Fibrosing mediastinitis.

Fibrosing mediastinitis is a rare benign disorder caused by proliferation of acellular collagen and fibrous tissue within the mediastinum. Although many cases are idiopathic, many (and perhaps most) cases in the United States are thought to be caused by an abnormal immunologic response to Histoplasma capsulatum infection. Affected patients are typically young and present with signs and symptoms of obstruction or compression of the superior vena cava, pulmonary veins or arteries, central airways, or esophagus. There may be two types of fibrosing mediastinitis: focal and diffuse. The focal type usually manifests on computed tomographic (CT) or magnetic resonance (MR) images as a localized, calcified mass in the paratracheal or subcarinal regions of the mediastinum or in the pulmonary hila. The diffuse type manifests on CT or MR images as a diffusely infiltrating, often noncalcified mass that affects multiple mediastinal compartments. CT and MR imaging play a vital role in the diagnosis and management of fibrosing mediastinitis.

Normal diffusing capacity in patients with PiZ alpha(1)-antitrypsin deficiency, severe airflow obstruction, and significant radiographic emphysema.

alpha(1)-Antitrypsin deficiency is usually suspected clinically in young adults with irreversible airflow obstruction that is out of proportion to their smoking history. Many patients with alpha(1)-antitrypsin deficiency receive an initial diagnosis of asthma or chronic bronchitis. Measurement of the diffusing capacity of the lung for carbon monoxide (DLCO) has been recommended as a way to help distinguish emphysema from asthma and chronic bronchitis. In this article, we describe four patients with severe alpha(1)-antitrypsin deficiency, each of whom had a repeatedly normal DLCO despite having a significant component of fixed airway obstruction and prominent panacinar emphysema on high-resolution CT scan (HRCT). Each patient also demonstrated significant bronchodilator responsiveness, and two patients received an initial diagnosis of asthma. Potential explanations for these findings are discussed. We report these findings to illustrate the limitations of DLCO in this setting. alpha(1)-Antitrypsin deficiency should be considered in patients with fixed airway obstruction that is out of proportion to their age and smoking history, regardless of their diffusing capacity and response to bronchodilators.

Primary cardiac and pericardial neoplasms: radiologic-pathologic correlation.

Primary cardiac and pericardial neoplasms are rare lesions and include both benign and malignant histologic types. Myxoma is the most frequent primary cardiac neoplasm, but other benign tumors include papillary fibroelastoma, rhabdomyoma, fibroma, hemangioma, lipoma, and paraganglioma. Cardiac sarcoma represents the second most common primary cardiac neoplasm. Lymphoma can also affect the heart primarily. Pericardial tumors that affect the heart include benign teratomas and malignant mesotheliomas. Patients affected with cardiac or pericardial neoplasms often present with cardiovascular compromise or embolic phenomena and exhibit cardiomegaly at chest radiography. Benign cardiac tumors typically manifest as intracavitary, mural, or epicardial focal masses, whereas malignant tumors demonstrate invasive features and may involve the heart diffusely. Benign lesions can usually be successfully excised, but patients with malignant lesions have an extremely poor prognosis.

Solutions to challenges facing a university digital library and press.

During the creation of a university digital library and press intended to serve as a medical reference and education tool for health care providers and their patients, six distinct and complex digital publishing challenges were encountered. Over nine years, through a multidisciplinary approach, solutions were devised to the challenges of digital content ownership, management, mirroring, translation, interactions with users, and archiving. The result is a unique, author-owned, internationally mirrored, university digital library and press that serves as an authoritative medical reference and education tool for users around the world. The purpose of this paper is to share the valuable digital publishing lessons learned and outline the challenges facing university digital libraries and presses.

From the archives of the AFIP: pulmonary vasculature: hypertension and infarction.

Pulmonary hypertension is the hemodynamic consequence of vascular changes within the precapillary (arterial) or postcapillary (venous) pulmonary circulation. These changes may be idiopathic, as in primary pulmonary hypertension or pulmonary veno-occlusive disease, but more commonly they represent a secondary response to alterations in pulmonary blood flow. The pulmonary and systemic bronchial circulations form broad anastomoses that largely prevent infarction except in settings of markedly elevated pulmonary venous pressure, underlying malignancy, or excessive embolic burden. Causes of precapillary pulmonary hypertension include long-standing cardiac left-to-right shunt, chronic thromboembolic disease, and widespread pulmonary embolism arising from intravascular malignant cells, parasites, or foreign materials. The classic radiologic features of precapillary pulmonary hypertension are central arterial enlargement, sharply pruned peripheral vascularity, and right-sided heart hypertrophy and chamber dilatation. Postcapillary pulmonary hypertension may develop secondary to focal venous constriction or to compromised pulmonary venous drainage due to left atrial neoplasia, mitral stenosis, or left ventricular failure. Radiologic manifestations of postcapillary pulmonary hypertension include prominent septal lines, small pleural effusions, and occasionally air-space opacities. In addition, radiologic evaluation of postcapillary pulmonary hypertension may demonstrate evidence of pulmonary arterial hypertension, secondary to the retrograde transmission of elevated pulmonary venous pressure across the capillary bed.

Thoracic carcinoids: radiologic-pathologic correlation.

Carcinoids are neuroendocrine neoplasms. Bronchial carcinoids are unusual, malignant primary neoplasms that characteristically involve the central airways and typically exhibit well-defined margins and bronchial-related growth. Bronchial carcinoids include low-grade typical carcinoids and the more aggressive atypical carcinoids. These tumors usually affect patients in the 3rd through 7th decades of life who are often symptomatic with cough, hemoptysis, or obstructive pneumonia. Bronchial carcinoids radiologically manifest as hilar or perihilar masses, with or without associated atelectasis, pneumonia, bronchiectasis, or mucoid impaction. At computed tomography, an anatomic relationship of these tumors to a bronchus is usually seen, and they may show contrast material enhancement or calcification. In rare cases, carcinoids occur in the thymus; when they do, they are aggressive tumors that affect adults who usually present with chest pain, cough, and dyspnea. Thymic carcinoids manifest radiologically as anterior mediastinal masses and may mimic thymomas. Thoracic carcinoids are treated by surgical excision. The prognosis for patients with typical bronchial carcinoids is excellent; patients with atypical bronchial or thymic carcinoids have a worse prognosis.

Realizing the promise: delivering pulmonary continuing medical education over the Internet.

STUDY OBJECTIVES: Continuing medical education (CME) is meant to bridge the gap between new scientific observations and clinical practice. However, traditional CME has not been effective at altering the behaviors of physicians. One reason for this failure of traditional CME programs may be their inflexibility. In traditional CME, the clinician does not choose the topic, the pace of the program, or the place of learning, and the CME material cannot be easily delivered to the point of care where the clinician needs the information. Computers and computer networks have the potential to accomplish these goals. CME has begun to appear on the Internet; however, there have been few evaluations of its usefulness, acceptance, and effectiveness. Over the last 18 months, we have developed three on-line pulmonary CME programs, and we have delivered them on the Virtual Hospital, the University of Iowa's digital health sciences library on the Internet. We report our initial experience with this CME material. DESIGN: We measured the frequency with which the Internet-delivered CME is accessed by monitoring page accessions and by using a log file analysis program (Analog 1.2.3; University of Cambridge Statistical Laboratory; Cambridge, UK). In addition, we collected all completed CME examinations and evaluation forms submitted by registered users. MEASUREMENTS AND RESULTS: We have found that the frequency with which the Internet-delivered CME is accessed has continued to increase with time (2.3-fold increase over 18 months), that evaluations of technical and content issues are strongly favorable, and that some clinicians have been willing to pay to receive CME through the medium of the Internet. CONCLUSIONS: We feel that with adequate peer review and quality control, physicians will use the Internet-delivered CME. However, several obstacles to wide use remain. These obstacles include issues regarding training in using the Internet for physicians, reluctance of physicians to participate in on-line commerce, and the current unavailability of CME to be delivered in small-grained quantities to the point of care. As these issues are addressed, we feel that on-line CME will represent an increasingly important CME medium for clinicians.

Lung nodules: improved wire for CT-guided localization.

The authors designed three localization wires that increase the utility of percutaneous localization of lung nodules performed in conjunction with video-assisted thorascopic resection. In 17 patients, the custom-made wires dislodged less frequently than did commercially available wires (two of 11 vs three of six, respectively) while allowing the surgeon to apply gentle retraction pressure, which aided the resection.

The Virtual Hospital: experiences in creating and sustaining a digital library.

A university and its faculty encompass a wealth of content, which is often freely supplied to commercial publishers who profit from it. Emerging digital library technology holds promise for allowing the creation of digital libraries and digital presses that can allow faculty and universities to bypass commercial publishers, retain control of their content, and distribute it directly to users, allowing the university and faculty to better serve their constituencies. The purpose of this paper is to show how this can be done. A methodology for overcoming the technical, social, political, and economic barriers involved in creating, distributing and organizing a digital library was developed, implemented, and refined over seven years. Over the seven years, 120 textbooks and booklets were placed in the Virtual Hospital digital library, from 159 authors in twenty-nine departments and four colleges at The University of Iowa. The digital library received extensive use by individuals around the world. A new paradigm for academic publishing was created, involving a university and faculty owned peer reviewed digital press implemented using digital library technology. The concept has been embraced by The University of Iowa, and it has pledged to sustain the digital press in order to allow. The University of Iowa to fulfill its mission of creating, organizing, and disseminating information better.

A performance comparison of communication links between rural hospitals and a digital health sciences library.

BACKGROUND: Rural physicians need access to digital health sciences libraries (DHSLs) that is easy and reasonably rapid. The goal of this project was to study rural hospitals' access to a DHSL on the Internet, by comparing differing access speeds with differing costs and their acceptability for retrieving text, image, and video information in a DHSL. METHODS: DHSL system response time was measured at three different times during the day over three different types of network connections (T1, Frame Relay, Modem). Text, image, and video information was retrieved. Costs were determined for installation and operation of the different types of network connections. RESULTS: System response times were consistent at the three different testing times for each media type retrieved by each of the three network connection types. System response times for text retrieval met literature standards for all connections. Image retrieval met literature standards for T1 and Frame relay connections. No connection met literature standards for video retrieval. CONCLUSIONS: High speed access to DHSLs is preferable; Frame relay connections provide substantively similar service as T1 connections at less cost. However, access via modem to a DHSL can provide access to the majority of information--text--in a DHSL with an acceptable system response time.

Evaluating overall usage of a digital health sciences library.

BACKGROUND: Digital health sciences library (DHSL) evaluation involves studying the usage of the DHSL by individuals as well as populations. The purpose of this study was to evaluate trends in overall usage of a DHSL as part of a process of continuous quality improvement in order to learn how to enhance a DHSL in order to meet its users' needs better. METHODS: Web server log file analysis was performed on a prototype DHSL, the Virtual Hospital, using two log file analysis programs on data from the month of February over four consecutive years, 1995 to 1998. RESULTS: Overall DHSL usage increased between 1995 and 1997 and leveled off in 1998. Fifteen percent of usage came from countries outside the United States. A broad spectrum of medical information for health care providers and patients was accessed and centered around specialty medical information. CONCLUSIONS: To be of optimal assistance to users, DHSLs should (1) contain a broad base of information on common and uncommon medical problems, (2) accommodate the needs of the significant percentage of users that are international through content translation and mirroring, and (3) ensure they are indexed and catalogued in the major Web search engines and Web general and medical indices so they can be easily found by users.

Barriers to rural physician use of a digital health sciences library.

BACKGROUND: Rural physicians need access to quality medical information, but accessing information is difficult in rural settings. Digital health sciences libraries (DHSLs) offer the potential to make information more accessible to rural physicians. A telemedicine network was deployed to six rural hospitals in Iowa. Computers were installed allowing access to a DHSL and training sessions were held. The purpose of this study was to examine the barriers to use of a DHSL by rural physicians. METHODS: Approximately one year after deployment of the telemedicine network, physicians were surveyed using a modified critical incident technique. RESULTS: Seventy percent of the eligible physicians responded and 33% had used the DHSL. Primary barriers included insufficient training, being too time consuming to use, and distance of computers from physicians' practice sites. Non-DHSL users cited the difficulty of using the DHSL as their greatest barrier, while DHSL users cited the quality of the information resources. CONCLUSIONS: This study identifies a number of barriers that exist to rural physicians use of a DHSL. Potential solutions to these barriers are discussed. DHSLs will finally reach their potential when they can be delivered by easy to use handheld computers seamlessly integrated into the rural physician's workflow.

Performing continuous quality improvement for a digital health sciences library through an electronic mail analysis.

BACKGROUND: The goal of this prospective, cross-sectional study was to determine the user demographics of a digital health sciences library (DHSL), motives for use, the nature of users information requests, and success rate in finding answers. METHODS: The content of 500 consecutive electronic mail messages (e-mails) submitted to a DHSL were analyzed using a predetermined coding scheme. Data were entered into a database and frequency analysis was performed. RESULTS: The number of information requests from the 500 e-mail messages was 751. The largest sender category was patients and laypersons followed by students, then physicians. Motivations for use were primarily medical advice (42.8%) and patient care (13.8%). E-mail subject areas were mainly medical (61.8%) and technical (20.6%). Answers to information requests were found 54.3% of the time and senders felt the DHSL was valuable (97.8%). CONCLUSIONS: A DHSL is a valuable medical resource. DHSLs must serve the broad information needs of patients and laypersons in addition to health care providers. Developers and managers of DHSLs can use this information to guide future development of DHSL information content and services, as has been done at The University of Iowa.

Pulmonary angiitis and granulomatosis: radiologic-pathologic correlation.

Five distinct clinical syndromes of pulmonary angiitis and granulomatosis are currently recognized: Wegener granulomatosis, lymphomatoid granulomatosis, necrotizing sarcoid granulomatosis, bronchocentric granulomatosis, and allergic angiitis and granulomatosis (Churg-Strauss syndrome). Patients typically present in middle age with fever, cough, hemoptysis, dyspnea, or chest discomfort. Upper airway involvement such as sinusitis suggests Wegener granulomatosis. Medical renal disease is associated with Wegener granulomatosis and Churg-Strauss syndrome. Asthma may be present in bronchocentric granulomatosis and Churg-Strauss syndrome. Pathologic examination of these entities demonstrates vasculitis, granulomatous inflammation, and parenchymal necrosis. The radiologic manifestations of pulmonary disease are varied, but the most typical appearance is that of multiple nodules or masses that may demonstrate cavitation. Diffuse multifocal air-space opacities with or without cavitation may also be seen. Pulmonary hemorrhage is a well-known presenting manifestation of Wegener granulomatosis and, less commonly, of Churg-Strauss syndrome. Because of the multifocal lung involvement in these diseases, pulmonary metastases and infectious causes are often considered in the differential diagnosis. Affected patients are treated with cytotoxic agents and corticosteroids. The prognosis is variable, depending on the specific syndrome, but may be favorable in the absence of significant complications.

SPR online: creating, maintaining, and distributing a virtual professional society on the Internet.

SPR Online (http:@www.pedrad.org) is a recently developed digital representation of the Society for Pediatric Radiology (SPR) that enables physicians to access pertinent information and services on the Internet. SPR Online was organized on the basis of the five main services of the SPR, which include Administration, Patient Care, Education, Research, and Meetings. For each service, related content from the SPR was digitized and placed onto SPR Online. Usage over a 12-month period was evaluated with server log file analysis. A total of 3,209 users accessed SPR Online, viewing 11,246 pages of information. A wide variety of information was accessed, with that from the Education, Administration, and Meetings services being the most popular. Fifteen percent of users came from foreign countries. As a virtual professional society, SPR Online greatly enhances the power and scope of the SPR and has proved to be a popular resource, meeting the diverse information needs of an international community of pediatric radiologists.

Peer reviewing and curating the health care information infrastructure: experiences and recommendations.

As part of a digital health sciences library's continuous quality improvement process, a digital textbook of common medical problems was created which contained links to authoritative medical information on the Internet for patients and health care providers. The accomplishments of this project were the: 1) Identification of 50 common medical problems, 2) Development of a methodology for identifying authoritative medical information related to these problems, 3) Creation of a digital textbook containing links to this information with a problem-based interface, 4) Development of a methodology to allow local peer review of this information, and 5) Evaluation of the use of the information and the local peer review methodology.

Evaluation of in vivo total and regional air content and distribution in primate lungs with high-resolution CT.

RATIONALE AND OBJECTIVES: The authors sought to determine whether gray-scale quantitative information from high-resolution computed tomography (CT) could reliably yield estimates of lung air content and help determine changes in air content with lung inflation and deflation. MATERIALS AND METHODS: High-resolution CT images (n = 40) of lungs of two anesthetized monkeys were obtained after inflation with known air volumes. Percentage air content was calculated for each voxel, and lung volumes and patterns of air distribution were determined. RESULTS: When corrected for pressure and temperature, high-resolution CT-based volumes correlated closely with inflation volumes (r = .99; standard error = 3.4%). Patterns of regional change in air content demonstrated known patterns of ventilation. CONCLUSION: Although the high-spatial-frequency algorithm used in high-resolution CT enhances edges of structures and improves visualization of anatomic detail, gray-scale values from the same high-resolution CT data set remain a reliable index of regional lung attenuation.