A customizable MR brain imaging atlas of structure and function for decision support

We present a MR brain atlas for structure and function (diffusion weighted images). The atlas is customizable for contrast and orientation to match the current patient images. In addition, the atlas also provides normative values of MR parameters (T1, T2 and ADC values). The atlas is designed on informatics principles to provide context sensitive decision support at the time of primary image interpretation. Additional support for diagnostic interpretation is provided by a list of expert created most relevant 'Image Finding Descriptors' that will serve as cues to the user. The architecture of the atlas module is integrated into the image workflow of a radiology department to provide support at the time of primary diagnosis.

Image content extraction: application to MR images of the brain

A system for automatically extracting image content features was developed that combines registration to a labeled atlas with natural language processing of free-text radiology reports. The system was then tested with T1-weighted, spoiled gradient-echo magnetic resonance (MR) imaging studies of the brain performed in nine patients. The locations of 599 structures were visually assessed by an experienced radiologist and compared with the locations indicated by automated output. The in-plane accuracy of the contours was subjectively evaluated as either good, moderate, or poor. The criterion for classifying a structure as correctly located was that 90% or more of all the images containing the structure had to be correctly identified. For 98% of the structures, the images identified by the automated algorithm agreed with those identified by the radiologist, and in 83% of cases, image contours showed a good in-plane overlap. The results of this validation study demonstrate that this combination of registration and natural language processing is accurate in identifying relevant images from brain MR imaging studies. However, the range of applicability of this technique has yet to be determined by applying the technique to a large number of studies.

Structure localization in brain images: application to relevant image selection

Recent advances in imaging have lead to increases in the number of images/study. Automated methods to select relevant images are critical to effectively convey study results. The proposed method combines natural language processing (NLP) and automatic structure localization to identify relevant images of a MR brain study. NLP extracts relevant locations of findings. Two algorithms were implemented and evaluated for structure localization. The first method involves registration of patient dataset to a labeled atlas. The second method involves an eigenimage search using a training set of images. A prototype was developed and tested on MR brain studies of nine patients. With the registration method, slices containing the relevant structure agreed with expert selection in 98% of cases. Structure localization by eigenimage search was able to locate the lateral ventricles correctly in all the test cases. The proposed method provides an accurate method for identifying relevant slices of an imaging study.

Disease specific intelligent pre-fetch and hanging protocol for diagnostic neuroradiology workstations

Clinical data sets for neuroradiological cases can be quite large. A typical brain tumor patient at UCLA will undergo 8-10 separate studies over a 2 year period, each study will produce 60-100 magnetic resonance (MR) images. Gathering and sorting through a patient s imaging events during the course of treatment can be both overwhelming and time consuming. The purpose of this research is to develop an intelligent pre-fetch and hanging protocol that automatically gathers the relevant prior examinations from a picture archiving, and communication systems (PACS) archive and sends the pertinent historical images to the diagnostic display station where the new examination is subsequently read out. The intelligent hanging protocol describes the type of layout and sequence for image display. We have developed a classification scheme to organize the pertinent patient information to selectively pre-fetch and intelligently present the images to review brain tumor cases for a diagnostic neuroradiology workstation.

Interactive software for generation and visualization of structured findings in radiology reports

OBJECTIVE

Our objectives were to develop a user-friendly graphic interface for a module that integrates traditional radiology reporting, natural language processing, and editing capabilities; to facilitate the structuring of radiology reports as part of routine clinical practice; to use a commercial speech recognition module for online transcription; and to implement the module in a hardware-independent environment.

CONCLUSION

After implementation, the module was tested with 150 chest radiology reports by two radiologists and assessed for ease of use and accuracy. Overall, accuracy was close to 90% and user satisfaction was high. When radiology reports are structured as a part of routine clinical practice, it is possible to accomplish intelligent indexing and retrieval to facilitate teaching and research.

Teleradiology as a foundation for an enterprise-wide health care delivery system

An effective, integrated telemedicine system has been developed that allows (a) teleconsultation between local primary health care providers (primary care physicians and general radiologists) and remote imaging subspecialists and (b) active patient participation related to his or her medical condition and patient education. The initial stage of system development was a traditional teleradiology consultation service between general radiologists and specialists; this established system was expanded to include primary care physicians and patients. The system was developed by using a well-defined process model, resulting in three integrated modules: a patient module, a primary health care provider module, and a specialist module. A middle agent layer enables tailoring and customization of the modules for each specific user type. Implementation by using Java and the Common Object Request Broker Architecture standard facilitates platform independence and interoperability. The system supports (a) teleconsultation between a local primary health care provider and an imaging subspecialist regardless of geographic location and (b) patient education and online scheduling. The developed system can potentially form a foundation for an enterprise-wide health care delivery system. In such a system, the role of radiologist specialists is enhanced from that of a diagnostician to the management of a patient's process of care.

A medical digital library to support scenario and user-tailored information retrieval

Current large-scale information sources are designed to support general queries and lack the ability to support scenario-specific information navigation, gathering, and presentation. As a result, users are often unable to obtain desired specific information within a well-defined subject area. Today's information systems do not provide efficient content navigation, incremental appropriate matching, or content correlation. We are developing the following innovative technologies to remedy these problems: 1) scenario-based proxies, enabling the gathering and filtering of information customized for users within a pre-defined domain; 2) context-sensitive navigation and matching, providing approximate matching and similarity links when an exact match to a user's request is unavailable; 3) content correlation of documents, creating semantic links between documents and information sources; and 4) user models for customizing retrieved information and result presentation. A digital medical library is currently being constructed using these technologies to provide customized information for the user. The technologies are general in nature and can provide custom and scenario-specific information in many other domains (e.g., crisis management).

Improving the quality of care through routine teleradiology consultation

RATIONALE AND OBJECTIVES

The hypotheses of this study were as follows: (a) University subspecialty radiologists can provide consultations effectively to general radiologists as part of routine clinical operations; (b) these consultations will improve the quality of the final radiologic report; and (c) the consultations will improve the care process and may save money, as well.

MATERIALS AND METHODS

For 2,012 consecutive computed tomographic or magnetic resonance (MR) imaging studies, the initial interpretations provided by radiology generalists were subsequently reviewed by specialists, with a final consensus report available. "Truth" was established by final consensus reports. To control for potential bias, 150 adult MR imaging and 250 pediatric radiologic studies were interpreted initially by specialists and then by generalists. Again, truth was established by final consensus reports.

RESULTS

There was disagreement between generalist and specialist radiologist interpretations in 427 (21.2%) of the cases reviewed. These disagreements were stratified further by independent specialists, who graded them as important, very important, or unimportant. Differences were considered important or very important in 99% of the cases reviewed.

CONCLUSION

Consultations by subspecialty radiologists improved the quality of the radiology reports studied and, at least in some cases, improved the process of care by eliminating unnecessary procedures or suggesting more specific follow-up examinations. The consultation services can be provided cost-effectively from the payer's perspective and may save additional costs when unnecessary procedures can be eliminated.

Evaluation of SNOMED3.5 in representing concepts in chest radiology reports: integration of a SNOMED mapper with a radiology reporting workstation

Standardized medical terminologies are gaining importance in the representation of medical data. In this paper, we present the evaluation of the SNOMED3.5 medical terminology to code concepts routinely used in chest radiology reports. Integration of this terminology mapper into a radiology reporting workstation that incorporates a speech recognition system and a natural language processor is also discussed. A total of 700 anatomical location terms (including synonyms) were tested and 72% of the terms had corresponding SNOMED terms. Of the 28% that did not result in a match, 16% were either morphological variants of SNOMED terms or could be found from a combination of terms from two or more SNOMED axes. Only 12% of the terms (primarily specialized radiology terms) were concepts not actually included in the SNOMED terminology.

Technical considerations in planning a distributed teleradiology system

A large-scale teleradiology project is under way to link a Florida imaging center to the UCLA Department of Radiology. The initial goal is to provide Florida patients in a routine clinical practice environment with subspecialty consultation by academic radiologists. The plan then calls for the addition of other domestic and international sites. Technical issues in planning to establish the necessary teleradiology infrastructure include wide area network design, image compression, distributed archiving, and special viewing station features. Special emphasis is placed on archive design that makes intelligent use of information, such as triggering events from the radiological information system (RIS) for image prefetching and visual cues from photo-icons for full-size image retrieval. Concepts such as teleconsultation and remote procedure monitoring are aimed at providing the same level of services at distant sites that would be available in-house. This article highlights the system design parameters that must be considered to engineer a scalable distributed teleradiology system.

Process models for telehealth: an industrial approach to quality management of distant medical practice

Process modeling is explored as an approach for prospectively managing the quality of a telemedicine/telehealth service. This kind of prospective quality management is more appropriate for dynamic health care environments compared to traditional quality assurance programs. A vector model approach has also been developed to match a process model to the needs of a particular site.

Case-based explanation of non-case-based learning methods

We show how to generate case-based explanations for non-case-based learning methods such as artificial neural nets or decision trees. The method uses the trained model (e.g., the neural net or the decision tree) as a distance metric to determine which cases in the training set are most similar to the case that needs to be explained. This approach is well suited to medical domains, where it is important to understand predictions made by complex machine learning models, and where training and clinical practice makes users adept at case interpretation.

Creating and indexing teaching files from free-text patient reports

Teaching files based on real patient data can enhance the education of students, staff and other colleagues. Although information retrieval system can index free-text documents using keywords, these systems do not work well where content bearing terms (e.g., anatomy descriptions) frequently appears. This paper describes a system that uses multi-word indexing terms to provide access to free-text patient reports. The utilization of multi-word indexing allows better modeling of the content of medical reports, thus improving retrieval performance. The method used to select indexing terms as well as early evaluation of retrieval performance is discussed.

MR-guided procedures using contemporaneous imaging frameless stereotaxis in an open-configuration system

Frameless MR-guided procedures have had limited application using conventional closed magnets, due largely to the technical difficulties involved. As a result of in-room MR image-monitoring capabilities, new open-design magnets now allow frameless stereotaxis using contemporaneous imaging to guide more invasive procedures. We evaluate our clinical experience with this new technique. An open-design 0.2 T magnet (Siemens OPEN) combined with an in-room monitor was used for 33 frameless MR-guided procedures (aspiration cytology, biopsy, and/or treatment) in a variety of locations in the head, neck, spine, brain, pelvis, and abdomen. Success of the procedure was based on the ability to accurately position the instrument in the target region to allow biopsy and/or treatment. The open-design magnet allowed the physician to directly access the patient for frameless stereotaxis as the procedure was performed. The in-room monitor provided contemporaneous imaging feedback during the procedure for successful placement of the instrument in the target region. Twenty-eight biopsy and five treatment procedures were performed. In all cases the technique resulted in successful placement of the instrument within the target tissue to complete the procedure. MR-guided procedures using contemporaneous imaging frameless stereotaxis are possible in an open-design magnet with in-room image monitoring and offer exciting possibilities for further development.

Effect of conversion from a fee-for-service plan to a capitation reimbursement system on a circumscribed outpatient radiology practice of 20,000 persons

PURPOSE

To assess the effect of a capitation reimbursement plan with attendant changes in service arrangements on the utilization of radiologic services, financially on the payer, and on the satisfaction of patients and referring physicians.

MATERIALS AND METHODS

Outpatient radiologic services for a defined population of 20,000 company employees and their dependents were converted from a point-of-service managed care plan to a capitation payment plan. Under the capitation plan, nonemergent outpatient diagnostic imaging was performed at a newly constructed imaging center staffed by general radiologists. All cross-sectional images and certain projectional studies were also over-read (read again after the initial reading by local radiologists) by subspecialists. Utilization data obtained before and after the conversion were analyzed. The financial effect on the employer and the satisfaction of patients and physicians were also assessed.

RESULTS

Quality imaging services were provided under the capitation plan with financial savings by the employer. Use was higher for cross-sectional imaging, especially magnetic resonance imaging studies, and was lower for nonmammographic plain radiography. Consumer satisfaction was high.

CONCLUSION

Under certain conditions, conversion to a capitation system for imaging can lead to improved quality of care and decreased overall health-care costs.

Imaging of the adrenal gland in children

Ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging have replaced intravenous urography and angiography in evaluation of children with suspected disease of the adrenal glands. Although the spatial resolution of MR imaging is still somewhat inferior to that of CT, it allows tissue characterization and better evaluation of tumor extension owing to its multiplanar imaging capability. Initial diagnosis of an adrenal mass in a child is made with US, which is also used to document regression of uncomplicated neonatal adrenal hemorrhage. MR imaging is used for evaluation of tumor extension when surgery is to be performed. Imaging findings such as size, shape, and signal intensity are often not specific for a pathologic condition and must be interpreted in conjunction with the patient's age, the clinical history (eg, trauma), results of physical examination (eg, palpable mass or presence of an endocrine syndrome), and hormone levels in blood and urine.

Imaging in pediatric liver transplantation

Liver transplantation is an accepted and successful mode of treatment for pediatric end-stage liver disease. On the basis of a review of 229 liver transplantations in 185 children, the authors describe the imaging findings of the preoperative evaluation, the uncomplicated transplantation, various postoperative complications, and the suggested percutaneous treatment of some of these complications. The most frequent indications for liver transplantation encountered in this review were biliary atresia (52%), acute fulminant hepatic failure (11%), alpha 1-antitrypsin deficiency (9%), cryptogenic cirrhosis (6%), and chronic active hepatitis (4%). (The remaining 18% were various rare indications, representing < 4% each.) Routine Doppler ultrasound is the modality of choice for the screening of postoperative complications, supplemented with computed tomography, hepatobiliary scintigraphy, and cholangiography or angiography as needed. Familiarity with the normal graft appearance, as influenced by various surgical and technical factors, and knowledge of the underlying condition of the patient and the clinical course of postoperative complications are crucial for a correct interpretation of the findings from imaging studies.

Teleconferencing for cost-effective sharing of radiology educational resources: potential and technical development

To develop a cost-effective method of sharing educational resources, a dial-up teleconferencing network was implemented between three radiologic sites for a 30-day period of evaluation. By means of standard dial-up telephone channels, compressed video and audio signals displayed radiologic images, slides, and text, allowing residents and faculty from the three sites to participate in sight and sound interactions. Each of the three sites used compressed video/audio coder-decoders (codecs) conforming to the Consultative Committee on International Telegraphy and Telephony H.261 standard. Four video cameras were used at each site, and the audio was run in full duplex mode. A multipoint video bridge was used to broadcast codec output signals to the input lines of the other codecs. Our evaluation found audio quality to be suboptimal, but capable of being improved; diagnostic image quality was adequate when a video zoom mode was used; the digital-archive mode of the codec proved advantageous; the H.261 codec permitted participation from all sites; and all conference lecturers were able to conduct their conferences as they were accustomed. Although audio quality and spatial resolution need to be improved, the results of this pilot study imply that dial-up compressed video conferencing has the potential to become a practical, cost-effective method of sharing educational resources by means of interactive radiologic multisite educational programs.

Magnetic resonance image synthesis from analytic solutions of spin-echo and radio frequency-spoiled gradient-echo images

RATIONALE AND OBJECTIVES

To synthesize magnetic resonance images (MRI) in real-time using a minimal data set obtained with routine clinical protocols and stored in a picture archiving and communication system (PACS) database.

METHODS

Analytic solutions for T1 and T2 were obtained from a double and a single spin-echo set, with routine parameters. Analytic solutions from radio frequency-spoiled gradient-echo images, with TRs as low as 33 mseconds, also were used to synthesize gradient-echo images.

RESULTS

Phantom studies showed that the errors in the synthesized images were significantly smaller than the errors in the T1- and T2-calculated images and similar to the source images. The gradient-echo images resulted in significant scan time savings.

CONCLUSION

MRI synthesis from analytic solutions of T1, T2, and rho saves computational time and yields accurate values for the intrinsic parameters while allowing the use of routine clinical protocols. The availability of clinical images in the PACS database and the ability to synthesize images in real-time has allowed the development of a practical interactive teaching module.

Design of a high-speed, high-resolution teleradiology network

A teleradiology system acquires radiographic images from one location and transmits them to one or more distant sites where they are displayed and/or converted to hard-copy film recordings. The long-term goal of teleradiology research is to show that teleradiology systems can provide diagnostically equivalent results when compared with conventional radiographic film interpretation. If this hypothesis is proven, provision of the following radiology services will be improved: (1) providing for primary interpretation of radiological images for patients in underserved areas as well as in other medical facilities; (2) integration of radiological services for multihospital/clinic health care provider consortiums; (3) improving emergency service and intensive care unit coverage; (4) offering consulting-at-a-distance with subspecialty radiologists; and (5) providing radiologists in the community or in rural areas with immediate access to large academic centers for help in the interpretation of difficult and problematic cases. We are designing a high-speed, high-resolution teleradiology network that will communicate between our level 3 medical center and several outlying medical centers within the metropolitan area. Computed tomography (CT), magnetic resonance (MR), and screen-film examinations will be digitized to 2,000 x 2,000 or 4,000 x 4,000 pixels at the remote sites, transmitted to the central referral facility, and sent to a laser film printer, replicating the original film. This film may then be used for primary diagnosis, overreading/consultative purposes, or for emergency department preparation. Inherently digital modality data (eg, MR and CT) can be sent without digitization of the multiformat film if desired.

A PACS-based interactive teaching module for radiologic sciences

This article describes an interactive teaching module, linked to a picture archiving and communications system (PACS) data base, for teaching radiology. The module is currently tailored to MR images but can be adapted to any other imaging technique. An algorithm has been developed that allows the use of MR images acquired with routine clinical protocols and stored in the data base to yield, in real time, images at any other arbitrary TE and TR. In the browse mode, the user can study either the effect of different scan parameters or clinical cases on synthesized or acquired images. The quiz mode has multiple-choice questions and answers, accompanied by images. In the teaching mode, the instructor has access to the clinical data base and WRITE privileges for setting up the browse or quiz mode. The module achieves considerable flexibility when linked to the PACS, with access to all archived images and the ability to subsequently synthesize MR images at arbitrary TE and TR values in real time. The module is also "dynamic" in character, in that the instructor can easily add new cases and comments to the teaching files, both to enhance its clinical aspects and to reflect advances in technology.

Receiver-operating-characteristic study of chest radiographs in children: digital hard-copy film vs 2K x 2K soft-copy images

Two methods are commonly used to visualize digital radiologic imaging data: (1) hard-copy viewing, in which the digital data are used to modulate the intensity of a laser beam that exposes an analog film and (2) soft-copy viewing, in which the digital data are converted to an analog video signal and presented on a CRT monitor. The film method allows new digital imaging systems to be easily integrated into conventional radiologic management and viewing methods. The second method, soft-copy viewing, allows digital imaging data to be managed and viewed electronically in a picture archiving and communication system (PACS). These PACS systems are hypothesized to have improved operational efficiency and enhanced image-analysis capabilities. The quality of soft-copy images is still not widely accepted. This article reports on the results of a large-scale receiver-operating-characteristic study comparing observers' performance in detecting various pediatric chest abnormalities on soft-copy 2048 x 2048K byte displays with their performance with digital laser-printed film from computed radiography. The disease categories studied were pneumothorax, linear atelectasis, air bronchogram, and interstitial disease. The selected data set included 239 images; 77 contained no proved abnormality and 162 contained one or more of the abnormalities mentioned. Seven pediatric radiologists participated in the study, two as judges and five as observers. Our results show no significant difference between viewing images on digital hard copy and soft copy for the detection of pneumothoraces and air bronchograms. A slight performance edge for soft copy was seen for interstitial disease and linear atelectasis. This result indicates that computed chest radiographs in children viewed in a soft-copy PACS environment should result in diagnoses similar to or slightly more accurate than those obtained in a laser-printed film-based environment.

Congenital disorders of sexual differentiation: MR findings

A broad spectrum of anomalies of sexual differentiation may exist at birth. These include male and female pseudohermaphroditism, gonadal dysgenesis, and true hermaphroditism. When ambiguous genitalia are present, expedient identification of the anomaly is required for proper gender assignment and appropriate surgical or hormonal correction. As the appearance of the external genitalia often is not distinctive enough to make a specific diagnosis, this must be accomplished by clinical findings along with a combination of cytogenetic, biochemical, and radiologic studies. Because the causes of abnormal sexual differentiation are diverse and often exhibit incomplete expression, they produce much anatomic variability. Sonographic and radiographic studies are often used initially to evaluate such conditions. The noninvasive multiplanar nature of MR imaging makes it a useful alternative method with which to characterize the abnormal anatomy in this group of disorders, as we illustrate in this pictorial essay.

Metastatic Head and Neck Malignancy Treated Using MRI Guided Interstitial Laser Phototherapy

Interstitial laser phototherapy (ILP) guided by magnetic resonance imaging (MRI) may become an attractive adjunctive modality for the treatment of deep and surgically inaccessible tumors of the head and neck when accurate methods of laser dosimetry and "real-time" monitoring techniques with the MRI are introduced. We recently demonstrated in ex vivo and in vivo models, a linear relationship between levels of laser energies, thermal profiles, MR signal intensity changes, and histopathological tissue damage. Results of treatment in a patient with an unresectable large right jugulodigastric metastatic squamous carcinoma using new approach of MRI guided ILP are now reported. The patient complained of significant right-sided neck pain and headaches secondary to a rapidly growing metastatic lymphadenopathy which recurred after previous surgery, radiation, and chemotherapy. Two treatment sessions were used at an interval of 2 weeks. Each treatment was performed in the MRI suite under heavy sedation. Using a 600-microns bare fiber of the Nd:YAG laser implanted interstitially under MR guidance, the metastatic node was treated at three sites. T1- and T2-weighted images were performed prior to, immediately after, 24 and 48 hours, and 4, 5, 7, 9, 16, and 25 days post-treatment. Successful relief of pain and growth arrest of this node was observed after the second treatment and at the 3-month follow-up. These results demonstrate that this technique of ILP guided by MRI may be feasible in humans, and will become clinically practical when appropriate methods of dosimetry and instrumentation are developed.

The pediatric patient with suspected adrenal neoplasm: which radiological test to use?

To establish which radiological test to use in a pediatric patient with suspected neoplasm, we retrospectively studied 19 children with proven adrenal neoplasm who had a combination of ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). The results show that US should remain the initial imaging modality for evaluating abdominal masses in children but that MRI is more accurate than CT and US in detecting the organ of origin and the extent of an adrenal lesion and should, therefore, be the modality of choice for the definitive evaluation of adrenal neoplasm in children.

Paranasal sinuses in pediatric patients by MRI: normal development and preliminary findings in disease

A two-part study using medium field strength magnetic resonance imaging (MRI) was designed to describe the normal paranasal sinus development and to provide preliminary criteria for clinical sinus disease. In part I of the study the paranasal sinuses were retrospectively evaluated in 80 infants and children aged 0-17 years undergoing brain MRI for indications both unrelated and related to sinus disease. We developed MRI criteria for independent grading of paranasal sinus development and 'anatomical' sinus disease, i.e., disease as seen by the radiologist. We quantified the variability in extent of sinus pneumatization (a measure of sinus development) in infants and young children. Part II of the study was a double-blind prospective study in 21 patients to correlate 'anatomical' disease with 'clinical' sinus disease. In this limited preliminary study, clinical sinus disease was only seen in the patients with moderate or severe anatomical disease (sensitivity 100%; specificity 100%).

Future directions of laser phototherapy for diagnosis and treatment of malignancies: fantasy, fallacy, or reality?

A new and highly promising adjunctive modality for the diagnosis and therapy of malignancies is under development using lasers and tumor targeting dyes. To reach the eventual goal of clinical treatment, several current "fantasies and fallacies" regarding laser applications in medicine must be identified and their problems clearly outlined. A multidisciplinary scientific approach is also required to enable the clinical practicality of this laser targeting approach. Many new dyes and laser wavelengths are being tested to improve specific tumor uptake and/or retention, lower systemic toxicity, increase tissue penetration, and identify fluorochromes with synergistic properties to further enhance laser tumoricidal effects. Rapid technological advancements in magnetic resonance imaging may now provide an extremely sensitive way to detect and monitor laser-tissue effects, and allow efficient interstitial laser phototherapy of deep and sometimes inaccessible tumors. The current and future prospectives of the emerging field of laser phototherapy are described.

PACS--clinical experience at UCLA

Implementation of picture archiving communication systems (PACS) at UCLA began with the evaluation of the systems in Pediatric Radiology, one of the 11 sections of the Department and the Coronary Care Unit, one of the 14 ICU's in the Hospital. We have now completed PACS development for all CT's and MR's which allows communication between a newly developed outpatient facility, the hospital, and the remote research facility in addition to Pediatric Radiology and the Coronary Care Unit. The following are some of the advantages of PACS from a clinical standpoint: (a) Conferences with clinicians have been more effective by spending more time on each case, but less total time for each conference; (b) Clinicians are satisfied with PACS at the remote site, but it is clear that the radiologists' interpretation must accompany the images; (c) PACS allows for the development of interactive teaching of the students; (d) PACS allows for a new method of radiology practice by analyzing the image and providing a more comprehensive, quantitative consultation, otherwise not possible with analog systems.

Renal ultrasound abnormalities in children with end-stage liver disease--reversal by liver transplantation

Ultrasound (US) imaging of the kidneys was performed in 43 pediatric patients with end-stage liver disease evaluated for orthotopic liver transplantation. Renal size was increased in 8 patients (19%) and echogenicity of the kidneys was increased in 12 patients (28%). In 12 patients studied after liver transplantation, US revealed normal renal size in all and increased echogenicity in only 2 patients shortly after transplantation. Normalization of renal US findings was also found in 2 patients studied before and after liver transplantation. The glomerular filtration rate varied from 65 to 225 ml/min per 1.73 m2 in 5 patients with abnormal US, and from 74 to 116 ml/min per 1.73 m2 in 3 patients with normal US. Nephromegaly and increased echogenicity on renal US are frequent in children with end-stage liver disease and appear to be mostly reversible by liver transplantation.

Advances in medical imaging

The field of medical imaging, stimulated by advances in digital and communication technologies, has grown tremendously. New imaging techniques that reveal greater anatomical detail are available in most diagnostic radiology departments. We discuss vascular imaging with ultrasound, high-resolution computed tomography of the thorax, magnetic resonance imaging applications, and picture archiving and communication systems. Vascular imaging with ultrasound requires duplex and color flow Doppler, which combine gray-scale ultrasound and the Doppler phenomenon. High-resolution computed tomography modifies conventional computed tomography technology and results in images with higher spatial resolution. Magnetic resonance imaging applications for all areas of the body are being investigated and are replacing older roentgenographic techniques such as computed tomography, arthrography, myelography, and even angiography in a growing number of indications. With these new digital imaging modalities, image management has become an important consideration that can be addressed by picture archiving and communication systems.

Magnetic resonance imaging of the musculoskeletal system in children

Pediatric applications of magnetic resonance imaging (MRI) differ from those in adults primarily with respect to the focus on congenital and developmental abnormalities and those pathologic conditions that are unique to children. Sedation is often required for younger children to avoid motion. Quality diagnostic images also require the use of appropriate sizes of surface and planar coils. MRI is an excellent method to evaluate bone marrow involvement and soft-tissue extension of osteosarcoma and Ewing's sarcoma. In children, it is important to be aware of the changes in normal bone marrow signal that occur with maturation and with the normal progression of the replacement of red marrow by yellow marrow. Aplastic and hypercellular anemias have differing MRI features. The high-contrast resolution of the soft tissues, including the spinal cord, and the capability for direct imaging in any plane make MRI an excellent modality for the evaluation of the spine, including congenital malformations.

Renal malformations in patients with Turner syndrome: imaging in 141 patients

Turner syndrome occurs in 1/2,000 to 1/5,000 live female births. The presence of renal malformations was evaluated in 141 patients with Turner syndrome and abnormalities were found in 47 (33%). Prior to 1980, IVP was the radiologic method used for initial screening, and subsequently, ultrasonography has been used as the initial imaging technique. With both methods, major malformations can be detected. Ten patients had a horseshoe kidney, 11 had double collecting systems, four had complete absence of one kidney, three had crossed ectopia, and one had a pelvic kidney. Three patients had ureteropelvic junction obstruction; two of these were asymptomatic and the obstructions were detected only because of the routine imaging. Two patients had ureterovesicular junction obstruction, with one studied as part of a routine evaluation for short stature. Four of these five patients required surgery. Ultrasonography should be used as the initial renal imaging study for all patients at the time the diagnosis of Turner syndrome is made.

Primary liver tumors in children: comparison of CT and MR imaging

A prospective study was performed at two institutions to determine the role of magnetic resonance (MR) imaging in the evaluation of primary pediatric liver tumors. The study compared the usefulness of MR imaging and computed tomography (CT) in providing a correct diagnosis, assessing resectability, and determining tumor recurrence in 23 children with liver tumors. The information obtained with both modalities was correlated with surgical data. The results indicate that the accuracy of MR imaging in helping to differentiate benign from malignant lesions is high and identical to that of CT, but not good enough to obviate surgical diagnosis. While all five hepatocellular carcinomas were correctly diagnosed preoperatively with both modalities, neither CT nor MR imaging could help differentiate these carcinomas from aggressive hepatoblastoma or primary hepatic lymphoma. MR imaging helped correctly predict tumor resectability in all 18 children with malignant hepatic tumors; in one, exact tumor extension was misjudged with CT. Postoperative MR studies suggested tumor recurrence in three children who had unremarkable CT examinations. Second-look surgery showed recurrent tumor in two and fibrosis with chronic inflammation at the surgical margin in the third child.

MR imaging in Drash syndrome

Drash syndrome is a disorder of the genitourinary ridge differentiation and includes abnormal genital development, nephropathy, and a predisposition to develop Wilms tumor. In three patients with Drash syndrome, magnetic resonance was correlated with ultrasound, CT, and surgical findings. Two patients with glomerulonephritis had enlarged kidneys, loss of corticomedullary differentiation, and overall decrease in signal intensity on T1-weighted sequences. Two large Wilms tumors were identified, but a small 1 cm nephroblastoma was not recognized. Anomalies associated with ambiguous genitalia, such as absent uterus, were also correctly diagnosed.

MR evaluation of early myelination patterns in normal and developmentally delayed infants

This study demonstrates the ability of MR imaging to show progression of myelination in 64 infants and young children (ages 4 days to 36 months). T2-weighted spin-echo pulse sequences, frequently used for routine screening of intracranial disease, were used. Gray-white matter differentiation was seen in all patients, and changes occurring with age were documented. Three distinct patterns were seen, and age ranges were established for each pattern in developmentally normal children: (1) infantile (birth-6 months); (2) isointense (8-12 months); and (3) early adult (10 months onward). There was a statistically significant difference between the age ranges of the normal and developmentally delayed children showing all three patterns. These data should be helpful for identifying and following sequentially both infants with clinically suspected developmental delay and those with dysmyelinating or demyelinating disease.

Chest MRI in children

MRI of the pediatric chest appears useful in evaluating the mediastinum, the bony thorax, and the lung parenchyma. MR seems to be more useful than other imaging modalities in evaluation of the mediastinum, particularly in defining the extent of the lesions. Coronal images provide additional information to those obtained axially. MR can in a selected number of cases replace x-ray CT in evaluation of the pediatric chest.

Magnetic resonance imaging of iron overload in children treated with peritoneal dialysis

The ability of magnetic resonance imaging (MRI) to detect iron overload in children with end-stage renal disease (ESRD) was studied in 18 multiply transfused patients, aged 15.5 +/- 4.8 years, and 5 nontransfused children without evidence of renal disease. In the transfused patients, the serum ferritin (SF) level was compared to (a) a subjective rating of signal intensity of MRI images (scale of 0-10), (b) mean T1 values of liver and spleen, and (c) computer-assisted measurements of spin echo intensity (SEI) of liver, spleen, muscle and fat tissue. On subjective evaluation, the mean signal intensity was significantly lower in transfused patients than in controls and a significant correlation with the SF levels was observed for ratings of both liver and spleen. Mean T1 values of liver and spleen did not correlate with the SF levels. On computer analysis, the ratios of SEI of fat/liver, fat/spleen, muscle/liver and muscle/spleen were significantly correlated with the SF levels as well as the subjective evaluation sources. These data indicate that MRI is a suitable technique of documenting the presence and degree of iron overload in multiply transfused children with ESRD.

Acquired cystic kidney disease in children undergoing long-term dialysis

Acquired cystic kidney disease (ACKD) occurs in adult patients undergoing long-term dialysis. Early detection is important because clinically significant hematuria and malignancies are associated with ACKD. We evaluated by magnetic resonance imaging (MRI) and ultrasonography (US) the incidence of ACKD in 15 patients aged 7.3-21.6 years (mean 15.9 years) with non-cystic primary renal disease. Nine patients had been treated with peritoneal dialysis only, and 6 with both hemodialysis and peritoneal dialysis for 24-73 months (mean 37 months). Three patients (20%) had no cysts. In 5 patients (33%) with bilateral multiple cysts, the diagnosis of ACKD was made by MRI and US. In another 5 patients, solitary cysts were localized to one kidney by MRI, and in 2 patients solitary cysts were seen in both kidneys. This study documents that ACKD is not limited to older patients with end-stage renal disease. Early detection of these cysts can be accomplished by MRI and is warranted since 1 patient developed neoplastic tubular changes which can precede tumor formation.

Magnetic resonance imaging of the pediatric spine

The authors conclude that MRI is the imaging mode of choice for the evaluation of extradural and intramedullary tumors and for the screening of all children with suspected spinal pathology.