Conventional SPECT Research Articles

An Introduction to Na18F Bone Scintigraphy: Basic Principles, Advanced Imaging Concepts, and Case Examples

Na(18)F, an early bone scintigraphy agent, is poised to reenter mainstream clinical imaging with the present generations of stand-alone PET and PET/CT hybrid scanners. (18)F PET scans promise improved imaging quality for both benign and malignant bone disease, with significantly improved sensitivity and specificity over conventional planar and SPECT bone scans. In this article, basic acquisition information will be presented along with examples of studies related to oncology, sports medicine, and general orthopedics. The use of image fusion of PET bone scans with CT and MRI will be demonstrated. The objectives of this article are to provide the reader with an understanding of the history of early bone scintigraphy in relation to Na(18)F scanning, a familiarity with basic imaging techniques for PET bone scanning, an appreciation of the extent of disease processes that can be imaged with PET bone scanning, an appreciation for the added value of multimodality image fusion with bone disease, and a recognition of the potential role PET bone scanning may play in clinical imaging.

A direct ROI quantification method for inherent PVE correction: accuracy assessment in striatal SPECT measurements

The clinical potential of striatal imaging with dopamine transporter (DAT) SPECT tracers is hampered by the limited capability to recover activity concentration ratios due to partial volume effects (PVE). We evaluated the accuracy of a least squares method that allows retrieval of activity in regions of interest directly from projections (LS-ROI). An Alderson striatal phantom was filled with striatal to background ratios of 6:1, 9:1 and 28:1; the striatal and background ROIs were drawn on a coregistered X-ray CT of the phantom. The activity ratios of these ROIs were derived both with the LS-ROI method and with conventional SPECT EM reconstruction (EM-SPECT). Moreover, the two methods were compared in seven patients with motor symptoms who were examined with N-3-fluoropropyl-2-beta-carboxymethoxy-3-beta-(4-iodophenyl) (FP-CIT) SPECT, calculating the binding potential (BP). In the phantom study, the activity ratios obtained with EM-SPECT were 3.5, 5.3 and 17.0, respectively, whereas the LS-ROI method resulted in ratios of 6.2, 9.0 and 27.3, respectively. With the LS-ROI method, the BP in the seven patients was approximately 60% higher than with EM-SPECT; a linear correlation between the LS-ROI and the EM estimates was found (r=0.98, p=0.03). The LS-ROI PVE correction capability is mainly due to the fact that the ill-conditioning of the LS-ROI approach is lower than that of the EM-SPECT one. The LS-ROI seems to be feasible and accurate in the examination of the dopaminergic system. This approach can be fruitful in monitoring of disease progression and in clinical trials of dopaminergic drugs.

Implementation of an iterative scatter correction, the influence of attenuation map quality and their effect on absolute quantitation in SPECT

We investigated the accuracy of qSPECT, a quantitative SPECT reconstruction algorithm we have developed which employs corrections for collimator blurring, photon attenuation and scatter, and provides images in units of absolute radiotracer concentrations (kBq cm−3). Using simulated and experimental phantom data with characteristics similar to clinical cardiac perfusion data, we studied the implementation of a scatter correction (SC) as part of an iterative reconstruction protocol. Additionally, with experimental phantom studies we examined the influence of CT-based attenuation maps, relative to those obtained from conventional SPECT transmission scans, on SCs and quantitation. Our results indicate that the qSPECT estimated scatter corrections did not change appreciably after the third iteration of the reconstruction. For the simulated data, qSPECT concentrations agreed with images reconstructed using ideal, scatter-free, simulated data to within 6%. For the experimental data, we observed small systematic differences in the scatter fractions for data using different combinations of SCs and attenuation maps. The SCs were found to be significantly influenced by errors in image coregistration. The reconstructed concentrations using CT-based corrections were more quantitatively accurate than those using attenuation maps from conventional SPECT transmission scans. However, segmenting the attenuation maps from SPECT transmission scans could provide sufficient accuracy for most applications.

SPECT/CT imaging using a spiral CT scanner for anatomical localization: Impact on diagnostic accuracy and reporter confidence in clinical practice

To evaluate the incremental benefit in routine clinical practice of computed tomography (CT) scans acquired for anatomical localization on an integrated SPECT/CT which incorporates a spiral CT scanner, in comparison with conventional planar and SPECT scanning. The first 50 studies acquired on the integrated system were evaluated by two experienced nuclear medicine physicians who were aware of the patient's clinical history. These included bone scans, gallium scans, octreotide scans, sestamibi parathyroid scans and MIBG scans. For each patient study, abnormalities were assessed on planar and SPECT images for location and provisional diagnosis and a quantitative scale was used to assess reporter confidence. The fused SPECT/CT images were then reviewed and the location and provisional diagnosis noted and reporter confidence was assessed using the same quantitative scale. There were 129 abnormalities detected in 50 patient studies. For localization of abnormalities, the inclusion of the CT resulted in a minor change in 16% of cases and a significant change in 11% over planar/SPECT imaging alone. The confidence of localization was improved moderately in 19% and improved significantly in 6%. For diagnosis, SPECT/CT resulted in a minor change in 10% and a significant change in 9% over planar/SPECT imaging. The confidence of diagnosis was improved moderately in 10% and improved significantly in a further 10% of cases. For the final scan interpretation, there would have been no change in 44% patients, a minor change in 30% and a significant change in 26% with the use of SPECT/CT. Use of integrated SPECT/CT with a high spatial resolution, spiral CT used for anatomical localization improves accuracy and reporter confidence in clinical practice. As a result, final reports were different in 56% of the cases, including being significantly different in 26% patients compared to reporting with planar/SPECT alone.

Separate analysis of asialoglycoprotein receptors in the right and left hepatic lobes using 99mTc-GSA SPECT in patients with acute hepatic damage

The asialoglycoprotein receptor (ASGPR) is abundantly expressed on the sinusoidal surfaces of hepatocytes. However, regional expression and clinical significance of the ASGPR in acute hepatic damage is presently unknown. Our aim was to clarify the clinical significance of the regional expression of ASGPR in human livers with acute hepatitis (AH) and fulminant hepatic failure (FHF). Eighteen volunteers, 42 patients with AH and 10 with FHF were studied using a newly developed, conventional (99m)Tc-GSA SPECT analysis. Using Cantlie's line as a guide, ASGPR expression was analyzed separately in the right and left hepatic lobes, as well as in the whole liver, using novel indices (the liver uptake ratio [LUR] and liver uptake density [LUD], which reflect the amount and density of ASGPRs in the liver, respectively). Mean LUR and LUD values for the whole liver and the right and left lobes decreased in accordance with the severity of acute hepatic damage. In the FHF group, the reduction in LUR and LUD values in the right lobes was more significant than in the left lobes. The LUR and LUD values for the whole liver correlated well with hepatic functional reserve and total bilirubin levels. The right LUR and LUD values in particular correlated well with these parameters. A time-course observation of 13 patients with either AH or FHF revealed that the expression of ASGPRs in the right lobe recovered faster than in the left. We first evaluated the regional expression of AGSPRs by (99m)Tc-GSA SPECT analysis in both AH and FHF patients, which is a clinically useful and reliable indicator for assessing the severity of regional hepatic damage and evaluating regional liver regeneration.

PET Imaging and Coronary Circulatory Function: Non-Invasive Mechanistic Insights and Cardiovascular Prognosis

The ability to determine regional myocardial blood flow (MBF) in absolute estimates by positron emission tomography (PET) contributes to the non-invasive identification and characterization of early stages of the development of coronary artery disease (CAD). Measurements of MBF at baseline, during pharmacologic vasodilation, or during physiologic stimuli, such as treadmill exercise or cold pressor testing (CPT), may permit a comprehensive assessment of the coronary circulatory function. By assessing alterations of MBF in absolute units (ml/g/min) in response to these stimuli, the functional consequences of morphological and/or functional changes in the coronary arteries may be identified before any angiographic-morphological changes are present. Thus, such measurements of MBF expand the diagnostic scope of conventional SPECT perfusion imaging to detect hemodynamically obstructive CAD, based on heterogeneity of relative myocardial perfusion, and early functional abnormalities of the coronary circulation in the absence of manifest CAD. Notably, invasive angiographic measures that indicate an impairment of endothelium-dependent coronary vascular function provide predictive information for future cardiovascular events. Consequently, it is intriguing to speculate that the non-invasive approach of PET flow-measurements to identify abnormal coronary circulatory function could serve as an important tool to identify individuals at increased risk for developing CAD and its atherothrombotic complications. MBF measurements by PET have been shown to allow the monitoring of beneficial effects of lifestyle modification, lipidlowering dietary changes, antioxidant interventions, effects of HMG-CoA reductase inhibitors, and effective glucoselowering therapy on coronary circulatory function. Whether such improvements in coronary vascular function do indeed translate into an improved clinical outcome in these patients and predict a reduction in cardiovascular events remains to be investigated. This review article describes PET-measured estimates of MBF, examines the responses of MBF to physiologic and pharmacologic stimuli and their relationship to coronary circulatory function, and examines the value of these measurements of MBF for monitoring medical intervention with regard to coronary vascular function.

A geometric system model of finite aperture in small animal pinhole SPECT imaging

Accurate system modeling of the photon acquisition process is essential for optimizing quality in pinhole SPECT imaging. Conventional pinhole SPECT imaging assumes ideal pinhole geometry. However, neglect of pinhole finite aperture could lead to unfavorable quality degradations, such as positioning bias and image distortion. In this work, we develop a system model in which the aperture width of a pinhole collimator is explicitly included. The system model describes the probability of a single photon from its emission to detection. The probability value is calculated based on the effective intersection area resulting from a simulated cone-beam light source emitting from the image voxel, passing through a finite aperture, and reaching the detector's frontal face. The proposed model can be integrated with the ordered subsets expectation maximization (OSEM) algorithm for fast 3D statistical image reconstruction. Monte Carlo-based phantom experiments are used to evaluate the performance of the proposed system model compared to the ideal pinhole model. Reconstructed image results demonstrate that the proposed model can improve image quality in terms of reducing location bias and maintaining better contrast recovery.

体幹部における３検出器型高速回転ＳＰＥＣＴ撮像法の開発―肺血流シンチ・ファントムスタディ―

A chest phantom study was conducted to evaluate the image quality of newly developed high-speed rotation multiplied projection-single photon emission computed tomography (HSRMP-SPECT) images. HSRMP-SPECT images of a chest phantom consisting of a simulated lung structure filled with 5000 ml of water containing 185 MBq Tc-99m-pertechnetate, and several small 11 mm simulated lung nodules of glass balls and one large 35 mm simulated lung nodule of a plastic sphere filled with water were obtained using a triple-headed SPECT system. During image acquisition, this phantom was regularly moving in the head-to-caudal direction with a range of 12 mm at a frequency of 15 cycles/min to simulate respiratory motion, and 360 degrees projection data of this moving phantom was acquired with an image acquisition time of 20 sec, which was repeated 10 times. To eliminate the setting time between projection and acquisition of multiple temporal samples of data, each detector was continuously rotated in the clockwise direction for 20 sec around a 120-degree arc. On the perspective SPECT images reconstructed from various numbers of the 20-sec projection data, the perfusion heterogeneity of the simulated lungs and perfusion defect clarity of the simulated nodules were assessed by the coefficient of variation (CV) of pixel counts and the defect-to-lung radioactivity ratios, respectively. The results were compared with those on conventional SPECT images of the moving phantom obtained with a data acquisition time of 8 min, and SPECT images of the standing phantom obtained with the same data acquisition time. The average CV value of 0.28+/-0.01 on the SPECT image reconstructed from 5 projection data sets was not significantly different from that of 0.27+/-0.01 on the SPECT image reconstructed from 10 projection data sets (p<0.05). The perfusion defect contrast of the simulated nodules obtained from 5 projection data was significantly higher than that on conventional SPECT images (0.50 vs. 0.73) . The present phantom study indicated that HSRMP-SPECT could be a useful technique for quickly obtaining high-quality SPECT images of a moving subject, thereby improving perfusion defect clarity in comparison with the conventional technique. This technique may have potential utility for obtaining high-quality breath-hold SPECT images of the chest in clinical practice.

Evaluating performance of a pixel array semiconductor SPECT system for small animal imaging

Small animal imaging has recently been focused on basic nuclear medicine. We have designed and built a small animal SPECT imaging system using a semiconductor camera and a newly designed collimator. We assess the performance of this system for small object imaging. We employed an MGC 1500 (Acrorad Co.) camera including a CdTe semiconductor. The pixel size was 1.4 mm/pixel. We designed and produced a parallel-hole collimator with 20-mm hole length. Our SPECT system consisted of a semiconductor camera with the subject holder set on an electric rotating stage controlled by a computer. We compared this system with a conventional small animal SPECT system comprising a SPECT-2000H scanner with four Anger type cameras and pinhole collimators. The count rate linearity for estimation of the scatter was evaluated for a pie-chart phantom containing different concentrations of 99mTc. We measured the FWHM of the 99mTc SPECT line source along with scatter. The system volume sensitivity was examined using a flood source phantom which was 35 mm long with a 32-mm inside diameter. Additionally, an in vivo myocardial perfusion SPECT study was performed with a rat. With regards to energy resolution, the semiconductor camera (5.6%) was superior to the conventional Anger type camera (9.8%). In the count rate linearity evaluation, the regression lines of the SPECT values were y = 0.019x + 0.031 (r2 = 0.999) for our system and y = 0.018x + 0.060 (r2 = 0.997) for the conventional system. Thus, the scatter count using the semiconductor camera was less than that using the conventional camera. FWHMs of our system and the conventional system were 2.9 +/- 0.1 and 2.0 +/- 0.1 mm, respectively. Moreover, the system volume sensitivity of our system [0.51 kcps/(MBq/ ml)/cm] was superior to that of the conventional system [0.44 kcps/(MBq/ml)/cm]. Our system provided clear images of the rat myocardium, sufficient for practical use in small animal imaging. Our SPECT system, utilizing a semiconductor camera, permits high quantitative analysis by virtue of its low scatter radiation and high sensitivity. Therefore, this system may contribute to molecular imaging of small animals and basic medical research.

Design and simulation of a high-resolution stationary SPECT system for small animals

Exciting new SPECT systems can be created by combining pinhole imaging with compact high-resolution gamma cameras. These new systems are able to solve the problem of the limited sensitivity-resolution trade-off that hampers contemporary small animal SPECT. The design presented here (U-SPECT-III) uses a set of detectors placed in a polygonal configuration and a cylindrical collimator that contains 135 pinholes arranged in nine rings. Each ring contains 15 gold pinhole apertures that focus on the centre of the cylinder. A non-overlapping projection is acquired via each pinhole. Consequently, when a mouse brain is placed in the central field-of-view, each voxel in the cerebrum can be observed via 130 to 135 different pinholes simultaneously. A method for high-resolution scintillation detection is described that eliminates the depth-of-interaction problem encountered with pinhole cameras, and is expected to provide intrinsic detector resolutions better than 150 µm. By means of simulations U-SPECT-III is compared to a simulated dual pinhole SPECT (DP-SPECT) system with a pixelated array consisting of 2.0 × 2.0 mm NaI crystals. Analytic calculations indicate that the proposed U-SPECT-III system yields an almost four times higher linear and about sixty times higher volumetric system resolution than DP-SPECT, when the systems are compared at matching system sensitivity. In addition, it should be possible to achieve a 15 up to 30 times higher sensitivity with U-SPECT-III when the systems are compared at equal resolution. Simulated images of a digital mouse-brain phantom show much more detail with U-SPECT-III than with DP-SPECT. In a resolution phantom, 0.3 mm diameter cold rods are clearly visible with U-SPECT-III, whereas with DP-SPECT the smallest visible rods are about 0.6–0.8 mm. Furthermore, with U-SPECT-III, the image deformations outside the central plane of reconstruction that hamper conventional pinhole SPECT are strongly suppressed. Simulation results indicate that future pinhole SPECT systems are likely to bring about significant improvements in radio-molecular imaging of small animals.

Development of “super rapid dynamic SPECT,” and analysis of retention process of99mTc-ECD in ischemie lesions: Comparative study with133Xe SPECT

To analyze the retention process of technetium-99m ethyl cysteinate dimer (99mTc-ECD) in normal and ischemic lesions, we developed a super rapid dynamic SPECT system based on the CERASPECT (DSI, Inc., Waltham, MA, USA). The system made it possible to take a SPECT series every 2 seconds. Each SPECT series contains a maximum of 16 slices (6.6 mm slice interval) in a matrix size of 32 x 32. The sensitivity of this system is 175 kcps/MBq/ml/cm slice thickness, and resolution is 12 mm FWHM at the center of a 20 cm(phi) water phantom. Using the super rapid SPECT system, the kinetic behavior of the 99mTc-ECD during retention in normal and ischemic lesions was analyzed. Twenty patients with ischemic lesions that were clearly demonstrated by 133Xe-rCBF (regional cerebral blood flow) SPECT but unclear on static 99mTc-ECD SPECT were examined. For the dynamic SPECT, 700 MBq of 99mTc-ECD was injected intravenously, and dynamic SPECT data were acquired every 2 seconds during a 90-second period. The serial dynamic SPECT and time-activity curves at some lesions with reduced rCBF and at the contralateral normal brain were analyzed. These dynamic SPECT data were compared with conventional static 99mTc-ECD SPECT and quantitative 133Xe-rCBF SPECT. All of mildly or moderately reduced rCBF lesions on the 133Xe-rCBF SPECT were recognized as low activity regions only at the early phase (during about 2-20 sec or less), with the lesions then gradually vanishing. These lesions were not recognized on the conventional static SPECT taken after the dynamic study. The time-activity curve at the reduced rCBF lesion was lower than that of contralateral normal brain at the early phase, and overtook the activity in the normal region with a gradual increase. The early phase images of 99mTc-ECD SPECT within 20 seconds by the super rapid dynamic SPECT were very useful to the same extent as the 133Xe-rCBF SPECT for detecting mild or moderate ischemic lesions. This study suggests that esterase activity, participating in the ECD retention mechanism, may be tolerable to mild or moderate ischemia. This tolerance may be the main cause of the nonlinear relationship between ECD accumulation and cerebral blood flow.

Hybrid parallel-slant hole collimators for SPECT imaging

We propose a new collimator geometry, the hybrid parallel-slant (HPS) hole geometry, to improve sensitivity for SPECT imaging with large field of view (LFOV) gamma cameras. A HPS collimator has one segment with parallel holes and one or more segments with slant holes. The collimator can be mounted on a conventional SPECT LFOV system that uses parallel-beam collimators, and no additional detector or collimator motion is required for data acquisition. The parallel segment of the collimator allows for the acquisition of a complete data set of the organs-of-interest and the slant segments provide additional data. In this work, simulation studies of an MCAT phantom were performed with a HPS collimator with one slant segment. The slant direction points from patient head to patient feet with a slant angle of 30/spl deg/. We simulated 64 projection views over 180/spl deg/ with the modeling of nonuniform attenuation effect, and then reconstructed images using an MLEM algorithm that incorporated the hybrid geometry. It was shown that sensitivity to the cardiac region of the phantom was increased by approximately 50% when using the HPS collimator compared with a parallel-hole collimator. No visible artifacts were observed in the myocardium and the signal-to-noise ratio (SNR) of the myocardium walls was improved. Compared with collimators with other geometries, using a HPS collimator has the following advantages: (a) significant sensitivity increase; (b) a complete data set obtained from the parallel segment that allows for artifact-free image reconstruction; and (c) no additional collimator or detector motion. This work demonstrates the potential value of hybrid geometry in collimator design for LFOV SPECT imaging.

Evaluation of penetration and scattering components in conventional pinhole SPECT: phantom studies using Monte Carlo simulation

In quantitative pinhole SPECT, photon penetration through the collimator edges (penetration), and photon scattering by the object (object scatter) and collimator (collimator scatter) have not been investigated rigorously. Monte Carlo simulation was used to evaluate these three physical processes for different tungsten knife-edge pinhole collimators using uniform, hotspot and donut phantoms filled with 201Tl, 99mTc, 123I and 131I solutions. For the hotspot phantom, the penetration levels with respect to total counts for a 1 mm pinhole aperture were 78%, 28% and 23% for 131I, 123I and 99mTc, respectively. For a 2 mm aperture, these values were 65% for 131I, 16% for 123I and 12% for 99mTc. For all pinholes, 201Tl penetration was less than 4%. The evaluated scatter (from object and collimator) with a hotspot phantom for the 1 mm pinhole was 24%, 16%, 18% and 13% for 201Tl, 99mTc, 123I and 131I, respectively. Summation of the object and collimator scatter for the uniform phantom was approximately 20% higher than that for the hotspot phantom. Significant counts due to penetration and object and collimator scatter in the reconstructed image were observed inside the core of the donut phantom. The collimator scatter can be neglected for all isotopes used in this study except for 131I. Object scatter correction for all radionuclides used in this study is necessary and correction for the penetration contribution is necessary for all radionuclides but 201Tl.

Exact inversion of the exponential x-ray transform for rotating slant-hole (RSH) SPECT

The RSH SPECT scanner provides parallel-beam attenuated projections for a fully 3D acquisition geometry. The geometry can be represented by circles on the unit sphere of projection directions, one circle for each position of the detector head. Unlike most other fully 3D geometries this one is particularly challenging because there are no 2D subsets in the data. When no attenuation is present, it is well known that an unmeasured projection can be synthesized if it lies inside one of the measured circles. The main result of this work is that under some assumptions on the attenuation distribution, attenuated projections within a circle can be synthesized from available attenuated projections. One consequence is that RSH SPECT projections can be rebinned into a conventional SPECT geometry for which analytic attenuation correction techniques are available.

A new high energy scintillating fiber optic single photon computed tomography detector

A new detector for imaging annihilation radiation is designed as an auxiliary unit for single photon computed tomography (SPECT) systems. Increased interest in higher energy medical imaging creates a demand for a low cost device that can be used with existing SPECT units. Key design features are: a custom high‐resolution collimator, a scintillator formed from plastic optical fibers, and a position‐sensitive photomultiplier. The optical fiber core is a ternary scintillator: Polystyrene (solvent) with solutes PPO and BS–MSB. High‐energy resolution (7.5 mm full‐width at half max (FWHM) at a source‐to‐collimator distance of 10 cm), improved total efficiency at a SCD of 10 cm), and low cost are hallmarks of the new detector. The FWHM is more than twice that available imaging 511 keV gammas with conventional SPECT cameras. Images are formed using Compton electrons, which are limited to one interaction inside the detector as opposed to detection by photoelectric interactions in conventional cameras. Computer simulations with the radiation transport code EGS4 verified the basic imaging concept and were then used to optimize the detector and collimator designs. A working prototype detector was manufactured, tested, and characterized. Positron emitting Germanium‐68 (Ge‐68) was used as a laboratory point source of annihilation radiation for testing. A larger area detector (4×4 array of 16 identical modules, each 5 cm ×5 cm ×20 cm with an expected planar sensitivity of specifically for augmented breast cancer diagnosis was then proposed and simulated as a possible application of this technology.

Scatter correction for camera based coincidence and single photon imaging protocols

The authors have investigated and tested a strategy for acquiring projection data from a mixed field of a positron emitter, a single photon source, and a transmission source, and independently reconstructing each of the three data sets. Tc-99m is imaged through the collimator using conventional SPECT techniques. The annihilation and the transmission radiations are detected as they penetrate (uncollimated) through the collimator septa. The success of independently reconstructing each data set rests on the effectiveness of the scatter subtraction method. A few scatter compensation methods were tested. A scatter compensation algorithm (based on 3 energy windows) within an iterative reconstruction algorithm was applied and quantitative improvements of the emission reconstructions are reported. The authors' experimental results of immediately sequential Tc-99m, FDG, and I-131 transmission data, demonstrate that each isotope can be imaged in the presence of the others. This method could be extended to truly simultaneous acquisitions.

The Role of 99mTc-Tetrofosmin Pinhole-SPECT in Breast Cancer Axillary Lymph Node Staging

The number of metastatic axillary nodes represents one of the most important prognostic factors in preoperative breast cancer patients. 99mTc-Tetrofosmin high resolution Pinhole (P)-SPECT was employed in 112 patients, 100 with breast cancer and 12 with benign mammary lesions, to ascertain axillary lymph node involvement. Axillary P-SPECT images were acquired utilizing specific software connected to a circular high resolution, single-head gamma camera equipped with a pinhole collimator with aperture size of 4.45 mm, rotating 180 degrees around the involved axilla. At the same time, patients also underwent conventional SPECT and planar acquisitions. Per-patient sensitivity and specificity were 100% and 93.6% for P-SPECT, 96.2% and 93.6% for SPECT and 56.6% and 100% for planar imaging, respectively. Moreover, P-SPECT detected more than 51% of lesions ascertained by histology, whereas SPECT and planar detected 32.6% and 20.3%, respectively. Only P-SPECT succeeded in identifying the exact number of metastatic axillary lesions in patients with multiple nodes; this procedure was able to correctly differentiate 88.67% of patients with 3 or less nodes from those with more than 3, thus giving important prognostic information. These data suggest 99mTc-Tetrofosmin P-SPECT is a reliable imaging method both for staging and prognostic purposes in breast cancer, and its routine use is recommended.

Tc-99m HMPAO brain perfusion SPECT images in a patient with Todd's paralysis.

Tc-99m HMPAO brain perfusion SPECT was performed in a 10-month-old patient with postepileptic transient left hemiplegia using a dual-headed gamma camera. Decreased perfusion to the right basal ganglia and thalamus was shown. Diagnostic information could be obtained on such a small patient with Todd's paralysis by conventional brain perfusion SPECT.

三検出器型ＳＰＥＣＴ装置による三次元画像骨シンチグラフィーの紹介

A three-head SPECT camera (PRISM-3000) can complete full-circle scans (360° scan) within a short time, a definite advantage over the conventional one-head SPECT unit. In addition, the clinical utility of the three-dimensional (3D) imaging system is greatly enhanced by its high-speed data processing.In the present study, we examined patients with osteomyelitis of the mandible and submandibular carcinoma that had spread to the mandible in order to determine the value of this system.Our results showed that 3D images provide clearer information than that provided by conventional images, and the position of bone lesions can be observed easily.

1010-66 Comparison of Supine and Upright SPECT Myocardial Perfusion Imaging

Cardiac tomography can be performed in the upright position using a stationary small FOV multicrystal camera (MCC) and a rotating chair. The chair both rotates and jogs to improve spatial resolution of the MCC. To investigate the diagnostic accuracy of this imaging technique compared to conventional supine SPECT, 25 patients with CAD (23 M, 2 F, mean age = 58 ± 10 years, 11 with prior MI) and 18 subjects with low pretest probability for having disease (9 M, 9 F, mean age 49 ± 11 years) underwent a one day rest/stress, low dose/high dose Tc-99m sestamibi study with sequential supine and upright SPECT imaging performed following rest and stress injections. Mean treadmill time for patients = 7.8 ± 2.1 mins, peak HR = 143 ± 17, and 11 were electrically positive. Mean treadmill time for subjects was 8.9 ± 3.4 mins, peak HR = 166 ± 17. Recent coronary angiography was performed in 17/23 CAD patients with 34 lesions &gt;50%. Each tomogram was divided into 7 segments and each segment scored as normal, reversible, or fixed. The agreement between the 2 sets of scans was 98% and the segment agreement with regard to reversibility was 90%. Supine SPECT detected 21/23 (91%) of patients with CAD, the chair detected 20/23% (87%). The chair detected 18/34 (53%) CA lesions, supine detected 20/34 (59%). Sensitivity and specificity for the chair was 88%, and 100%, and for supine was 92%, and 100%. In conclusion, in this small population, there were no significant differences between supine and upright SPECT imaging for diagnosing CAD, identifying individual stenoses, or identifying defect reversibility.