顺应现代影像学发展创建断层解剖学课程

７０年代以来,超声（ＵＳ）、ＣＴ、ＭＲＩ、单光子发射断层扫描（ＳＰＥＣＴ）、正电子发射断层扫描（ＰＥＴ）和介入放射学相继崛起并迅速普及,已成为影像学诊治的主流。这些影像技术赖以诊断和介入治疗的形态学基础是断层解剖学,因此,在医药院校内开设断层解剖学课...     

断层影像解剖学的现状与未来：首届全国断层影像解剖学论坛总结

断层影像解剖学的现状与未来——首届全国断层影像解剖学论坛总结刘树伟①张绍祥②吴德昌③刘丰春④汪亚晴⑤赵斌⑥本世纪７０年代以来，超声、ＣＴ、ＭＲＩ、ＳＰＥＣＴ、ＰＥＴ、介入放射学及立体定向技术（γ—刀、Ｘ—刀）已成为医学影像学诊治的主流，是当代医学迈入...     

SPECT受检者检查前后的细胞遗传学研究

对单光子发射计算机断层（ＳＰＥＣＴ）受检者进行了检查前及检查后的自身对照分析，发现检查（采用９９ｍＴｃ－ＭＤＰ，剂量５５５～９２５ＭＢｑ）后２４小时受检者染色体畸变率、微核率、姐妹染色单体交换及脆性部位表达频率均明显增加，但对细胞增殖周期无延缓作用。提示，ＳＰＥＣＴ检查时注入受检者体内的９９ｍＴｃ－ＭＤＰ（５５５～９２５）ＭＢｑ）诱发了人类遗传物质的损伤，应引起临床医生的重视。     

发作间期PET和SPECT检查对颞叶癫痫定位的诊断价值

目的：探讨发作间期１８Ｆ脱氧葡萄糖（ＦＤＧ）正电子发射断层扫描（ＰＥＴ）和９９ｍＴｃ已撑半胱氨酸（ＥＣＤ）单光子发射断层扫描（ＳＰＥＣＴ）对难治性颞叶癫痫（ＴＬＥ）的定位诊断价值。方法：５３例脑电图（ＥＥＧ）定位明确的难治性ＴＬＥ患者分别行发作间期１８ＦＦＤＧＰＥＴ和９９ｍＴｃＥＣＤＳＰＥＣＴ检查。其中２１例磁共振（ＭＲＩ）显示有结构性病变并与ＥＥＧ定位结果一致。结果：ＭＲＩ异常组均在ＰＥＴ和ＳＰＥＣＴ相应部位出现低代谢和低灌注表现。ＭＲＩ正常组，ＰＥＴ定位准确率为８４％，显著高于ＳＰＥＣＴ的５６％（Ｐ＜００５）。结论：对于无结构性病变的颞叶癫痫，发作间期ＰＥＴ检查有较高的定位诊断价值，ＳＰＥＣＴ的临床意义相对较小。     

短暂性缺血性发作的SPECT改变

本文采取ＳＰＥＣＴ对２５例ＴＩＡ患者的脑血流动力学进行观察和分析。结果可见ＳＰＥＣＴ对无临床症状的ＴＩＡ的脑血流动力学改变具有很高的敏感性。在ＳＰＥＣＴ所显示的低灌流的改变中发现：（１）ＳＰＥＣＴ所显示低灌流区的大小与过去是否有过反复发作有关。（２）ＳＰＥＣＴ所见的低灌流范围与ＣＴ或ＭＲＩ结果比较发现，低灌流范围小的ＣＴ或ＭＲＩ有腔隙性梗塞灶的多；低灌流范围较大的脑萎缩的多。（３）同时伴有同侧丘脑和小脑血流降低。用ＳＰＥＣＴ对ＴＩＡ病人的脑血液动力学进行观察，不仅能了解病人的脑血流混乱的程度，也可以根据检查结果及时给以血管扩张剂或抗凝治疗，有助于防止脑梗塞的形成。     

^99mTc—MIBI心肌断层显像与冠状动脉造影的相关 …

目的 定量评价核素心肌断层显像（ＳＰＥＣＴ）与冠状动脉造影血管病变的相关性。方法对５０例冠心病（ＣＡＤ）病变血管狭窄程度、狭窄面积与ＳＰＥＣＴ心肌缺血程度、缺血面积进行双定量分析比较。结果 病变血管直径、血管面积和血管狭窄程度、血管狭窄面积相关性很高，ｒ＝０．９８、０．９３；血管狭窄程度、血管狭窄面积与ＳＰＥＣＴ心肌缺血程度、心肌缺血面积相关性较低（ｒ＝－０．２６、０．３３）；病变血管直径与ＳＥＰ     

患消化性溃疡,慢性胃炎的飞行人员性格和某些神经内分泌测定

本文对３３例患消化性溃疡或／和慢性胃炎的飞行人员进行艾森克人格问卷（ＥＰＱ）测试，并测定其血浆β－内腓肽（β－ＥＰ）、强腓肽（ＤＹＮＡ）、ＡＣＴＨ、胃泌素（ＳＨＧ）、胃动素（ＭＴＬ）、ＣＡＭＰ、ＣＧＭＰ水平，同时和３１例健康飞行人员对照。经统计学处理后显示：Ｎ、Ｐ、Ｅ分与对照组无显著性差异，β－ＥＰ、ＡＣＴＨ、ＳＨＧ、ＣＡＭＰ呈上升趋势，临床治愈后均有下降，并趋于正常，与对照组比较和治疗前后比较均有显著性差异。     

急性一氧化碳中毒后迟发性脑病的诱发电位、CT和脑电图研究

目的：研究急性一氧化碳中毒后迟发性脑病（ＤＥＡＣＭＰ）患者的诱发电位（ＥＰ）、ＣＴ和脑电图（ＥＥＧ）。方法：对４６例ＤＥＡＣＭＰ患者进行ＥＰ、ＣＴ和ＥＥＧ检查。结果：异常率体感诱发电位（ＳＥＰ）８３％、视觉诱发电位（ＶＥＰ）６３％，脑干听觉诱发电位（ＢＡＥＰ）３０％，ＣＴ７１％，ＥＥＧ１００％。ＳＥＰ中的Ｐ４０、Ｎ５０、Ｐ６０和Ｎ７５峰潜伏期（ＰＬ）比正常对照组显著延长。ＶＥＰ的Ｐ１００ＰＬ较对照组明显延长。ＢＡＥＰ的Ⅰ、Ⅲ和Ⅴ波ＰＬ及Ⅰ—Ⅲ、Ⅲ—Ⅴ和Ⅰ—Ⅴ峰间期（ＩＰＬ）与对照组比较无显著性差异。结论：ＥＰ、ＣＴ和ＥＥＧ结合临床观察，对ＤＥＡＣＭＰ的定位诊断、病情判断与预后评估均有意义。     

断层影像解剖学网络教学模式的构建初步探讨

超声成像 (ＵＳＧ)、ＣＴ、ＭＲＩ、单电子发射计算机断层显像(ＳＰＥＣＴ)和正电子发射计算机断层显像 (ＰＥＴ)等成为医学影像诊治的主流。这些断层影像技术赖以诊断和介入性治疗疾病的形态学基础是断层解剖学 ,断层解剖学与影像解剖学结合 ,即形成了一门新兴的学科。这是当代医学迈入影像医学时代的重要标志。在医学院校内开设断层影像解剖学课程 ,是现代医学发展的迫切需求 ,对提高教学质量和培养高层次的临床医师 ,具有十分重要的理论和实用价值。根据教学方法发展方向及满足临床发展的需要 ,并借鉴国内外网络教学的经验 ,笔者结合医学…     

正常老人认知功能与神经学检查的相关分析

目的：探讨正常老人脑结构改变、脑电生理学变化与认知功能的关系。方法：对４１名正常老人做系统的神经心理测验（ＮＰＴ）、头颅ＣＴ摄片（ＣＴ）、脑电地形图（ＢＥＡＭ）及脑诱发电位（ＢＥＰ）检查。结果：ＮＰＴ指标与ＣＴ测量值相关显著者不多，仅侧脑室前角扩大（额叶萎缩）与部分认知功能下降有显著相关；而ＮＰＴ指标与ＢＥＡＭ反映的脑电活动，尤其是左侧前额和额区的慢波化密切相关；大部分认知功能与脑诱发电位的潜伏期Ｐ２相关。结论：正常老人的额叶萎缩，额区、前额的慢波化可能是其受控加工认知功能下降的基础。     

Statistical and heuristic image noise extraction (SHINE): a new method for processing Poisson noise in scintigraphic images

Poisson noise is one of the factors degrading scintigraphic images, especially at low count level, due to the statistical nature of photon detection. We have developed an original procedure, named statistical and heuristic image noise extraction (SHINE), to reduce the Poisson noise contained in the scintigraphic images, preserving the resolution, the contrast and the texture. The SHINE procedure consists in dividing the image into 4 x 4 blocks and performing a correspondence analysis on these blocks. Each block is then reconstructed using its own significant factors which are selected using an original statistical variance test. The SHINE procedure has been validated using a line numerical phantom and a hot spots and cold spots real phantom. The reference images are the noise-free simulated images for the numerical phantom and an extremely high counts image for the real phantom. The SHINE procedure has then been applied to the Jaszczak phantom and clinical data including planar bone scintigraphy, planar Sestamibi scintigraphy and Tl-201 myocardial SPECT. The SHINE procedure reduces the mean normalized error between the noisy images and the corresponding reference images. This reduction is constant and does not change with the count level. The SNR in a SHINE processed image is close to that of the corresponding raw image with twice the number of counts. The visual results with the Jaszczak phantom SPECT have shown that SHINE preserves the contrast and the resolution of the slices well. Clinical examples have shown no visual difference between the SHINE images and the corresponding raw images obtained with twice the acquisition duration. SHINE is an entirely automatic procedure which enables halving the acquisition time or the injected dose in scintigraphic acquisitions. It can be applied to all scintigraphic images, including PET data, and to all low-count photon images.     

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.     

Validation of the Monte Carlo simulator GATE for indium-111 imaging

Monte Carlo simulations are useful for optimizing and assessing single photon emission computed tomography (SPECT) protocols, especially when aiming at measuring quantitative parameters from SPECT images. Before Monte Carlo simulated data can be trusted, the simulation model must be validated. The purpose of this work was to validate the use of GATE, a new Monte Carlo simulation platform based on GEANT4, for modelling indium-111 SPECT data, the quantification of which is of foremost importance for dosimetric studies. To that end, acquisitions of (111)In line sources in air and in water and of a cylindrical phantom were performed, together with the corresponding simulations. The simulation model included Monte Carlo modelling of the camera collimator and of a back-compartment accounting for photomultiplier tubes and associated electronics. Energy spectra, spatial resolution, sensitivity values, images and count profiles obtained for experimental and simulated data were compared. An excellent agreement was found between experimental and simulated energy spectra. For source-to-collimator distances varying from 0 to 20 cm, simulated and experimental spatial resolution differed by less than 2% in air, while the simulated sensitivity values were within 4% of the experimental values. The simulation of the cylindrical phantom closely reproduced the experimental data. These results suggest that GATE enables accurate simulation of (111)In SPECT acquisitions.     

A dual modality approach to quantitative quality control in emission tomography

Routine quality control (QC) and optimization of image quality of reconstructed images in single photon emission computed tomography (SPECT) and positron emission tomography (PET) remains a relatively qualitative exercise. With the advent of combined SPECT/CT and PET/CT devices, and accurate post hoc co-registration algorithms, the potential exists to utilize high resolution structural information for QC evaluation in addition to their use for anatomical correlation in clinical studies. The aim of this work was to explore, in principle, the uses of x-ray CT data of QC phantoms used in SPECT and PET to develop more objective assessments of performance of the emission tomographic (ET) devices and reconstructed data. A CT reconstruction of a novel ET QC phantom was segmented into the various compartments it contained. Using software, the voxel values in the different compartments were then altered to correspond to the concentration of the radioactivity in the actual scan of the same phantom on the SPECT system. This produces a high resolution version of a 'perfect' ET scan. Image co-registration techniques were then used to spatially align the synthetic high resolution SPECT scan to the measured SPECT scan. Various parameters can then be objectively derived from the registered data, for example, image contrast, spatial resolution, spatial non-uniformity, etc. In this study, we have used this approach to estimate spatial resolution (full width at half maximum, FWHM) and recovered contrast in reconstructed images of a SPECT phantom. Two independent methods were used to measure spatial resolution, obtaining excellent agreement. In conclusion, the ability to produce high resolution synthetic phantoms in emission tomography QC affords an objective approach to assessing system performance and optimizing protocols which is readily automated and quantifiable.     

Performance of a PSPMT based detector for scintimammography

In breast scintigraphy, compact detectors with high intrinsic spatial resolution and small inactive peripheries can provide improvements in extrinsic spatial resolution, efficiency and contrast for small lesions relative to larger conventional cameras. We are developing a pixelated small field-of-view gamma camera for scintimammography. Extensive measurements of the imaging properties of a prototype system have been made, including spatial resolution, sensitivity, uniformity of response, geometric linearity and energy resolution. An anthropomorphic torso phantom providing a realistic breast exit gamma spectrum has been used in a qualitative study of lesion detectability. A new type of breast imaging system that combines scintimammography and digital mammography in a single upright unit has also been developed. The system provides automatic co-registration between the scintigram and the digital mammogram, obtained with the breast in a single configuration. Intrinsic spatial resolution was evaluated via calculation of the phase-dependent modulation transfer function (MTF). Measurements of extrinsic spatial resolution, sensitivity and uniformity of response were made for two types of parallel hole collimator using NEMA (National Electrical Manufacturers Association) protocols. Geometric linearity was quantified using a line input and least squares analysis of the measured line shape. Energy resolution was measured for seven different crystal types, and the effectiveness of optical grease coupling was assessed. Exit gamma spectra were obtained using a cadmium zinc telluride based spectrometer. These were used to identify appropriate radioisotope concentrations for the various regions of an anthropomorphic torso phantom, such that realistic scatter conditions could be obtained during phantom measurements. For prone scintimammography, a special imaging table was constructed that permits simultaneous imaging of both breasts, as well as craniocaudal views. A dedicated breast imaging system was also developed that permits simultaneous acquisition and superposition of planar gamma images and digital x-ray images. The intrinsic MTF is nonstationary, and is dependent on the phase relationship between the signal and the crystal array matrix. Averaged over all phases, the MTF is approximately 0.75, 0.57 and 0.40 at spatial frequencies of 1.0, 1.5 and 2.0 cycles per cm, respectively. The phase averaged line spread function (LSF) has a FWHM value of 2.6 mm. Following uniformity corrections, the RMS deviations in flood images are only slightly greater than is predicted from counting statistics. Across an 80 mm section of the active area, the differential linearity is 0.83 mm and the absolute linearity 2.0 mm. Using an anthropomorphic torso phantom with detachable breasts, scatter radiation similar to that observed exiting the breast of scintimammography patients was observed. It was observed that scattered gamma rays can constitute the majority of the radiation incident on the detector, but that the scatter-to-primary ratio varies significantly across the field of view, being greatest in the caudal portion of the breast, where scatter from the liver is high. Using a lesion-to-breast concentration ratio of 6:1, a 1.0 cm3 simulated breast lesion was detectable in lateral images obtained with both the developmental camera and with a clinical camera, while a 0.35 cm3 lesion was detectable in neither. Utilization of the dual x-ray transmission, gamma emission breast imaging system greatly increases the conspicuity of scintimammographic lesions relative to prone imaging, as well as greatly facilitating the localization and identification of structures in the gamma image. The prototype imaging gamma detector exhibits spatial resolution superior to that of conventional cameras, and comparable uniformity of response and geometric linearity. Because of light losses in the crystals, the energy resolution is inferior to that of single crystal NaI(Tl) came     

Joint optimization of collimator and reconstruction parameters in SPECT imaging for lesion quantification

Obtaining the best possible task performance using reconstructed SPECT images requires optimization of both the collimator and reconstruction parameters. The goal of this study is to determine how to perform this optimization, namely whether the collimator parameters can be optimized solely from projection data, or whether reconstruction parameters should also be considered. In order to answer this question, and to determine the optimal collimation, a digital phantom representing a human torso with 16 mm diameter hot lesions (activity ratio 8:1) was generated and used to simulate clinical SPECT studies with parallel-hole collimation. Two approaches to optimizing the SPECT system were then compared in a lesion quantification task: sequential optimization, where collimation was optimized on projection data using the Cramer–Rao bound, and joint optimization, which simultaneously optimized collimator and reconstruction parameters. For every condition, quantification performance in reconstructed images was evaluated using the root-mean-squared-error of 400 estimates of lesion activity. Compared to the joint-optimization approach, the sequential-optimization approach favoured a poorer resolution collimator, which, under some conditions, resulted in sub-optimal estimation performance. This implies that inclusion of the reconstruction parameters in the optimization procedure is important in obtaining the best possible task performance; in this study, this was achieved with a collimator resolution similar to that of a general-purpose (LEGP) collimator. This collimator was found to outperform the more commonly used high-resolution (LEHR) collimator, in agreement with other task-based studies, using both quantification and detection tasks.     

A prototype instrument for single pinhole small animal adaptive SPECT imaging

The authors have designed and constructed a small-animal adaptive SPECT imaging system as a prototype for quantifying the potential benefit of adaptive SPECT imaging over the traditional fixed geometry approach. The optical design of the system is based on filling the detector with the region of interest for each viewing angle, maximizing the sensitivity, and optimizing the resolution in the projection images. Additional feedback rules for determining the optimal geometry of the system can be easily added to the existing control software. Preliminary data have been taken of a phantom with a small, hot, offset lesion in a flat background in both adaptive and fixed geometry modes. Comparison of the predicted system behavior with the actual system behavior is presented, along with recommendations for system improvements.     

The effects of different correction techniques on absolute volume determination with SPECT using a threshold edge detection method

Quantitation of planar radionuclide images is hampered by structures containing radioactivity which overlie or underlie the organ of interest. The introduction of single photon emission computerized tomography (SPECT) overcame this problem to a large extent and enhanced the contrast of the images. Attenuation of photons, however, degrades the resultant SPECT images and correction methods for photon absorption and scatter were subsequently proposed. The different correction methods have variable effects on the reconstructed images. If threshold techniques are used to quantitate organ volume, i.e., combining pixels with the same percentage of the maximum pixel count in the volume, the selected threshold values which give the most accurate volume determination, will be affected by the specific correction method used. In this study, the effect of various SPECT image correction methods on threshold was investigated. A thorax phantom containing volumes ranging from 30 to 1200 ml was used. Threshold values varying from 45.6% (210 ml without any correction) to 23.7% (1200 ml with a combination of scatter subtraction and attenuation correction) were used to produce correct quantitation when different methods were investigated. A negative correlation was found between threshold and volume. This reduction in threshold was most prominent when scatter and attenuation correction were combined. This study shows that correction methods for attenuation of photons influence the threshold value for volume quantitation and the use of a constant threshold value could lead to underestimation of larger volumes.     

Design and performance of a multi-pinhole collimation device for small animal imaging with clinical SPECT and SPECT-CT scanners

A multi-pinhole collimation device is developed that uses the gamma camera detectors of a clinical SPECT or SPECT-CT scanner to produce high-resolution SPECT images. The device consists of a rotating cylindrical collimator having 22 tungsten pinholes with 0.9 mm diameter apertures and an animal bed inside the collimator that moves linearly to provide helical or ordered-subsets axial sampling. CT images also may be acquired on a SPECT-CT scanner for purposes of image co-registration and SPECT attenuation correction. The device is placed on the patient table of the scanner without attaching to the detectors or scanner gantry. The system geometry is calibrated in-place from point source data and is then used during image reconstruction. The SPECT imaging performance of the device is evaluated with test phantom scans. Spatial resolution from reconstructed point source images is measured to be 0.6 mm full width at half maximum or better. Micro-Derenzo phantom images demonstrate the ability to resolve 0.7 mm diameter rod patterns. The axial slabs of a Micro-Defrise phantom are visualized well. Collimator efficiency exceeds 0.05% at the center of the field of view, and images of a uniform phantom show acceptable uniformity and minimal artifact. The overall simplicity and relatively good imaging performance of the device make it an interesting low-cost alternative to dedicated small animal scanners.     

Direct reconstruction of single-photon emission computed tomography images using retained matrix elements

In clinical applications, two methods of single-photon emission computed tomography (SPECT) reconstruction are widely used. These are filtered backprojection and iterative reconstruction. Filtered backprojection is fast and produces acceptable images. Iterative reconstruction is slow, but produces images of greater accuracy than backprojection. The authors sought to develop a method of SPECT reconstruction that would have the advantages of both established methods: close in speed to backprojection and with the accuracy of iterative reconstruction. This was accomplished by computing a direct solution to the set of linear equations governing SPECT reconstruction. We tested this method of SPECT reconstruction using a set of projections from a cold rod and sphere phantom. Direct reconstruction produced images having equivalent resolution to backprojected images, but with double the contrast ratio. The direct method required 10 seconds of computation per slice on a Macintosh Quadra 950 (Apple Computer; Cupertin, CA), significantly faster than most iterative methods.