Understanding and using DICOM, the data interchange standard for biomedical imaging.

The Digital Imaging and Communications in Medicine (DICOM) Standard specifies a non-proprietary data interchange protocol, digital image format, and file structure for biomedical images and image-related information. The fundamental concepts of the DICOM message protocol, services, and information objects are reviewed as background for a detailed discussion of the functionality of DICOM; the innovations and limitations of the Standard; and the impact of various DICOM features on information system users. DICOM addresses five general application areas: (1) network image management, (2) network image interpretation management, (3) network print management, (4) imaging procedure management, (5) off-line storage media management. DICOM is a complete specification of the elements required to achieve a practical level of automatic interoperability between biomedical imaging computer systems--from application layer to bit-stream encoding. The Standard is being extended and expanded in modular fashion to support new applications and incorporate new technology. An interface to other Information Systems provides for shared management of patient, procedure, and results information related to images. A Conformance Statement template enables a knowledgeable user to determine if interoperability between two implementations is possible. Knowledge of DICOM's benefits and realistic understanding of its limitations enable one to use the Standard effectively as the basis for a long term implementation strategy for image management and communications systems.

Estimation of nongravid uterine volume based on a nomogram of gravid uterine volume: its value in gynecologic uterine abnormalities.

To facilitate accurate and standard methods of reporting pathologic uterine corpus enlargement, we constructed a nomogram using the gravid uterine corpus volumes from five to 20 weeks' gestation in 186 patients. The volume was calculated by measuring the maximum length and anteroposterior and transverse diameters of the uterine corpus, and using the formula for the volume of a prolate ellipsoid: V = 0.52 X (L X AP X T). Clinicians can use the nomogram for better understanding in assessing uterine volume.

Image acquisition. Sites, technologies, and approaches.

This article examines the current and future methodologies for image capture. Data conversion devices and systems, radiographic techniques of ionizing and nonionizing radiation, passive imaging, and digital image data requirements are explored. The author also discusses the problem of how to connect acquisition devices to PACS.

Computer applications in diagnostic imaging.

This article has introduced the nature, generation, use, and future of digital imaging. As digital technology has transformed other aspects of our lives--has the reader tried to buy a conventional record album recently? almost all music store stock is now compact disks--it is sure to continue to transform medicine as well. Whether that transformation will be to our liking as physicians or a source of frustration and disappointment is dependent on understanding the issues involved.

From being a radiologist to watching a radiologist: impact of filmless operation on the training of radiology residents.

RATIONALE AND OBJECTIVES: The authors performed this study to investigate the impact of changing from a film-based image interpretation system to one using digital image workstations on the training of radiology residents in the interpretation of radiographs. MATERIALS AND METHODS: Data were collected during a period when a conventional system of image interpretation with hard-copy images and multiviewers was used and during a period when digital image workstations were used. During each period, it was noted whether the first interpretation of the radiographs was performed by a radiology resident, by an attending radiologist, or as a group effort including both an attending radiologist and a radiology resident(s). In addition, it was noted whether a radiology resident or an attending radiologist dictated the report. RESULTS: The proportion of images first interpreted by the radiology resident alone decreased from 38% (53 of 139) when using the conventional system to 17% (34 of 199) after the switch to interpreting images on the workstations (P = .001). During the film-based period, radiology residents dictated 45% of reports (141 of 312), but during the workstation period, radiology residents dictated only 4% of reports (24 of 667; P = .001). CONCLUSION: The authors observed a decrease in autonomous participation by radiology residents in image interpretation and dictation of reports and an increase in "group reading" after the switch from a film-based system to a workstation system.

PACS workstation design.

This paper covers some of the recent concepts in designing a digital imaging workstation in a multimodality Picture Archiving and Communications Systems (PACS) network. A workstation in a multimodality PACS network must access, display, and analyze digital images from different imaging modalities with very different formats. The user interface should allow clinicians with minimal or no computer manipulation skills to use complex analysis tools. General guidelines of a graphics oriented user interface, based on windows and icons, are proposed. Instantaneous (real-time) response in the primary display and processing functions is vital for user acceptance. The hardware architectural concepts to achieve such a performance speed are described. Finally, a workstation environment conducive to comfortable viewing by the radiologists is discussed.

PACS clinical experience at Georgetown University.

Georgetown University Hospital has been operating an image management and communications system (IMACS or PACS) for three-and-a-half years. This work was initially funded under the Army Medical Research and Development Command Digital Imaging Network Systems (DINS) project. The system was taken from a research system supporting only radiology tasks to one extended to clinical use, and has been used in clinical work for two-and-a-half years. This paper will summarize our PACS clinical experience and will describe the operational features implemented and those still necessary.

Review of the American College of Radiology--National Electrical Manufacturers' Association standards activity.

The American College of Radiology and the National Electrical Manufacturers' Association published the ACR-NEMA Digital Imaging and Communications Standard in 1985. Implementations are just now becoming available. During this time, working groups of the committee responsible for the standard have been very active. An expanded version of the standard was published in 1988 and a third version, to be known as Digital Imaging and Communications in Medicine (DICOM), is being prepared for publication in 1992. This paper briefly reviews the history of the standard, describes recent activities, outlines the extensions planned for the DICOM standard, and describes the participation of the committee in international radiological imaging standards activities.

Electronic imaging workstations: ergonomic issues and the user interface.

The electronic imaging workstation serves as the interface between an electronic system and a user. Although the performance aspects of electronic displays are crucial considerations in workstation design, experience suggests that human factors in mechanical operation, software accessibility, and workstation environment are also important. Generally, workstations should have monitors arranged horizontally, and the work environment should be designed to minimize glare from lighting fixtures and to accommodate requirements for low luminance. Devices that control the workstation (eg, key pads, track balls) should be designed so that the user can operate primary and auxiliary controls with efficiency of hand and eye movements. Although many innovations in software (eg, graphical user interfaces) have allowed current workstations to be operated by users who have no knowledge of computer operations, further improvements in interactive software are necessary if such systems are to be accepted by radiologists.

Sonographic demonstration of buckling of the great vessels of the neck.

Clinical, sonographic, and radiographic features in 11 patients with pulsatile neck masses due to buckling of the great vessels were reviewed. The pulsatile neck masses corresponded to buckling of the innominate and right subclavian arteries in five patients and buckling of the right common carotid arteries in six. Real-time sonography provides a noninvasive and accurate method to diagnose buckling of the great vessels of the neck as the cause of pulsatile neck masses and obviates angiography for diagnosis.

Introduction to the ACR-NEMA DICOM standard.

In 1982, the American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) formed a committee to develop standards for the interconnection of digital imaging devices. Version 1.0 of the standard, published in 1985, specifies a hardware interface supporting point-to-point (not network) image transmission, a data dictionary (a set of rules for encoding information), and a set of commands to initiate transactions. Version 2.0, published in 1988, also addresses point-to-point image transmission and provides semantic rules by which messages (streams of bits representing information in transit from one device to another) are organized. Version 3.0, also referred to as DICOM (Digital Imaging and Communications in Medicine), will be finalized in 1992. The DICOM standard encourages open systems interconnection of imaging equipment over standard networks, while maintaining compatibility with earlier point-to-point connection standards. The DICOM standard conforms fully with the International Standards Organization reference model for network communications (ISORM), addresses the issue of conformance, and incorporates the concept of object-oriented design.

PACS mini refresher course. Network and ACR-NEMA protocols.

The backbone of the picture archiving and communication system (PACS) is the electronic network used to move information. Communications networks require electronic rules of operation or protocols so that a set of data being transmitted reaches the intended destination and does not collide with another set of transmitted data. The most efficient protocol is flexible and can respond to the fluctuations in volume of data transmitted via the network. Successful network connection of PACS devices requires standardized interfaces so that equipment from multiple vendors can use the network protocol. The American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) have developed a standard for imaging equipment interfaces: DICOM (Digital Imaging and Communications in Medicine). The DICOM standard allows interoperability among different computers and operating systems. It is flexible and will allow modification and expansions as new imaging techniques evolve. The authors and the ACR-NEMA committee believe that the DICOM standard represents an important choice for radiologists, since it was developed with their interests in mind.

Modular extension of the ACR-NEMA DICOM standard to support new diagnostic imaging modalities and services.

The American College of Radiology-National Electrical Manufacturers Association (ACR-NEMA) Standard for Digital Imaging and Communications in Medicine (DICOM) (NEMA PS3-1993, DICOM) enables interconnection of imaging equipment and exchange of diagnostic images over standard networks. The widespread adoption of DICOM by industry and the benefits of standardized image management have attracted international attention. Other medical specialties, dentistry, and veterinary medicine have indicated strong interest in extending the DICOM Standard to support nonradiological image modalities. Parts 1 through 9 of DICOM were published in 1992 and 1993. Additional features developed in response to requests from the user community are being added in DICOM Supplements. The ACR, NEMA, and committees from other medical specialties working under the coordination of the American National Standards Institute Healthcare Informatics Standards Planning Panel Message Standards Developers Subcommittee Joint Working Group for Diagnostic Image Communication have defined new image object classes to support X-Ray Angiography, Radio-Fluoroscopy, Positron Emission Tomography, Endoscopy, and Light Microscopy. ACR-NEMA has also developed new service classes for Storage Commitment and Worklist Management. In joint work with the standards development committee of the Japanese Industries for Radiation Apparatus and the Japanese Medical Information System Development Center, ACR-NEMA has developed specifications for multibyte character set support and for a DICOM file format for transportable media. Other work is in progress. New DICOM features have provided and can continue to provide significant new functionality for digital image management systems. The demonstrated capability of efficient extension of the base standard is evidence of the effectiveness of the object oriented strategy of DICOM.

Transcutaneous sonography of the postoperative spine.

Transcutaneous sonography of the spine was performed in 83 patients with prior laminectomies for tumors of the spinal canal and the spinal cord. These patients presented with signs or symptoms of recurrent tumor. When the spinal cord could be visualized, the sonographic examination provided information about the presence or absence of tumor, the character (solid or complex) of the tumor and its location, and associated findings in the extramedullary space. The correlation of the transcutaneous sonograms with other imaging methods and with intraoperative sonographic and surgical findings was excellent. Nonvisualization of the spinal cord was found to be related to age with a higher success rate (70% visualized) in the pediatric age group (to age 21) than in the adult group (52% visualized). A very short laminectomy was also found to cause problems in visualizing the full extent of a recurrent tumor. Nonetheless, the simplicity of the technique and the amount of information that can be gained from it make it a very valuable adjunct to other imaging methods for the postoperative spine. For the pediatric age group, it should be one of the first diagnostic methods employed.

Multimodality image display: desirable frame buffer characteristics.

The intent of this paper is to understand the characteristics of those frame buffers currently used to display images, versus more ideal frame buffers for medical image display purposes. This study is based on current needs and what characteristics might be desirable. Two case examples are presented: (1) a system developed for high quality computer graphics and (2) a system developed for nuclear medicine and radiation therapy treatment planning. Our study considers: (1) defining a pixel depth sufficient to hold data, (2) the desirability of multiple color look-up tables, (3) how cine loops are managed, and (4) display memory size.

Sonography of the accessory spleen.

The sonographic features of 20 accessory spleens in 19 patients are presented. They are round or oval solid structures with their echogenicity similar to that of the main spleen. They are surrounded by high-amplitude interfaces that separate them from adjacent parenchymal organs. Sonographic demonstration of blood supply to the accessory spleens from the splenic artery or vein was diagnostic and was possible in 90% of the cases. Sonography could be used preoperatively in detecting and locating accessory spleens in patients who may need splenectomy for hematologic disease.

Diffuse testicular disease: sonographic features and significance.

Sonographic findings in 26 patients with diffuse testicular disease were retrospectively analyzed for features to differentiate diffuse neoplasms from diffuse orchitis or infarct. Diffuse neoplasms were associated with moderate to marked enlargement, globular shape, lobulated contour, and heterogeneous texture of the testis; the epididymis and scrotal skin were normal. In diffuse inflammatory disease, the testis was mild to moderately enlarged, the oval shape and smooth contour were preserved, and the texture was generally homogeneous; the epididymis was often enlarged, and scrotal skin was almost always thickened.

Abdominal sonography in AIDS. A review.

Sonographic examination of the abdomen was performed in 155 patients with clinical diagnosis of AIDS. Approximately one half of the patients had hyperechoic (fatty) liver and splenomegaly. About one third of the patients had lymphadenopathy and hyperechoic kidneys. Intravenous drug abusers were more likely to have renal parenchymal changes, whereas patients with sexually transmitted AIDS have a greater incidence of splenomegaly. Lymphadenopathy is the most consistent finding that would question the immune competency of a patient in the appropriate clinical setting. The usefulness of sonography lies in the detection or exclusion of potentially treatable complications in AIDS.

Post-cesarean section pain secondary to intussuscepting colonic adenocarcinoma.

The differential diagnosis for lower abdominal and pelvic pain following Cesarean section includes many causes, such as endometritis, abscess, pelvic hematoma, wound complications, pelvic vein thrombophlebitis, gastrointestinal dysfunction and obstruction. Colonic obstruction secondary to intussusception is a rare cause. We present a case of post-Cesarean section pain in a 26-year-old patient due to obstructing colonic intussusception secondary to colonic adenocarcinoma. Review of the literature failed to identify a previous case report of colonic adenocarcinoma with intussusception presenting early in the postpartum period. The diagnosis was initially made by ultrasound, and later corroborated by computed tomography, barium enema and laparotomy.