Clinical evaluation of irreversible image compression: analysis of chest imaging with computed radiography

To implement a picture archiving and communication system, clinical evaluation of irreversible image compression with a newly developed modified two-dimensional discrete cosine transform (DCT) and bit-allocation technique was performed for chest images with computed radiography (CR). CR images were observed on a cathode-ray-tube monitor in a 1,024 X 1,536 matrix. One original and five reconstructed versions of the same images with compression ratios of 3:1, 6:1, 13:1, 19:1, and 31:1 were ranked according to quality. Test images with higher spatial frequency were ranked better than those with lower spatial frequency and the acceptable upper limit of the compression ratio was 19:1. In studies of receiver operating characteristics for scoring the presence or absence of nodules and linear shadows, the images with a compression ratio of 25:1 showed a statistical difference as compared with the other images with a compression ratio of 20:1 or less. Both studies show that plain CR chest images with a compression ratio of 10:1 are acceptable and, with use of an improved DCT technique, the upper limit of the compression ratio is 20:1.     

JPEG2000 compression of thin-section CT images of the lung: effect of compression ratio on image quality

PURPOSE: To assess retrospectively the effect of the Joint Photographic Experts Group 2000 (JPEG2000) compression ratio on the quality of thin-section computed tomographic (CT) images. MATERIALS AND METHODS: In this institutional review board-approved investigation (protocol 238/2004), thin-section CT images were subjected to irreversible JPEG2000 compression by using five compression ratios (3:1, 5:1, 7:1, 9:1, and 11:1). Three radiologists independently evaluated 60 thin-section CT images, of various diseases, that were obtained with single-detector (weighted dose index, 14.4 mGy) and multidetector (weighted dose index, 9.8 mGy) CT. Toggling between the original and compressed images, readers had to identify the original image by using a forced-choice two-alternative model and to subjectively rank the quality of what they believed to be the compressed image. To assess the reader's ability to distinguish the compressed from the original image, a binomial test was used. Bonferroni correction was applied for all multiple tests. RESULTS: Images compressed with a ratio of 3:1 were not distinguishable from original images (P > .2 for all readers). With use of the 5:1 ratio, minor differences in appearance between the compressed and original images were seen by one of the three readers. With use of higher compression ratios (>/=7:1), all readers (P < .001) recognized the original image. The quality of more than 90% of the images compressed with a 7:1 or higher ratio was substantially degraded. Single-detector and multidetector CT results were not significantly different. CONCLUSION: The highest ratio that yielded visually lossless compression of thin-section CT images was 3:1. With the 5:1 ratio, there was minor image quality loss, while use of higher compression ratios (>/=7:1) caused substantial degradation of image quality and potential loss of diagnostic information.     

Neurogenic hypertension. A new MRI protocol for the evaluation of neurovascular compression of the cranial nerves IX and X root-entry zone

OBJECTIVE: Neurovascular compression of the rostral ventrolateral medulla (RVLM) has been implicated in the pathogenesis of essential hypertension. Although MRI has been widely used to evaluate the morphologic relation of structures in this region, spatial resolution of the previously used techniques was limited. This article describes the use of a new MRI protocol that combines two sequences with improved spatial resolution and complementary image information as well as a set of defined criteria for image analysis. METHODS: MRI of the brain stem was performed in 60 hypertensive and 50 normotensive subjects using a 3D-CISS and a 3D-FISP-MRA sequence. Neurovascular contact in the RVLM was independently assessed by four readers using predefined criteria and compared with a consensus finding. Agreement was expressed by kappa statistics on a 0 to 1 scale. RESULTS: Left-sided neurovascular contact within the RVLM was found in 13 (22%) hypertensive and 6 (12%) control subjects. The inter-reader agreement for positive and negative findings ranged from 0.47 to 0.79; agreement to the consensus finding ranged from 0.65 to 0.90. CONCLUSIONS: The combination of 3D-CISS and arterial flow-sensitive 3D-FISP, together with the evaluation criteria defined in this study, can be used for describing the finer anatomic features of the brain stem, and in particular for investigation of neurovascular contact of the IX/X cranial nerve root-entry zone. The high quality of images and the substantial or almost perfect reader-consensus agreement should make this protocol useful for future investigations of the neurovascular compression syndrome in patients with essential hypertension and possibly in other neurovascular compression syndromes, such as trigeminal neuralgia and hemifacial spasm.     

A model for a PC-based,universal-format,multimedia digitization system: moving beyond the scanner

RATIONALE AND OBJECTIVES: Digitizing images for use in case presentations based on hardcopy films, slides, photographs, negatives, books, and videos can present a challenging task. Scanners and digital cameras have become standard tools of the trade. Unfortunately, use of these devices to digitize multiple images in many different media formats can be a time-consuming and in some cases unachievable process. The authors' goal was to create a PC-based solution for digitizing multiple media formats in a timely fashion while maintaining adequate image presentation quality. MATERIALS AND METHODS: The authors' PC-based solution makes use of off-the-shelf hardware applications to include a digital document camera (DDC), VHS video player, and video-editing kit. With the assistance of five staff radiologists, the authors examined the quality of multiple image types digitized with this equipment. The authors also quantified the speed of digitization of various types of media using the DDC and video-editing kit. RESULTS: With regard to image quality, the five staff radiologists rated the digitized angiography, CT, and MR images as adequate to excellent for use in teaching files and case presentations. With regard to digitized plain films, the average rating was adequate. As for performance, the authors recognized a 68% improvement in the time required to digitize hardcopy films using the DDC instead of a professional quality scanner. CONCLUSIONS: The PC-based solution provides a means for digitizing multiple images from many different types of media in a timely fashion while maintaining adequate image presentation quality.     

口内X线片直接数字化摄影技术的临床应用

目的：研究口内X线片直接数字化摄影(direct digital radiography，DDR)与传统口内片摄影技术方法的不同点及优越性。材料和方法：采用ATMEL Dental Intra-oral system研究口内片DDR的临床应用技术及优越性。结果：得到不同的中心线投射角度及X线曝射参数。结论：与传统摄影技术相比，DDR技术在图像即时显示、图像处理及图像存储方面均具有不可比拟的优越性，该技术是口内X线片发展的方向。     

双向可调式椎板撑开压缩固定器的研制及应用

目的研制双向可调式椎板撑开压缩固定器,并观察其治疗颈椎脱位及不稳的临床效果.方法采用无磁性医用钛金属加工制作成双向可调式椎板撑开压缩固定器,治疗寰枢椎脱位4例及下颈椎脱位7例.其中压缩复位8例,撑开固定2例,压缩-撑开并用1例.术后定期X线检查,观察手术椎节的稳定性和复位及骨融合情况.结果随访6个月～3年,平均15个月.X线平片显示,双向可调式椎板撑开压缩固定器复位和固定性能良好,骨性融合时间3～4个月.除1例固定器脱钩外,无其他并发症.结论双向可调式椎板撑开压缩固定器操作简便,复位和固定可靠,适用于颈椎后路复位及椎板间固定.     

An evaluation of the financial impacts of optical disk storage for digital radiography.

While the digitization of radiographic patient information and the use of picture archiving and communication systems (PACS) have become a subject of increased interest and controversy, discussion of the methodology for archiving this information is not common. Optical disks have been proposed as one solution to the archival problem which faces most large radiology departments as the transition to digitization occurs. An in-depth financial analysis of the costs incurred by both traditional film archival and optical disk archival provides sufficient information to emphatically state that over a seven-year period, optical disk archival is more cost efficient than traditional radiographic film archival for radiology facilities with workloads greater than 25,000 procedures. For simplification purposes, however, only those cost directly associated with image archival were considered; all other factors relating to PACs, such as personnel costs and hardware required for image review and transfer, were ignored.     

Clinical assessment of a radiolucent cushion for mammography

Purpose: To determine whether use of a radiolucent cushion could significantly decrease pain during screening mammography without compromising image quality or other technical factors.

Material and Methods: 838 patients presenting for routine screening mammography were evaluated. The radiolucent cushions were placed on the compression surfaces of the mammographic equipment and were used while imaging the right breast. No pads were used while imaging the left breast. Patient age, hormonal status, compression force, and radiation dose values were collected on all patients. Each subject completed a visual analog pain scale (VAS) rating the degree of pain experienced with and without the cushions. All mammographic images obtained (CC and MLO views) were compared, side by side (cushioned versus non-cushioned) by the readers.

Results: Use of radiolucent cushions reduced pain by 10% or more in 66% (555/838) of women. Patients in this “benefited group” experienced an average pain reduction of 53%. No compromise of image quality was observed. Compression force and radiation dose values were highly correlated between the cushioned and non-cushioned sides.

Conclusion: Two-thirds of women experienced a significant reduction of pain when the radiolucent cushions were used during mammography. Pain reduction was accomplished without any clinically significant change in compression force, radiation dose values, or image quality.     

关节骨折的螺旋CT三维重建评价

目的：探讨螺旋CT三维重建技术在关节骨折中的诊断价值。方法：使用Philips Aura螺旋CT对31例患者的损伤关节进行容积扫描，所得原始数据传送到工作站做三维重建处理，显示立体图像，并与X线平片及CT平扫比较。结果：螺旋CT三维重建技术逼真地显示关节骨折的情况，与临床实际相符，确诊率96．8％，明显高于X线平片(67.7％)及CT平扫(87．1％)。结论：螺旋CT三维重建技术能清楚显示关节骨折的细节，有利于临床诊断和治疗，减少手术创伤。     

A statistical method for evaluation quality of medical images: a case study in bit discarding and image compression.

Many studies have been performed on quality evaluation for subtle differences in medical images. However, only limited success has been achieved. In this paper, medical images were prior manipulated by denoising, lossy compression and filtering. The Moran statistics is then applied to extract spatial information of images and using Kolmogorov-Smirnov (KS) test to determine whether the manipulated and original images differ significantly. Results show that on average discarding 1-2 bits in T1 and CR images or 2-3 bits in T2 and body CT images are indistinguishable. This method is also applied to a reconstructed MR, body CT image and an electronic SMPTE (Society of Motion Picture and Television Engineer) phantom from lossy image compression software. Compression ratios of 16:1 for a MR image, 8-9:1 for a cropped body CT image, 7:1 and 5:1 for high- and low-resolution regions in electronic phantom is proved undifferentiated from original. The proposed method is useful for complementing the human visual system, to optimize the performance of image compression technique.     

足月新生儿急性呼吸窘迫综合征的X线表现

目的：探讨足月新生儿急性呼吸窘迫综合征(ARDS)胸部诊断标准。方法：参照1994年美国和欧洲ARDS评审会议制订的ARDS诊断标准,对1999年1月一2002年3月我院符合诊断标准的足月新生儿87例进行回顾性分折,对符合足月新生儿ARDS诊断标准的10例病例资料进行分折。结果：X线表现为“白肺”4例;肺野呈“毛玻璃”样1例;双肺大片状浸润3例;双肺纹理增多模糊,弥漫性小片状浸润伴代偿性肺气肿2例。结论：ARDS的x线表现有一定特点,可为临床诊断提供重要影像学依据,同时可评估治疗效果。     

Choosing a thallium-201 or technetium 99m sestamibi imaging protocol

During the past decade progress in the field of myocardial perfusion imaging has resulted in a myriad of choices for perfusion imaging protocols, including choices in types of stressor, imaging modality, perfusion tracer, method of analysis, and a wide range of choices of imaging protocols. This review will examine this latter aspect in the context of choices of perfusion tracers that are now available for wide use. Manipulations of thallium protocols have revolved primarily around optimizing identification of stress defect reversibility and regional myocardial viability. The high image quality and long retention time afforded by the technetium-labeled agents allow the potential for streamlining imaging protocols to maximize efficiency and cost-effectiveness, such as performing stress only imaging in a subset of patients and performing simultaneous assessment of perfusion and function.     

RD-06诊断X射线千伏计的研制

目的 研制一种非介入式X射线千伏计,用于检测放射诊断X射线机管电压。方法 通过测量不同材料、不同厚度过滤的双半导体探测器对X射线响应信号的比值,测定X射线机管电压。结果 千伏计的测量范围为60~150 kV,测量准确度为 (1%±2) kV;千伏计在测量管电压的同时还具备测量曝光时间功能,测量误差不大于20 ms。结论 千伏计可以与诊断X射线剂量仪联合使用或单独使用实现诊断X射线机的质量控制。     

经皮加压钢板治疗老年股骨粗隆间骨折38例临床疗效分析

目的 研究应用经皮加压钢板(PCCP)技术治疗股骨粗隆间骨折的有效性及安全性.方法 2008年3月～2010年1月我院对38例股骨粗隆间骨折行PCCP内固定术.男性18例,女性20例;平均年龄76岁.术后随访3～20个月.统计手术时间、切口大小、术中X线透视时间、术中失血量及功能恢复情况.结果 手术时间平均50分钟,X...     

Compression of radiological images with 512, 1,024, and 2,048 matrices

A comprehensive study was performed using the full-frame bit-allocation compression technique on 78 radiological images, including digitized radiographs, computed radiographs, and computed tomography images. Each radiograph was digitized to 2,048 X 2,048 X 10, 1,024 X 1,024 X 10, and 512 X 512 X 10 matrices, respectively, with a laser scanner. Five compression ratios were used to compress each image, and reconstructed images from each compressed data set were obtained. Altogether, the authors studied 842 images, including the original and compressed-reconstructed images and the images obtained from the difference between the original and the reconstructed images. The results indicate that acceptable compression ratios for 2,048, 1,024, and 512 matrices are 25:1, 20:1, and 10:1, respectively, based on a mean-square error of 0.02%.     

Observer sensitivity to small differences: a multipoint rank-order experiment.

OBJECTIVE: To evaluate observer sensitivity to small differences in image presentation, a multipoint rank-order experiment was used to identify small differences or trends in observations. MATERIALS AND METHODS: Ten observers were presented with 50 sets of breast images that had been compressed at five different levels. Each set contained six images ranging from noncompressed to approximately 101:1 compression. Observers were asked to review all images of a case side by side and rank order the quality of each to enable determination of the presence or absence of masses and clustered microcalcifications. RESULTS: As a group, observers were able to detect small differences among the images, even at the lower compression levels (p < .001). As compression levels and image degradation increased, the ability to identify differences between different modes also increased. Large observer variability in discrimination ability was observed. CONCLUSION: Multipoint rank ordering of images viewed side by side can be an efficient method to identify small differences in image presentation. This approach to image ranking could be used to rule out or confirm the need for objective observer performance-type studies.     

Radiological image compression using full-frame cosine transform with adaptive bit-allocation

We report a new bit-allocation scheme based on the full-frame cosine transform for radiological image compression. The new technique differs from a previously reported method in its use of a two-dimensional bit-allocation table to encode the compression data. This allows for an improved treatment of high frequency components in the transform domain. Consequently, it has the capability of faithfully reproducing limited numbers of high-contrast sharp edges in the image. Previously reported artifacts, induced in the reconstructed image by sharp edges in the original, have been eliminated. Experiments with 10 radiological chest images show almost no perceivable degradation in the reconstructed image at compression ratios below 10:1. Image quality at a fixed compression ratio is, in every case, comparable or superior to results using the old method. Furthermore, the new algorithm lends itself to hardware implementations that are both simple and fast.     

Patient discomfort during screen-film mammography

Vigorous compression is required to minimize radiation dose and maximize image quality for screen-film mammography. Of 356 women who adequately completed a questionnaire following mammography, 171 (48%) reported mammography to be comfortable, 135 (38%) uncomfortable but tolerable, 39 (11%) very uncomfortable, and only 11 (3%) found the examination to be intolerable. Only 14 women (4%) indicated that they would not return for mammography at our facility in the future. Because of this high level of acceptance of compression by women, technologists and radiologists should not hesitate to use vigorous compression to optimize image quality and decrease radiation dose to the patient.     

X线影像工作站在X线造影中的应用

目的　总结X线影像工作站在X线造影中的应用价值。方法　在透视下进行造影 ,用X线工作站采集和储存造影图像 ,打出图文一体的X线诊断报告。结果　全过程采集和储存各种造影图像 ,提供动态的造影图像。消除传统造影中的假阳性 ,减少了漏误诊 ,提高了诊断正确率。对图像进行后处理 ,打印图文一体的诊断报告 ,将X线造影图像传输或刻录到光盘 ,方便会诊、教学和学术交流。结论　X线影像工作站应用于X线造影中 ,实现了造影图像采集和储存 ,弥补了传统X线造影的不足。     

小儿先天性肺囊肿11例临床X线分析

目的:提高小儿先天性肺囊肿的X线确诊率,降低其误诊率,提出鉴别诊断。材料与方法:对11例小儿先天性肺囊肿患者作回顾性分析,阐述X线特征。结果:11例中囊肿出现在右肺者9例,左肺2例,单发性囊肿9例,多发性囊肿2例。以囊肿的内容物分为三型:液囊肿(1例),气液囊肿(7例),气囊肿(3例),术前确诊7例,误诊4例。结论:肺囊肿的诊断应综合临床、X线片或CT等影像学检查,确诊后及早手术。