Radiographics recent issues

[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.

[RSNA Education Exhibits] Bowel Wall Thickening in Children: CT Findings

d'Almeida, M., Jose, J., Oneto, J., Restrepo, R. — 2008-05-14

A wide variety of bowel diseases, some of which are unique to or more prevalent in pediatric patients, may manifest with intestinal wall thickening at computed tomography (CT). Common causes of bowel wall thickening include edema, hemorrhage, infection, graft-versus-host disease, and inflammatory bowel disease; more unusual causes include immunodeficiencies, lymphoma, hemangioma, pseudotumor, and Langerhans cell histiocytosis. Radiologists must be familiar with the CT signs of bowel disease and should take careful note of the bowel characteristics (eg, extent and distribution of disease involvement, bowel dilatation, mural stratification, perienteric findings) to generate an adequate differential diagnosis. The study should be tailored and optimized in advance according to the clinical scenario to decrease radiation exposure due to repeated or delayed scanning. With spiral CT scanners, studies can be performed quickly, thereby eliminating the need for sedation, and multiple reconstructed images can be generated. CT is an invaluable diagnostic tool in the evaluation of pediatric diseases involving the bowel, in spite of the use of ionizing radiation.

[RSNA Education Exhibits] Cirrhosis-associated Hepatocellular Nodules: Correlation of Histopathologic and MR Imaging Features

2008-05-14

Cirrhotic livers are characterized by advanced fibrosis and the formation of hepatocellular nodules, which are classified histologically as either (a) regenerative lesions (eg, regenerative nodules, lobar or segmental hyperplasia, focal nodular hyperplasia) or (b) dysplastic or neoplastic lesions (eg, dysplastic foci and nodules, hepatocellular carcinomas). The differentiation of these lesions is important because regenerative nodules are benign, whereas dysplastic and neoplastic nodules are premalignant and malignant, respectively. However, their accurate characterization may be difficult even at histopathologic analysis. Differential diagnosis may be facilitated by comparing the clinical and pathologic findings with radiologic imaging features; in particular, nodule size, vascularity, hepatocellular function, and Kupffer cell density assessed at magnetic resonance (MR) imaging are suggestive of the correct diagnosis. MR imaging is more useful than computed tomography for such assessments because it provides better soft-tissue contrast and a more nuanced depiction of different tissue properties. Moreover, a wider variety of contrast agents is available for use in MR imaging. Familiarity with the MR imaging characteristics of cirrhosis-associated hepatocellular nodules is therefore important for optimal diagnosis and management of cirrhotic disease.

[RSNA Education Exhibits] Total Hip Arthroplasty in Patients with Bone Deficiency of the Acetabulum

2008-05-14

Total hip replacement (THR) requires revision in only a minority of cases (approximately 17% of prosthetic hips fail), but when THR failures occur there may be significant acetabular bone deficiency. There is a variety of surgical hardware and strategies available to address this problem. The causes of primary THR revision include aseptic loosening or particle disease, infection, recurrent dislocation, implant failure, periprosthetic fracture, and leg length discrepancy. Almost all patients who need THR revision undergo a standard radiographic evaluation of the pelvis and hip. In general, CT is an excellent tool for evaluating loosening of the prosthesis caused by either mechanical reasons or infection, and MR imaging is best suited for evaluating the soft tissues surrounding the prosthesis. Nuclear medicine studies are performed when results of CT and MR imaging are inconclusive. When patients are evaluated for revision THR, radiologists must check for acetabular cup loosening, the amount and type of bone stock loss, the amount of component migration, and the presence or absence of liner wear. Before revision hardware is placed, bone stock loss must be repaired, either by using bone grafting or by placing accessory acetabular hardware such as cups, rings, or cages. The long-term success of revision acetabular surgery varies; there is acetabular cup presence at 5 years after surgery in 60%–94% of cases. Complications include postoperative infections, repeat liner wear, bone graft failure, periprosthetic or prosthetic fractures, dislocation, vascular injury, and nerve injury.

[RSNA Education Exhibits] Multidetector CT Arthrography of the Wrist Joint: How to Do It

Moser, T., Dosch, J.-C., Moussaoui, A., Buy, X., Gangi, A., Dietemann, J.-L. — 2008-05-14

With its exquisite spatial resolution, multidetector computed tomographic (CT) arthrography of the wrist is a valuable tool for the diagnosis and evaluation of a wide spectrum of articular disorders. Traumatic tears of the interosseous ligaments can be classified as complete or incomplete and as partial- or full-thickness tears at multidetector CT arthrography and can also be differentiated from asymptomatic degenerative lesions. In addition, tears of the triangular fibrocartilage complex can be differentiated according to their location. A tailored contrast material injection technique and multiplanar reformation are recommended for optimal assessment of these structures. Multidetector CT arthrography is also remarkably effective in demonstrating cartilage and bone abnormalities, many of which cannot be depicted with other imaging techniques. The chief limitation of multidetector CT arthrography lies in the evaluation of soft-tissue abnormalities, which may benefit from the addition of other imaging techniques such as ultrasonography or magnetic resonance imaging. A basic knowledge of the relevant anatomy, pathophysiologic features, and imaging technique is mandatory for obtaining high-yield diagnostic information concerning the wrist joint.

[RSNA Education Exhibits] Neoplastic and Nonneoplastic Conditions of Serosal Membrane Origin: CT Findings

2008-05-14

Computed tomography (CT) is an important imaging modality for diagnosis and follow-up of neoplastic or nonneoplastic conditions of the serosal membrane. The characteristic CT findings of malignant pleural mesothelioma include unilateral pleural effusion, thickening of the mediastinal pleura, and circumferential and nodular pleural thickening of greater than 1 cm. Malignant peritoneal mesothelioma manifests as a large mass or diffuse peritoneal thickening without a definable mass and is difficult to differentiate from peritoneal carcinomatosis or tuberculosis. The imaging features of primary serous papillary carcinoma of the peritoneum resemble those of peritoneal carcinomatosis; however, the ovary is usually of normal size. The possibility of desmoplastic small round cell tumor should be considered in children or young adults with multiple peritoneal masses and no identifiable primary malignancy. The CT findings of secondary tumors include a variable amount of fluid in the serosal cavity, thickening of the serosal lining (irregular and nodular), and serosal implants. Nonneoplastic conditions manifest as focal or diffuse thickening of the serosal membrane, a variable amount of fluid in the serosal cavity, and a soft-tissue mass at CT. Although the CT findings of some of the conditions overlap, knowledge of the typical findings is helpful in narrowing the differential diagnosis.

[RSNA Education Exhibits] Invited Commentary

Galvin, J. R. — 2008-05-14

[RSNA Education Exhibits] The Inguinal Canal: Anatomy and Imaging Features of Common and Uncommon Masses

Bhosale, P. R., Patnana, M., Viswanathan, C., Szklaruk, J. — 2008-05-14

A variety of benign and malignant masses can be found in the inguinal canal (IC). Benign causes of masses in the IC include spermatic cord lipoma, hematoma, abscess, neurofibroma, varicocele, desmoid tumor, air, bowel contrast material, hydrocele, and prostheses. Primary neoplasms of the IC include liposarcoma, Burkitt lymphoma, testicular carcinoma, and sarcoma. Metastases to the IC can occur from alveolar rhabdomyosarcoma, monophasic sarcoma, prostate cancer, Wilms tumor, carcinoid tumor, melanoma, or pancreatic cancer. In patients with a known malignancy and peritoneal carcinomatosis, the diagnosis of metastases can be suggested when a mass is detected in the IC. When peritoneal disease is not evident, a mass in the IC is indicative of stage IV disease and may significantly alter clinical and surgical treatment of the patient. A combination of the clinical history, symptoms, laboratory values, and radiologic features aids the radiologist in accurately diagnosing mass lesions of the IC. Supplemental material available at radiographics.rsnajnls.org/cgi/content/full/28/3/819/DC1.

[RSNA Education Exhibits] MR Imaging of Nonmalignant Penile Lesions

Kirkham, A. P. S., Illing, R. O., Minhas, S., Minhas, S., Allen, C. — 2008-05-14

Magnetic resonance (MR) imaging is potentially useful in the assessment of many benign penile diseases. When T1- and T2-weighted sequences are used, MR imaging can clearly delineate the tunica albuginea and can be used to diagnose penile fracture and Peyronie disease; in both conditions, MR imaging may help refine the surgical approach. It is also useful in cases of priapism; in these cases, intravenously administered contrast material can help assess the viability of the corpora cavernosa and the presence of penile fibrosis. In the assessment of a penile prosthesis, MR imaging provides excellent anatomic information and is the investigation of choice. In the evaluation of erectile dysfunction, MR imaging has limited value, and for urethral stricture, it has not yet proved adequately superior to other modalities to justify its routine use.

[RSNA Education Exhibits] Rare Causes of Hematuria Associated with Various Vascular Diseases Involving the Upper Urinary Tract

2008-05-14

Hematuria is a commonly encountered symptom of a wide spectrum of diseases, including calculi, tumors, and vascular abnormalities. In rare cases, hematuria is caused by life-threatening vascular diseases. When hematuria is encountered, physicians sometimes fail to include vascular diseases in the differential diagnosis because of their rare association with hematuria. Likewise, radiologists often fail to do so because of the low frequency of occurrence of these diseases. Multidetector computed tomography performed with the bolus injection technique should be the first-line diagnostic test when vascular disease is suspected. Radiologists should be familiar with the various imaging findings of hematuria caused by vascular disease. They should also be familiar with the management options (including endovascular techniques) for hematuria caused by vascular disease, since in some cases affected patients can be treated with interventional procedures.

[RSNA Education Exhibits] CT Findings after Laryngectomy

2008-05-14

The goal of surgical treatment of laryngeal cancer is to achieve tumor control while preserving, whenever possible, the three primary functions of the larynx: breathing, swallowing, and phonation. The surgical procedure may consist of either a partial, conservative excision (eg, cordectomy, vertical partial laryngectomy, horizontal supraglottic laryngectomy, supracricoid laryngectomy with cricohyoidopexy or cricohyoidoepiglottopexy, or near total laryngectomy) or a radical excision (total laryngectomy). The procedure depends largely on the location and extension of the tumor, the stage of disease, and the patient’s needs and preferences. Familiarity with the typical imaging appearance of the larynx after each procedure is crucial for differentiating normal postsurgical changes from persistent or recurrent disease as well as for diagnosing associated second primary malignancies. Since computed tomography (CT) is often used for follow-up evaluations, an ability to interpret the characteristic CT features is particularly important.

[AFIP Archives] From the Archives of the AFIP: Pulmonary Alveolar Proteinosis

2008-05-14

Pulmonary alveolar proteinosis (PAP) may develop in a primary (idiopathic) form, chiefly during middle age, or less commonly in the setting of inhalational exposure, hematologic malignancy, or immunodeficiency. Current research supports the theory that PAP is the result of pathophysiologic mechanisms that impair pulmonary surfactant homeostasis and lung immune function. Clinical symptomatology is variable, ranging from mild progressive dyspnea to respiratory failure. There is a strong association with tobacco use. The predominant computed tomographic feature of PAP is a "crazy-paving" pattern (smoothly thickened septal lines on a background of widespread ground-glass opacity), often with lobular or geographic sparing. The radiologic differential diagnosis of crazy-paving includes pulmonary edema, pneumonia, alveolar hemorrhage, diffuse alveolar damage, and lymphangitic carcinomatosis. Definitive diagnosis is made with lung biopsy or bronchoalveolar lavage specimens that reveal intraalveolar deposits of proteinaceous material, dissolved cholesterol, and eosinophilic globules. Symptomatic treatment includes whole-lung lavage, and multiple procedures may be required. New therapies directed toward the identified defect in immune defense have met with moderate clinical success.

[Illuminations] Pulmonary Alveolar Proteinosis

Cooper, J. A. — 2008-05-14

[AFIP Archives] Best Cases from the AFIP: Extraabdominal Desmoid-type Fibromatosis

McDonald, E. S., Yi, E. S., Wenger, D. E. — 2008-05-14

[Letters to the Editor] Re: MR Urographic Techniques

Buckley, O., Colville, J., Torreggiani, W. C., Leyendecker, J. R. — 2008-05-14

[Continuing Education] RadioGraphics: CME Objectives and Tests

2008-05-14

[Quality Initiatives] Radiologic Measurements of Tumor Response to Treatment: Practical Approaches and Limitations

2008-03-18

Objective response assessment is important to describe the treatment effect of anticancer drugs. Standardization by using a "common language" is also important for comparison of results from different trials. In contrast to clinical results, which can be subjective, diagnostic imaging provides a greater opportunity for objectivity and standardization. It was generally accepted that a decrease in tumor size correlated with treatment effect; as a result, imaging was adopted for lesion measurement in the World Health Organization (WHO) criteria in 1979. However, because of some limitations of the WHO criteria, the Response Evaluation Criteria in Solid Tumors (RECIST) were introduced in 2000. In RECIST, imaging was recognized as indispensable for response evaluation of solid tumors. Nevertheless, the widespread use of multidetector computed tomography and other imaging innovations have made RECIST outdated, with a concomitant need for modifications. Meanwhile, newer anticancer agents with targeted mechanisms of action have demonstrated an inherent limitation and unsuitability of anatomic tumor evaluation that assesses only lesion size. In addition, the effect of these new drugs changes the paradigm according to which tumor response or response rate is measured. Complete and partial responses cannot be the end points in all clinical trials; in some cases, disease control or progression-free survival may be the more relevant end point.

[Informatics] Informatics in Radiology: Automatic and Adaptive Brain Morphometry on MR Images

Hu, Q., Qian, G., Teistler, M., Huang, S. — 2008-03-18

Automatic segmentation of brain tissue on magnetic resonance images remains a challenge due to variations in brain shape and size, use of different pulse sequences, overlapping signal intensities, and imaging artifacts. An image analysis system that combines robust image processing techniques with anatomic knowledge was developed to meet this challenge. The system is fast, accurate, and robust to the variability of brain anatomy and imaging conditions and is useful for studying the brain in healthy adults, patients with a shrunken brain due to brain atrophy, and children. With this new thresholding method, the range of the proportion of brain tissue can be determined, thereby making good segmentation possible even in the presence of intrasectional inhomogeneity and noise. The system can adaptively adjust the morphologic processing to break the connection between brain and nonbrain tissue while preserving small brain fragments. It can also segment the white matter and gray matter of the two hemispheres separated by the midsagittal plane. The segmentation results can be visualized in either two or three dimensions. The system has been validated against 53 public data sets and qualitatively tested on 47 clinical data sets, yielding a better accuracy than that of the four most popular methods of brain segmentation.

[Special Communications] A Note of Thanks

McLoud, T. C., Olmsted, W. W. — 2008-03-18

[RSNA Education Exhibits] Vascular and Biliary Variants in the Liver: Implications for Liver Surgery

2008-03-18

Accurate preoperative assessment of the hepatic vascular and biliary anatomy is essential to ensure safe and successful hepatic surgery. Such surgical procedures range from the more complex, like tumor resection and partial hepatectomy for living donor liver transplantation, to others performed more routinely, like laparoscopic cholecystectomy. Modern noninvasive diagnostic imaging techniques, such as multidetector computed tomography (CT) and magnetic resonance (MR) imaging performed with liver-specific contrast agents with biliary excretion, have replaced conventional angiography and endoscopic cholangiography for evaluation of the hepatic vascular and biliary anatomy. These techniques help determine the best hepatectomy plane and help identify patients in whom additional surgical steps will be required. Preoperative knowledge of hepatic vascular and biliary anatomic variants is mandatory for surgical planning and to help reduce postoperative complications. Multidetector CT and MR imaging, with the added value of image postprocessing, allow accurate identification of areas at risk for venous congestion or devascularization. This information may influence surgical planning with regard to the extent of hepatic resection or the need for vascular reconstruction.

[RSNA Education Exhibits] Spectrum of CT Findings after Radiofrequency Ablation of Hepatic Tumors

Park, M.-h., Rhim, H., Kim, Y.-s., Choi, D., Lim, H. K., Lee, W. J. — 2008-03-18

Image-guided radiofrequency (RF) ablation has been used to treat both resectable and nonresectable hepatic tumors. A precise imaging assessment of the therapeutic response and of any complications is mandatory after ablation. Contrast material–enhanced ultrasonography, computed tomography (CT), and magnetic resonance imaging all may be useful for this assessment. At most institutions, a three-phase contrast-enhanced CT examination is performed immediately or within 1 month after RF ablation to assess the technical success of treatment. If ablation was technically successful, three-phase CT may be repeated at 3-month intervals for evaluation of tumor recurrence. The typical CT finding in the zone subjected to RF ablation is an area of low attenuation that encompasses the tumor and an ablative margin. However, the appearance of the ablative zone may vary greatly, depending on the success of treatment and the time elapsed after the procedure. Ringlike enhancement representing benign reactive hyperemia around the ablation zone, central high-attenuation areas representing greater cellular disruption, and tiny air bubbles frequently are seen at immediate follow-up CT but usually have disappeared by the first or second follow-up examination. The successfully ablated zone gradually involutes. The appearance of the zone differs when residual tumor tissue or local tumor progression is present. Immediate or delayed complications also may be seen at follow-up CT. Radiologists must be familiar with both typical and atypical CT findings and their clinical significance.

[RSNA Education Exhibits] Invited Commentary

Arellano, R. S. — 2008-03-18

[RSNA Education Exhibits] Added Diagnostic Value of Multiplanar Reformation of Multidetector CT Data in Patients with Suspected Appendicitis

Kim, H. C., Yang, D. M., Jin, W., Park, S. J. — 2008-03-18

Computed tomography (CT) is an accurate and effective modality for the diagnosis and staging of appendicitis. CT provides rapid and complete evaluation of patients with suspected appendicitis and clearly demonstrates the typical findings of appendicitis, including a distended appendix, periappendiceal fat stranding, an appendicolith, and focal thickening of the cecum. Identification of an inflamed appendix at CT may be difficult in certain patients (eg, patients with scanty intraabdominal fat, an unusual location of the cecum and appendix, prominent cecal wall thickening and pericecal fat stranding, small bowel dilatation, or abscess formation adjacent to the right adnexa). In such cases, multiplanar reformation (MPR) of multidetector CT data may provide improved appendiceal visualization and increase the physician’s confidence in diagnosing appendicitis. Moreover, the use of MPR in addition to conventional CT may provide improved visualization of the normal appendix and thereby enhance confidence in excluding appendicitis and diagnosing diseases that mimic appendicitis. Consequently, the radiologist should obtain MPR images in the evaluation of patients with suspected appendicitis to help ensure the correct diagnosis.

[RSNA Education Exhibits] Invited Commentary

Rhea, J. T. — 2008-03-18

[RSNA Education Exhibits] Velocity-encoded Cine MR Imaging in Aortic Coarctation: Functional Assessment of Hemodynamic Events

Hom, J. J., Ordovas, K., Reddy, G. P. — 2008-03-18

Velocity-encoded cine magnetic resonance (MR) imaging is becoming the modality of choice for the clinical evaluation of aortic coarctation, a congenital narrowing of the thoracic aorta, in which a functional assessment of hemodynamic obstruction is as important as anatomic delineation. A flow-sensitive phase-contrast technique, velocity-encoded cine MR imaging is based on the principle that moving protons change phase in proportion to their velocity. Because it enables precise hemodynamic characterization, the technique is especially useful for evaluating the severity of aortic coarctation. By enabling a qualitative assessment of the presence and direction of collateral circulation, velocity-encoded cine MR imaging provides information about the presence and severity of obstruction. It also allows accurate quantitation of key hemodynamic parameters such as flow velocity, flow volume, and pressure gradients across the coarctation—functional information that is clinically useful for both preoperative planning and postinterventional monitoring. The results of recent experience indicate that velocity-encoded cine MR imaging also may be applicable for the detection of recurrent stenosis after stent placement or angioplasty.

[RSNA Education Exhibits] Hypoxic-Ischemic Brain Injury: Imaging Findings from Birth to Adulthood

Huang, B. Y., Castillo, M. — 2008-03-18

Global hypoxic-ischemic injury (HII) to the brain is a significant cause of mortality and severe neurologic disability. Imaging plays an important role in the diagnosis and treatment of HII, helping guide case management in the acute setting and providing valuable information about long-term prognosis. Appropriate radiologic diagnosis of HII requires familiarity with the many imaging manifestations of this injury. Factors such as brain maturity, duration and severity of insult, and type and timing of imaging studies all influence findings in HII. Severe hypoxia-ischemia in both preterm and term neonates preferentially damages the deep gray matter, with perirolandic involvement more frequently observed in the latter age group. Less profound insults result in intraventricular hemorrhages and periventricular white matter injury in preterm neonates and parasagittal watershed territory infarcts in term neonates. In the postnatal period, severe insults result in diffuse gray matter injury, with relative sparing of the perirolandic cortex and the structures supplied by the posterior circulation. Profound hypoxia-ischemia in older children and adults affects the deep gray matter nuclei, cortices, hippocampi, and cerebellum. Because findings at conventional imaging may be subtle or even absent in the acute setting, particularly in neonates, magnetic resonance spectroscopy can help establish the diagnosis of HII. Promising new neuroprotective strategies designed to limit the extent of brain injury caused by hypoxia-ischemia are currently under investigation.

[RSNA Education Exhibits] Pediatric Facial Fractures: Children Are Not Just Small Adults

2008-03-18

Radiologic imaging is essential for diagnosing pediatric facial fractures and selecting the optimal therapeutic approach. Trauma-induced maxillofacial injuries in children may affect functioning as well as esthetic appearance, and they must be diagnosed promptly and accurately and managed appropriately to avoid disturbances of future growth and development. However, these fractures may be difficult to detect on images, and they are frequently underreported. The interpretation of facial radiographs is particularly challenging, and computed tomography (CT) is necessary in many cases to achieve an accurate diagnosis. To keep the radiation dose as low as reasonably achievable, ultrasonography may be used instead of radiography for the initial imaging evaluation when the clinical suspicion of fracture is low; if evidence of fracture is found, CT then may be performed for a more detailed evaluation. Regardless of the modality used, a familiarity with the characteristic imaging features of pediatric facial fractures is necessary for accurate image interpretation. In addition, knowledge of the epidemiologic and anatomic distribution of pediatric facial fractures is helpful. Particular kinds of fracture (nondisplaced, greenstick, displaced, comminuted) tend to occur at specific anatomic sites in children, with the severity and extent of the fracture varying according to the patient’s age and the stage of skeletal development. Midfacial fractures and fractures that are severely displaced and comminuted may be accompanied by neurocranial injuries or other complications and should be evaluated at CT with multiplanar reformatting of image data.

[RSNA Education Exhibits] MR Imaging Appearances of Acromioclavicular Joint Dislocation

Alyas, F., Curtis, M., Speed, C., Saifuddin, A., Connell, D. — 2008-03-18

The key structures involved in dislocation of the acromioclavicular joint (ACJ) are the joint itself and the strong accessory coracoclavicular ligament. ACJ dislocations are classified with the Rockwood system, which comprises six grades of injury. Treatment planning requires accurate grading of the ACJ disruption, but correct classification can be difficult with clinical assessment. Magnetic resonance (MR) imaging has a well-established role in evaluation of ACJ pain. MR imaging performed in the coronal oblique plane parallel to the distal clavicle allows assessment of the acromioclavicular and coracoclavicular ligaments owing to its in-plane orientation in relation to these structures. This technique enables distinction between grade 2 and grade 3 injuries, which can be difficult with conventional clinical and radiographic evaluation. In addition, diagnosis of grade 1 injuries is possible by demonstration of a ruptured superiodorsal acromioclavicular ligament. Resultant thickening of the acromioclavicular or coracoclavicular ligament allows identification of chronic ACJ injuries.

[RSNA Education Exhibits] Accessory Muscles: Anatomy, Symptoms, and Radiologic Evaluation

2008-03-18

A wide array of supernumerary and accessory musculature has been described in the anatomic, surgical, and radiology literature. In the vast majority of cases, accessory muscles are asymptomatic and represent incidental findings at surgery or imaging. In some cases, however, accessory muscles may produce clinical symptoms. These symptoms may be related to a palpable swelling or may be the result of mass effect on neurovascular structures, typically in fibro-osseous tunnels. In cases in which an obvious cause for such symptoms is not evident, recognition and careful evaluation of accessory muscles may aid in diagnosis and treatment.

[RSNA Education Exhibits] Paws for Thought: Comparative Radiologic Anatomy of the Mammalian Forelimb

Gough-Palmer, A. L., Maclachlan, J., Routh, A. — 2008-03-18

All mammals share a remarkably similar skeleton based on a common template. This commonality is particularly well illustrated by the versatile pentadactyl limb, upon which all mammalian limbs are based. For most mammals, the primary function of the forelimb is locomotion. The forelimb has been successfully adapted in mammals of all sizes and in terrestrial, arboreal, aquatic, and airborne environments. In primates, the forelimbs have developed such that speed and stamina have been sacrificed for an increased range of movement, which in turn has provided increased manual dexterity. For instance, chimpanzee hands are pronated and the fingers are flexed, and the phalanges are longer and exhibit much more robust insertion areas for flexor tendons. Ungulates (hoofed mammals), on the other hand, have evolved to maximize speed and stamina in quadrupedal locomotion. The two main orders of ungulates have elongated phalanges and metacarpals; all ungulates have lost the first metacarpal. The cat family represents some of the most highly evolved predators. Cats’ forelimbs are designed for speed, power, and acceleration rather than for stamina; they maintain all five metacarpals and phalanges, although the first digit is relatively small.

[RSNA Education Exhibits] Imaging of Idiopathic Spinal Cord Herniation

Parmar, H., Park, P., Brahma, B., Gandhi, D. — 2008-03-18

Idiopathic spinal cord herniation, unlike spinal cord herniation with a known traumatic or postoperative origin, is a relatively rare condition; however, it has been diagnosed and reported with increasing frequency in recent years. Such herniation most often occurs in the thoracic spine, between the T4 and T7 vertebrae. Brown-Séquard syndrome is the most frequently reported clinical feature. Early manifestations may include numbness and decreased temperature sensation in the legs, gait disturbances, pain, and incontinence. Symptoms often worsen over time, but timely diagnosis and treatment may allow the reversal of neurologic deficits. Surgical reduction typically is performed in patients with a history of symptom progression, but patients whose symptoms are less severe may be eligible for less invasive therapy and monitoring. Imaging features of spinal cord herniation generally include a dural tear through which a portion of the cord protrudes. Cerebrospinal fluid flows freely through the defect, causing increased turbulence in the fluid just dorsal to the site of herniation. The observation of this feature may allow the differentiation of spinal cord herniation from an arachnoid cyst. In addition, the calcification of nucleus pulposus leakage from a herniated disk may produce a linear area of hyperattenuation at computed tomography or signal hyperintensity at magnetic resonance imaging, an imaging feature known as the "nuclear trail" sign.

[RSNA Education Exhibits] Fournier Gangrene: Role of Imaging

Levenson, R. B., Singh, A. K., Novelline, R. A. — 2008-03-18

Fournier gangrene is a rapidly progressing necrotizing fasciitis involving the perineal, perianal, or genital regions and constitutes a true surgical emergency with a potentially high mortality rate. Although the diagnosis of Fournier gangrene is often made clinically, emergency computed tomography (CT) can lead to early diagnosis with accurate assessment of disease extent. CT not only helps evaluate the perineal structures that can become involved by Fournier gangrene, but also helps assess the retroperitoneum, to which the disease can spread. Findings at CT include asymmetric fascial thickening, subcutaneous emphysema, fluid collections, and abscess formation. Subcutaneous emphysema is the hallmark of Fournier gangrene but is not seen in all cases. Compared with radiography and ultrasonography, CT provides a higher specificity for the diagnosis of Fournier gangrene and superior evaluation of disease extent; however, diagnosis and evaluation can also be performed with these other modalities. The administration of broad-spectrum antibiotics and aggressive surgical débridement of the nonviable tissue are both essential for successful treatment. An awareness of the CT features of Fournier gangrene is imperative for prompt diagnosis and effective treatment planning.

[RSNA Education Exhibits] Multidetector CT Angiography of Infrainguinal Arterial Bypass

2008-03-18

Infrainguinal arterial bypass (IGAB) surgery is commonly performed in patients with claudication, critical limb ischemia, or other arterial problems in the lower extremities. An IGAB is constructed from different materials depending on the anatomy of the lesion and the availability of an autogenous vein. The ideal material for IGAB is the greater saphenous vein, especially for distal below-knee bypass. In patients with no available autogenous vein, IGAB can be performed by using different prosthetic materials or biologic grafts. After the surgery, periodic surveillance is performed with duplex ultrasonography and clinical assessment of peripheral pulses and ankle-brachial indexes. If complications are detected, further work-up is performed with conventional arteriography, multidetector computed tomographic (CT) angiography, or magnetic resonance angiography. CT angiography has become a powerful tool for assessing the potential early and late complications of IGAB and for planning further therapy in a fast, reliable, and noninvasive manner.

[RSNA Education Exhibits] Invited Commentary

Matalon, T. A. S. — 2008-03-18

[RSNA Education Exhibits] Imaging of Non-Small Cell Lung Cancer of the Superior Sulcus: Part 1: Anatomy, Clinical Manifestations, and Management

2008-03-18

Non–small cell carcinomas of the superior pulmonary sulcus represent 3% of all lung cancers and are associated in most cases with a poor clinical outcome. Multimodality therapy with irradiation, chemotherapy, and surgery offers the best possibility for long-term survival and cure in most cases. For patients with pulmonary sulcus tumors that are not surgically resectable, chemoradiotherapy may help prolong survival and provide long-term pain relief. To accurately determine tumor resectability and to help optimize the planning and delivery of therapy, radiologists need a detailed knowledge of the clinical and imaging manifestations of disease in the individual patient and an awareness of the therapeutic options available. Accurate three-dimensional imaging and image interpretation are essential for mapping of the primary tumor before irradiation or surgical resection. Familiarity with the complex anatomy of the superior pulmonary sulcus is particularly crucial for determining the local-regional extension of a tumor and the most appropriate surgical approach.

[RSNA Education Exhibits] Imaging of Non-Small Cell Lung Cancer of the Superior Sulcus: Part 2: Initial Staging and Assessment of Resectability and Therapeutic Response

2008-03-18

Imaging plays a crucial role in the diagnosis and staging of superior sulcus tumors, assessment of their resectability, determination of the optimal approach to disease management, and evaluation of the response to therapy. Computed tomography (CT), magnetic resonance (MR) imaging, and positron emission tomography (PET)/CT contribute important and complementary information. Whereas CT is optimal for depicting bone erosion and for staging of intrathoracic disease, MR imaging is superior for evaluating tumor extension to the intervertebral neural foramina, the spinal cord, and the brachial plexus, primarily because of the higher contrast resolution and multiplanar capability available with MR imaging technology. Use of PET/CT enables the detection of unsuspected nodal and distant metastases. However, imaging has only limited usefulness for evaluating the response of a tumor to induction therapy and detecting local recurrence, and surgical biopsy often is necessary to verify the results of therapy.

[Special Exhibits] Radiologic History Exhibit: The American Association for Women Radiologists (AAWR): 25 Years of Promoting Women in Radiology

2008-03-18

On the 25th anniversary of the American Association for Women Radiologists (AAWR), the association’s accomplishments in promoting the careers of women radiologists were reviewed. Programs that feature opportunities for women to balance their careers and their personal lives have contributed greatly to promoting networking opportunities at national meetings. Highlights of women’s accomplishments in national radiology organizations underline how far women have advanced in the specialty. Future initiatives for the organization center on increasing women’s involvement in recruiting and mentoring other women in radiology.

[AFIP Archives] From the Archives of the AFIP: Primary Peritoneal Tumors: Imaging Features with Pathologic Correlation

Levy, A. D., Arnaiz, J., Shaw, J. C., Sobin, L. H. — 2008-03-18

Primary peritoneal tumors are uncommon lesions that arise from the mesothelial or submesothelial layers of the peritoneum. Primary malignant mesothelioma, multicystic mesothelioma, primary peritoneal serous carcinoma, leiomyomatosis peritonealis disseminata, and desmoplastic small round cell tumor are the most prominent of these rare lesions. Primary malignant mesothelioma is a highly aggressive malignancy that occurs most commonly in older men and that has a strong association with high levels of asbestos exposure. It manifests most often as diffuse sheetlike or nodular thickening of the peritoneal surfaces, but it may occasionally be a localized mass. Multicystic mesothelioma occurs most frequently in women and has benign or indolent biologic behavior in the majority of patients. It is a multilocular cystic mass that arises from the pelvic peritoneal surfaces. Primary peritoneal serous carcinoma occurs almost exclusively in women. It is histologically identical to ovarian serous carcinoma and may be indistinguishable from metastatic ovarian carcinoma at imaging studies. Leiomyomatosis peritonealis disseminata is a rare, benign proliferative process that also occurs exclusively in women and is characterized by multiple smooth muscle nodules throughout the peritoneum. Desmoplastic small round cell tumor is a highly aggressive malignancy of unknown origin that occurs most often in the peritoneal cavity of young men. This unusual group of tumors is linked together by a common site of origin and imaging manifestations that mimic those of peritoneal carcinomatosis. Knowledge of the spectrum of imaging findings in this group of primary peritoneal tumors, along with their clinical and pathologic characteristics, is important in the evaluation of patients with diffuse peritoneal disease.

[AFIP Archives] Best Cases from the AFIP: Fibrolamellar Hepatocellular Carcinoma

Smith, M. T., Blatt, E. R., Jedlicka, P., Strain, J. D., Fenton, L. Z. — 2008-03-18

[Continuing Education] CME Objectives and Tests

2008-03-18

[Editorials] Editor's Page: Twenty-seven Years and Counting: The Pursuit of Excellence in Radiologic Education

Olmsted, W. W. — 2008-01-18

[Quality Initiatives] Editorial: Quality Initiatives in Radiology: Historical Perspectives for an Emerging Field

Kruskal, J. B. — 2008-01-18

[Quality Initiatives] Quality Initiatives in Radiology: President's Address from the Opening Session of RSNA 2006: Strengthening Professionalism

Hattery, R. R. — 2008-01-18

[Lifelong Learning] Education Techniques for Lifelong Learning: International Variations in Initial Certification and Maintenance of Certification in Radiology: A Multinational Survey

Bresolin, L., McLoud, T. C., Becker, G. J., Kwakwa, F. — 2008-01-18

A survey was sent to representatives of national and regional radiology societies around the world regarding the status of certification, maintenance of certification (MOC), and continuing medical education (CME) requirements. Data were forthcoming from 24 countries (response rate, 71%), including the United States. The survey results indicated that most responding countries now have a standardized process and requirements for initial certification of diagnostic and therapeutic radiologists. Similarly, most reporting countries now have some form of mandatory CME, although the degree to which compliance is tracked varies. There is considerable heterogeneity in what these countries require for recertification or MOC, and the development of such requirements is cited as a goal for many of the countries. The standardization and institutionalization of certification and recertification requirements is in rapid evolution globally.

[Lifelong Learning] Perspective on Maintenance of Certification

Hattery, R. R., Becker, G. J., Bosma, J. — 2008-01-18

[RSNA Education Exhibits] MR Urography: Techniques and Clinical Applications

Leyendecker, J. R., Barnes, C. E., Zagoria, R. J. — 2008-01-18

Magnetic resonance (MR) urography comprises an evolving group of techniques with the potential for allowing optimal noninvasive evaluation of many abnormalities of the urinary tract. MR urography is clinically useful in the evaluation of suspected urinary tract obstruction, hematuria, and congenital anomalies, as well as surgically altered anatomy, and can be particularly beneficial in pediatric or pregnant patients or when ionizing radiation is to be avoided. The most common MR urographic techniques for displaying the urinary tract can be divided into two categories: static-fluid MR urography and excretory MR urography. Static-fluid MR urography makes use of heavily T2-weighted sequences to image the urinary tract as a static collection of fluid, can be repeated sequentially (cine MR urography) to better demonstrate the ureters in their entirety and to confirm the presence of fixed stenoses, and is most successful in patients with dilated or obstructed collecting systems. Excretory MR urography is performed during the excretory phase of enhancement after the intravenous administration of gadolinium-based contrast material; thus, the patient must have sufficient renal function to allow the excretion and even distribution of the contrast material. Diuretic administration is an important adjunct to excretory MR urography, which can better demonstrate nondilated systems. Static-fluid and excretory MR urography can be combined with conventional MR imaging for comprehensive evaluation of the urinary tract. The successful interpretation of MR urographic examinations requires familiarity with the many pitfalls and artifacts that can be encountered with these techniques.

[Online Only] Dynamic MR Angiography of Upper Extremity Vascular Disease: Pictorial Review

2008-01-18

Unlike peripheral lower extremity vascular disease, upper extremity vascular disease is relatively uncommon. While atherosclerosis and embolic disease are the most common causes of upper extremity ischemia, a wide variety of systemic diseases and anatomic abnormalities can affect the upper extremity. Upper extremity ischemia poses a significant diagnostic and therapeutic challenge for both clinicians and radiologists. Although history and physical examination remain the mainstays of diagnosis, imaging can be vital in confirming suspected disease and guiding treatment planning. Digital subtraction angiography is often the preferred method for detection of upper extremity vascular disease, particularly for characterization of complex arteriovenous anatomy such as in vascular malformations and for evaluation of dialysis fistulas and grafts. However, this modality is invasive, requires iodinated contrast agents and radiation, and may fail to demonstrate significant extraluminal disease. More recently, magnetic resonance (MR) angiography techniques have made important advances, permitting higher temporal and spatial resolution that is preferable for diagnosing upper extremity vascular disorders. In this review, the authors present an overview of upper extremity MR angiography techniques and protocols, revisit the often variable vascular anatomy of the arm and hand, and offer examples of various pathologic entities diagnosed with MR angiography. Finally, several imaging pitfalls that one must be aware of for accurate diagnosis are illustrated and reviewed.

[RSNA Education Exhibits] Invited Commentary

Hosseinzadeh, K. — 2008-01-18

[RSNA Education Exhibits] MR Imaging Features of Vaginal Malignancies

Parikh, J. H., Barton, D. P. J., Ind, T. E. J., Sohaib, S. A. — 2008-01-18

Primary vaginal malignancies are rare, accounting for only 1%–2% of all gynecologic malignancies. Squamous cell carcinoma makes up about 85% of primary vaginal malignancies. This tumor characteristically arises from the posterior wall of the upper third of the vagina. The main patterns of disease are an ulcerating or fungating mass or an annular constricting lesion. At magnetic resonance (MR) imaging, squamous cell carcinoma has intermediate signal intensity on T2-weighted images and low signal intensity on T1-weighted images. The tumors that account for the remaining 15% of primary vaginal malignancies are adenocarcinoma, melanoma, and sarcomas. The signal intensity characteristics on MR images correlate with the histologic subtypes and reflect the MR imaging appearances of these histologic subtypes elsewhere in the body. Secondary malignancy of the vagina is far more frequent than primary vaginal malignancy. Most vaginal metastases occur by means of direct local spread from the cervix, uterus, or rectum. The MR imaging appearances of these metastases reflect the MR imaging appearances of the primary tumor.

[RSNA Education Exhibits] Imaging Features of von Hippel-Lindau Disease

Leung, R. S., Biswas, S. V., Duncan, M., Rankin, S. — 2008-01-18

von Hippel–Lindau (VHL) disease is a rare, autosomal dominantly inherited multisystem disorder characterized by development of a variety of benign and malignant tumors. The spectrum of clinical manifestations of the disease is broad and includes retinal and central nervous system hemangioblastomas, endolymphatic sac tumors, renal cysts and tumors, pancreatic cysts and tumors, pheochromocytomas, and epididymal cystadenomas. The most common causes of death in VHL disease patients are renal cell carcinoma and neurologic complications from cerebellar hemangioblastomas. The various manifestations can be demonstrated with different imaging modalities such as ultrasonography, computed tomography, magnetic resonance imaging, and nuclear medicine. Although genetic testing is available, the manifestations of the syndrome are protean; therefore, imaging plays a key role in identification of abnormalities and subsequent follow-up of lesions. It is also used for screening of asymptomatic gene carriers and their long-term surveillance. Screening is important because the lesions in VHL disease are treatable; thus, early detection allows use of more conservative therapy and may enhance the patient’s length and quality of life. A multidisciplinary team approach is important in screening for VHL disease.

[RSNA Education Exhibits] Multimodality Imaging Following 90Y Radioembolization: A Comprehensive Review and Pictorial Essay

2008-01-18

Radioembolization with yttrium 90 (⁹⁰Y) microspheres represents an emerging transarterial therapy for the treatment of liver malignancies that continues to generate interest in the medical community. The classic indication of treatment response is a reduction in tumor size; however, parenchymal changes (eg, necrosis, lack of enhancement, specific findings at positron emission tomography and functional magnetic resonance imaging) and other benign findings (pleural effusions, perivascular edema, contralateral hypertrophy, ring enhancement, perihepatic fluid, fibrosis) may occur following treatment, requiring proper image interpretation. With classic imaging findings and surrogates (time to progression, duration of response, disease-free interval), response rates range from 20% to 80% in patients treated for hepatocellular carcinoma or metastatic disease to the liver. Complications of ⁹⁰Y radioembolization include cholecystitis, abscess, and bilomas and should be recognized early in the imaging follow-up of these patients. Radiologists who are involved in the posttreatment assessment of patients undergoing ⁹⁰Y radioembolization should be familiar with the imaging findings and potential imaging pitfalls associated with this therapy.

[RSNA Education Exhibits] Recent Advances in Transarterial Therapy of Primary and Secondary Liver Malignancies

Kalva, S. P., Thabet, A., Wicky, S. — 2008-01-18

The management of liver malignancies presents many challenges. Few patients with primary hepatocellular carcinoma or metastatic disease of the liver are eligible for surgery, which is the only curative therapeutic option. Because the hepatic tumor burden is often a determinant of eligibility for surgery and is a primary contributor to morbidity and mortality, an increasing number of innovative techniques based on the transarterial administration of liver-directed drug-eluting or radiation-emitting microspheres are being tested for use in cytoreductive and palliative therapy. The delivery of therapy via a transarterial route takes advantage of the fact that hepatic malignancies are primarily supplied by the hepatic artery. The early results of clinical trials are promising; the clinical effectiveness and safety of drug-eluting and yttrium-90–bearing microspheres have been demonstrated; however, further clinical investigation is needed to verify a benefit in survival. Transarterially administered gene therapy holds promise but is still in the early stages of investigation. For all transarterial therapies, the outcome depends heavily on meticulous patient selection, careful preparation and administration of therapy, and early and regular follow-up evaluations by using an interdisciplinary approach.

[RSNA Education Exhibits] Evaluation of Biliary Abnormalities with 64-Channel Multidetector CT

Hashimoto, M., Itoh, K., Takeda, K., Shibata, T., Okada, T., Okuno, Y., Hino, M. — 2008-01-18

Precise preoperative assessment of the vascular and biliary anatomy is important in ensuring the safety of hepatobiliary surgical procedures, including laparoscopic cholecystectomy, living donor liver transplantation, and tumor resection of the liver. Endoscopic retrograde cholangiography and percutaneous transhepatic cholangiography clearly depict the biliary anatomy but are considered invasive procedures. Magnetic resonance cholangiopancreatography is noninvasive but sometimes fails to depict the normal intrahepatic bile ducts. Multidetector computed tomography (CT) has contributed greatly to the evaluation of the normal anatomy, anatomic variants, and disease extent in this setting. With 64-channel multidetector CT, high-resolution three-dimensional images can be reconstructed from isotropic data with a 0.625-mm section thickness. Because of its capacity for thin-section scanning and multiplanar reformation, 64-channel multidetector CT cholangiography can clearly demonstrate the biliary anatomy, a variety of anatomic variants, and the extent of disease—information that is indispensable for successful hepatobiliary surgery.

[RSNA Education Exhibits] MR Imaging of the Gallbladder: A Pictorial Essay

2008-01-18

The gallbladder serves as the repository for bile produced in the liver. However, bile within the gallbladder may become supersaturated with cholesterol, leading to crystal precipitation and subsequent gallstone formation. The most common disorders of the gallbladder are related to gallstones and include symptomatic cholelithiasis, acute and chronic cholecystitis, and carcinoma of the gallbladder. Other conditions that can affect the gallbladder include biliary dyskinesia (functional), adenomyomatosis (hyperplastic), and postoperative changes or complications (iatrogenic). Ultrasonography (US) has been the traditional modality for evaluating gallbladder disease, primarily owing to its high sensitivity and specificity for both stone disease and gallbladder inflammation. US performed before and after ingestion of a fatty meal may also be useful for functional evaluation of the gallbladder. However, US is limited by patient body habitus, with degradation of image quality and anatomic detail in obese individuals. With the advent of faster and more efficient imaging techniques, magnetic resonance (MR) imaging has assumed an increasing role as an adjunct modality for gallbladder imaging, primarily in patients who are incompletely assessed with US. MR imaging allows simultaneous anatomic and physiologic assessment of the gallbladder and biliary tract in both initial evaluation of disease and examination of the postoperative patient. This assessment is accomplished chiefly through the use of MR imaging contrast agents excreted preferentially via the biliary system.