Search

A new group contribution model based on a modified double lattice (MDL) theory is developed and applied to describe the ionic conductivities of perfluorosulfonic acid (PFSA) membrane/water systems. The proposed model includes a combinatorial energy contribution that consists of the revised Flory–Huggins entropy of mixing, the van der Waals energy from dispersion, polar force and specific energy contributions. We investigated six groups used for PFSA membranes and changed the configuration of polymer, which was calculated separately. To obtain good mechanical properties of PFSA membranes, the specific polymer configuration was optimized. As a result, shorter CF2CF2 groups in polymer backbone chain and in the side chain lead to a higher ionic conductivity, as does a single CF2CFCF3O group in the side chain. Quantitative description according to the proposed model is in good agreement with experimentally observed physical property for a given system.

A 60-year-old woman was referred for 64-slice multidetector computed tomography because of the incidental findings of abnormality on a chest radiograph. Her computed tomography showed an absent right lung and a rudimentary main bronchus ending in a blind pouch; this established the diagnosis of pulmonary aplasia. We report here on a rare case of incidentally found right pulmonary aplasia, and we include a brief review of the relevant literature.

The regulation of medical use of radiation is dualistic in Korea. Nuclear medicine and therapeutic radiation are under the supervision of the Ministry of Education, Science and Technology while diagnostic radiation is managed by the Ministry of Health and Welfare. In some countries, the regulatory framework is more unified with specialists addressing each field and working under one system. With the Korean system, if the International Atomic Energy Agency (IAEA) were to recommend a policy in diagnostic radiation, this would have to be communicated through the Ministry of Education, Science and Technology and might not reach those societies in diagnostic radiology, thus posing a barrier to its implementation. Considering the Korean circumstances, there are numerous obstacles preventing this dualistic regulatory system to be unified as one. Therefore, the government should strengthen its efforts to directly communicate issues, discussions and policies in diagnostic radiation through the Ministry of Health and Welfare to the relevant societies and organizations. Despite this dualistic system, topics in diagnostic radiation are actively researched, taught, and promoted by the academic societies, including the Korean Society of Radiology (KSR). This chapter will further explain the current advances in diagnostic radiation through the Korean government and academic societies.

Digital radiography is often performed at a higher dose rate than analogue radiography for image acquisition. The authors measured the Entrance Surface Dose (ESD) of analogue and digital radiography techniques for 14 radiographic examinations from randomly selected medical centres in the central district of Korea. It was that the mean ESD of the digital examinations was 2.84 mGy (range, 0.37-6.38 mGy) and that of the analogue examinations was 1.83 mGy (range, 0.38-4.74 mGy), resulting in a 55.25 % higher ESD for digital technique. Although this survey is not completely representative of Korea, findings of this study indicate a need for closer exposure management in digital radiography to minimise patient dose.

Within the past 20 years, the radiographic examination in the medical field has increased by a factor of about 3 to 5 times, while the total radiation dose has increased by a factor of about 200-400. This has ascribed to the rapid increase in CT usage (1). The increased demand for CT scans has drawn the public's attention about radiological hazards and paved the way for the effort to reduce radiation exposure in every medical imaging field. There are some evidences why the radiation exposure management has become the most important issue nowadays. One study by Berrington et al. (2) estimated 29,000 cancer patients due to 70 million scans in the USA. The other study by Brenner and Hall (3) reported that 600,000 CTs performed on children under age 15 could lead to 500 deaths. CT scans for the pediatric imaging played a significant role in the raised incident rate of leukemia or brain tumors (4). Two things should be considered to reduce radiation exposure dose (5-7). The first one is justification. The justification is based by the fact that radiographic examinations are essential for the diagnosis, which needs to be recognized first and then the examination is carried out subsequently. Justification includes a legitimate explanation to patients, and this ought to be always considered with the ethical issues. The medical ethics and the healthcare environment ethics have to hold a dominant position. Physician autonomy over the prescription along with obligation has to be ensured for this process. If the qualification for justification is sufficed, the second conception, optimization, should be reckoned to reduce radiation exposure dose. In other words, provided the radiographic examination has been prescribed for the diagnosis, now think of how to minimize the detrimental effect from radiation. In spite of the minimum amount of radiation, it may produce delayed radiation damage such as cancer statistically 10-20 years later (8). That's why the dose of radiation has to be reduced to prevent radiation hazard. It is recommended to comply with a standard guide for radiographic examination to have the optimal imaging condition for a variety of situations and to wear proper radiation protection devices. If feasible, radiographic examinations have to be taken based on the principle of As Low As Reasonably Achievable (ALARA), which means that making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical. In addition to justification and optimization, another one which should be kept in mind is that the amount of radiation is not everything to be concerned in the medical radiological examination. The inappropriate treatment by neglected or omitted procedures owing to the expected radiation exposure damage may give rise to disastrous consequences. Nowadays, CT screening is new topic issue in the point of radiation safety. CT is a very useful examination in the early detection of cancer because of its diagnostic accuracy. However, in the periodic CT screening, radiation hazards may be greater than the diagnostic benefit. So, if necessary, screening CT may be carried out with strict indications. It is crucial for the medical institutions to monitor the amount of radiation exposure dose from CT scans or radiological procedures in optimization. Currently, the international organizations and each country are running or preparing various programs for the reduction of radiation exposure dose such as Smart card project in IAEA, My Child's Medical Imaging Record in American College of Radiology, Wallet card in Beaumount Hospital in Pennsylvania, California Senate Bill 1237 (Regulating CT Radiation Dose Practices in California into Law), Radiation Passport Project in Canada, Patient Exposure Registry (PER) in European Union (Dose DataMed (DDM) ProjectPACS), and Radiation Exposure Monitoring (REM) Integration Profile in Japan. Rehani et al. (9) has investigated with the help of the IAEA about the implementation of radiation exposure monitoring program. In a total survey of 76 countries, 11% are running a research on this program and 4% are drawing a blueprint only for the medical tests performed. Of them, 89% responded that these kinds of programs were assumed effective on reduction of radiation exposure dose, and 99% of the participating countries in this survey displayed an interest in such programs. By 2015, patient dose management systems which are developed in each country will be embodied. The government of Korea recognized the importance of the management of the radiation dose tracking in patients. Since 2012, they have been developing a method for measuring the radiation dose. In 2012, that system for CT scan had built up frames already, and the thing for the plain radiography will be created in 2013. It is very important to acknowledge the correct information about the radiology in the reduction of radiation exposure dose. In other countries, websites such as Image Gently (the society for pediatric radiology) and Image Wisely (radiation safety in adult medical imaging) provide the radiology-related information, education, and campaign. Also radiology-related organizations work together through these websites where tasks are publicized to accomplish justification and optimization for patients, physicians, radiological technologists, medical physicists and radiologists. In recent years, Choosing Wisely contributes to decrease unnecessary examinations in each medical field. In Korea, the Korean Alliance for Radiation Safety and Culture in Medicine (KARSM) was founded by the medical radiation related society, which aims promotion, education, and campaign of radiology-related affairs. Endeavor to reduce radiation exposure dose can be done by national systematization. The government recommends Diagnostic Reference Level (DRL), which suggests medical institutions to limit the radiation exposure levels in each examination. DRL in CT scans and the plain radiograph has been established and recommended in Korea. When taking a closer look at the recommendation, CT scans set the bounds CTDIvol for skull 60 mGy, and for abdomen 20 mGy, and dose length product (DLP) for skull 1,000 mGy*cm, and for abdomen 700 mGy*cm. The radiation exposure dose for plain radiograph is delimitated skull AP 2.23 mGy, skull lateral 1.87 mGy, Chest PA 0.34 mGy, Chest lateral 2.80 mGy, Abdomen AP 2.77 mGy, Pelvis AP 3.42 mGy, C-spine AP 1.86 mGy, C-spine lateral 1.03 mGy, T-spine AP 3.79 mGy, T-spine lateral 8.15 mGy, L-spine AP 4.08 mGy, L-spine lateral 10.53 mGy, and L-spine oblique 6.35 mGy (10, 11). Nevertheless, the research and the recommendation of the safe radiation exposure levels in radionuclide imaging, cardiac CT, or cardiac catheterization and other imaging procedures have not done yet. Therefore, it is absolutely imperative that a strenuous study for the safety level should be completed for each medical radiation field and needs to be presented soon. In conclusion, those who concern about reduced radiation exposure dose insist a greater effort to achieve their goal. Doctors are demanded to prescribe a radiographic imaging under the medically justified ethics in the optimal condition so that the maximal benefit from the examinations and the minimal unforeseen injuries are guaranteed. Not only radiologists or related specialists but also patients and the government should cooperate fully to resolve this issue, thereby excluding pruning away gratuitous examinations and fostering better environment for radiographic examinations. Fear of the unknown accidents with a probability of 1 of 100,000 can be vanquished by collaboration firmly by justification and optimization with a wide variety of means. This collaboration connects every single nation into one to attain the true healthy medical environment.

Medical imaging is an indispensible diagnostic tool in modern medicine enabling fast and accurate diagnosis. Recent technological advances in medical equipment and increased utilization of the imaging modality have resulted in a significant increase in the exposure to ionizing radiation. After the rapid adoption of multi-detector computed tomography, computed tomography (CT) is now the single largest source of diagnostic radiation exposure to patients. The risks and benefits from radiation must be carefully considered in all examinations using ionizing radiation, and the principles of justification and optimization should be considered in the proper use of CT examination. Justification means that the examination must be medically indicated and useful. Optimization means that the imaging should be performed using doses that are ALARA (as low as reasonably achievable), consistent with the diagnostic task. This includes understanding and changing CT protocols to perform the same diagnostic task with the minimal amount of radiation exposure while maintaining diagnostic accuracy. Protocols and guidelines are important tools for radiation dose reduction. Understanding the parameters and dose information for CT examination is essential for optimization. If the exam is justified, then the parameters must be optimized to the imaging indication, scan area, body size, age, and weight of the patients. The physician should always assess the radiation risk-benefit ratio for each patient before ordering an examination that uses radiation. Continuing education is essential for the implementation of the principles of patient radiation dose reduction. Physicians and radiologists must be aware of the radiation risks associated with CT exams.

Objective. To evaluate the serial sonographic findings of experimental muscle injury and to correlate those findings with the pathologic findings at each period. Methods. A muscle injury was artificially inflicted in 18 legs of 9 rabbits. Sonographic follow-up images were obtained 1, 3, and 7 days and 2, 3, 4, 6, and 8 weeks after infliction of muscle injury. Pathologic specimens were obtained for comparison with sonographic findings on each date. Results. There was high echogenicity in the central portion after 3 days. It changed to low echogenicity after 7 days. There were linear echogenic lines in the central portion after 4 weeks, and these lines increased in number after 6 weeks. The peripheral portion exhibited high echogenicity up to 7 days. This high echogenicity was normalized after 2 weeks. Pathologic specimens showed hematomas, fibrin, and necrotic muscle fibers in the central portion up to 3 days after injury. Fibrin occupied most of the central portion after 2 weeks. Regenerating muscle fibers appeared within the fibrin clot after 4 weeks, and they became more prominent after 6 weeks. Necrotic muscle fibers, hemorrhage, and inflammatory cells of the peripheral portion disappeared after 2 weeks. Conclusions. Serial sonography of muscle injury was well correlated with the pathologic specimen up to 7 days after injury. After 4 weeks, regenerating muscle fibers showed a good correlation with the finding on sonography. Therefore, sonography can be helpful in diagnosis of muscle injury as well as in evaluation of the regenerating muscle fibers.

Malignant melanoma accounts for 1.5% of all reported cancers with prevalence increasing in the past decade. Skin is the most common site for primary malignant melanoma, but it can involve virtually every organ system where melanin cells exist. They can frequently metastasize to the liver, lung, brain and bone before the primary lesion in the skin is clinically evident (1). Here, we report a case of malignant melanoma representing superior mediastinal mass without extrathoracic primary lesion.

†‡ § Due to the introduction of CR and DR, it has been neglected the use of the X-ray beam collimator and field size. This study examines nationwide survey of the proper use of collimator and field size by area in a specific field of plain radiography and the current status. Authors emphasized the need for the field size criteria, and propose a standard reference field size in each specific radiologic examination. Total 333 medical institutions (included in Seoul, Gyeonggi-do, Jeolla, Chungcheong, Gangwon-do, Busan area), were investigated in relation to the status of the X-ray beam collimation field size, type specific inspection areas, medical facilities, and image analyses by type to figure out whether they use the adjustment of image field to the specific examination. To assess the awareness and the impact of radiation exposure to th e collimation adjustable, 168 radiographers who was working in 10 general hospitals, 10 hospitals, and 10 clini cs, were surveyed how they haver adjusted the actual field size. We examine that 61.3% of medical institution s used the “Proper collimation” and only 49.9% of them employed proper one in lumbar spine densely crowded by major organs. 69% among general hospitals, and 65% among hospitals using DR system were using proper colli mation. Radiographers recognized that proper adjustment of collimation could reduce the harmful radiation do se on patients. In the survey, 97.6% of respondents were aware of this fact, but only 83.3% of respondents did the adjustment of the size of the collimation field. The using of proper collimation field was low in the nationwide survey, so the effort to reduce the radiation dose on the patients is urgently needed. A unified standard for the field accompanied by thorough education should be needed.

증례 보고 39세 남자가 건강검진상 시행한 흉부 X선 사진에서 이상소 견으로 호흡기내과 외래에 방문하였다. 환자는 동반되는 호흡 기 증상은 없었고 다른 기저 질환의 병력이나, 외상, 입원, 수술 의 기왕력은 없었다. 가족력상에도 특이사항이 없었다. 흉부 후전 사진상에서 왼쪽 폐첨부에 흉막하종양 또는 폐종 양이 의심되었다(Fig. 1A). 이후 시행된 흉부전산화단층촬영 (Chest CT; 이하 CT)상에서 경계가 명확한 여러 개의 타원형 종양이 좌상부 흉강에서 발견되었으며 두 번째 늑골에 연하여 흉막에 넓게 접하고 있었으며 주변조직과의 경계는 명확하였 다. 조영증강 후 CT에서 여러 개의 타원형 종양은 조영증강이 안 되는 균질한 저음영을 보였으며 내부에 조영증강되는 고형 부분은 없었다(Fig. 1B). 흉강경상에서 두 번째 늑골사이 공간에 위치하며 두 번째 늑 간신경을 따라서 분포하는 다발성 종양이 있었고(Fig. 1C) 종 양을 완전 절제하였으며 다발성 종양은 흉막, 늑간근과 늑골 로부터 쉽게 분리되었다. 육안상 종양은 연한 노란색을 띠고 매끈한 피막으로 둘러싸 여 있었으며 내부에는 많은 수의 낭성 종양과 여러 개의 작은 결절들이 있었다(Fig. 1D). 작은 결절들에 대한 현미경 검사에 서는 여러 개의 결절 모두에서 방추형 세포가 주로 보였으며, 세포 밀도가 낮고 여러 개의 낭성변성을 보였다(Fig. 1E). 이에 Case Report pISSN 1738-2637 J Korean Soc Radiol 2012;66(3):267-270

Purpose: High-voltage techniques applicable for analog radiographs are usually used in digital radiographs. We compared the image quality of the different exposure conditions to produce conditions of high image quality and low radiation dose. Materials and Methods: The tube voltage ranged from 70 to 133 kV, whereas the tube current ranged from 2 to 6.3 mAs. The digital radiograph images of a chest phantom were obtained at each setting. We measured the radiation doses of each condition, and counted the visible test objects. The numbers of objects for each condition were compared with the standards used at our institution. Results: The standard settings were set at 133 kVp and 2 or 4 mAs. Compared to the image quality at 133 kVp and 2 mAs, the radiation dose was lowest at a setting of 109 kVp and 2 mAs. Compared to the image quality of 133 kVp and 4 mAs, the radiation dose was lowest at 109 kVp and 4 mAs. Conclusion: The results of our study suggest that radiation dose can be reduced without compromising image quality by a low-voltage technique in digitial radiography.

Neurofibromatosis type I is an autosomal dominant disease with variable clinical manifestations related to dermatologic, neurologic, skeletal, and endocrine system. Lung parenchymal involvement such as lung fibrosis and massive bullous emphysema is infrequent. Here, we report on a 36-year-old man with symptoms of dyspnea, and who has a spontaneous pneumothorax, multiple bullae, and pathologically confirmed neurofibromatosis type I.

Purpose: to evaluate the serial ultrasonographic findings of experimental intramuscular hemorrhaging to determine if there is a correlation with the pathologic findings. Materials and Methods: An uiltrasonography (US) was performed before and immediately after an intramuscular blood injection in nine rabbits. In addition, follow-up US images were obtained at 1, 4, 7, 10, 14, 21, and 28 days after the intramuscular blood injections in seven of the rabbits. The pathologic specimens, compared to the US findings on each date, and consisted of samples of left thigh muscle. Results: A US, performed immediately after a blood injection, showed two patterns; 6 cases of hyperechoic muscle thickening and 3 cases of hyperechoic muscle thickening with extravasation between the epimysium and muscle bundle or within muscle bundle. A follow-up US showed a marked decrease in intramuscular hemorrhaging and microcalcifications, which appeared on the 4th, 7th and 10th day after the blood injection. The pathologic findings revealed several short echogenic lines in the muscular bundles which were hemosiderin. Moreover, a 28 day follow-up US revealed that the normal findings are correlated with the normal gross pathologic findings. Conclusion: The US findings of the intramuscular hemorrhaging, for each of the follow-up dates, in comparison to the pathologic findings, revealed a high correlation with the pathologic specimens. Consequently, a US transducer with high resolution can be considered as a helpful technique in the diagnosing and evaluating the follow-up treatment of intramuscular hemorrhaging.

= Abstract = The term tracheal bronchus refers to an abnormal bronchus that comes directly off of the lateral wall of the trachea (above the carina and supplies ventilation to the upper lobe. Tracheal bronchi occur almost exclusively on the right trachea and are associated with other congenital anomalies. In addition tracheai bronchus may be related to other inflammatory conditions with persistent wheezing such as recurrent pneumonia chronic bronchitis and bronchiectasis which is a result of the relatively poor local drainage of the involved bronchi. An infant with recurrent wheezing is likely to be a challenge for a clinician in the evaluation of the etiology of airway obstruction and in the differential diagnosis of wheezy breathing. The authors report a case of an 8-month-old female infant with a ventricular septal defect who presented with stridor and recurrent respiratory infection and finally was finally diagnosed with a tracheal bronchus using computed tomography and a bronchoscopy. Therefore tracheal bronchus should be included in the differential diagnosis of any child who presents with chronic or recurrent respiratory tract symptoms such as coughing wheezing stridor and recurrent respiratory infection particularly in children with other congenital deformities. (Korean J Pediatr 2008;51:660-664

Purpose: We created an 'AAPM TG18 Evaluation Tool' and we determined its usefulness for the quality control of a diagnostic monitor. Materials and Methods: We created an evaluation tool (the AAPM TG18) for conducting quality control of a diagnostic monitor, and we evaluated the measurement items of the AAPM TG18 evaluation tool. The measurement items were geometric distortion, fixed quantity assessment and visual assessment of the veiling glare, and we carried out adjustment for the luminance meter 0% calibration, which was used to revise the diagnostic monitor DICOM LUT. Results: With the AAPM TG18 Evaluation Tool, we measured the 2-dimensional length when evaluating the quantitative geometric distortions in the TG18-QC test pattern, and we measured the veiling-glare ring response function, which provided information regarding the spatial extent of the luminance spread, and this measurement of the can be performed using the TG18-GV pattern. Additionally, the AAPM TG18 Evaluation Tool can be used for sensor calibration to standardize the basic rate of 0% luminance when performing periodic calibration. Conclusion: The evaluation tool is a very useful for easily evaluating many of the examination items of the AAPM TG18 for performing quality control of a diagnostic monitor.

not Available.

An acute aortic thrombosis in the absence of atherosclerosis, aortic dissection, or aneurysm is an infrequent clinical entity and has been rarely reported in the literature. However, because of serious complications such as an embolism that can be fatal, one should always pay attention to the possibility of its occurrence. We report two cases of an acute aortic thrombosis of lung cancer patients treated with chemotherapy and a review of the literature.

not Available.

The clinical and radiographic findings of lung cancer have been well established many journals. Even if the radiographic findings of lung cancer show a typical pattern, the specific cell type of lung cancer sometimes needs to be determined prior to a pathological diagnosis. For example, the usual finding of a squamous cell carcinoma is similar to other cancer types such as an adenocarcinoma or a small cell carcinoma but with a lower incidence. Therefore, it should not be used to make a diagnosis of the cell type prior to a pathological diagnosis. Many unusual findings of lung cancer, so called atypical pattern have been reported, but atypical findings are widely accepted. The more important thing is not to diagnose a specific cell type of cancer but to differentiate it from other benign conditions such as tuberculosis, fungal infections or organizing pneumonia. This paper presents typical information of the cell type of lung cancer along with the atypical radiographic findings.

We report a very rare case of mediastinal tuberculosis in a 57-year old woman who presented with a large mediastinal cyst on chest radiography. She had a 10-year history of exertional dyspnea, but felt comfortable at a rest. A subsequent chest CT suggested a mediastinal cyst with mediastinal lymphadenopathy and communicating pericardial sac. She underwent a thoracotomy and excision of the mass, which was histologically revealed to be of tuberculous origin. Although rare, the apparent increase in the incidence of tuberculosis may result mediastinal cysts being diagnosed mediastinal tuberculosis. We also briefly review mediastinal lymphadenopathy due to tuberculosis.

Many disorders and abnormalities are accompanied by cavitary lesoin of the lung and one of the most common causes of cavitary lung disease are primary and metastatic lung neoplasms. but cavitary formation of primary lung cancer is not frequent and cavitary or cystic pulmonary metastases of this is also rare. We report a case of cavitary pulmonry metastases of primary lung cancer proven by bronchoscopic biopsy and chest CT. The patients was 60 year-old heavy smoker who had no known underlying lung diseases 7 years ago and complained chronic cough. The chest CT showed primary lung cancer in right low lobe with multiple cavitary or cystic metastases in both lungs and multiple lymphatic metastases.

Tracheopathia osteoplastica is a rare, benign pathologic condition chahacterized the occurrence of numerous cartilage and bony nodules within the tissue of mucosa. We report a case of tracheopathia osteoplastica that involved both larynx and trachea. The patient was 73 years old male and had hoarseness. The neck CT showed thickened and irregular wall of the trachea extending to the level of the carina with multiple calcified nodules and plaques of bony density projecting into the lumen.

Leiomyomas are the most common benign tumors found in the esophagus. They are mostly solitary and multiple diffuse lesions are rare, occurring in only 2.4% of cases (1). We describe the case of a 13-year-old boy with a history of Alport syndrome who complained of progressive dysphagia and postprandial vomiting, and in whom diffuse leiomyomatosis of the esophagus was diagnosed. Chest PA showed mediastinal widening, and a barium study revealed diffuse esophageal wall thickening with dilatation, and obstruction at the level of the distal esophagus. Manometry showed increased pressure in the lower esophagus, and CT demonstrated diffuse thickening of the entire esophageal wall and an intraluminal mass in the distal esophagus. Follow-up CT three years later showed further esophageal wall thickening, as well as luminal narrowing. By means of distal esophagectomy, diffuse leiomyomatosis involving the entire esophageal wall and intraluminal mass was diag-nosed.

Purpose : To evaluate the incidence and type of low attenuation seen on high resolution computed tomogra-phy (HRCT) performed after artificially induced pulmonary embolism. Materials and Methods : Using permanent embolic materials, pulmonary embolism was induced in ten Yorkshire pigs. Pre- and postembolic pulmonary angiography was performed, and HRCT was performed im-mediately and 1, 3, and 6 weeks after embolization. The incidence and type of low attenuation of all segments, as seen on HRCT, was evaluated. Low attenuation was classified as mottled, lobular, segmental, or peripheral. The pigs were sacrified after 6 weeks and contact radiographs were obtained. Results : Low attenuation developed in eight of ten pigs. Pulmonary angiography revealed arterial occlusion in 15 large and 19 small segmental arteries (34 of 45 segments). In the remaining 11 segments, follow-up HRCT demonstrated areas of low attenuation. This was present in 25 of 35 segments (71%) as seen on HRCT images obtained immediately; in 16 of 41 segments (39 %) on images obtained 1 week after embolization; in 17 of 41 segments (41 %) on those acquired at 3 weeks; and in 25 of 45 segments (56 %) on those acquired at 6 weeks. The overall incidence of low attenuation was 83/166 (50 %). The types of low attenuation were mottled in 32/83 cases, lobular in 13/83, segmental in 13/83, and peripheral in 25/83. In large segmental arterial occlusion, the incidence of low attenuation on HRCT was 100% immediately, 57% at 1 week, 60% at 3 weeks, and 80 % at 6 weeks. In small segmental arterial occlusion, the incidence was 47%, 25 %, 11 %, and 21 % respectively. The overall incidence of low attenuation was 40/55 (73 %) in large segmental arterial occlusion and 18/71 ( 25%) in small segmental arterial occlusion. Conclusion : Low attenuation on HRCT is a finding of pulmonary embolism and is more common on HRCT performed immediately after embolization (71%) and in large segmental arterial occlusion (73%). Low attenu-ation on HRCT is an ancillary finding and may be useful in the diagnosis of pulmonary embolism.

Purpose : To evaluate the correlation between CT and pathologic findings of pulmonary fat embolism in rabbits. Materials and Methods : In 16 rabbits, pulmonary fat embolism was induced by intravenous injection of autol-ogous bone marrow(mean 3.3 mL). Chest CT scans were obtained immediately(within 1 hour), and 1, 3, and 7 days after embolization. The rabbits were divided into four groups. Group 1 underwent CT scanning immedi-ately after embolization, group 2 immediately and 1 day after embolization, group 3 immediately, 1 day and 3 days after embolization, group 4 immediately, 1 day, 3 days and 7 days after embolization. Pathologic speci-mens were obtained immediately after the last CT scan. Results : The earliest CT findings of pulmonary fat embolism in rabbits were peripheral lung lucency(16/16, 1 00 %), perivascular ground-glass (12/16, 75.0 %) and enlargement of the central pulmonary artery(11/16, 6 8 .8 %). Pathologically, perivascular ground-glass opacity correlated with extensive perivascular alveolar con-gestion and enlargement of the central pulmonary artery correlated with perivascular connective tissue edema and reactive pulmonary arterial engorgement. Peripheral lung lucency was probably caused by embolic occlu-sion of the pulmonary artery and decreased perfusion and air trapping induced by arterial and bronchial s-pasm associated with hypoxia. CT scans obtained 1 and 3 days after embolization showed nodules and patchy ground-glass opacity and consolidation. Aggregation of nodules resulted in patch opacities. Pathologically, pul-monary nodules correlated with focal inflammation surrounding an artery and parenchymal opacity correlat-ed with parenchymal consolidation and hemorrhagic edema. CT scans and pathologic specimens obtained 7 days after embolization showed improvement of parenchymal lung abnormalities. Conclusion : Pulmonary fat embolism in rabbits show CT and pathologic findings which vary with dynamic change. Typical earliest findings of pulmonary fat embolism were peripheral lung lucency, perivascular ground-glass opacity and enlargement of the central pulmonary artery.

We report the case of a 20-year-old female with lymphoma of the breast. Mammography showed an asymmetric pattern of confluent densities without any discrete mass. Sonography revealed diffuse heterogenous echoic mass intermingled with low-and medium level echoes. We present the clinical, radiographic and histologic features of primary breast lymphoma with a brief review of the literatures.

Superior mediastinal widening on chest radiograph in patients with trauma has been considered the hallmark of mediastinal hemorrhage. The usual causes of superior mediastinal widening are hematoma, aortic rupture, and rupture of the esophagus or tracheobronchial tree. Very rarely, a cause of superior mediastinal widening is leakage of the cerebrospinal fluid. This report descrbes a case of superior mediastinal widening from traumatic cerebrospinal fluid leakage with spinal fracture.