电子束CT犬实验性梗塞心肌的三维重建与病理对照

用电子束ＣＴ重建能表示梗塞部位及形态的心脏三维图象，通过结扎犬心冠状动脉左旋支及其分支，形成左室侧壁梗塞区，经电子束ＣＴ增强容积扫描方式得到犬心断面。利用区域扩充法对梗塞心肌进行自动分割，采用表面重建法完成犬心的三维重建，用硝基四唑对病理切片进行染色，结果：清晰显示出了犬心的三维图象，并在三维图象上精确表示出了梗塞的部位及形态。结论：在造影剂注射量与扫描起始时间适宜的条件下，利用电子束ＣＴ可以诊断梗塞的部位与大小，且能重建出反应病变情况的心脏三维图象     

Image feature analysis and computer-aided diagnosis in digital radiography: automated detection of pneumothorax in chest images.

In order to aid radiologists in the diagnosis of pneumothorax from chest radiographs, an automated method for detection of subtle pneumothorax is being developed. The computerized method is based on the detection of a fine curved-line pattern, which is a unique feature of radiographic findings of pneumothorax. Initially, regions of interest (ROIs) are determined in each upper lung area, where subtle pneumothoraces commonly appear. The pneumothorax pattern is enhanced by the selection of edge gradients within a limited range of orientations. Rib edges included in this edge-enhanced image are removed, based on the locations of posterior ribs that are determined separately. A subtle curved line due to pneumothorax is then detected by means of the Hough transform. The detected pneumothorax pattern is marked on the chest image displayed on a CRT monitor. With the present computer method applied to 50 chest images (28 normals and 22 abnormals with pneumothorax), we were able to detect 77% of pneumothoraces, with 0.44 false-positives per image.     

Solution for Nonuniformities and Spatial Noise in Medical LCD Displays by Using Pixel-Based Correction

Liquid crystal displays (LCD) are rapidly replacing cathode ray tube displays (CRT) for medical imaging. LCD technology has improved significantly in the last few years and has important advantages over CRT. However, there are still some aspects of LCD that raise questions as to the usefulness of liquid crystal displays for very subtle clinical diagnosis such as mammography. One drawback of modern LCD displays is the existence of spatial noise expressed as measurable stationary differences in the behavior of individual pixels. This type of noise can be described as a random stationary image superposed on top of the medical image being displayed. It is obvious that this noise image can make subtle structures invisible or add nonexistent patterns to the medical image. In the first case, subtle abnormalities in the medical image could remain undetected, whereas in the second case, it could result into a false positive. This paper describes a method to characterize the spatial noise present in high-resolution medical displays and a technique to solve the problem. A medical display with built-in compensation for the spatial noise at pixel level was developed and improved image quality is demonstrated.     

Diagnostic usefulness of chest computed radiography—Film versus cathode-ray tube images

Seventy-one plain chest images obtained by computed radiography (CR) with an imaging plate were interpreted on film and two kinds of cathode-ray tube (CRT) monitors installed separately at two facilities (1,024 × 1,536 pixels, 8 bits, and 1,024 × 1,280 pixels, 10 bits) by 20 radiologists and four chest internists. The clinical categories of these 71 cases included pulmonary nodules and interstitial abnormalities. Image reading sessions were held over a total of 4 days, ie, 2 days and then another 2 days, 3 weeks later. Twenty-four observers formed four groups with six members each. Two groups read either films or CRT images at one of the two facilities. In the second experiment, 26 of 71 images were compressed at 10∶1, 19 of 71 were compressed at 20∶1, and 26 were not compressed. Analyses of the areas under the receiver-operating characteristic curves showed no significant differences in detection of pulmonary abnormalities between film and CRT. In detecting interstitial pulmonary abnormalities, film was more sensitive than CRT monitor. There were no significant differences in observers’ performances between the two different kinds of CRT workstation. Subjective evaluation of image quality showed that images irreversibly compressed to the ratios of 10∶1 and 20∶1 were inferior to original images. Although further considerations are needed with regard to spatial resolution requirements, image processing, and image compression, the utilization of CR CRT image as a substitute for CR film image will be possible.

     

The Right Mediastinal Border and Central Venous Anatomy on Frontal Chest Radiograph—Direct CT Correlation

We describe a direct and accurate method for defining chest radiographic anatomy and use this method to delineate the anatomic composition of the right mediastinal border in an adult population. Intravenous contrast-enhanced computed tomographic scans of the chest and accompanying scout tomograms from 99 adults without previously known or detected cardiopulmonary disease that could potentially distort mediastinal, cardiac, or pulmonary anatomy were retrospectively evaluated. Transverse CT images through the mediastinum were directly referenced to the respective acquisition location on the scout tomogram via the acquisition reference line. The anatomic composition of the right mediastinal border on the scout tomogram was determined by drawing a vertical line tangential to the most lateral right mediastinal structure in each transverse CT image. The lengths and relationships of these structures were tabulated. These results will help to create a consensus among radiologists and other clinicians regarding radiographic anatomy, allowing improved localization of mediastinal pathology and enabling more optimal positioning of vascular and cardiac support devices.     

Low-cost soft-copy display accuracy in the detection of pulmonary nodules by single-exposure dual-energy subtraction: Comparison with hard-copy viewing

This study endeavored to clarify the usefulness of single-exposure dual-energy subtraction computed radiography (CR) of the chest and the ability of soft-copy images to detect low-contrast simulated pulmonary nodules. Conventional and bone-subtracted CR images of 25 chest phantom image sets with a low-contrast nylon nodule and 25 without a nodule were interpreted by 12 observers (6 radiologists, 6 chest physicians) who rated each on a continuous confidence scale and marked the position of the nodule if one was present. Hard-copy images were 7 x 7-inch laser-printed CR films, and soft-copy images were displayed on a 21-inch noninterlaced color CRT monitor with an optimized dynamic range. Soft-copy images were adjusted to the same size as hard-copy images and were viewed under darkened illumination in the reading room. No significant differences were found between hard- and soft-copy images. In conclusion, the soft-copy images were found to be useful in detecting low-contrast simulated pulmonary nodules.     

Characterization of color CRT display systems for monochrome applications

Soft-copy presentation of medical images is becoming more and more important as medical imaging is strongly moving toward digital technology, and health care facilities are converting to filmless hospital and radiological information management. Although most medical images are monochrome, frequently they are displayed on color CRTs, particularly if general-purpose workstations or PCs are used for medical viewing. In the present report, general measurement and modeling procedures for the characterization of color CRT monitors for monochrome presentation are introduced. The contributions from the three color channels (red, green, and blue) are weighted according to the spectral sensitivity of the human eye for photopic viewing. The luminance behavior and the resolution capabilities of color CRT monitors are analyzed with the help of photometer and charge-coupled device (CCD) camera measurements. For the evaluation of spatial resolution, a two-dimensional Fourier analysis of special test images containing white noise (broadband response) is employed. A stage model for a color CRT monitor is developed to discuss the effects of scanning and dot sampling. Furthermore, display intrinsic veiling glare and reflectivity of typical color CRT monitors are measured and compared with those of monochrome CRT monitors. The developed methods and models allow one to describe the image quality aspects of color monitors if they are applied for medical monochrome image presentation. Particularly, because of the reduced luminance and dynamic range of color monitors, the calibration and control of their luminance curves is a very important task. For present color CRT monitors, 1,280 x 1,024 turns out to be an intrinsic limit for the displayable matrix of medical images.     

Correlation of magnetic resonance imaging with histopathology in arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C)

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an asymptomatic cardiac disease characterized by fatty infiltration of the right ventricular myocardium and often results in sudden cardiac death. ARVD/C diagnosis includes the assessment of fatty infiltration, which can be achieved noninvasively with cardiovascular magnetic resonance (CMR). The standard CMR protocol places the signal-generating coil directly on the anterior chest wall and produces a nonspecific high intensity signal that obscures the high signal from fatty infiltration. The aim of this study was to determine whether increasing the coil-to-chest distance would improve identification of fatty infiltration. Thoraces from seven embalmed cadavers were imaged on a conventional 1.5 Tesla CMR scanner using the control protocol and an experimental protocol, with a 6 cm coil-to-chest distance. A representative axial MR image and corresponding gross section of the heart were analyzed in each case. Fatty infiltration was graded in a blinded fashion on the MR images with independent histopathologic assessment. In five of the seven cases, the experimental protocol provided a correlation between CMR and histopathology that was as good as or better than the control protocol. The experimental protocol was also better in preventing false positive diagnosis in cases of minimal infiltration. Thus, the experimental protocol showed a stronger correlation with histopathology than did the control protocol. Increasing the distance between the anterior surface coil and chest wall may improve classification of presence or absence of fatty infiltration in the right ventricular myocardium, potentially improving the noninvasive detection of ARVD/C with CMR.     

Recognition of chest radiograph orientation for picture archiving and communications systems display using neural networks

A neural network classification scheme was developed that enables a picture archiving and communications system workstation to determine the correct orientation of posteroanterior or anteroposterior chest images. This technique permits thoracic images to be displayed conventionally when called up on the workstation, and therefore reduces the need for reorientation of the image by the observer. Feature data were extracted from 1,000 digitized chest radiographs and used to train a two-layer neural network designed to classify the image into one of the eight possible orientations for a posteroanterior chest image. Once trained, the neural network identified the correct image orientation in 888 of 1,000 images that had not previously been seen by the neural network. Of the 112 images that were incorrectly classified, 106 were mirror images of the correct orientation, whereas only 6 actually had the caudal-cranial axis aligned incorrectly. The causes for misalignment are discussed.     

Optical disk archiving using a personal computer: a solution to image storage problems in diagnostic imaging departments

The paper describes an approach to solving the problem of providing a large-capacity image archive for diagnostic imaging departments at reasonable cost. Optical disk stores, when fitted retrospectively to scanners, are very expensive and may not be compatible with existing computer hardware. We describe the use of an industry standard personal computer (PC) linked to a standard 5 1/4-in. optical disk drive as a 'stand-alone' image store. Image data are transferred from the scanner using 8-in. floppy disks, and these are read into the PC using an attached 8-in. floppy disk drive and then transferred to the optical disk. The patient details (patient name, ID, date, etc.) are entered into a database program held on the PC and these are used to generate a reference pointer to the optical disk file through which the data can be retrieved. Data retrieval involves entering the patient details into the data base and inserting a blank 8-in. floppy disk into the drive attached to the PC. A sector copy is then made from the optical disk to the 8-in. floppy disk, which can then be used at the viewing station at the scanner. The system is flexible since it can accept data from a variety of sources in any format; it is also low cost and operates independently of the scanner. The hardware is industry standard, ensuring low maintenance costs.     

Multiple extranodal follicular dendritic cell tumors initially presenting in the soft tissue in the chest wall

A follicular dendritic cell (FDC) tumor that involved the soft tissue of the chest wall, liver and thyroid was reported in a 72-year-old Japanese man. A biopsy specimen from the chest wall showed an uncommon malignant soft-tissue tumor. No distinct immunohistochemical reactions were found. The patient died 1 year after the initial presentation. No definite diagnosis was given until autopsy was performed. Upon autopsy, each tumor was well-circumscribed and a solid tan-gray color on cut section. Microscopically, the tumor cells were composed of oval to spindle cells arranged in a short fascicular growth pattern. The autopsy specimen from the soft tissue of the chest wall had a strong reaction for CD21/CD35 and clusterin, a new FDC marker, whereas the biopsy specimen had an undistinct reaction for CD21/CD35 and a weak reaction for clusterin. FDC makers assisted in this diagnosis, especially with the autopsy specimen. In conclusion, it was difficult to diagnose an FDC tumor because of the particular tumor sites involved, lack of characteristic microscopic features, and because of aggressive tumor behavior.     

Mathematical model of chest wall mechanics: A phenomenological approach

A mathematical model of chest wall mechanics, based on a phenomenological approach to force balances, provides a quantitative framework for analyzing many types of chest wall movements by using orthogonal displacement coordinates. The moveable components of the ventilatory system include the rib cage, diaphragm, and abdomen. A distinction is made between the lung-apposed and diaphragm-apposed actions on the rib cage. The model equations are derived from “pressure” balances and geometrical relations of the compartments; the stress-displacement relations are hyperbolic. With this model we simulated stiff and flaccid chest wall behavior under normal and constrained conditions associated with abdominal compression, a Mueller maneuver, and a diaphragmatic isometric inspiration. We also examined situations that produce paradoxical as well as orthodox inspiratory movements. The results of these simulations were quantitatively consistent with available data from the literature. A phenomenon predicted by the stiff-wall model during quasi-static inspiration is that the rib cage displacement is negligible near residual volume, but then increases dramatically with lung volume. Since this mathematical model has a sound physical basis and is more comprehensive than previous models, it can be used to predict and analyze the behavior of the chest wall under a wide variety of circumstances.     

Investigation of basic imaging properties in digital radiography. 9. Effect of displayed grey levels on signal detection

Results of an 18-alternative forced-choice experiment have shown that observers were capable of detecting a signal with a contrast of 1 in terms of 10-bit data which were displayed on a CRT monitor with an 8-bit video generator and a window width setting of 1024. We investigated the conditions under which 10-bit signal data can be detected when displayed using an 8-bit video generator. Results show that the 10-bit digital quantum noise, which was approximately Gaussian distributed, can act as a carrier of the signal data, thus allowing a signal having a contrast of a fraction of a displayed grey level to be detected. We demonstrate the relationship between the rms value of the digital noise (obtainable with a clinical digital subtraction angiography system under various exposure levels), the number of bits available in the display video generator, and the "transmitted" signal contrast displayed on the CRT monitor.     

Mesenchymal hamartomas of the chest wall in infancy: radiologic and pathologic correlation

Mesenchymal hamartoma of the chest wall is a rare tumor with about 53 reported cases in the English literature. We reviewed six chest wall mesenchymal hamartomas in four patients, including two cases with multiple lesions, with specific focus on the radiologic and pathologic correlation. All cases occurred in neonates or infants with ages ranging from seven hours to seven months. They were diagnosed with plain chest radiographs (n=6), ultrasonography (n=2), chest CT scan (n=6), whole body bone scan (n=2) and MRI (n=3). All cases except a small one without cystic change showed the typical features of mesenchymal hamartoma radiographically and pathologically. Radiologically they were well-circumscribed masses with solid and cystic components with multiple fluid-fluid levels in association with single or multiple rib destruction or change. The CT scan showed the typical findings of chest wall hamartoma, and the MR showed heterogeneous signal intensities of the mass on T1- and T2-weighted images. The MR also revealed more concisely a secondary aneurysmal bone cyst formation with multiple fluid-fluid levels on the T2-weighted image. Microscopically, they showed alternating areas of cartilaginous islands and primitive appearing mesenchymal proliferation, which corresponded well with the solid component on the radiologic findings. The areas of bone formation and blood-filled cystic spaces matched the calcified or ossified densities and the cystic components, respectively. A small case without cystic change showed peculiar radiological and pathological findings resembling an osteochondroma. In conclusion, mesenchymal hamartoma of the chest wall in infancy is quite rare and sometimes can be misdiagnosed as malignancy due to the bone-destroying radiographic appearance and the highly cellular and mitotically active microscopic features, unless the radiologists and pathologists are aware of the characteristic clinical, radiological, and pathological findings. Imaging studies can usually make a correct diagnosis with good correlation to the pathologic findings.     

Unusual association of pulmonary artery sling with right aortic arch and aberrant left subclavian artery

We present an unusual case of vascular sling, tracheal stenosis by complete cartilaginous ring, and aberrant left subclavian artery with right aortic arch that underwent successful surgical repair for the sling. These abnormalities were suspected from unusual multiple indentations found on esophagogram. Complete preoperative diagnosis was established with chest computerized tomogram combined with angiography.     

Epithelioid angiosarcoma at chest wall which needs to be carefully distinguished from malignant mesothelioma: report of a rare case

Angiosarcoma is a malignant soft tissue tumor the cells of which variably recapitulate the morphologic and functional features of normal endothelium. Most lesions are located in the deep muscles of the lower extremities followed by the arm, trunk and head and neck. Herein we present a case of epithelioid angiosarcoma which is a variant of angiosarcoma at chest wall in a 73-year-old female. Morphologically, the tumor cells are arranged predominantly in luminal structures which can be seen in both angiosarcoma and malignant mesothelioma. Most of the tumor cells are large rounded “epithelioid” cells with abundant eosinophilic cytoplasm which can be also seen in both tumors. The epithelioid of cytomorphology and the localization at chest wall of this case may remind of a diagnosis of malignant mesothelioma which should be carefully distinguished from epithelioid angiosarcoma from imaging and morphology. CT scanning of the patient shows a mass at her chest wall, the majority of which is around the rib but not inside the lung which indicates a tumor originates more likely from soft tissues of chest wall but not pleura. Immunohistochemical staining shows that the tumor cells are positive for cytokeratin, CD31, Vimentin and WT1, and negative for CEA, TTF-1, Calretinin, Mesothelial Cell (MC), CD56, CK19, and Hepatocyte. Thus this case is diagnosed as epithelioid angiosarcoma but not malignant mesothelioma. From this case we suggest that carefully reading and understanding of the imaging are a very important clue for appropriate diagnosis. A misdiagnosis may occur on the basis of misunderstanding of tumor localization and a consequent inappropriate immunohistochemical staining programme.     

一种新计算机三维重建法用于猫肺连续切片

介绍了基于计算机工作站的连续组织学切片图像三维重建与显示技术。常规制作猫肺连续石蜡切片,切片图像经微机图像分析系统数字化后存在微机磁盘,将图像数据文件传输到Ｓｕｎ工作站硬盘上,作数字图像处理,采用“金字塔异或指数”方法完成图像对位,较好地解决了连续切片图像的精确对位问题,具体的重建算法采用光线追踪进行三维显示的体积显示算法,在计算机屏幕上从不同角度显示了肺内血管和细支气管等结构的立体图像。     

The determination of short-term breast volume changes and the rate of synthesis of human milk using computerized breast measurement.

The feasibility of using sequential breast volume measurements as a method of studying short-term rates of milk synthesis in women has been established. We have developed a rapid Computerized Breast Measurement system for the determination of breast volume, based upon the Shape Measurement System. A circle encompassing all the breast tissue is drawn in black face paint on the subject's skin. Six patterns of sixty-four horizontal light stripes are projected onto the breast and chest wall surface. A CCD camera relays video images to a computer, which produces a model of the chest by active triangulation. The volume of the breast and the chest wall segment enclosed by the circle is then calculated. The precision of the method was dependent upon the subject repositioning carefully. The coefficient of variation of replicate measurements was 1.6%. The accuracy of the method was established by comparing the change in breast volume before and after a breast-feed with the amount of milk removed by the infant as determined by test weighing. There was a close relationship between the removal of milk by the infant (x) and the change in breast volume (y), (r = 0.93, n = 73, y = 1.10x - 3.25). The rates of milk synthesis between breast-feeds, for six women determined on one to eight occasions, varied from 11 to 58 ml/h. The results show that the amount of milk available in the breast is not necessarily an important determinant of the amount of milk removed by the infant at a breast-feed.