Mahesh M. Thapa

Neuroimaging of Pediatric Central Nervous System Cytomegalovirus Infection

Cytomegalovirus (CMV) is a ubiquitous virus that usually results in asymptomatic or clinically benign infection. However, there are two groups of patients whose response to CMV infection is much more severe: those who are infected during fetal development and those who are immunocompromised. Although the manifestations of these types of infection differ, both often result in substantial neurologic sequelae. Imaging plays a key role in the diagnosis of both congenital and acquired CMV infection. Neurologic findings of congenital CMV infection include intracranial calcification, migrational abnormalities, cerebral and cerebellar volume loss, ventriculomegaly, and white matter disease. The presence of these findings in children with neurodevelopmental delays is suggestive of congenital CMV infection, even if the child was asymptomatic at birth. Certain imaging features also may indicate future neurologic deficits in symptomatic infants. Acquired CMV infection is potentially deadly in immunocompromised patients such as those infected with human immunodeficiency virus or with acquired immune deficiency syndrome and those with a history of solid organ or bone marrow transplantation. Imaging findings of acquired CMV infection often are nonspecific; however, they may indicate a need for further serologic analysis to determine if CMV infection is present. Early recognition and treatment of central nervous system CMV infection is vital for effective treatment, and familiarity with the imaging findings of this common infection is important for accurate diagnosis.

Pediatric CT: Strategies to Lower Radiation Dose

OBJECTIVE The introduction of MDCT has increased the utilization of CT in pediatric radiology along with concerns for radiation sequelae. This article reviews general principles of lowering radiation dose, the basic physics that impact radiation dose, and specific CT integrated dose-reduction tools focused on the pediatric population. CONCLUSION The goal of this article is to provide a comprehensive review of the recent literature regarding CT dose reduction methods, their limitations, and an outlook on future developments with a focus on the pediatric population. The discussion will initially focus on general considerations that lead to radiation dose reduction, followed by specific technical features that influence the radiation dose.

Pediatric Bone Imaging: Imaging Elbow Trauma in Children???A Review of Acute and Chronic Injuries

OBJECTIVE Pediatric elbow trauma is challenging because of the complex nature of the growing skeleton. The objectives of this article are to review the anatomy and radiographic landmarks and to discuss common acute and chronic injuries sustained. CONCLUSION Radiographic evaluation of elbow trauma in the acute setting requires a firm understanding of developmental anatomy, radiographic landmarks, and the common injury patterns. Both radiography and MRI are vital tools for diagnosing chronic elbow overuse injuries in adolescent athletes.

Heterotopic Ossification of the Temporomandibular Joint in Juvenile Idiopathic Arthritis

Objective. To describe the clinical, laboratory, pathologic, and radiographic imaging characteristics of a series of children with juvenile idiopathic arthritis (JIA) and radiographic imaging evidence of heterotopic ossification of their temporomandibular joint (TMJ). Methods. Children were identified through search of an administrative database of imaging results at Seattle Children’s Hospital. Retrospective chart review was performed to collect data on each patient’s clinical and laboratory characteristics, systemic therapies, timing and number of TMJ intraarticular corticosteroid injections (IAS), TMJ symptoms, and TMJ findings on physician examination. TMJ imaging studies for which heterotopic ossifications were reported were reviewed. Pathology specimens were reviewed for the 2 children who underwent synovial biopsy of their TMJ. Results. Twelve children were identified. The average duration between onset of JIA and detection of heterotopic ossification of TMJ on an imaging study was 36 months (range 19–94). Half the children had abnormal mouth-opening for age when the calcifications were first detected. In each case, the heterotopic ossification was first detected by computed tomography scan, and in 11 of the cases they were associated with synovial pannus formation as documented on an imaging study. Two children underwent synovial biopsy, which revealed reactive parosteal osteochondromatosis in one case and findings consistent with an intraarticular rheumatoid nodule in the other. Conclusion. Heterotopic ossifications of the TMJ may be seen in children with JIA and are associated with particularly severe TMJ arthritis, joint destruction, and pannus formation. Pathology from these joints suggests that the heterotopic ossification may result from multiple pathological processes.

Pictorial essay: The many faces of craniosynostosis.

Craniosynostosis is a common condition in the pediatric age group, which may either be isolated or may present as part of a craniofacial syndrome. This pictorial review illustrates the underlying mechanisms and pathophysiology of craniosynostosis, the various types of craniosynostoses, common craniofacial syndromes and the role of imaging in their diagnosis and management.

Dissemination of radiological information using enhanced podcasts.

RATIONALE AND OBJECTIVES Podcasts and vodcasts (video podcasts) have become popular means of sharing educational information via the Internet. MATERIALS AND METHODS In this article, we introduce another method, an enhanced podcast, which allows images to be displayed with the audio. Bookmarks and URLs may also be imbedded within the presentation. This article describes a step-by-step tutorial for recording and distributing an enhanced podcast using the Macintosh operating system. Enhanced podcasts can also be created on the Windows platform using other software. An example of an enhanced podcast and a demonstration video of all the steps described in this article are available online at web.mac.com/mthapa. RESULTS An enhanced podcast is an effective method of delivering radiological information via the Internet. Viewing images while simultaneously listening to audio content allows the user to have a richer experience than with a simple podcast. Incorporation of bookmarks and URLs within the presentation will make learning more efficient and interactive. CONCLUSION The use of still images rather than video clips equates to a much smaller file size for an enhanced podcast compared to a vodcast, allowing quicker upload and download times.

The Growing Skeleton: MR Imaging Appearances of Developing Cartilage

Developing hyaline cartilage at ends of long bones consists of the epiphyseal, physeal, and articular cartilage components, each of which has specific imaging characteristics that reflect biochemical and macromolecular composition. Standard MR imaging protocols used in adults do not provide sufficient information when used for children, and MR imaging techniques need to be tailored to the developmental stage of the child. This article presents the biochemical and histologic features of normal hyaline cartilage and its MR imaging characteristics, followed by a practical approach to optimizing imaging protocols for cartilage imaging. Finally, common abnormalities and advanced hyaline cartilage imaging techniques are described.

MRI of Pediatric Patients: Part 2, Normal Variants and Abnormalities of the Knee

OBJECTIVE The purpose of this article is to discuss MRI of the pediatric knee and familiarize the reader with conditions encountered in the pediatric population. Clinical scenarios are included to convey important concepts and to orient the learner to normal variants and abnormalities of the pediatric knee. The conditions discussed include, but are not limited to, distal femoral metaphysial irregularity, isolated popliteus tendon avulsion, juvenile idiopathic arthritis, and discoid meniscus. CONCLUSION The knee is the joint that is most commonly imaged by MRI in children. Injury patterns and signs of other pathologic processes seen in skeletally immature patients are different from those seen in adults. Interpreting pediatric knee MRI studies may be a challenge for those unfamiliar with the evolving patterns of normal development and of the signs of conditions that are more prevalent in children. Through case scenarios, this article describes and provides images that depict conditions commonly encountered in the pediatric knee. Most of the described normal findings and abnormalities are more prevalent in the pediatric population than in adults, and a few of the conditions are, in fact, unique to pediatric patients.

Water-bath method for sonographic evaluation of superficial structures of the extremities in children

High-resolution sonography using a stand-off pad or a gel mound is a standard technique for the evaluation of soft-tissue structures of the hands and feet in children. However, the complex curved surfaces of the hands and feet often yield suboptimal contact between the transducer and the skin. Additionally, the small field of view, relative compressibility of the soft-tissue structures by the transducer, patient motion and discomfort from contact of the transducer with the pathology often limit conventional US evaluation. A water-bath technique overcomes these limitations. We present our experience of water-bath technique of superficial sonography in 23 children. Water-bath technique was performed with good patient cooperation and was superior to the standard technique for depiction of shallow skin ulcers, subcutaneous masses, vascular malformations, osteomyelitis and foreign bodies.

Safety essentials: acute reactions to iodinated contrast media.

The objectives of this article are to review the diagnosis and management of acute nonrenal reactions to iodinated contrast media. We will begin by discussing the types of contrast media and their correlative rates of reaction. The mechanism of contrast reactions, predisposing risk factors, and preventative measures will then be discussed. The remainder of the article will review the assessment of potential reactions, initial management, and treatment algorithms for specific reactions.