial viability

A significant body of evidence now suggests that clinically adequate planar and SPECT myocardial perfusion/FDG metabolism studies can be performed for assessment of myocardial viability with conventional gamma cameras. This might reduce the need for more sophisticated PET scanners in this patient subgroup and also increase the general applicability of metabolic assessment of myocardial viability with FDG. The procedure is technically demanding in terms of both equipment and interpretation, and requires further careful evaluation before it can be recommended for widespread use. Nevertheless, it appears to have enough potential to warrant evaluation along with improving techniques of using myocardial perfusion tracers, PET imaging, and stress echocardiography to identify the most cost-effective options for assessing viability of myocardium in clinical situations in which this becomes important.

Pulmonary studies using positron emission tomography

The detailed investigation of regional differences in lung function at a local level began when suitable gamma-ray emitting isotopes and focused external radiation detectors (especially the Anger gamma-camera) became available. A major recent advance has been the development of positron emission tomography (PET), which provides a powerful combination of highly accurate tomographic reconstruction of radioisotope concentration with a potentially unlimited list of biological compounds to be labelled with the positron emitting isotopes of oxygen, carbon and fluorine. Early studies using PET focused on the inhalation of 11CO (or C15O) and 19Ne gases and the intravenous injection of 13N in saline and H215O for the measurement of relatively simple aspects of regional lung function, such as tissue, blood and gas volumes, blood flow, ventilation and ventilation/perfusion (V'A/Q'). More recent work has been directed towards the more challenging areas of regional endothelial permeability, carbohydrate utilization, enzyme and receptor binding assays, and in vivo pharmacokinetics. The short physical half-lives of the isotopes (17 s to 2 h) and the noninvasive nature of PET allows serial measurements to be made on patients (within the constraints of permitted radiation doses) to assess the effect of physiological and therapeutic interventions.

Rationale for the rational development of new cardiac imaging agents.

There are several prerequisites for the development of new diagnostic cardiovascular radiopharmaceuticals. Agents which are proposed for clinical use must offer significant advantages in one or more of the following categories: I) Radiopharmacy [dosimetry, dose preparation, dose availability]; II) Imaging characteristics [spatial and temporal resolution, radiotracer biokinetics, patient throughput and acquisition protocols]; and III) Measurement of a previously unmeasurable physiologic or pharmacologic event [metabolic pathways, receptors, neural pathways, preclinical disease]. Technetium-99m-based radiopharmaceuticals are particularly attractive, in view of their excellent characteristics for imaging with the Anger gamma camera. In addition, the increasing use of tomographic imaging and reconstruction techniques has magnified the importance of developing radiotracers with minimal soft tissue attenuation effects. Technetium-99m and positron emitting radioisotopes offer this advantage. A wide choice of biologically and pharmacologically relevant ligands are available for complexing with these radiotracers. The clinical studies are underway in order to validate these new agents, and to determine their value in the modern practice of nuclear medicine. Technetium-99m sestamibi is just one example of a novel radiotracer with improved imaging characteristics that has undergone careful pre-clinical and clinical testing, and which has emerged as a useful diagnostic imaging agent. Future studies should be directed towards the development of tracers with well-defined biokinetic characteristics, which are advantageous for tomographic imaging. The future applications of tracer imaging techniques for the pre-clinical diagnosis of cardiovascular, oncologic and other medical conditions are significant and are expanding.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical high resolution skeletal single photon emission tomography using a triple-headed gamma camera.

Planar skeletal scintigraphy has become established as a standard diagnostic test performed within the nuclear medicine department. Since the 1970s good quality images have been produced using an Anger gamma camera and 99Tcm-labelled diphosphonates. Single photon emission tomography (SPET) has improved the sensitivity of detection and the ability to localize bony pathology, particularly benign bone disease in the spine. Recently multi-detector gamma cameras dedicated to SPET have become available. One such system, the Toshiba GCA-9300A, has been used to perform routine clinical skeletal SPET in 81 patients. Good quality images have been obtained using an 8 min acquisition in the axial skeleton and a 16 min acquisition protocol in the peripheral skeleton. Multiple sites can be tomographed in the same patient during the same examination using two or more 8 min acquisitions. Such a multi-detector gamma camera offers advantages over the standard single-headed rotating camera for skeletal SPET in terms of both imaging time and image quality. A cost analysis was performed which demonstrated that the additional cost of purchasing such a multidector gamma camera was less than 30.00 pounds per SPET study.

Quantitation of metastatic tumor burden from human colon tumor xenografts using radiolabelled monoclonal antibody 17-A fragments.

In realistic models of human tumor xenograft metastasis, the metastatic foci arise in perivascular sites and rarely grow to sizes which are easily quantifiable by visual inspection. As an alternative approach, we have used monoclonal antibody (MAb) 17-1A F(ab')2 fragments labelled with radioiodine (125I) to study the differential accumulation of label in xenografts and metastatic tumor sites as well as in noninvolved tissues of NIH Swiss nude mice receiving HT-29 human colon tumor cells. Images of the whole-body distribution and sites of localization were determined using a pinhole-collimated Angergamma camera. Radioactivity was determined in tissue samples using a well scintillation system, and pharmacokinetics were assessed during the initial 72 h after injection of antibody fragments. The half-life of 125I-F(ab')2 fragments in the blood, 8.6 h, was similar in nontumor-bearing control and tumor-bearing mice. The half-life in subcutaneous tumor xenografts was 30.1 h. The tumor xenograft to tissue activity ratios per unit weight (radiolocalization indices) at 72 h were: blood 90, lung 65, pancreas 50, muscle 35, spleen 20, liver and mesenteric lymph node 10. All subcutaneous xenografts were successfully imaged, and images of 5 of 9 mice (55%) appeared to demonstrate the presence of metastatic tumor by differential and focal accumulation of MAb fragments after 48 or 72 h in the lung (2 cases) or abdominal cavity (3 cases). Necropsy and subsequent histological and biodistribution studies confirmed the presence of metastatic tumor in these sites and identified tumor in several additional sites. The smallest volume of metastatic tissue in liver or lung determined at necropsy which appeared to have been detected by imaging was about 20 mm3. Generally, for mice with metastatic tumors, the radioactivity per unit weight of metastatic tumor-bearing organs compared to tumor-free organs was 2- to 7-fold greater. The results indicate that a radiolocalization index of > or = 2 is generally necessary for metastatic tumor detection by imaging although this is influenced by the extent of anatomical location of the tumor. It was possible to predict the tissue distribution of the fragments from the planar image for the amounts of radioactivity (approximately 1 mCi/kg body weight) employed in this study. These results demonstrate the utility of this approach to quantitate the metastatic burden arising from human colon tumor xenografts in this experimental model.

Clinical SPRINT Imaging

We have performed initial clinical studies using the high resolution single photon ring tomograph (SPRINT) and Tc-99m HMPAO. To determine what additional anatomic detail can be depicted using this high resolution, dedicated head, multidetector SPECT device compared to conventional SPECT, six patients with stroke and one normal volunteer were imaged after the injection of 20 mCi Tc-99m HMPAO on a conventional rotating Anger gamma camera (GE-400AC), followed immediately by imaging on SPRINT. Imaging acquisition on the GE-400AC gamma camera was performed using 360 degrees rotation, 64 stops, at 30 sec/stop, yielding an average of 985,714 counts for a 10.0 mm thick slice. GE-400AC images were of good quality, having in-plane full width half maximum (FWHM) resolution of approximately 15 mm. SPRINT acquisition of image data was performed using both the high resolution and high sensitivity apertures, with data collection over 15 or 20 minutes of imaging time accumulating approximately 500,000 counts and 1,000,000 counts, respectively, from patients in a 10.0 mm thick slice, achieving an in-plane FWHM resolution of approximately 8 mm and 10 mm for the two apertures, respectively. Both image resolution and contrast for visualization of gray, white, and cerebral spinal fluid filled brain structures were improved using SPRINT compared with the GE-400AC. We conclude that SPRINT is well suited for brain imaging with Tc-99m HMPAO and is of particular value for applications demanding high resolution.