Performance of coincidence imaging with long-lived positron emitters as an alternative to dedicated PET and SPECT

An important application of quantitative imaging in nuclear medicine is the estimation of absorbed doses in radionuclide therapy. Depending on the radionuclide used for therapy, quantitative imaging of the kinetics of the therapeutic radiopharmaceutical could be done using planar imaging, SPECT or PET. Since many nuclear medicine departments have a gamma camera system that is also suitable for coincidence imaging, the performance of these systems with respect to quantitative imaging of PET isotopes that could be of use in radionuclide dosimetry is of interest. We investigated the performance of a gamma camera with coincidence imaging capabilities with 99mTc, 111In, 18F and 76Br and a dedicated PET system with 18F and 76Br, using a single standard set of phantom measurements. Here, 76Br was taken as a typical example of prompt gamma-emitting PET isotopes that are applicable in radionuclide therapy dosimetry such as 86Y and 124I. Image quality measurements show comparable image contrasts for 76Br coincidence imaging and 111In SPECT. Although the spatial resolution of coincidence imaging is better than single photon imaging, the contrast obtained with 76Br is not better than that with 99mTc or 111In because of the prompt gamma involved. Additional improvements are necessary to allow for quantitative coincidence imaging of long-lived, prompt gamma producing positron emitters.     

Performance evaluation of a pinhole SPECT system for myocardial perfusion imaging of mice

The increasing use of transgenic mice as models of human physiology and disease has motivated the development of dedicated in vivo imaging systems for anatomic and functional characterization of mice as an adjunct to or a replacement for established ex vivo techniques. We have developed a pinhole single photon emission computed tomography (SPECT) system for high resolution imaging of mice with cardiovascular imaging as the primary application. In this work, we characterize the system performance through phantom studies. The spatial resolution and sensitivity were measured from images of a line source and point source, respectively, and were reported for a range of object-to-pinhole distances and pinhole diameters. Tomographic images of a uniform cylindrical phantom, Defrise phantom, and grid phantom were used to characterize the image uniformity and spatial linearity. The uniform phantom image did not contain any ring or reconstruction artifacts, but blurring in the axial direction was evident in the Defrise phantom images. The grid phantom images demonstrated excellent spatial linearity. A novel phantom modeling perfusion of the left ventricle of a mouse was designed and built with perfusion defects of varying sizes to evaluate the system performance for myocardial perfusion imaging of mice. The defect volumes were measured from the pinhole SPECT images and correlated to the actual defect volumes calculated according to geometric formulas. Linear regression analysis produced a correlation coefficient of r = 0.995 (p < 0.001), demonstrating the feasibility for measurement of perfusion defect size in mice using pinhole SPECT. We have performed phantom studies to characterize the spatial resolution, sensitivity, image uniformity, and spatial linearity of the pinhole SPECT system. Measurement of the perfusion defect size is a valuable phenotypic assessment and will be useful for hypothesis testing in murine models of cardiovascular disease.     

Characterization of a rotating slat collimator system dedicated to small animal imaging

Some current investigations based on small animal models are dedicated to functional cerebral imaging. They represent a fundamental tool to understand the mechanisms involved in neurodegenerative diseases. In the radiopharmaceutical development approach, the main challenge is to measure the radioactivity distribution in the brain of a subject with good temporal and spatial resolutions. Classical SPECT systems mainly use parallel hole or pinhole collimators. In this paper we investigate the use of a rotating slat collimator system for small animal brain imaging. The proposed prototype consists of a 64-channel multi-anode photomultiplier tube (H8804, Hamamatsu Corp.) coupled to a YAP:Ce crystal highly segmented into 32 strips of 0.575 × 18.4 × 10 mm(3). The parameters of the rotating slat collimator are optimized using GATE Monte Carlo simulations. The performance of the proposed prototype in terms of spatial resolution, detection efficiency and signal-to-noise ratio is compared to that obtained with a gamma camera equipped with a parallel hole collimator. Preliminary experimental results demonstrate that a spatial resolution of 1.54 mm can be achieved with a detection efficiency of 0.012% for a source located at 20 mm, corresponding to the position of the brain in the prototype field of view.     

Comparison between coated vs. uncoated suture middle cerebral artery occlusion in the rat as assessed by perfusion/diffusion weighted imaging

Differences among models in the temporal evolution of ischemia after middle cerebral artery occlusion (MCAO) in rats may considerably influence the results of experimental treatment studies. Using diffusion and perfusion imaging, we compared the spatiotemporal evolution of ischemia in Sprague-Dawley rats after permanent MCAO (pMCAO) with different types of sutures. Male Sprague-Dawley rats were randomly assigned to pMCAO produced with either 4-0 silicone coated (n=8), or 3-0 uncoated monofilaments (n=8). Serial determination of quantitative cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) maps were performed up to 3 h after pMCAO. Lesion volumes were calculated by using previously validated thresholds and correlated with infarct volume corrected for edema defined by 2,3,5-triphenyltetrazolium chloride (TTC) staining at 24 h after MCAO. The ADC/CBF-defined mismatch volume in the 4-0 coated suture model was present significantly longer (up to 120 min) compared to the uncoated 3-0 suture model (30 min). The TTC-derived infarct volume was significantly larger in the coated model (290.3+/-32.8 mm(3)) relative to the uncoated model (252.3+/-34.6 mm(3)). This study demonstrates that the type of suture may significantly influence the spatiotemporal evolution of the ADC/CBF-mismatch as well as the final infarct volume. These inter-model variations must be taken into account when assessing new therapeutic approaches on ischemic lesion evolution in the rat MCAO model.     

Single photon emission tomography with 99mTc-exametazime in major depression and the pattern of brain activity underlying the psychotic/neurotic continuum.

Forty patients with a major depressive episode were investigated at rest using Single Photon Emission Tomography (SPET or SPECT) with 99mTc-exametazime, an intravenous ligand taken into brain in proportion to regional cerebral blood flow, thereby providing an estimate of regional metabolism. All patients were unipolar and were rated on the Newcastle scale and with the 17-item Hamilton scale. They also completed a range of neuropsychological tests. They were compared with 20 control subjects matched for age, gender, premorbid intelligence and education. The uptake of 99mTc-exametazime was expressed for a range of anatomically defined regions of interest relative to calcarine/occipital cortex. The depressed group showed reduced uptake in the majority of cortical and sub-cortical regions examined, most significantly in temporal, inferior frontal and parietal areas. Unexpectedly, there was a strong positive association between uptake and scores on the Newcastle scale, especially in cingulate areas and frontal cortex. After removing the variance attributable to the Newcastle ratings, however, there emerged the expected negative association between Hamilton scores and anterior tracer uptake. The associations between neuropsychological impairment and regional brain uptake of tracer in part reflected the pattern seen with the Newcastle scale: for example, impairment of memory function correlated with higher uptake into posterior cingulate areas. We propose that depressive illness may be characterised by two processes. One leads to an overall reduction in anterior neocortical function, perhaps related to symptom severity. The other mechanism is manifest as relatively increased function, most notably within cingulate and frontal areas of the cerebral cortex in association with psychotic symptoms. The findings offer new understanding of the brain states underlying depressive illness and a potential focus to subsequent neuropharmacological analysis.     

PET imaging with [11C]PBR28 can localize and quantify upregulated peripheral benzodiazepine receptors associated with cerebral ischemia in rat

Peripheral benzodiazepine receptors (PBRs) are upregulated on activated microglia. We recently developed a promising positron emission tomography (PET) ligand, [11C]PBR28, with high affinity and excellent ratio of specific to nonspecific binding. We assessed the ability of [11C]PBR28 PET to localize PBRs in a rat permanent middle cerebral artery occlusion (MCAO) model of neuroinflammation. [11C]PBR28 was intravenously administered to rats at 4 and 7 days after permanent MCAO. In all experiments, arterial blood was sampled for compartmental modeling of regional distribution volumes, and rat brains were sampled after imaging for in vitro [3H]PK 11195 autoradiography and histological evaluation. [11C]PBR28 PET and [3H]PK 11195 autoradiography showed similar areas of increased PBRs, especially in the peri-ischemic core. Results from these in vivo and in vitro methods were strongly correlated. In this first study to demonstrate neuroinflammation in vivo with small animal PET, [11C]PBR28 had adequate sensitivity to localize and quantify the associated increase in PBRs.     

Comparison of pinhole collimator materials based on sensitivity equivalence

Pinhole SPECT often provides an excellent resolution sensitivity trade-off for radionuclide imaging compared to SPECT with parallel holes, particularly when imaging small experimental animals like rodents. High absorption pinhole materials are often chosen because of their low edge penetration and therefore good system resolution. Capturing more photons in the edges however results in decreased system sensitivity if the pinhole diameter remains the same, which may partly undo the beneficial effect on the resolution. In the search for an optimal trade-off we have compared pinhole projection data and reconstructed images of different materials with pinhole aperture diameters adjusted to obtain equal sensitivity. Monte Carlo calculations modeling the transmission, penetration and scattering of gamma radiation in single pinholes of uranium, gold, tungsten and lead were performed for a range of pinhole opening angles, diameters and gamma ray energies. In addition, reconstructed images of a hot rod phantom were determined for a multipinhole SPECT system and for a system that can image the 511 keV annihilation photons of positron emitting tracers with clustered pinholes. Our results indicate that, under the condition of equal sensitivity, tungsten and for SPECT also lead pinholes perform just as well as gold and uranium ones, indicating that a significant cost reduction can be achieved in pinhole collimator manufacturing while the use of rare or impractical materials can be avoided.     

LSCI检测不同缺血期对大鼠缺血再灌注过程脑血流的影响

目的　考察不同缺血期对大鼠缺血再灌注过程脑血流的影响。 方法　通过激光散斑成像技术（LSCI）检测大鼠大脑中动脉不同栓塞时间后,对再灌注过程中脑血流的影响,并对再灌注过程中的低灌注状态、无复流现象、血流流速及管径变化进行研究分析。 结果　2 h的栓塞后,大鼠脑部血流量趋向低灌注状态,约为栓塞前血流基值的(35±10)%;栓塞时间越长,无复流现象越多;在再灌注期间,缺血2 h组的血流比0.5 h组的低灌注水平低10%。 结论　长时间的脑缺血期再灌注过程可能是造成脑损伤程度加重的主要原因之一。LSCI可应用于脑部血流实时监测,操作简便,成像灵敏、稳定,结果可靠。     

A multipinhole small animal SPECT system with submillimeter spatial resolution

Single photon emission computed tomography (SPECT) is an important technology for molecular imaging studies of small animals. In this arena, there is an increasing demand for high performance imaging systems that offer improved spatial resolution and detection efficiency. We have designed a multipinhole small animal imaging system based on position sensitive avalanche photodiode (PSAPD) detectors with the goal of submillimeter spatial resolution and high detection efficiency, which will allow us to minimize the radiation dose to the animal and to shorten the time needed for the imaging study. Our design will use 8 x 24 mm2 PSAPD detector modules coupled to thallium-doped cesium iodide [CsI(Tl)] scintillators, which can achieve an intrinsic spatial resolution of 0.5 mm at 140 keV. These detectors will be arranged in rings of 24 modules each; the animal is positioned in the center of the 9 stationary detector rings which capture projection data from the animal with a cylindrical tungsten multipinhole collimator. The animal is supported on a bed which can be rocked about the central axis to increase angular sampling of the object. In contrast to conventional SPECT pinhole systems, in our design each pinhole views only a portion of the object. However, the ensemble of projection data from all of the multipinhole detectors provide angular sampling that is sufficient to reconstruct tomographic data from the object. The performance of this multipinhole PSAPD imaging system was simulated using a ray tracing program that models the appropriate point spread functions and then was compared against the performance of a dual-headed pinhole SPECT system. The detection efficiency of both systems was simulated and projection data of a hot rod phantom were generated and reconstructed to assess spatial resolution. Appropriate Poisson noise was added to the data to simulate an acquisition time of 15 min and an activity of 18.5 MBq distributed in the phantom. Both sets of data were reconstructed with an ML-EM reconstruction algorithm. In addition, the imaging performance of both systems was evaluated with a uniformity phantom and a realistic digital mouse phantom. Simulations show that our proposed system produces a spatial resolution of 0.8 mm and an average detection efficiency of 630 cps/MBq. In contrast, simulations of the dual-headed pinhole SPECT system produce a spatial resolution of 1.1 mm and an average detection efficiency of 53 cps/MBq. These results suggest that our novel design will achieve high spatial resolution and will improve the detection efficiency by more than an order of magnitude compared to a dual-headed pinhole SPECT system. We expect that this system can perform SPECT with submillimeter spatial resolution, high throughput, and low radiation dose suitable for in vivo imaging of small animals.     

An investigation of inconsistent projections and artefacts in multi-pinhole SPECT with axially aligned pinholes

Multiple pinholes are advantageous for maximizing the use of the available field of view (FOV) of compact small animal single photon emission computed tomography (SPECT) detectors. However, when the pinholes are aligned axially to optimize imaging of extended objects, such as rodents, multiplexing of the pinhole projections can give rise to inconsistent data which leads to 'ghost point' artefacts in the reconstructed volume. A novel four pinhole collimator with a baffle was designed and implemented to eliminate these inconsistent projections. Simulation and physical phantom studies were performed to investigate artefacts from axially aligned pinholes and the efficacy of the baffle in removing inconsistent data and, thus, reducing reconstruction artefacts. SPECT was performed using a Defrise phantom to investigate the impact of collimator design on FOV utilization and axial blurring effects. Multiple pinhole SPECT acquired with a baffle had fewer artefacts and improved quantitative accuracy when compared to SPECT acquired without a baffle. The use of four pinholes positioned in a square maximized the available FOV, increased acquisition sensitivity and reduced axial blurring effects. These findings support the use of a baffle to eliminate inconsistent projection data arising from axially aligned pinholes and improve small animal SPECT reconstructions.     

Neuroprotective effects of safflor yellow B on brain ischemic injury

The present study was conducted to investigate whether safflor yellow B (SYB) had a protective effect on cerebral ischemic injury and to determine the possible mechanisms in vivo and in vitro. In vivo, Male Wistar–Kyoto (WKY) rats were used to make the model of middle cerebral artery occlusion (MCAO). The behavioral test was used to measure neurological deficit scores for evaluation of the ischemic damage of brain. The infarction area of brain was assessed in brain slices stained with 2% solution of 2,3,5-triphenyl tetrazolium chloride (TTC). Spectrophotometric assay was used to determine the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx), contents of malondialdehyde (MDA) and adenosine triphosphate (ATP) of the brain. Furthermore, the respiratory control ratio (RCR = state 3/state 4) was assessed in the brain mitochondria. In vitro, the effect of SYB was tested in cultured fetal cortical cells exposed to glutamate to identify its neuroprotection against neurons damage. The results in vivo showed that SYB at doses of 3.0 and 6.0 mg kg⁻¹ markedly decreased the neurological deficit scores and the infarction area in MCAO rats. At the same time, SYB significantly improved mitochondrial energy metabolism, decreased MDA content, and increased SOD and GPx activities in ischemic brain. The results in vitro showed that SYB remarkably inhibited neuron damage induced by glutamate in cultured fetal cortical cells. These suggest that SYB might act as a potential neuroprotective agent against the cerebral ischemia-induced injury in rat brain through reducing lipid peroxides, scavenging free radicals, and improving the energy metabolism.     

Optical imaging of Tc-99m-based tracers: in vitro and in vivo results

It has been recently shown that optical imaging (OI) methods can be used to image the in vivo biodistribution of several radiopharmaceuticals labeled with beta or alpha emitters. In this work particular attention has been focused on investigating the weaker optical signal induced by an almost pure gamma emitter like Tc-99m. Visible light emission measurements of a water solution containing Tc-99m were performed using a small animal OI system. A sequence of images was acquired for 24 h in order to study the decay of the luminescence signal. The difference between the luminescence decay half life and well-known Tc-99m half life was equal to 1%. in vivo imaging was performed by injecting one control nude mice with Tc-99m-MDP. Optical images obtained with equipment designed for bioluminescence imaging showed that a visible light emission was distinguishable and correctly localized in the bladder region where a higher concentration of Tc-99m-MDP was expected. The bladder to background ratio was always greater than 1. We conclude that the experimental data presented in this paper show that it is possible to detect in vivo luminescence optical photons induced by Tc-99m. This is important especially considering the large number of Tc-99m-based radiopharmaceutical currently available.     

激光多普勒血流仪评价活体大鼠大脑中动脉栓塞模型成功的可行性分析

目的：探讨激光多普勒血流仪（LDF）评价活体大鼠脑缺血/再灌注损伤模型制作成功的可行性和可靠性分析。方法：10只体重280-310 g的雄性SD大鼠用传统线栓法制作单侧大脑中动脉阻塞（MCAO）模型,神经功能评分,LDF监测插栓前后大鼠脑血流动态变化。于缺血2 h和再灌注24 h断头取脑,TTC染色检测脑片梗死灶体积。结果：基线血流均值为 (224.99±75.00) PU,局灶神经功能障碍评分0分。插栓成功MCAO模型,缺血2 h血流均值为 (67.23±6.90) PU,与基线血流差值为157.76PU,降幅约为70%（P<0.01）,差异显著。拔拴后血流均值为 (216.01±7.30) PU,与缺血2 h血流差值为148.78PU（P＜0.01）,差异显著;与基线血流差值为-8.98 PU（P>0.05）,无显著差异。再灌注24 h后,局灶神经功能障碍评分10.35分,脑片TTC染色显示梗死及水肿灶。插栓不成功模型LDF监测显示仍有血流通过,降幅少于基线的50%,再灌注24 h后,局灶神经功能障碍评分0分,TTC染色未见梗死灶。结论：LDF对大鼠脑血流的监测是除神经功能评分以外另一种判断活体大鼠MCAO模型制作成功的可靠而实用的方法。     

Expression of Fos protein in brainstem after application of l-menthol to the rat nasal mucosa

The regenerative potential of stem cells from various sources has been under intense investigation in the experimental models of cerebral ischemia. To end up with a restorative therapeutic treatment, it is crucial to get the cell transplants to the site of injury. Here, we evaluated the feasibility of small animal SPECT/CT in assessing the definite accumulation of (111)In-oxine-labeled human embryonic stem (ES) cell-derived neural progenitors and rat hippocampal progenitors after intravenous or intra-arterial administration (femoral vein vs. common carotid artery) in middle cerebral artery occlusion (MCAO) and sham-operated rats. Cell detection was carried out immediately and 24h after the infusion using a SPECT/CT device. The results showed that after intravenous injections both cell types accumulated primarily into internal organs, instead of brain. In contrast, after intra-arterial injection, a weak signal was detected in the ischemic hemisphere. Additional studies showed that the detection sensitivity of SPECT/CT device was approximately 1000 (111)In-oxine-labeled cells and labeling did not affect the cell viability. In conclusion, a small animal SPECT is powerful technique to study the whole body biodistribution of cell-based therapies. Our data showed that intravenous administration is not an optimal route to deliver neural progenitor cell-containing transplants into the brain after MCAO in rats.     

Integration of SimSET photon history generator in GATE for efficient Monte Carlo simulations of pinhole SPECT

The authors developed and validated an efficient Monte Carlo simulation (MCS) workflow to facilitate small animal pinhole SPECT imaging research. This workflow seamlessly integrates two existing MCS tools: simulation system for emission tomography (SimSET) and GEANT4 application for emission tomography (GATE). Specifically, we retained the strength of GATE in describing complex collimator/detector configurations to meet the anticipated needs for studying advanced pinhole collimation (e.g., multipinhole) geometry, while inserting the fast SimSET photon history generator (PHG) to circumvent the relatively slow GEANT4 MCS code used by GATE in simulating photon interactions inside voxelized phantoms. For validation, data generated from this new SimSET-GATE workflow were compared with those from GATE-only simulations as well as experimental measurements obtained using a commercial small animal pinhole SPECT system. Our results showed excellent agreement (e.g., in system point response functions and energy spectra) between SimSET-GATE and GATE-only simulations, and, more importantly, a significant computational speedup (up to approximately 10-fold) provided by the new workflow. Satisfactory agreement between MCS results and experimental data were also observed. In conclusion, the authors have successfully integrated SimSET photon history generator in GATE for fast and realistic pinhole SPECT simulations, which can facilitate research in, for example, the development and application of quantitative pinhole and multipinhole SPECT for small animal imaging. This integrated simulation tool can also be adapted for studying other preclinical and clinical SPECT techniques.     

微小RNA-181b通过调节热休克蛋白A5在缺血性脑卒中小鼠中的作用

目的 探讨微小RNA-181b（miR-181b）在缺血性脑卒中小鼠脑损伤中的作用及机制。 方法 采用小鼠大脑中动脉阻塞(MCAO)模型模拟缺血性脑损伤;Real-time PCR检测miR-181b mRNA表达情况;蛋白印迹观察miR-181b靶蛋白热休克蛋白A5 (HSP A5)蛋白水平变化情况;Nissl方法检测皮层缺血神经元的缺失情况;行为学方法评估小鼠的神经行为学功能损伤程度。 结果 侧脑室注射miR-181b拮抗剂可使脑内miR-181b表达水平明显降低(P<0.05,n=3);MCAO后小鼠的神经行为学功能受到严重损伤,miR-181b拮抗剂可明显缓解这些行为学改变(P<0.05,n=6);下调miR-181b可以提高HSPA5蛋白水平(P<0.05, n=3); MCAO后小鼠皮层有一定程度的神经细胞缺失,预先给予miR-181b拮抗剂发挥保护作用,神经细胞缺失减少(P<0.05,n=3)。 结论 miR-181b可能通过调节HSPA5蛋白的表达在缺血性脑卒中小鼠脑损伤中发挥重要作用。     

Nylon filament coated with paraffin for intraluminal permanent middle cerebral artery occlusion in rats

A variety of intraluminal nylon filament has been used in rat middle cerebral artery occlusion (MCAO) models. However the lesion extent and its reproducibility vary among laboratories. The properties of nylon filament play a part of reasons for these variations. In the present study, we used paraffin-coated nylon filament for rat MCAO model, tested the effects and advanced improvement for making the rat MCAO. Forty male Sprague-Dawley (SD) rats were randomized into two groups, MCAO with traditional uncoated nylon filament (uMCAO) and MCAO with paraffin-coated nylon filament (cMCAO), three rats as normal group and sham group respectively. Assessment included mortality rates, model success rates, neurological deficit evaluation, and infarct volume. The study showed two rats died in uMCAO group, no rat died in cMCAO group within the 12 h. The model success rate of uMCAO was 100%, while the uMCAO group was 55% (n = 20, two died within 12 h, seven rats were excluded as the brain slices showed no TTC staining due to subarachanoid hemorrhage). Neurological evaluation demonstrated group cMCAO had more worse neurological outcomes than group uMCAO, and the difference was statistically signification (p < 0.05). TTC staining cMCAO group had significantly larger infarct volumes than uMCAO group, and also showed statistically significant difference (p < 0.05). The result demonstrated that the paraffin-coated nylon filament intraluminal occlusion provide better occlusion of middle cerebral artery than the uncoated nylon filament, improve the consistent of model, and raise the success rate to reduce the number of experimental animals. These positive results are much encouraging and interesting.     

骨髓单个核细胞移植脑梗塞大鼠的行为学评价及对乙酰胆碱水平的影响

目的观察人骨髓单个核细胞（BMMC）移植对脑梗塞大鼠的影响。方法制备大鼠大脑中动脉闭塞（MCAO）模型,将骨髓单个核细胞静脉注射脑梗塞大鼠体内进行治疗。用平横木行走实验评价大鼠运动功能;用TTC染色法观察脑梗塞区坏死比例;采用化学显色反应法测定各组大鼠脑组织和血浆中乙酰胆碱（Ach）浓度和乙酰胆碱酯酶（TChE）活性。结果与模型组比较,给予骨髓单个核细胞组大鼠行为学评分明显变高（P〈0.05）,大脑坏死面积明显减少（P〈0.01）,脑组织和血浆中的Ach水平和TChE活性显著增高和增强（P〈0.05）。结论静脉注射骨髓单个核细胞可促进脑梗塞大鼠中枢神经系统功能恢复及胆碱能系统恢复。     

骨显像诊断恶性肿瘤骨转移临床价值的探讨

探讨骨显像在诊断恶性肿瘤骨转移中的临床应用价值。478例已确诊恶性肿瘤患者均行SPECT99mTc-MDP全身骨显像,结合CT、MRI检查结果,分析计算全身骨显像对恶性肿瘤骨转移的灵敏度、特异性、阳性预测值、阴性预测值、诊断准确率等,并统计恶性肿瘤骨转移的高发部位。获得数据采用χ2检验分析处理。结果显示：骨显像的灵敏度、特异性、阳性预测值、阴性预测值和诊断准确率分别为：91.9%、68.2%、90.6%、74.1%和79.3%。结论：骨显像对探测骨骼病理改变的灵敏度非常高,在早期诊断恶性肿瘤骨转移方面较MRI/CT敏感（χ2=3.99P〈0.05）。做为一种简便、安全、灵敏的显像技术,其性价比很高,值得临床大力推广。     

无痴呆综合症的艾滋病患者局部脑血流的变化

目的:观察无痴呆综合症的艾滋病(AIDS)患者局部脑血流(rCBF)的变化。方法:对4例无痴呆综合症的男性AIDS患者(IV期)进行了^99mTc-双半胱乙脂(ECD)脑血流灌注断层显像, 并定量测定rCBF。16例性别、年龄匹配的健康者作正常对照。结果:4例无痴呆综合症的AIDS患者双侧额、顶、颞叶、基底节和丘脑、以及直回和桥脑rCBF明显低于正常对照组(P＜0.01)。结论:无痴呆综合症的AIDS患者存在脑皮层和皮层下rCBF减少。