Chest imaging with flat-panel detector at low and standard doses: comparison with storage phosphor technology in normal patients

The purpose of this study was to evaluate the performance of standard-dose and low-dose cesium iodide (CsI)-doted amorphous silicon (a-Si) flat-panel detector technology (FDT) as compared with storage-phosphor technology (SPT) in the depiction of relevant anatomical structures in chest radiography. In 75 patients referred for thoracic CT, digital chest radiographs were randomly obtained with either SPT at a standard dose (speed class S400, n=25), standard-dose FDT (S400, n=25) or FDT at a low dose (S800, n=25). Five radiologists evaluated the visibility of eight pulmonary and mediastinal anatomical structures using a five-point rating scale. To determine statistically significant differences between the three groups, the Mann-Whitney U-test was employed. No statistically significant differences were found in the depiction of eight criteria between SPT and standard-dose or low-dose FDT chest radiographs. The performance of FDT S400 was equal to SPT for most criteria and better for retrocardiac structures and soft tissue. FDT S800 was inferior to both SPT and FDT S400. Standard-dose FDT is equivalent to SPT in the depiction of relevant anatomical structures of the chest. Our results also indicate that a dose reduction of 50% with FDT may result in small but not significant decrease of image quality.     

优化组合CR系统自动曝光控制成像参数

目的:优化组合CR系统自动曝光控制成像参数.材料和方法:采用两种规格的成像(IP)板,用不同组合的成像参数对胸部拟人水模摄影,检测电离室密度补偿与曝光参数的变化.以所得成像数据和两种规格的IP板,对A、B、C三组患者(每组各180例),不同部位摄影,检测不同曝光剂量组合摄影的影像质量和影像的密度值.结果:A组以两种规格的IP板、125kV摄胸部,图像对比度差;病灶细微结构显示不清.以73～85kV摄胸部,其图像明显好于125kV;B组与C组的小规格IP板(20.5cm×25.6cm)优于大规格IP板的(35cm×35cm)图像质量;影像密度值均在0.8～1.30范围内.结论:CR系统不宜采用高kV摄影;应使用合适规格的成像板.     

NMR anatomy of the brain using inversion-recovery sequences

Summary The use of NMR inversion-recovery (IR) sequences to demonstrate brain anatomy is illustrated. The high level of grey-white matter contrast is of value in localising anatomical structures and demonstrating myelination during childhood. While the resemblance of IR scans to gross anatomical sections in different planes is close, it is limited by the spatial resolution of the NMR scanner, artefacts and partial volume effects.     

Prevalence of zygomatic air cell defect in adults--a retrospective panoramic radiographic analysis

Objectives

This research involved retrospectively evaluating panoramic radiographs of patients from India with the intention of assessing the prevalence of Zygomatic Air Cell Defect (ZACD) and establishing its dominant location and type.

Methods

Seven thousand seven hundred and fifty-five panoramic radiographs of routine outpatients aged between 19 and 91 years were concomitantly evaluated by four investigators for estimating the prevalence and characteristics of the Zygomatic Air Cell Defect.

Results

The prevalence of ZACD was noted to be 1.82%, with male preponderance. Unilateralality and multilocular appearance of ZACD were the dominant patterns observed.

Conclusion

The frequency of ZACD amongst Indian population is in harmony with most of the similar studies conducted on various geographic populations.     

High-resolution MR imaging of the carpal tunnel and the wrist. Application of a 5-cm surface coil

Purpose:
To make a comparative analysis of transversal tomograms obtained by high-resolution MR imaging with frozen cross-sections of an anatomical forearm specimen. Twenty-two healthy volunteers were also examined using the same coil system to test for a range of possible clinical applications and for the depiction of morphological and morphometrical values of normal anatomy in vivo.
Material and Methods:
MR images of the carpal tunnel of 22 healthy volunteers were obtained with a 1.5-T whole-body system with a 5-cm surface coil. Measurements were recorded with a field-of-view between 50×50 mm² and 60×60 mm² in a 256×256 pixel matrix for the T1 sequence. A slice thickness of 2 mm was used. The images were acquired using a T1-weighted SE sequence (TR/TE 500/38 ms) and a T2-weighted SE sequence (TR/TE 2000/70 ms). Additionally, a formalin-fixed anatomical forearm specimen was imaged for anatomic correlation. The imaged transversal cross-section levels in the specimen were subsequently freeze-sectioned. The anatomical structures of the MR findings were identified and compared with the macroscopical sections of the specimen.
Results:
Based on the good depiction of details at this coil system with a pixel size in T1 of 0.195×0.195 mm, high-resolution MR imaging enabled identification of the interior structures of the carpal tunnel, as well as delineation of connective tissue. The clinical value of high-resolution MR includes the diagnosis of carpal tunnel syndrome and inflammatory disorders of the wrist.
Conclusion:
Our results support the feasibility of high-resolution MR imaging of the carpal tunnel and the wrist using small surface coils.     

数字化X线系统在消化道双对比造影检查中的临床应用

目的 通过使用数字化X线系统(Digital radiological sysrem简称DRS)对消化道造影检查的影像分析、评价DRS的临床应用价值。方法 使用DRS对1964例患行消化道气钡双对比低张造影检查，全部图像均采取DF电视监视下即时曝光采集存盘。根据诊断需要筛选图像，部分图像使用图像后处理技术处理，由激光打印机打印出激光胶片。将图像质量分为4级：据此标准，由两位主任医师、两位主治医师、两位住院医师各自评价全部图像。结果 数字化成像系统所得消化道低张气钡双重造影图像质量十分理想，Ⅰ—Ⅱ级片1815例，占92．41％。Ⅲ级片114例，占5．81％。Ⅳ级片35例，占1．78％。结论 数字化影像其成像速度快，可有效地减少消化道蠕动对图像质量的影响，能更好的显示细微结构，极大的丰富了形态医学诊断的信息和层次，显提高了X线影像的质量，较传统的电视遥控X线机有其独特的优势。     

Performance of a flat-panel detector in the detection of artificial erosive changes: comparison with conventional screen-film and storage-phosphor radiography

The purpose of this study was to compare a large-area, direct-readout, flat-panel detector system with a conventional screen-film system, a storage-phosphor system, and a mammography screen-film system with regard to the detection of artificial bone erosions simulating rheumatoid disease, and to assess its diagnostic performance with decreasing exposure dose. Six hundred forty regions were defined in 160 metacarpophalangeal and proximal interphalangeal joint specimens from 20 monkey paws (4 regions per joint). Artificial bone erosions were created in 320 of these 640 regions. Specimens were enclosed in containers filled with water to obtain absorption and scatter radiation conditions similar to those of a human hand. Imaging was performed using a flat-panel system, a speed class 200 screen-film system, a mammography screen-film system, and a storage-phosphor system under exactly matched conditions. Different exposure doses equivalent to speed classes of S=100, 200, 400, 800, 1600, and 3200 were used. In all images the presence or absence of a lesion was assessed by three radiologists using a five-level confidence scale. Receiver operating characteristic (ROC) analysis was performed for a total of 21,120 observations (1920 for each imaging modality and exposure level) and diagnostic performance estimated by the area under the ROC curve (A_z). The significance of differences in diagnostic performance was tested with analysis of variance. The ROC analysis showed A_z values of 0.809 (S=200), 0.768 (S=400), 0.737 (S=800), 0.710 (S=1600), and 0.685 (S=3200) for the flat-panel system, 0.770 for the speed class 200 screen-film system, 0.781 (S=200), 0.739 (S=400), 0.724 (S=800), 0.680 (S=1600) for the storage-phosphor system, and 0.798 for the mammography screen-film system. Analysis of variance showed significant differences between different combinations of imaging modalities and exposure doses ( p <0.05). The diagnostic performance of the flat-panel detector system is superior to that of a screen-film system and a storage-phosphor system for the detection of erosive lesions at clinical exposure settings (S=200). Using the flat-panel system the exposure dose can be reduced by 50% to obtain a diagnostic performance comparable to a speed class 200 screen-film system. Electronic Publication     

数字成像系统在选择性支气管造影中的应用

目的探讨数字成像系统在支气管造影中的应用价值。方法应用数字成像系统对27例可疑支气管扩张病人,进行选择性支气管造影,共检查35个肺段。结果数字成像系统可清晰、连续的显示整个造影过程。造影表现为:单纯支气管扩张27例,其中柱状扩张12例,囊状扩张8例,混合扩张5例,2例慢性支气管炎。结论数字成像系统在选择性支气管造影中有较高的应用价值。     

A new MRI technique for demonstrating the surface of the brain together with the cortical veins

We assessed combining of surface-anatomy scanning (SAS) MRI and MR venography (MRV). We obtained SAS images with a half-Fourier single-shot fast spin-echo sequence, then MRV of the identical section with a two-dimensional phase-contrast technique. We then added the two sets of images. The combined images, which were obtained within 10 min, provided information about the surface anatomy and cortical veins. This simple technique is useful for demonstrating brain surface structures, especially in patients from whom one plans to excise a lesion. Received: 3 August 1998 Accepted: 2 November 1998     

Postsurgical change in the tracheal bifurcation angle after upper lobectomy: radiographic evaluation

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate postsurgical changes in the tracheal bifurcation angle on chest radiographs after upper lobectomy and to determine whether bronchial repositioning after upper lobectomy mimics that in upper lobe collapse. MATERIALS AND METHODS: The authors selected 81 patients who had undergone upper lobectomy with complete mediastinal and subcarinal lymph node dissection and in whom chest radiographs had been obtained before operation and at four postoperative intervals. The interbronchial angle and the subcarinal angle were measured on the preoperative and postoperative radiographs and compared statistically. RESULTS: The average interbronchial angle and subcarinal angle during any postoperative period were significantly smaller than those before lobectomy (P < .001). These average angles decreased gradually during the postoperative periods. CONCLUSION: The tracheal bifurcation angle was decreased on follow-up chest radiographs in most patients who underwent upper lobectomy with mediastinal lymph node dissection. This finding may be useful for establishing a history of this surgical procedure on the basis of chest radiographs.     

Effect of alternative photostimulable phosphor plates erasing times on subjective digital image quality

Objective

To evaluate the influence of alternative erasing times of DenOptix® (Dentsply/Gendex, Chicargo, IL) digital plates on subjective image quality and the probability of double exposure image not occurring.

Methods

Human teeth were X-rayed with phosphor plates using ten different erasing times. Two observers evaluated the images for subjective image quality (sharpness, brightness, contrast, enamel definition, dentin definition and dentin-enamel junction definition) and for the presence or absence of double exposure image. Spearman''s correlation analysis and ANOVA was performed to verify the existence of a linear association between the subjective image quality parameters and the alternative erasing times. A contingency table was constructed to evaluate the agreement among the observers, and a binominal logistic regression was performed to verify the correlation between the erasing time and the probability of double exposure image not occurring.

Results

All 6 parameters of image quality were rated high by the examiners for the erasing times between 25 s and 130 s. The same erasing time range, from 25 to 130 s, was considered a safe erasing time interval, with no probability of a double exposure image occurring.

Conclusions

The alternative erasing times from 25 s to 130 s showed high image quality and no probability of double image occurrence. Thus, it is possible to reduce the operating time of the DenOptix® digital system without jeopardizing the diagnostic task.     

计算机X射线摄影系统与屏-片系统能量响应的对照研究

目的探讨计算机X射线摄影(CR)影像像素值与曝光因子(kVp和mAs)、被照体厚度的关系，传统屏-片系统照片密度与曝光因子、被照体厚度的关系，并对两种能量响应的关系进行比较，为使用CR影像像素值和成像板(IP)平均入射照射量的测量值作为自动曝光控制系统的设定参数提供依据。方法厚度为10、15、20cm的丙烯树脂板分别在50～90、70～120、90～140kVp和密度档为-2时成像，对照屏-片系统与CR系统在不同管电压、相同被照体和密度档时的自动曝光响应。以上测试都使用滤线栅，用电离室测量IP的入射照射量。结果在获得满足临床诊断要求的情况下，CR所需曝光量大约是高速屏-片系统的2倍。CR系统的管电压像素值关系曲线与管电压照射量曲线相同。10cm被照体时，50～90kVp间的照片密度差值为1．21，像素差值为270；而20cm被照体时，90～130kVp间的密度差值为0．30，像素差值为100；15cm被照体时密度和像素差值居于两者之间，分别为0．62和160。结论Kodak CR900系统的感度值与中速屏-片系统的感度比较接近。均匀野影像的曝光指示器值EI和IP照射量测量值可以用来设定自动曝光控制系统的光电计时器。屏-片系统照片密度和CR影像像素值随kVp变化的规律以及两者的差异，对自动曝光控制系统的校准起参照作用。     

旋转DSA技术在肺栓塞诊疗中应用的研究

目的研究旋转DSA技术在肺栓塞(pulmonary embolism，PE)诊疗中的应用。方法建立小型猪肺栓塞模型13头，进行常规肺动脉造影并应用旋转DSA技术，对造影结果进行分析、评价和研究。结果将每头猪的肺分为相应的15条血管，共有195条血管。以病理阳性结果为标准，评价肺动脉造影及旋转。DSA技术诊断PE的价值。肺动脉造影及旋转。DSA共有47个血管阳性(24．1％)，敏感性为98％，特异性为99％，诊断准确性98％；有2个血管数字减影肺动脉造影阳性，病理阴性，假阳性率为1％；有1个血管数字减影肺动脉造影阴性，病理阳性，假阴性率为2％。结论旋转DSA技术有助于肺栓塞诊断，尤其对疑似病变有一定临床意义。     

Radiographers' experiences and perspectives of forensic imaging in Australia: A qualitative study

IntroductionForensic imaging plays a pivotal role regarding medico-legal issues by investigating the cause(s) of injuries to living or deceased individuals. There is currently a gap in the literature on forensic imaging due to limited national and international guidelines, protocols and scope of duties and responsibilities of radiographers undertaking forensic imaging. Thus, this study aimed to investigate the gap by exploring the experiences and perspectives of radiographers on forensic imaging in Australia.MethodsA qualitative approach collected data from fifteen purposively sampled qualified Australian radiographers through individual in-depth interviews. The verbatim transcribed data were thematically analysed.ResultsTwo themes were identified: 1) Radiographers' experiences of forensic imaging; 2) Radiographers' perceptions of forensic imaging within the job scope of a qualified radiographer.ConclusionsParticipants' experiences of forensic imaging ranged from anxiety to a positive experience, and others posed ethical and situational dilemmas heightened by the lack of dedicated forensic imaging protocols. While some radiographers expressed that every radiographer should conduct forensic imaging, others felt it was not mandatory.Implications for practiceRadiographers' shared subjective experiences, thoughts and feelings provided insight into forensic imaging and the need for more significant support from educational and governing bodies.     

Influence of the intergonial distance on image distortion in panoramic radiographs

Objectives

The aim of this study was to evaluate the influence of the intergonial distance during the formation of panoramic radiographic images by means of horizontal and vertical measurements.

Methods

30 macerated mandibles were categorized into 3 different groups (n = 10) according to their intergonial distances as follows: G1, mean distance 8.2 cm, G2, mean distance 9.0 cm and G3, mean distance 9.6 cm. Three metal spheres 0.198 cm in diameter and placed at an incline using an isosceles triangle were separately placed over the internal and external surfaces of the mandibles before radiographic exposure for the purpose of taking the horizontal and vertical measurements. The occlusal planes of the mandibles were horizontally placed on the chin rest of the panoramic machine Orthopantomograph® OP 100 (Instrumentarium Imaging, Tuusula, Finland) and were then radiographed. In the panoramic radiographs, an expert radiologist measured the distances between the metal spheres in the horizontal and vertical directions using a digital caliper. The data were tabled and statistically analysed by Student''s t-test and analysis of variance with Tukey post-test (α = 0.05).

Results

In all three groups magnification of the distances between spheres was observed when compared with the real distance in both horizontal and vertical measurements (p < 0.05). Differences in both horizontal and vertical measurements were observed between the different regions (p < 0.05), however there were no differences between groups in the same region (p > 0.05). Differences between horizontal and vertical measurements were observed in different regions in all evaluated groups (p < 0.05).

Conclusion

The intergonial distance is a factor that had no influence on image formation in the panoramic radiograph.     

喙锁韧带的影像学分析

目的 研究喙锁韧带的影像学表现.方法 选取正常胸部正位CR片400例,其中男、女各200例,观察喙锁关节和喙锁韧带附着处锁骨粗隆显示率,测量喙锁韧带部喙突和锁骨间距.选取正常肩关节MRI 30例,观察喙锁韧带显示率和测量喙锁韧带长度和宽度;选取临床已证实的肩锁关节Ⅱ、Ⅲ级损伤MRI检查8例.结果 400例800侧中见1例(0.25%)存在喙锁关节.198 侧(198/800;24.8%)显示喙锁韧带锁骨附着处粗隆存在.正常喙突锁骨间距为(6.92±3.16) mm.30例正常人MRI斜冠状扫描均可显示喙锁韧带,其锥状韧带长度(11.48±1.43) mm,宽度为(4.82±1.21) mm,梯状韧带长度(9.09±0.84) mm,宽度为(5.10±0.87) mm.肩锁关节损伤8例,MR检查发现:肩锁关节Ⅱ级损伤肩锁韧带撕裂,Ⅲ级损伤并喙锁韧带撕裂.结论 本文建立了正常喙锁韧带的X线和MRI测量标准,为诊断喙锁韧带等疾病提供了依据,肩锁关节Ⅲ级损伤有喙锁韧带撕裂.     

Study of edge detection task in dental panoramic radiographs

The purpose of this study is (1) to introduce a new approach for edge detection in orthopantograms (OPGs) and an improved automatic parameter selector for common edge detectors, (2) to present a comparison between our novel approach with common edge detectors and (3) to provide faster outputs without compromising quality. A new approach for edge detection based on statistical measures was introduced: (1) a set of N edge detection results is calculated from a given input image and a selected type of edge detector, (2) N correspondence maps are constructed from N edge detection results, (3) probabilities and average probabilities are computed, (4) an overall correspondence is evaluated for each correspondence map and (5) the correspondence map providing the best overall correspondence is taken as the result of edge detection procedure. A comparison with common edge detectors (the Roberts, Prewitt, Sobel, Laplacian of the Gaussian and Canny methods) with various parameter settings (304 combinations for each test image) was carried out. The methods were assessed objectively [edge mismatch error (EME), modified Hausdorff distance (MHD) and principal component analysis] and subjectively by experts in dentistry and based on time demands. The suitability of the new approach for edge detection in OPGs was confirmed by experts. The current conventional methods in edge detection in OPGs are inadequate (none of the tested methods reach an EME value or MHD value below 0.1). Our proposed approach for edge detection shows promising potential for its implementation in clinical dentistry. It enhances the accuracy of OPG interpretation and advances diagnosis and treatment planning.     

磁共振STIR和DWI在疲劳骨折诊断中的应用价值

目的：探讨磁共振STIR和DWI对早期疲劳骨折诊断价值,以提高对该病的诊断、鉴别诊断及愈合进行评估。方法通过对43例疲劳骨折患者的X线、CT、MRI影像学资料进行对比、分析,总结疲劳骨折X线、CT、MRI的影像学表现。结果本组病例中早期仅有临床症状的病例,X线及CT检查可为阴性,中晚期病例则X线和CT的诊断价值无差别;磁共振对疲劳骨折的敏感性、特异性较X线和CT高,特别是T2WI STIR和DWI敏感性更高,可作为疲劳骨折的早期诊断及对其愈合进行评估。结论疲劳骨折在磁共振检查中STIR和DWI的影像学表现有较高的特异性和敏感性,可对早期疲劳骨折进行诊断、鉴别诊断和对其愈合进行评估。     

Anatomic Variation in Intrahepatic Bile Ducts: an Analysis of Intraoperative Cholangiograms in 300 Consecutive Donors for Living Donor Liver Transplantation

Objective

To describe the anatomical variation occurring in intrahepatic bile ducts (IHDs) in terms of their branching patterns, and to determine the frequency of each variation.

Materials and Methods

The study group consisted of 300 consecutive donors for liver transplantation who underwent intraoperative cholangiography. Anatomical variation in IHDs was classified according to the branching pattern of the right anterior and right posterior segmental duct (RASD and RPSD, respectively), and the presence or absence of the first-order branch of the left hepatic duct (LHD), and of an accessory hepatic duct.

Results

The anatomy of the intrahepatic bile ducts was typical in 63% of cases (n=188), showed triple confluence in 10% (n=29), anomalous drainage of the RPSD into the LHD in 11% (n=34), anomalous drainage of the RPSD into the common hepatic duct (CHD) in 6% (n=19), anomalous drainage of the RPSD into the cystic duct in 2% (n=6), drainage of the right hepatic duct (RHD) into the cystic duct (n=1), the presence of an accessory duct leading to the CHD or RHD in 5% (n=16), individual drainage of the LHD into the RHD or CHD in 1% (n=4), and unclassified or complex variation in 1% (n=3).

Conclusion

The branching pattern of IHDs was atypical in 37% of cases. The two most common variations were drainage of the RPSD into the LHD (11%) and triple confluence of the RASD, RPSD and LHD (10%).