Radiographics recent issues

[Online Only] Radiologic and Clinical Findings of Behcet Disease: Comprehensive Review of Multisystemic Involvement

2008-09-15

Behçet disease is a chronic, relapsing, systemic disorder of unknown etiology, characterized by recurrent oral and genital ulcers, uveitis, and other clinical manifestations in multiple organ systems. Although the diagnosis is made on the basis of the combination of typical clinical symptoms, radiologic findings of Behçet disease show characteristic features of its involvement in the gastrointestinal, neurologic, cardiovascular, and thoracic organ systems. In the gastrointestinal tract, Behçet disease may produce various types of ulcers in the esophagus, stomach, and small and large intestines, as well as deeply penetrating ulcerations in the ileocecal region, with frequently accompanying enteric fistulas. Neurologic involvement includes typical and atypical parenchymal neurobehcet disease, dural sinus thrombosis, cerebral arterial aneurysm, occlusion, dissection, and meningitis. Vascular involvement is divided into three subsets including venous occlusion, arterial occlusion, and arterial aneurysm. Cardiac manifestations include intracardiac thrombus, endomyocardial fibrosis, periaortic pseudoaneurysm, and rupture of the sinus of Valsalva. Manifestations of Behçet disease in the thorax include pulmonary arterial aneurysm, pulmonary arterial thromboembolism, thrombosis in the superior vena cava, pulmonary infarction, hemorrhage, and vasculitis of the pleura and pericardium. These various manifestations of Behçet disease respond to steroid treatment; however, one of the characteristics of Behçet disease is the high rate of complications and recurrence after surgery. Familiarity with its various radiologic and clinical characteristics is essential in making an accurate early diagnosis and for prompt treatment of patients with Behçet disease.

[Quality Initiatives] Managing an Acute Adverse Event in a Radiology Department

Kruskal, J. B., Siewert, B., Anderson, S. W., Eisenberg, R. L., Sosna, J. — 2008-09-16

Many local and national regulatory organizations require that all serious adverse events be promptly investigated, managed, and reported, with the first goal being to institute actions to prevent or minimize the occurrence of similar events. However, the tools and processes necessary for effective incident review and management have been developed largely by industrial organizations, and radiologists may not be familiar with such processes. Data analysis requires a root cause analysis to identify all possible active and latent contributors to the event, as well as the use of algorithms to determine the degree of responsibility when human error is implicated. Acceptable corrective actions that are reasonable, achievable, and measurable should be instituted. These changes should be monitored according to defined timelines by a designated person. In some cases, additional training or even remediation may be required. Subsequently, the focus should be on actively managing and improving error detection and reporting systems, as well as on seeking strategies for minimizing the occurrence of preventable errors.

[Informatics] Informatics in Radiology: An Inexpensive Distance Learning Solution for Delivering High-Quality Live Broadcasts

Jeun, B. S., Javan, R., Gay, S. B., Olazagasti, J. M., Bassignani, M. J. — 2008-09-16

Providing an adequate method of distance learning is a challenge faced by many multicenter residency programs. The delivery of live didactics over the Internet is a convenient means of providing a uniform and equivalent educational experience to residents at distant sites. An application called MedCast has been developed with use of existing technologies, without the need for costly commercial products or equipment. MedCast captures the presenter’s computer screen and audio from a microphone source to produce a streaming video that is transmitted online and archived on a local server. Offsite residents can view broadcasts in real time or access archived conference sessions for later viewing. MedCast is available for download at no cost and offers several advantages, including a user-friendly graphical display interface, near-perfect preservation of image quality, and cost efficiency. Future plans include objective assessment of the efficacy of MedCast by comparing postlecture examinations to help evaluate for any differences between on- and offsite residents in terms of knowledge gained. A movie clip to supplement this article is available online at http://radiographics.rsnajnls.org/cgi/content/full/28/5/285085701/DC1.

[Editorials] Increasing User Satisfaction with Healthcare Software

Flanders, A. E. — 2008-09-15

[Illuminations] Nasal Airway

Fung, K.-h. — 2008-09-15

[RSNA Education Exhibits] Cholangiocarcinoma: Current and Novel Imaging Techniques

2008-09-15

The radiologic manifestations of cholangiocarcinomas are extremely diverse, since these tumors vary greatly in location, growth pattern, and histologic type. Familiarity with the imaging manifestations of cholangiocarcinomas is important for accurate detection and characterization of these tumors and assessment of resectability. Advances in imaging techniques have led to the availability of an array of modalities that, used independently or in combination, can aid in the accurate diagnosis and evaluation of cholangiocarcinomas in preparation for advanced surgical procedures and treatment planning. Response to novel targeted therapies can also be assessed with newer imaging tools. Hence, knowledge of current and emerging imaging applications is essential for correct diagnosis and appropriate management of these tumors.

[RSNA Education Exhibits] The Diaphragmatic Crura and Retrocrural Space: Normal Imaging Appearance, Variants, and Pathologic Conditions

Restrepo, C. S., Eraso, A., Ocazionez, D., Lemos, J., Martinez, S., Lemos, D. F. — 2008-09-15

The retrocrural space (RCS) is a small triangular region within the most inferior posterior mediastinum bordered by the two diaphragmatic crura. Multiplanar imaging modalities such as computed tomography and magnetic resonance imaging allow evaluation of the RCS as part of routine examinations of the chest, abdomen, and spine. Normal structures within the retrocrural region include the aorta, nerves, the azygos and hemiazygos veins, the cisterna chyli with the thoracic duct, fat, and lymph nodes. There is a wide range of normal variants of the diaphragmatic crura and of structures within the RCS. Diverse pathologic processes can occur within this region, including benign tumors (lipoma, neurofibroma, lymphangioma), malignant tumors (sarcoma, neuroblastoma, metastases), vascular abnormalities (aortic aneurysm, hematoma, azygos and hemiazygos continuation of the inferior vena cava), and abscesses. An understanding of the anatomy, normal variants, and pathologic conditions of the diaphragmatic crura and retrocrural structures facilitates diagnosis of disease processes within this often overlooked anatomic compartment.

[Editorials] Resident Learning Portfolio

Bisset, G. S., Bresolin, L. B. — 2008-09-15

[RSNA Education Exhibits] Hepatic Capsular and Subcapsular Pathologic Conditions: Demonstration with CT and MR Imaging

2008-09-15

A variety of pathologic conditions and pseudolesions occur at the capsular and subcapsular regions of the liver and are detected with cross-sectional abdominal imaging. These entities are related to anatomic and hemodynamic characteristics of the liver such as negative subdiaphragmatic pressure, connection with other viscera and extraperitoneal sites by the perihepatic ligaments, and a "third inflow" of blood from sources other than the usual hepatic arterial and portal venous sources. Pathologic conditions can affect the hepatic capsular and subcapsular regions by way of peritoneal, hematogenous, biliary, and perihepatic ligamentous routes. Pseudolesions or benign conditions may also be identified on the basis of altered hemodynamics of the liver. Computed tomography and magnetic resonance imaging with a multiphasic approach can be used to identify and characterize these entities. Familiarity with the wide spectrum of pathologic conditions and pseudolesions at the hepatic capsular and subcapsular regions and precise knowledge of the anatomic and hemodynamic characteristics of the liver will aid the radiologist in diagnosing pathologic conditions and differentiating pseudolesions from true lesions.

[Editorials] Practice Corner * Apocalypse Soon?

Heilman, R. S. — 2008-09-15

[RSNA Education Exhibits] Pitfalls in Renal Mass Evaluation and How to Avoid Them

Israel, G. M., Bosniak, M. A. — 2008-09-15

Characterization of renal masses with computed tomography (CT) and magnetic resonance (MR) imaging is usually clear-cut and accurate. However, potential pitfalls exist in diagnosis of renal masses, and it is necessary to understand these pitfalls to avoid misdiagnosis and possibly unnecessary surgery. Although some of the pitfalls are related to technical factors of the CT and MR imaging equipment, others are related to errors in image interpretation. To maximize detection and characterization of renal masses, the study should include images obtained before and after administration of intravenous contrast material, including images obtained during the nephrographic phase of enhancement. One should be aware of the potential unreliability of absolute Hounsfield unit measurements and of the existence of possible CT pseudoenhancement. When CT results are indeterminate, MR imaging may be helpful in demonstrating enhancement in renal masses. Before diagnosing a renal mass as a malignant neoplasm or suggesting surgery for a renal mass, one should consider alternative benign diagnoses; when appropriate, previous images or a supporting history should be obtained.

[RSNA Education Exhibits] Imaging and Histopathologic Features of HIV-related Renal Disease

Symeonidou, C., Standish, R., Sahdev, A., Katz, R. D., Morlese, J., Malhotra, A. — 2008-09-15

Despite extraordinary recent advances in the management of human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome, patients infected with HIV are still susceptible to a variety of complications that stem either from immunodeficiency or from side effects of antiretroviral regimens. Diagnosis is often challenging, since every organ in the body can be affected by HIV, and the kidneys have been increasingly shown to be involved by a variety of disease processes. Opportunistic infections including those caused by atypical organisms, malignancies such as lymphoma and Kaposi sarcoma, and disease processes specific to HIV infection such as HIV-associated nephropathy have all been shown to affect the kidneys. In this era of highly active antiretroviral therapy (HAART), renal disease arising secondary to antiretroviral medication has been added to the list. Furthermore, the introduction of HAART has increased survival of HIV-infected patients; consequently, the frequency of HIV-associated and incidental renal disease is expected to rise in this population. Because mortality and morbidity rates are affected by the early recognition of renal disease in HIV-infected patients, it is paramount that the radiologist be familiar with the imaging features that can be encountered in such cases.

[RSNA Education Exhibits] Pearls and Pitfalls in Diagnosis of Ovarian Torsion

Chang, H. C., Bhatt, S., Dogra, V. S. — 2008-09-15

Ovarian torsion is defined as partial or complete rotation of the ovarian vascular pedicle and causes obstruction to venous outflow and arterial inflow. Ovarian torsion is usually associated with a cyst or tumor, which is typically benign; the most common is mature cystic teratoma. Ultrasonography (US) is the primary imaging modality for evaluation of ovarian torsion. US features of ovarian torsion include a unilateral enlarged ovary, uniform peripheral cystic structures, a coexistent mass within the affected ovary, free pelvic fluid, lack of arterial or venous flow, and a twisted vascular pedicle. The presence of flow at color Doppler imaging does not allow exclusion of torsion but instead suggests that the ovary may be viable, especially if flow is present centrally. Absence of flow in the twisted vascular pedicle may indicate that the ovary is not viable. The role of computed tomography (CT) has expanded, and it is increasingly used in evaluation of abdominal pain. Common CT features of ovarian torsion include an enlarged ovary, uterine deviation to the twisted side, smooth wall thickening of the twisted adnexal cystic mass, fallopian tube thickening, peripheral cystic structures, and ascites. Understanding the imaging appearance of ovarian torsion will lead to conservative, ovary-sparing treatment.

[RSNA Education Exhibits] Mucoid Impactions: Finger-in-Glove Sign and Other CT and Radiographic Features

2008-09-15

Mucoid impaction is a relatively common finding at chest radiography and computed tomography (CT). Both congenital and acquired abnormalities may cause mucoid impaction of the large airways that often manifests as tubular opacities known as the finger-in-glove sign. The congenital conditions in which this sign most often appears are segmental bronchial atresia and cystic fibrosis. The sign also may be observed in many acquired conditions, include inflammatory and infectious diseases (allergic bronchopulmonary aspergillosis, broncholithiasis, and foreign body aspiration), benign neoplastic processes (bronchial hamartoma, lipoma, and papillomatosis), and malignancies (bronchogenic carcinoma, carcinoid tumor, and metastases). To point to the correct diagnosis, the radiologist must be familiar with the key radiographic and CT features that enable differentiation among the various likely causes. CT is more useful than chest radiography for differentiating between mucoid impaction and other disease processes, such as arteriovenous malformation, and for directing further diagnostic evaluation. In addition, knowledge of the patient’s medical history, clinical symptoms and signs, and predisposing factors is important.

[RSNA Education Exhibits] Smoking-related Interstitial Lung Disease: Radiologic-Clinical-Pathologic Correlation

2008-09-15

Cigarette smoking is a recognized risk factor for development of interstitial lung disease (ILD). There is strong evidence supporting a causal role for cigarette smoking in development of respiratory bronchiolitis ILD (RB-ILD), desquamative interstitial pneumonitis (DIP), and pulmonary Langerhans cell histiocytosis (PLCH). In addition, former and current smokers may be at increased risk for developing idiopathic pulmonary fibrosis (IPF). The combination of lower lung fibrosis and upper lung emphysema is being increasingly recognized as a distinct clinical entity in smokers. High-resolution computed tomography is sensitive for detection and characterization of ILD and may allow recognition and classification of the smoking-related ILDs (SR-ILDs) into distinct individual entities. However, the clinical, radiologic, and histologic features overlap among the different SR-ILDs, and mixed patterns of disease frequently coexist in the same patient. The overlap is most significant between RB-ILD and DIP. Macrophage accumulation is bronchiolocentric in RB-ILD, producing centrilobular ground-glass opacity, and more diffuse in DIP, producing widespread ground-glass changes. The coexistence of upper lung nodules and cysts in a smoker allows confident diagnosis of PLCH. Final diagnosis of an SR-ILD and identification of the specific entity can be achieved with certainty only after the pulmonologist, radiologist, and pathologist have reviewed all of the clinical, radiologic, and pathologic data.

[RSNA Education Exhibits] Invited Commentary * Authors' Response

2008-09-15

[RSNA Education Exhibits] Rare Breast Lesions: Correlation of Imaging and Histologic Features with WHO Classification

2008-09-15

Mammographers occasionally are surprised by the diagnosis of a rare lesion at breast biopsy. The imaging features of some breast lesions are unfamiliar because they are rarely seen in routine mammographic practice and they are not well described or well documented in the radiologic literature. Moreover, there may be wide variation in the appearances of rare breast lesions at mammography and ultrasonography (US). In addition, although a few rare breast lesions have a typical imaging appearance, most have mammographic and US features similar to those of breast carcinomas, and a needle biopsy is almost always necessary to obtain a diagnosis. However, even when a rare breast lesion is diagnosed on the basis of a needle biopsy, knowledge of the imaging features of such lesions may help the radiologist decide whether the results of pathologic analysis concur with the imaging findings and whether surgical excision is necessary. It is therefore important that radiologists be familiar with the broad spectrum of imaging features of rare breast lesions as well as with the correlation between their histopathologic features and their current classification according to the World Health Organization classification system.

[RSNA Education Exhibits] Athletic Pubalgia and "Sports Hernia": Optimal MR Imaging Technique and Findings

2008-09-15

Groin injuries are common in athletes who participate in sports that require twisting at the waist, sudden and sharp changes in direction, and side-to-side ambulation. Such injuries frequently lead to debilitating pain and lost playing time, and they may be difficult to diagnose. Diagnostic confusion often arises from the complex anatomy and biomechanics of the pubic symphysis region, the large number of potential sources of groin pain, and the similarity of symptoms in athletes with different types or sites of injury. Many athletes with a diagnosis of "sports hernia" or "athletic pubalgia" have a spectrum of related pathologic conditions resulting from musculotendinous injuries and subsequent instability of the pubic symphysis without any finding of inguinal hernia at physical examination. The actual causal mechanisms of athletic pubalgia are poorly understood, and imaging studies have been deemed inadequate or unhelpful for clarification. However, a large-field-of-view magnetic resonance (MR) imaging survey of the pelvis, combined with high-resolution MR imaging of the pubic symphysis, is an excellent means of assessing various causes of athletic pubalgia, providing information about the location of injury, and delineating the severity of disease. Familiarity with the pubic anatomy and with MR imaging findings in athletic pubalgia and in other confounding causes of groin pain allows accurate imaging-based diagnoses and helps in planning treatment that targets specific pathologic conditions.

[RSNA Education Exhibits] Radiation Dose Descriptors: BERT, COD, DAP, and Other Strange Creatures

Nickoloff, E. L., Lu, Z. F., Dutta, A. K., So, J. C. — 2008-09-15

Over the years, a number of terms have been used to describe radiation dose. Eight common radiation dose descriptors include background equivalent radiation time (BERT), critical organ dose (COD), surface absorbed dose (SAD), dose area product (DAP), diagnostic acceptable reference level (DARLing), effective dose (ED), fetal absorbed dose (FAD), and total imparted energy (TIE). BERT is compared to the annual natural background radiation (about 3 mSv per year) and is easily understandable for the general public. COD refers to the radiation dose delivered to an individual critical organ. SAD is the radiation dose delivered at the skin surface. DAP is a product of the irradiated surface area multiplied by the radiation dose at the surface. DARLing is usually the radiation level that encompasses 75% (the third quartile) of the data derived from a nationwide or regional survey. DARLings are meant for voluntary guidance. Consistently higher patient doses should be investigated for possible equipment deficiencies or suboptimal protocols. ED is obtained by multiplying the radiation dose delivered to each organ by its weighting factor and then by adding those values to get the sum. It can be used to assess the risk of radiation-induced cancers and serious hereditary effects to future generations, regardless of the procedure being performed, and is the most useful radiation dose descriptor. FAD is the radiation dose delivered to the fetus, and TIE is the sum of the energy imparted to all irradiated tissue. Each of these descriptors is intended to relate radiation dose ultimately to potential biologic effects. To avoid confusion, the key is to avoid using the terms interchangeably. It is important to understand each of the radiation dose descriptors and their derivation in order to correctly evaluate radiation dose and to consult with patients concerned about the risks of radiation.

[RSNA Education Exhibits] Radiation Dose Modulation Techniques in the Multidetector CT Era: From Basics to Practice

2008-09-15

Radiation exposure to the patient has become a concern for the radiologist in the multidetector computed tomography (CT) era. With the introduction of faster multidetector CT scanners, various techniques have been developed to reduce the radiation dose to the patient; one method is automatic exposure control (AEC). AEC systems make use of different types of control, including patient-size AEC, z-axis AEC, rotational or angular AEC, or a combination of two or more of these types. AEC systems operate on the basis of several methods: standard deviation, noise index, reference milliamperage, and reference image. A clear understanding of how to use different AEC systems on different multidetector CT scanners will allow users to modulate radiation dose, reduce photon starvation artifacts, and maintain image quality throughout the body. Further development of AEC systems and their successful introduction into clinical practice will require user education and good communication between users and manufacturers.

[Letters to the Editor] Clinical Significance of High-attenuation Mucus in Patients with Allergic Bronchopulmonary Aspergillosis

Galwa, R. P., Gupta, P., Mumtaz, H. A. — 2008-09-15

[RSNA Education Exhibits] Parathyroid Scintigraphy in Patients with Primary Hyperparathyroidism: 99mTc Sestamibi SPECT and SPECT/CT

Eslamy, H. K., Ziessman, H. A. — 2008-09-15

The clinical diagnosis of primary hyperparathyroidism is based largely on serum laboratory test results, as patients often are asymptomatic. Surgery, often with bilateral exploration of the neck, has been considered the definitive treatment for symptomatic disease. However, given that approximately 90% of cases are due to a single parathyroid adenoma, a better treatment may be the selective surgical excision of the hyperfunctioning parathyroid gland after its preoperative identification and localization at radiologic imaging. Scintigraphy and ultrasonography are the imaging modalities most often used for preoperative localization. Various scintigraphic protocols may be used in the clinical setting: Single-phase dual-isotope subtraction imaging, dual-phase single-isotope imaging, or a combination of the two may be used to obtain planar or tomographic views. Single photon emission computed tomography (SPECT) with the use of technetium-99m (^99mTc) sestamibi as the radiotracer, especially when combined with x-ray–based computed tomography (CT), is particularly helpful for preoperative localization: The three-dimensional functional information from SPECT is fused with the anatomic information obtained from CT. In addition, knowledge of the anatomy and embryologic development of the parathyroid glands and the pathophysiology of primary hyperparathyroidism aid in the identification and localization of hyperfunctioning glands.

[Special Exhibits] Scenes from the Past: Common and Unexpected Findings in Mummies from Ancient Egypt and South America as Revealed by CT

Jackowski, C., Bolliger, S., Thali, M. J — 2008-09-15

Computed tomography (CT) has proved to be a valuable investigative tool for mummy research and is the method of choice for examining mummies. It allows for noninvasive insight, especially with virtual endoscopy, which reveals detailed information about the mummy’s sex, age, constitution, injuries, health, and mummification techniques used. CT also supplies three-dimensional information about the scanned object. Mummification processes can be summarized as "artificial," when the procedure was performed on a body with the aim of preservation, or as "natural," when the body’s natural environment resulted in preservation. The purpose of artificial mummification was to preserve that person’s morphologic features by delaying or arresting the decay of the body. The ancient Egyptians are most famous for this. Their use of evisceration followed by desiccation with natron (a compound of sodium salts) to halt putrefaction and prevent rehydration was so effective that their embalmed bodies have survived for nearly 4500 years. First, the body was cleaned with a natron solution; then internal organs were removed through the cribriform plate and abdomen. The most important, and probably the most lengthy, phase was desiccation. After the body was dehydrated, the body cavities were rinsed and packed to restore the body’s former shape. Finally, the body was wrapped. Animals were also mummified to provide food for the deceased, to accompany the deceased as pets, because they were seen as corporal manifestations of deities, and as votive offerings. Artificial mummification was performed on every continent, especially in South and Central America.

[AFIP Archives] From the Archives of the AFIP: Pigmented Villonodular Synovitis: Radiologic-Pathologic Correlation

2008-09-15

Pigmented villonodular synovitis (PVNS) represents an uncommon benign neoplastic process that may involve the synovium of the joint diffusely or focally (PVNS) or that may occur extraarticularly in a bursa (pigmented villonodular bursitis [PVNB]) or tendon sheath (pigmented villonodular tenosynovitis [PVNTS]). Pathologic specimens of the hypertrophic synovium may appear villous, nodular, or villonodular, and hemosiderin deposition, often prominent, is seen in most cases. The knee, followed by the hip, is the most common location for PVNS or PVNB, whereas PVNTS occurs most often in the hand and foot. PVNTS is also referred to as giant cell tumor of the tendon sheath (GCTTS). PVNTS is the most common form of this disease by a ratio of approximately 3:1. Radiographs reveal nonspecific features of a joint effusion in PVNS, a focal soft-tissue mass in PVNB or PVNTS, or a normal appearance. Extrinsic erosion of bone (on both sides of the joint) may also be seen and is most frequent with intraarticular involvement of the hip (>90% of cases). Cross-sectional imaging reveals diffuse involvement of the synovium (PVNS), an intimate relationship to the tendon (PVTNS), or a typical bursal location (PVNB), findings that suggest the diagnosis. However, the magnetic resonance (MR) imaging findings of prominent low signal intensity (seen with T2-weighting) and "blooming" artifact from the hemosiderin (seen with gradient-echo sequences) are nearly pathognomonic of this diagnosis. In addition, MR imaging is optimal for evaluating lesion extent. This information is crucial to guide treatment and to achieve complete surgical resection. Recurrence is more common with diffuse intraarticular disease and is difficult to distinguish, both pathologically and radiologically, from the rare complication of malignant PVNS. Recognizing the appearances of the various types of PVNS, which reflect their pathologic characteristics, improves radiologic assessment and is important for optimal patient management.

[AFIP Archives] Best Cases from the AFIP: Pigmented Villonodular Synovitis

Garner, H. W., Ortiguera, C. J., Nakhleh, R. E — 2008-09-15

[AFIP Archives] Best Cases from the AFIP: Appendiceal Mucinous Cystadenoma

Honnef, I., Moschopulos, M., Roeren, T. — 2008-09-15

[Online Only] Abdominal Applications of 3.0-T MR Imaging: Comparative Review versus a 1.5-T System

2008-07-17

With the development of dedicated receiver coils and increased gradient performance, 3.0-T magnetic resonance (MR) systems are gaining wider acceptance in clinical practice. The expected twofold increase in signal-to-noise ratio (SNR) compared with that of 1.5-T MR systems may help improve spatial resolution or increase temporal resolution when used with parallel acquisition techniques. Several issues must be considered when applying 3.0-T MR in the abdomen, including the alteration of the radiofrequency field and relaxation time, increase in energy deposition and susceptibility effects, and problems associated with motion artifacts. For the evaluation of liver lesions, higher SNR and greater resolution achieved with the 3.0-T system could translate into better detection of malignant lesions on T2-weighted images obtained with adjusted imaging parameters. For the evaluation of pancreatic and biliary diseases, high-resolution T2-weighted imaging using single-shot turbo spin-echo sequences is useful; improvement in SNR was noticeable on two-dimensional MR cholangiopancreatographic images. For the preoperative imaging of rectal cancer, a single-shot sequence is useful for dramatically decreasing imaging time while maintaining image quality. Substantial modification of examination protocols, with optimized imaging parameters and sequence designs along with ongoing development of hardware, could contribute to an increased role of the 3.0-T system for abdominal MR examinations.

[Editorial] Editor's Page: RadioGraphics Readership Survey: A Time for Reflection and an Opportunity for Change

Olmsted, W. W. — 2008-08-13

[Quality Initiatives] Quality Initiatives * Respiratory Instructions for CT Examinations of the Lungs: A Hands-on Guide

Bankier, A. A., O'Donnell, C. R., Boiselle, P. M. — 2008-07-17

In computed tomographic (CT) examinations of the lung, accurate visualization of the natural contrast between the low attenuation of air and the relatively higher attenuation of vessels, airways, and interstitial structures requires cooperative and coordinated respiratory maneuvers by the patient. Inadequate respiratory maneuvers can influence differences in lung attenuation and lead to misinterpretation by (a) increasing attenuation to simulate disease in normal patients, (b) decreasing attenuation to simulate normal contrast in patients with disease, or (c) creating motion artifacts. For respiratory maneuvers to be effective, patients have to be instructed before the examination and coached during it. However, comprehensive descriptions of such instructions and coaching are lacking in the radiology literature. Therefore, respiratory instructions specifically for use in thoracic CT examinations have been devised. Along with patient coaching, use of these instructions can improve image quality. With this hands-on guide, both radiologists and technologists can optimize the respiratory instructions given to their patients and thereby improve the quality of thoracic CT examinations.

[Special Communications] Congratulations to the 2007 Outstanding Educator: Robert Novelline, MD

Osborn, A. G., Jost, R. G. — 2008-07-17

[Informatics] Informatics in Radiology: IHE Teaching File and Clinical Trial Export Integration Profile: Functional Examples

2008-07-17

The digital revolution in radiology introduced the need for electronic export of medical images. However, the current export process is complicated and time consuming. In response to this continued difficulty, the Integrating the Healthcare Enterprise (IHE) initiative published the Teaching File and Clinical Trial Export (TCE) integration profile. The IHE TCE profile describes a method for using existing standards to simplify the export of key medical images for education, research, and publication. This article reviews the authors’ experience in implementing the TCE profile in the following three processes: (a) the retrieval of images for a typical teaching file application within a TCE-compliant picture archiving and communication system (PACS); (b) the export of images, independent of TCE compliance of the PACS, to a typical teaching file application; and (c) the TCE-compliant transfer of images for publication. These examples demonstrate methods with which the TCE profile can be implemented to ease the burden of collecting key medical images from the PACS.

[Illuminations] Using Three- dimensional CT to Create Fine Art

Fung, K.-h. — 2008-07-17

[RSNA Education Exhibits] Role of Static and Dynamic MR Imaging in Surgical Pelvic Floor Dysfunction

Boyadzhyan, L., Raman, S. S., Raz, S. — 2008-07-17

Pelvic floor dysfunction (PFD) is a hidden women’s health epidemic in the United States, with over 10% of women having a lifetime risk for undergoing a surgical repair for this problem. Given the paucity of understanding of PFD pathophysiology and the high rate of recurrence and repeat surgery, imaging plays a major role in its clinical management, especially for the preoperative assessment of patients with multicompartment defects and failed surgical repairs. The recent development of fast magnetic resonance (MR) imaging sequences allows noninvasive, radiation-free, rapid, high-resolution evaluation of the entire pelvis in one examination. The H line, M line, organ prolapse (HMO) classification system, which is applied to dynamic MR images, allows consistent standardization and grading of various forms of PFD. In addition, the HMO system clearly defines and differentiates between the two main components of PFD: pelvic floor relaxation and pelvic organ prolapse. In addition to serving as an objective diagnostic tool in patients with surgical PFD, MR imaging has tremendous potential to be used as a research tool in trying to understand the pathophysiology of these complex disorders.

[RSNA Education Exhibits] Imaging Findings of Complications and Unusual Manifestations of Ovarian Teratomas

Park, S. B., Kim, J. K., Kim, K.-R., Cho, K.-S. — 2008-07-17

Ovarian teratomas can be associated with various complications and demonstrate a wide spectrum of clinical and imaging features. The complications include torsion (16% of ovarian teratomas), rupture (1%–4%), malignant transformation (1%–2%), infection (1%), and autoimmune hemolytic anemia (<1%). These complications require different therapeutic strategies; therefore, timely and accurate diagnosis of these complications is important for optimal patient treatment. In cases of complicated ovarian teratomas, the clinical manifestations provide only limited information and often overlap with those of other diseases. Furthermore, ovarian teratomas may have unusual clinical and imaging manifestations, thereby leading to misdiagnosis. These unusual manifestations include immature teratomas, monodermal teratomas (struma ovarii), combination tumors and collision tumors containing teratomas, and mature cystic teratomas without demonstrable fat or with pure fatty components. To provide adequate treatment and prevent misdiagnosis, it is necessary to be familiar with the imaging findings of both the complications and the unusual manifestations of ovarian teratomas.

[RSNA Education Exhibits] MR Imaging of Renal Masses: Correlation with Findings at Surgery and Pathologic Analysis

2008-07-17

Magnetic resonance (MR) imaging is useful in the characterization of renal masses. The MR imaging manifestations and pathologic diagnoses of 82 renal masses were reviewed and correlated. The MR imaging appearance of clear cell type renal cell carcinoma varies depending on the presence of cystic components, hemorrhage, and necrosis. Papillary renal cell carcinomas appear as well-encapsulated masses with homogeneous low signal intensity on T2-weighted images and homogeneous low-level enhancement after the intravenous administration of contrast material, or as cystic hemorrhagic masses with peripheral enhancing papillary projections. Transitional cell carcinoma may be seen as an irregular, enhancing filling defect in the pelvicaliceal system or ureter. Lymphomatous masses are usually hypointense relative to the renal cortex on T2-weighted images and enhance minimally on delayed gadolinium-enhanced images. Bulk fat is a distinguishing feature of angiomyolipoma. Oncocytoma has a variable and nonspecific appearance at MR imaging. MR imaging findings may allow the characterization of various renal masses and can provide valuable information for their clinical management.

[RSNA Education Exhibits] Neoplastic and Non-neoplastic Proliferative Disorders of the Perirenal Space: Cross-sectional Imaging Findings

2008-07-17

The perirenal space, located between the anterior and the posterior renal fasciae, is shaped like an inverted cone with an apex that extends into the iliac fossa. Perirenal tumors and pseudotumors primarily originate either from the kidney or as part of a systemic disease process and have characteristic histopathologic features and biologic behavior. The lesions may be classified on the basis of their distribution and imaging features as solitary soft-tissue masses (renal cell carcinoma, lymphangioma, hemangioma, and leiomyoma), rindlike soft-tissue lesions (lymphoma, retroperitoneal fibrosis, and Erdheim-Chester disease), masses containing macroscopic fat (angiomyolipoma, liposarcoma, myelolipoma, and extramedullary hematopoiesis), and multifocal soft-tissue masses (metastases, plasma cell tumors). Because of overlap in imaging findings among these diverse perirenal lesions, a definitive diagnosis in most cases can be established only at histopathologic analysis. However, an imaging pattern–based approach may facilitate the diagnosis and optimal management of perirenal tumors and pseudotumors.

[RSNA Education Exhibits] Diagnostic Imaging of Solitary Tumors of the Spine: What to Do and Say

2008-07-17

Metastatic disease, myeloma, and lymphoma are the most common malignant spinal tumors. Hemangioma is the most common benign tumor of the spine. Other primary osseous lesions of the spine are more unusual but may exhibit characteristic imaging features that can help the radiologist develop a differential diagnosis. Radiologic evaluation of a patient who presents with osseous vertebral lesions often includes radiography, computed tomography (CT), and magnetic resonance (MR) imaging. Because of the complex anatomy of the vertebrae, CT is more useful than conventional radiography for evaluating lesion location and analyzing bone destruction and condensation. The diagnosis of spinal tumors is based on patient age, topographic features of the tumor, and lesion pattern as seen at CT and MR imaging. A systematic approach is useful for recognizing tumors of the spine with characteristic features such as bone island, osteoid osteoma, osteochondroma, chondrosarcoma, vertebral angioma, and aneurysmal bone cyst. In the remaining cases, the differential diagnosis may include other primary spinal tumors, vertebral metastases and major nontumoral lesions simulating a vertebral tumor, Paget disease, spondylitis, echinococcal infection, and aseptic osteitis. In many cases, vertebral biopsy is warranted to guide treatment.

[Illuminations] The Aging Radiologist: "You Are Old, Dr Williams"

Bachman, D. M. — 2008-07-17

[RSNA Education Exhibits] MR Imaging of Cartilage Repair in the Knee and Ankle

Choi, Y. S., Potter, H. G., Chun, T. J. — 2008-07-17

Because of the relative avascularity of articular cartilage, lesions that are caused by trauma or degeneration of the cartilage do not heal spontaneously and must be repaired surgically. The interventional procedures that have been developed for the repair of such lesions include abrasion, microfracture, autologous osteochondral transplantation, allograft transplantation, and autologous chondrocyte implantation. An accurate imaging assessment of the repair tissue is necessary in order to objectively evaluate the postoperative outcome. Magnetic resonance (MR) imaging and arthroscopy provide complementary information and are especially useful for follow-up evaluation of cartilage repair in the knee and ankle. Standard MR imaging techniques may be used postoperatively to evaluate the success of implantation and the state of cartilage healing. Newer matrix assessment techniques, which include delayed gadolinium-enhanced MR imaging and mapping of T1 and T2 values, may provide useful supplemental information about the histologic and biochemical contents of reparative tissue. The normal postoperative appearance of the joints after cartilage repair varies according to the surgical technique used and the stage of healing. To identify potential complications, it is important to be familiar with the various repair procedures and the characteristic MR imaging features of the repair tissue at various postoperative intervals.

[RSNA Education Exhibits] Fetal Skeletal Dysplasia: An Approach to Diagnosis with Illustrative Cases

Dighe, M., Fligner, C., Cheng, E., Warren, B., Dubinsky, T. — 2008-07-17

Skeletal dysplasias are a heterogeneous group of conditions associated with various abnormalities of the skeleton. These conditions are caused by widespread disturbance of bone growth, beginning during the early stages of fetal development and evolving throughout life. Despite recent advances in imaging, fetal skeletal dysplasias are difficult to diagnose in utero due to a number of factors, including the large number of skeletal dysplasias and their phenotypic variability with overlapping features, lack of precise molecular diagnosis for many disorders, lack of a systematic approach, the inability of ultrasonography (US) to provide an integrated view, and variability in the time at which findings manifest in some skeletal dysplasias. US of suspected skeletal dysplasia involves systematic imaging of the long bones, thorax, hands and feet, skull, spine, and pelvis. Assessment of the fetus with three-dimensional US has been shown to improve diagnostic accuracy, since additional phenotypic features not detectable at two-dimensional US may be identified. The radiologist plays a major role in making an accurate diagnosis; however, representatives of other disciplines, including clinicians, molecular biologists, and pathologists, can also provide important diagnostic information.

[RSNA Education Exhibits] Neuroimaging in Pediatric Epilepsy: A Multimodality Approach

Rastogi, S., Lee, C., Salamon, N. — 2008-07-17

Pediatric patients with intractable epilepsy represent a challenging clinical population. However, recent advances in neuroimaging with a multimodality imaging approach that combines fluorine 18 fluorodeoxyglucose positron emission tomography, magnetoencephalography, diffusion tensor imaging, and magnetic source imaging with conventional magnetic resonance imaging continue to improve diagnosis and treatment in affected patients. These advances are increasing the understanding of the underlying disease process and improving the ability to noninvasively detect epileptogenic foci that in the past went undetected and whose accurate localization is crucial for a good outcome following surgical resection.

[RSNA Education Exhibits] SPECT/CT Imaging: Clinical Utility of an Emerging Technology

2008-07-17

Single-photon emission computed tomography (SPECT) has been a mainstay of nuclear medicine practice for several decades. More recently, combining the functional imaging available with SPECT and the anatomic imaging of computed tomography (CT) has gained more acceptance and proved useful in many clinical situations. Most vendors now offer integrated SPECT/CT systems that can perform both functions on one gantry and provide fused functional and anatomic data in a single imaging session. In addition to allowing anatomic localization of nuclear imaging findings, SPECT/CT also enables accurate and rapid attenuation correction of SPECT studies. These attributes have proved useful in many cardiac, general nuclear medicine, oncologic, and neurologic applications in which the SPECT results alone were inconclusive. Optimal clinical use of this rapidly emerging imaging modality requires an understanding of the fundamental principles of SPECT/CT, including quality control issues as well as potential pitfalls and limitations. The long-term clinical and economic effects of this technology have yet to be established.

[RSNA Education Exhibits] Mimics of Cholangiocarcinoma: Spectrum of Disease

2008-07-17

Cholangiocarcinoma is the second most common primary malignant hepatobiliary neoplasm, accounting for approximately 15% of liver cancers. Diagnosis of cholangiocarcinoma is challenging and the prognosis is uniformly poor, with recurrence rates of 60%–90% after surgical resection. A wide spectrum of neoplastic and nonneoplastic conditions of the biliary tract may masquerade as cholangiocarcinoma, adding to the complexity of management in patients suspected to have cholangiocarcinoma. Mimics of cholangiocarcinoma constitute a heterogeneous group of entities that includes primary sclerosing cholangitis, recurrent pyogenic cholangitis, acquired immunodeficiency syndrome cholangiopathy, autoimmune pancreatitis, inflammatory pseudotumor, Mirizzi syndrome, xanthogranulomatous cholangitis, sarcoidosis, chemotherapy-induced sclerosis, hepatocellular carcinoma, metastases, melanoma, lymphoma, leukemia, and carcinoid tumors. These entities demonstrate characteristic histomorphology and variable clinicobiologic behaviors. The imaging findings of these disparate entities are protean and may be indistinguishable from those of cholangiocarcinoma. In most cases, a definitive diagnosis can be established only with histopathologic examination of a biopsy specimen.

[RSNA Education Exhibits] Neuroendocrine Tumors: Role of Interventional Radiology in Therapy

2008-07-17

The management of neuroendocrine tumors (NETs) is complex. Although NETs can affect a variety of organ systems, hepatic metastatic disease in particular lends itself to a wide range of interventional treatment options. Prior detailed radiologic assessment and careful patient selection are required. Curative surgery should always be considered but is rarely possible. Embolization, radionuclide therapy, or ablative techniques may then be undertaken. Transcatheter arterial embolization (TAE) may be used alone or in combination with transcatheter arterial chemoembolization (TACE). NET type and extent of hepatic involvement are factors that can help predict the success of either TAE or TACE. Embolization techniques can also be useful in patients with nonhepatic NETs. Radionuclide therapy is emerging as a valuable adjunct and is dependent on positive somatostatin receptor status. Therapeutic radiopeptides may be delivered arterially. Ablative techniques have been shown to play a role in the palliation of symptoms and principally involve radiofrequency ablation. Hepatic cryotherapy and percutaneous ethanol injection have also been used. A multidisciplinary approach to treatment and follow-up is important. Imaging should involve dual-phase multidetector computed tomography and contrast material–enhanced magnetic resonance imaging. The role of the interventional radiologist will continue to expand as imaging techniques become more refined.

[RSNA Education Exhibits] Steady-State MR Imaging Sequences: Physics, Classification, and Clinical Applications

Chavhan, G. B., Babyn, P. S., Jankharia, B. G., Cheng, H.-L. M., Shroff, M. M. — 2008-07-17

Steady-state sequences are a class of rapid magnetic resonance (MR) imaging techniques based on fast gradient-echo acquisitions in which both longitudinal magnetization (LM) and transverse magnetization (TM) are kept constant. Both LM and TM reach a nonzero steady state through the use of a repetition time that is shorter than the T2 relaxation time of tissue. When TM is maintained as multiple radiofrequency excitation pulses are applied, two types of signal are formed once steady state is reached: preexcitation signal (S–) from echo reformation; and postexcitation signal (S+), which consists of free induction decay. Depending on the signal sampled and used to form an image, steady-state sequences can be classified as (a) postexcitation refocused (only S+ is sampled), (b) preexcitation refocused (only S– is sampled), and (c) fully refocused (both S+ and S– are sampled) sequences. All tissues with a reasonably long T2 relaxation time will show additional signals due to various refocused echo paths. Steady-state sequences have revolutionized cardiac imaging and have become the standard for anatomic functional cardiac imaging and for the assessment of myocardial viability because of their good signal-to-noise ratio and contrast-to-noise ratio and increased speed of acquisition. They are also useful in abdominal and fetal imaging and hold promise for interventional MR imaging. Because steady-state sequences are now commonly used in MR imaging, radiologists will benefit from understanding the underlying physics, classification, and clinical applications of these sequences.

[RSNA Education Exhibits] Optimizing Cardiac MR Imaging: Practical Remedies for Artifacts

Saremi, F., Grizzard, J. D., Kim, R. J. — 2008-07-17

With ongoing technical advances in magnetic resonance (MR) imaging, the clinical demand for cardiac MR evaluations has been increasing. Cardiac MR imaging techniques have evolved from traditional spin-echo sequences to breath-hold spoiled gradient-echo and balanced steady-state free precession sequences. The most recently developed techniques allow evaluation of myocardial function, perfusion, and viability; coronary angiography; flow quantification; and standard morphologic assessments. However, even with the most sophisticated acquisition techniques, artifacts commonly occur at cardiac MR imaging. Knowledge of the origin, imaging appearance, and significance of these artifacts is essential to avoid misinterpreting them as true lesions. Some artifacts are caused by simple errors in positioning of the patient, coil, or electrocardiographic leads; radiofrequency interference from nearby electronic equipment; or metallic objects within the magnetic field. Others are directly related to a specific MR imaging sequence or technique. Accelerated imaging techniques such as parallel imaging, which are used to shorten acquisition and breath-hold times in cardiac evaluations, are particularly vulnerable to artifacts. If an artifact severely degrades image quality, the acquisition should be repeated with appropriate adjustments to decrease or eliminate the problem.

[Special Exhibits] Scenes from the Past: Nikola Tesla and the Discovery of X-rays

Hrabak, M., Padovan, R. S., Kralik, M., Ozretic, D., Potocki, K. — 2008-07-17

[AFIP Archives] From the Archives of the AFIP * Pediatric Orbit Tumors and Tumorlike Lesions: Osseous Lesions of the Orbit

Chung, E. M., Murphey, M. D., Specht, C. S., Cube, R., Smirniotopoulos, J. — 2008-07-17

Many extraocular masses involving the pediatric orbit have an osseous origin. The most common is the dermoid inclusion cyst; these cystic lesions may contain lipid and are most often found near the zygomaticofrontal suture, adjacent to an indolent-appearing erosion of bone. Some primary bone lesions may involve the orbit, producing a lytic or dense lesion with enlargement of the bone; these lesions include fibrous dysplasia, juvenile ossifying fibroma, and osteosarcoma. Fibrous dysplasia tends to produce a mass of ground-glass appearance with longitudinal osseous expansion, whereas juvenile ossifying fibroma is likely to produce a mixed lytic and sclerotic lesion and focal osseous enlargement. Osteosarcoma causes marked bone destruction and variable osteoid production. Langerhans cell histiocytosis, an idiopathic reticuloendothelial proliferative disorder, tends to involve the bones of the skull, especially the lateral orbital roof; it produces lytic destruction of bone with a sclerotic rim and a large intraorbital soft-tissue mass. Granulocytic sarcoma is a solid tumor that may occur in children with myelogenous leukemia. These tumors tend to arise in the subperiosteum of the lateral orbital wall, although they usually do not disrupt the bone. Finally, the orbit is a common site for bone metastases from neuroblastoma, which cause aggressive periosteal reaction in the orbital roof or lateral wall. The last three conditions are often bilateral. At imaging evaluation, osseous lesions may appear similar to each other and to nonosseous masses of the orbit. Knowledge of the pathologic features of these tumors and how these features are reflected in their imaging appearances may help radiologists differentiate them.

[AFIP Archives] Best Cases from the AFIP: Adamantinoma of the Tibia and Fibula with Cytogenetic Analysis

Camp, M. D., Tompkins, R. K., Spanier, S. S., Bridge, J. A., Bush, C. H. — 2008-07-17

[AFIP Archives] Best Cases from the AFIP: Multilocular Cystic Renal Tumor: Cystic Nephroma

Silver, I. M. F., Boag, A. H., Soboleski, D. A. — 2008-07-17

[AFIP Archives] Invited Commentary

Takahashi, N., Kawashima, A., Lewin, M., King, B. F., Cheville, J. C. — 2008-07-17

[Online Only] Multimodality Imaging of Tracheobronchial Disorders in Children

2008-05-14

The trachea and bronchial airways in children are subject to compromise by a number of extrinsic and intrinsic conditions, including congenital, inflammatory, infectious, traumatic, and neoplastic processes. Stridor, wheezing, and respiratory distress are the most common indications for imaging of the airway in children. Frontal and lateral chest and/or neck radiography constitute the initial investigations of choice in most cases. Options for additional imaging include airway fluoroscopy, contrast esophagography, computed tomography (CT), and magnetic resonance (MR) imaging. Advanced imaging techniques such as dynamic airway CT, CT angiography, MR angiography, and cine MR imaging are valuable for providing relevant vascular and functional information in certain settings. Postprocessing techniques such as multiplanar reformatting, volume rendering, and virtual bronchoscopy assist in surgical planning by providing a better representation of three-dimensional anatomy. A systematic approach to imaging the airway based on clinical symptoms and signs is essential for the prompt, safe, and accurate diagnosis of tracheobronchial disorders in children.

[Quality Initiatives] Quality Initiatives: Missed Lesions at Abdominal Oncologic CT: Lessons Learned from Quality Assurance

Siewert, B., Sosna, J., McNamara, A., Raptopoulos, V., Kruskal, J. B. — 2008-05-14

The evaluation of oncology patients represents a substantial volume of the workload in many radiology departments. Interpreting the results of oncologic examinations is often challenging and time-consuming because many abnormalities are identified in the same examination and must be compared with the findings in previous studies. However, errors in the interpretation of oncologic computed tomographic (CT) scans can have significant effects on patient care. These effects may range from withdrawal from a clinical trial or cessation of therapy to repeat CT examination because of a technically inadequate study, CT-guided biopsy of newly identified lesions, or initiation of therapy for previously unrecognized lesions. A root cause analysis of reported errors in the interpretation of abdominal and pelvic CT scans led to the identification of potential pitfalls that may be encountered when interpreting oncologic CT scans and factors that contribute to these errors. Awareness of the spectrum of factors that contribute to misinterpretation of CT scans in oncology patients may improve the performance of the individual radiologist and ultimately translate into improved patient care.

[Informatics] Informatics in Radiology: GUIBOLD: A Graphical User Interface for Image Reconstruction and Data Analysis in Susceptibility-weighted MR Imaging

Deistung, A., Rauscher, A., Sedlacik, J., Witoszynskyj, S., Reichenbach, J. R. — 2008-05-14

Susceptibility-weighted (SW) magnetic resonance (MR) imaging provides high-resolution, distortion-free blood oxygen level–dependent (BOLD) data for assessment of cerebral veins, blood products, and brain lesions. Currently, reconstruction of SW imaging data is not implemented on all MR imaging systems or is restricted in terms of parameter adjustments. New developments in SW imaging have been implemented into a graphical user interface (GUI), which is named GUIBOLD. The GUI was designed for imaging system–independent off-line data reconstruction with interactive setting of parameters on the basis of k-space data and Digital Imaging and Communications in Medicine images. GUIBOLD is capable of presenting magnitude, unwrapped phase, and SW images in different orientations and parallel projections with various rendering methods and region-of-interest–based data analysis tools. Moreover, GUIBOLD affords easy and comprehensive data reconstruction possibilities for venographic and arterial imaging and anatomic phase imaging. As a direct application, differentiation between cavernous and calcified lesions on the basis of their magnetic susceptibility on phase images was performed. GUIBOLD widens the range of potential applications of SW imaging and makes it more accessible for use in the clinical routine as well as in medical research.

[RSNA Education Exhibits] Multidetector CT and Three-dimensional CT Angiography for Suspected Vascular Trauma of the Extremities

Fishman, E. K., Horton, K. M., Johnson, P. T. — 2008-05-14

The evolution of computed tomography (CT) from four to 16 to 64 sections since its inception in the late 1970s has led to more widespread use of this imaging modality in the emergent setting. CT angiography has become a crucial diagnostic technique for identifying vascular injury in the trauma patient. Regardless of the nature of the traumatic injury (eg, stab wound, gunshot wound, injury from a motor vehicle accident), use of multidetector CT with two-dimensional (2D) reformation and three-dimensional (3D) rendering allows visualization of injury to bone, muscle, and vasculature. The radiologist should be familiar with the indications for CT angiography, optimization of current multidetector CT acquisition protocols, utility of 2D and 3D displays, and CT findings in the presence of vascular injury to ensure prompt diagnosis and treatment.

[RSNA Education Exhibits] Invited Commentary

Covey, A. M. — 2008-05-14

[RSNA Education Exhibits] Imaging the Inferior Vena Cava: A Road Less Traveled

Kandpal, H., Sharma, R., Gamangatti, S., Srivastava, D. N., Vashisht, S. — 2008-05-14

A broad spectrum of congenital anomalies and pathologic conditions can affect the inferior vena cava (IVC). Most congenital anomalies are asymptomatic; consequently, an awareness of their existence and imaging appearances is necessary to avoid misinterpretation. Imaging also plays a central role in the diagnosis of Budd-Chiari syndrome secondary to membranous obstruction of the intrahepatic IVC. Primary malignancy of the IVC is far less common than intracaval extension of malignant tumors arising in adjacent organs, and imaging can accurately help determine the presence and extent of tumor thrombus, information that is crucial for surgical planning. However, the radiologist should be aware that artifactual filling defects at computed tomography and magnetic resonance imaging can mimic true thrombus in the IVC and must be able to differentiate true from pseudo filling defects. Other imaging findings such as flat IVC and early enhancement of the IVC are useful in limiting the differential diagnosis. Familiarity with the imaging features of the various congenital and pathologic entities that can affect the IVC is paramount for early diagnosis and management.

[RSNA Education Exhibits] Normal Doppler Spectral Waveforms of Major Pediatric Vessels: Specific Patterns

Chavhan, G. B., Parra, D. A., Mann, A., Navarro, O. M. — 2008-05-14

Every major vessel in the human body has a characteristic flow pattern that is visible in spectral waveforms obtained in that vessel with Doppler ultrasonography (US). Spectral waveforms reflect the physiologic status of the organ supplied by the vessel, as well as the anatomic location of the vessel in relation to the heart. In addition, the waveforms may be affected by age- and development-related hemodynamic differences. For example, adults tend to have higher flow velocities, whereas neonates, particularly those born prematurely, have higher resistance to flow, especially in the cerebral and renal vascular beds. As Doppler US is performed with increasing frequency for vascular evaluation in children, the recognition of normal flow patterns has become imperative. Familiarity with the waveforms characteristic of specific veins and arteries in children is important. In addition, an understanding of the hemodynamic factors involved provides a useful basis for interpreting waveform abnormalities.

[RSNA Education Exhibits] Extraosseous Langerhans Cell Histiocytosis in Children

2008-05-14

Langerhans cell histiocytosis, a rare disease that occurs mainly in children, may produce a broad range of manifestations, from a single osseous lesion to multiple lesions involving more than one organ or system. The clinical course varies widely in relation to the patient’s age. Multisystem disease may demonstrate especially aggressive behavior in very young children, with the outcome depending largely on the stage of disease and the degree of related organ dysfunction at the time of diagnosis. Extraosseous manifestations are less commonly seen than osseous ones and may be more difficult to identify. To accurately detect extraosseous Langerhans cell histiocytosis at an early stage, radiologists must recognize the significance of individual clinical and laboratory findings as well as the relevance of imaging features for the differential diagnosis. The pattern and severity of pulmonary, thymic, hepatobiliary, splenic, gastrointestinal, neurologic, mucocutaneous, soft-tissue (head and neck), and salivary involvement in Langerhans cell histiocytosis generally are well depicted with conventional radiography, ultrasonography, computed tomography, and magnetic resonance imaging. However, the imaging features are not pathognomonic, and a biopsy usually is necessary to establish a definitive diagnosis.