Imaging Informatics: from Image Management to Image Navigation

Objective To review the rapid evolution of imaging informatics dealing with issues of management and communication of digital images starting from the era of simple storage and transfer of images to today’s world of interactive navigation in large sets of multidimensional data.

Methods This paper will review the initial concepts of Picture Archiving and Communication Systems (PACS) and the early developments and standardization efforts that lead to the deployment of large intra-institutional networks of image distribution allowing radiologists and physicians to access and review images digitally. With the deployment of PACS came along the need for advanced tools for image visualization and image analysis.

Results Review of the history of PACS and Imaging Informatics clearly shows that the early developments were focused on the radiologist’s requirements for diagnosis and image interpretation. These early developments lagged behind the rapid adoption of digital imaging in areas outside radiology. Only recently, imaging informatics shifted toward the development of new tools geared toward the needs of other users such as surgeons, referring physicians and care-providers, and even for the patients themselves. Also in the recent years, the development of multimedia and communication tools in the consumer market has influenced the design and strategic development of image management platforms inside and outside healthcare institutions.

Conclusions The focus of imaging informatics has clearly shifted in the last decade from basic infrastructure design to complete data and image navigation systems. While the challenge of storing and managing large volumes of imaging data have slowly vanished with the rapid development if information technology, the new challenge emerged from the new requirements of image manipulation and analysis in clinical practice.

A Humanist’s Legacy in Medical Informatics: Visions and Accomplishments of Professor Jean-Raoul Scherrer

Objective: To report about the work of Prof. Jean-Raoul Scherrer, and show how his humanist vision, his medical skills and his scientific background have enabled and shaped the development of medical informatics over the last 30 years.

Results: Starting with the mainframe-based patient-centered hospital information system DIOGENE in the 70s, Prof. Scherrer developed, implemented and evolved innovative concepts of man-machine interfaces, distributed and federated environments, leading the way with information systems that obstinately focused on the support of care providers and patients. Through a rigorous design of terminologies and ontologies, the DIOGENE data would then serve as a basis for the development of clinical research, data mining, and lead to innovative natural language processing techniques. In parallel, Prof. Scherrer supported the development of medical image management, ranging from a distributed picture archiving and communication systems (PACS) to molecular imaging of protein electrophoreses. Recognizing the need for improving the quality and trustworthiness of medical information on the Web, Prof. Scherrer created the Health-On-the-Net (HON) foundation.

Conclusions: These achievements, made possible thanks to his visionary mind, deep humanism, creativity, generosity and determination, have made of Prof. Scherrer a true pioneer and leader of the human-centered, patient-oriented application of information technology for improving healthcare.

Combined evaluation of myocardial perfusion and coronary morphology in the identification of subclinical CAD

Purpose: To evaluate the mean effective radiation dose of 13N-ammonia PET/CT and ECGpulsing CT angiography (CTA) in the evaluation of myocardial perfusion, myocardial blood flow (MBF) and coronary morphology for the identification of subclinical CAD. Patients, material, methods: Following rest-stress 13N-ammonia PET/CT perfusion imaging and MBF quantification, ECG-pulsing CTA at a pulse window of 70% of the R-R cycle was performed in ten healthy controls and in sixteen individuals with cardiovascular risk factors. Individual radiation dose exposure for ECG-pulsing CTA was estimated from the dose-length product. Results: PET demonstrated normal perfusion in all study individuals, while hyperemic MBFs during dipyridamole stimulation and the myocardial flow reserve (MFR) in cardiovascular risk individuals were significantly lower than in healthy controls (1.34 ± 0.26 vs. 2.28 ± 0.47 ml/g/min and 1.48 ± 0.39 vs. 3.24 ± 0.81, both p . 0.0001). Further, ECG-pulsing CTA identified mild calcified and non-calcified coronary plaque burden in 7 (43%) individuals of the cardiovascular risk group. Rest-stress 13N-ammonia PET/CT perfusion study yielded a mean effective radiation dose of 3.07 ± 0.06 mSv (2.07 ± 0.06 mSv from the rest-stress 13N-ammonia injections and 1.0 mSv from the 2 CT transmission scans), while ECG-pulsing CTA was associated with 5.57 ± 2.00 mSv. The mean effective radiation dose of the combined 13N-ammonia PET/CT and ECG-pulsing CTA exams in the evaluation of myocardial perfusion and coronary morphology was 8.0 ± 1.5 mSv. Conclusion: 13N-ammonia PET/CT and ECG-pulsing CTA affords cardiac hybrid imaging studies in the evaluation of subclinical CAD with a relatively low mean effective radiation exposure of 8.0 ± 1.5mSv.

Improving workflows of neuro-interventional procedures with autostereoscopic 3D visualization of multi-modality imaging in hybrid interventional suites

PURPOSE

Recent developments in interventional neuroradiology techniques, medical imaging modalities, endovascular stenting and embolization materials lead to an increasing number of patients with cerebral aneurysms and arteriovenous malformations that are eligible for endovascular treatment and have opened new perspectives for novel ways for patient treatment in general. In this paper, we describe a software tool for 3D image fusion of multi-modal acquisitions to assist endovascular treatment of cerebral malformations. The software and an autostereoscopic 3D display were implemented and tested in clinical applications in a hybrid interventional suite that is used for radio-interventional as well as neurosurgical procedures. Our hypothesis is that fusion of image data acquired prior to intervention procedures with images acquired during those procedures should allow better visualizing and navigating through complex cerebral vasculature. This should also improve workflows of neuro-interventional procedures.

METHODS

Preoperative and intra-operative acquisitions of vascular images of the brain were performed and transferred to a dedicated imaging workstation to be processed with our image fusion and visualization software tool. The tool was developed as a plugin extension to the open-source DICOM viewer OsiriX and is based on a modular and scalable architecture. Several processing modules were implemented to allow spatial co-registration and fusion of preoperative and intra-operative modalities. A special extension was also implemented for interactive autostereosopic, glass-free 3D visualization of fused results.

RESULTS

The software platform was validated and evaluated in nine in vivo procedures by expert users. All patient cases were related to interventional treatment of neuro-vascular diseases. The emphasis was laid on the added value of spatial co-registration and fusion of preoperative and intra-operative modalities, as well as the overall impact on workflow during the intervention. The co-registered and fused images were visualized on an autostereoscopic 3D monitor installed in hybrid interventional suite. All experiments were evaluated and scored by interventional physicians and technicians.

CONCLUSIONS

Displaying 3D-4D representations of brain vascular anomalies based on multi-modal acquisitions on a 3D autostereoscopic display is beneficial for the workflow and efficiency of interventional radiologists. The implemented software tool fulfills the premise of applicability of an open-source platform for more advanced, multi-modal visualization and processing of brain vascular structures for image-guided therapeutic interventions.

Significance of 18F-fluorocholine PET/CT positive pulmonary lesions in prostate cancer patients

AIM

To assess the frequency and the significance of incidental pulmonary lesions with 18F-fluorocholine (18F-FCH) PET/CT in prostate cancer (PCa) patients.

PATIENTS, METHODS

225 consecutive PCa patients referred for 18F-FCH PET/CT (median age 68 years) were retrospectively evaluated for the presence of lesions in the lungs: 173 referred for restaging and 52 for initial staging regarding their high risk of extra prostatic extension. The final diagnosis was based on histopathological or on clinical and radiological follow-up.

RESULTS

13 patients had 18F-FCH positive pulmonary and 8 patients malignant lesions: 5 patients (38%) had a primary lung cancer (2 squamous cell carcinomas, 1 papillary adenocarcinoma, 1 typical pulmonary carcinoid, 1 bronchioloalveolar carcinoma) and 3 patients (23%) PCa metastases. Benign lesions were found in 5 subjects (38%). SUVmax and maximum diameter were neither significantly different in primary and metastatic tumors nor between malignant and benign lesions.

CONCLUSIONS

Although our results suggest that incidental uptake in the lungs in PCa patients are nonspecific, their detection may have a significant impact on patient management knowing that more than 60% represent malignant disease.

Long-term HIV infection and antiretroviral therapy are associated with bone microstructure alterations in premenopausal women

We evaluated the influence of long-term HIV infection and its treatment on distal tibia and radius microstructure. Premenopausal eumenorrheic HIV-positive women displayed trabecular and cortical microstructure alterations, which could contribute to increased bone fragility in those patients.

INTRODUCTION

Bone fragility is an emerging issue in HIV-infected patients. Dual-energy X-ray absorptiometry (DXA) quantified areal bone mineral density (BMD) predicts fracture risk, but a significant proportion of fracture risk results from microstructural alterations.

METHODS

We studied the influence of long-term HIV infection on bone microstructure as evaluated by high-resolution peripheral quantitative computed tomography (HR-pQCT) in 22 HIV-positive (+ve) premenopausal eumenorrheic women and 44 age- and body mass index (BMI)-matched HIV-negative (-ve) controls. All subjects completed questionnaires regarding calcium/protein intakes and physical activity, and underwent DXA and HR-pQCT examinations for BMD and peripheral skeleton microstructure, respectively. A risk factor analysis of tibia trabecular density using linear mixed models was conducted.

RESULTS

In HIV+ve women on successful antiretroviral therapy (undetectable HIV-RNA, median CD4 cell count, 626), infection duration was 16.5 ± 3.5 (mean ± SD) years; median BMI was 22 (IQR, 21-26) kg/m². More HIV+ve women were smokers (82 versus 50 %, p = 0.013). Compared to controls, HIV+ve women had lower lumbar spine (spine T-score -0.70 vs -0.03, p = 0.014), but similar proximal femur BMD. At distal tibia, HIV+ve women had a 14.1 % lower trabecular density and a 13.2 % reduction in trabecular number compared to HIV-ve women (p = 0.013 and 0.029, respectively). HR-pQCT differences in distal radius were significant for cortical density (-3.0 %; p = 0.029).

CONCLUSIONS

Compared with HIV-ve subjects, premenopausal HIV+ve treated women had trabecular and cortical bone alterations. Adjusted analysis revealed that HIV status was the only determinant of between group tibia trabecular density differences. The latter could contribute to increased bone fragility in HIV+ve patients.

Treatment with levetiracetam in a patient with pervasive developmental disorders, severe intellectual disability, self-injurious behavior, and seizures: a case report

Pervasive developmental disorder is characterized by various symptoms that often include self-injurious behavior (SIB). Episodes of SIB occur in the context of high emotional arousal, anger, or fear and may be related to epilepsy. We report the case of a 20-year-old man with pervasive developmental disorder presenting with SIB non-responsive to antipsychotic medication. Positron emission tomography showed a right temporoparietal hypometabolic focal lesion suggestive of an epileptic focus. Two weeks after initiation of levetiracetam (Keppra®), SIB disappeared, without recurrence 24 months later. Levetiracetam (Keppra®) may be beneficial for such patients.

Design and performance evaluation of a whole-body Ingenuity TF PET-MRI system

The Ingenuity TF PET-MRI is a newly released whole-body hybrid PET-MR imaging system with a Philips time-of-flight GEMINI TF PET and Achieva 3T X-series MRI system. Compared to PET-CT, modifications to the positron emission tomography (PET) gantry were made to avoid mutual system interference and deliver uncompromising performance which is equivalent to the standalone systems. The PET gantry was redesigned to introduce magnetic shielding for the photomultiplier tubes (PMTs). Stringent electromagnetic noise requirements of the MR system necessitated the removal of PET gantry electronics to be housed in the PET-MR equipment room. We report the standard NEMA measurements for the PET scanner. PET imaging and performance measurements were done at Geneva University Hospital as described in the NEMA Standards NU 2-2007 manual. The scatter fraction (SF) and noise equivalent count rate (NECR) measurements with the NEMA cylinder (20 cm diameter) were repeated for two larger cylinders (27 cm and 35 cm diameter), which better represent average and heavy patients. A NEMA/IEC torso phantom was used for overall assessment of image quality. The transverse and axial resolution near the center was 4.7 mm. Timing and energy resolution of the PET-MR system were measured to be 525 ps and 12%, respectively. The results were comparable to PET-CT systems demonstrating that the effect of design modifications required on the PET system to remove the harmful effect of the magnetic field on the PMTs was negligible. The absolute sensitivity of this scanner was 7.0 cps kBq(-1), whereas SF was 26%. NECR measurements performed with cylinders having three different diameters, and image quality measurements performed with IEC phantom yielded excellent results. The Ingenuity TF PET-MRI represents the first commercial whole-body hybrid PET-MRI system. The performance of the PET subsystem was comparable to the GEMINI TF PET-CT system using phantom and patient studies. It is conceived that advantages of hybrid PET-MRI will become more evident in the near future.

[Pretherapeutic and posttherapeutic laryngeal imaging]

Cross-sectional imaging with CT, MRI and more recently PET CT plays an indispensable complementary role to endoscopy in the pretherapeutic diagnostic and staging of laryngeal neoplasms and in the evaluation of the operated or irradiated larynx. Adequate interpretation of the CT, PET CT and MR images requires a thorough knowledge of the patterns of submucosal spread and familiarity with the diagnostic signs of neoplastic invasion as seen with each modality. In addition, one should be aware of the implications of imaging for staging and treatment. Both CT and MR imaging are highly sensitive for the detection of neoplastic invasion of the preepiglottic and paraglottic spaces, subglottic region and cartilage. The high negative predictive value of both CT and MRI allows a relatively reliable exclusion of neoplasm cartilage invasion. The specificity of both CT and MRI is, however, moderately high and both methods may, therefore, overestimate the extent of tumor spread. However, recent investigations have shown that the specificity of MRI may be significantly improved by using new diagnostic criteria which allow differentiation of tumor from peritumoral inflammation in many instances. Both cross-sectional imaging methods also significantly improve the pretherapeutic staging accuracy of laryngeal tumors if used in addition to clinical examination and endoscopic biopsy. In the presence of a submucosal mass, CT and MRI play a key role for the diagnosis, as they may characterize the lesion, reliably depict its submucosal extent and guide the endoscopist to perform deep biopsies which allow the definitive histological diagnosis. Cross-sectional imaging also plays a key role in the evaluation of laryngoceles, recurrent laryngeal nerve paralysis and fractures.

Three-phase 18F-fluorocholine PET/CT in the evaluation of prostate cancer recurrence

AIM

Contribution of 3-phase 18F-fluorocholine PET/CT in suspected prostate cancer recurrence at early rise of PSA.

PATIENTS, METHODS

Retrospective analysis was performed in 47 patients after initial treatment with radiotherapy (n=30) or surgery (n=17). Following CT, 10 minutes list-mode PET acquisition was done over the prostate bed after injection of 300 MBq of 18F-fluorocholine. Three timeframes of 3 minutes each were reconstructed for analysis. All patients underwent subsequent whole body PET/CT. Delayed pelvic PET/CT was obtained in 36 patients. PET/CT was interpreted visually by two observers and SUVmax determined for suspicious lesions. Biopsies were obtained from 13 patients.

RESULTS

Biopsies confirmed the presence of cancer in 11 of 13 patients with positive PET for a total of 15 local recurrences in which average SUVmax increased during 14 minutes post injection and marginally decreased in delayed scanning. Conversely inguinal lymph nodes with mild to moderate metabolic activity on PET showed a clearly different pattern with decreasing SUVmax on dynamic images. Three-phase PET/CT contributed to the diagnostic assessment of 10 of 47 patients with biological evidence of recurrence of cancer. It notably allowed the discrimination of confounding blood pool or urinary activity from suspicious hyperactivities. PET/CT was positive in all patients with PSA>or=2 ng/ml (n=34) and in 4/13 patients presenting PSA values<2 ng/ml.

CONCLUSION

18F-fluorocholine 3-phase PET/CT showed a progressively increasing SUVmax in biopsy confirmed cancer lesions up to 14 minutes post injection while decreasing in inguinal lymph nodes interpreted as benign. Furthermore, it was very useful in differentiating local recurrences from confounding blood pool and urinary activity.

Imaging informatics: from image management to image navigation

OBJECTIVE

To review the rapid evolution of imaging informatics dealing with issues of management and communication of digital images starting from the era of simple storage and transfer of images to today's world of interactive navigation in large sets of multidimensional data.

METHODS

This paper will review the initial concepts of Picture Archiving and Communication Systems (PACS) and the early developments and standardization efforts that lead to the deployment of large intra-institutional networks of image distribution allowing radiologists and physicians to access and review images digitally. With the deployment of PACS came along the need for advanced tools for image visualization and image analysis.

RESULTS

Review of the history of PACS and Imaging Informatics clearly shows that the early developments were focused on the radiologist's requirements for diagnosis and image interpretation. These early developments lagged behind the rapid adoption of digital imaging in areas outside radiology. Only recently, imaging informatics shifted toward the development of new tools geared toward the needs of other users such as surgeons, referring physicians and care-providers, and even for the patients themselves. Also in the recent years, the development of multimedia and communication tools in the consumer market has influenced the design and strategic development of image management platforms inside and outside healthcare institutions.

CONCLUSIONS

The focus of imaging informatics has clearly shifted in the last decade from basic infrastructure design to complete data and image navigation systems. While the challenge of storing and managing large volumes of imaging data have slowly vanished with the rapid development if information technology, the new challenge emerged from the new requirements of image manipulation and analysis in clinical practice.

A humanist's legacy in medical informatics: visions and accomplishments of Professor Jean-Raoul Scherrer

OBJECTIVE

To report about the work of Prof. Jean-Raoul Scherrer, and show how his humanist vision, his medical skills and his scientific background have enabled and shaped the development of medical informatics over the last 30 years.

RESULTS

Starting with the mainframe-based patient-centered hospital information system DIOGENE in the 70s, Prof. Scherrer developed, implemented and evolved innovative concepts of man-machine interfaces, distributed and federated environments, leading the way with information systems that obstinately focused on the support of care providers and patients. Through a rigorous design of terminologies and ontologies, the DIOGENE data would then serve as a basis for the development of clinical research, data mining, and lead to innovative natural language processing techniques. In parallel, Prof. Scherrer supported the development of medical image management, ranging from a distributed picture archiving and communication systems (PACS) to molecular imaging of protein electrophoreses. Recognizing the need for improving the quality and trustworthiness of medical information on the Web, Prof. Scherrer created the Health-On-the-Net (HON) foundation.

CONCLUSIONS

These achievements, made possible thanks to his visionary mind, deep humanism, creativity, generosity and determination, have made of Prof. Scherrer a true pioneer and leader of the human-centered, patient-oriented application of information technology for improving healthcare.

Computer-aided design and modeling of workstations and radiology reading rooms for the new millennium

Three-dimensional (3D) computer modeling, simulation, and rendering techniques were used to redesign the diagnostic workstations and radiology reading rooms for a proposed hospital with particular attention given to lighting conditions, noise reduction, and optimal use of limited workspace. The results were presented to a panel of multidisciplinary experts and iteratively improved and redesigned with the development or addition of new design criteria or requirements. These 3D techniques allowed faster, more efficient design and presentation of multiple options than is possible with traditional two-dimensional drawings, thereby expediting decision making and resulting in significant savings. The current workstation designs can easily be developed and implemented with available technology at a reasonable cost. They can also accommodate anticipated advances in computer and display technology as well as new imaging paradigms (eg, changes in keyboard and control ergonomics such as adjustable virtual keys on touch-sensitive screens, digital drawing tablets for annotations and controls, direct film digitizing, personal identification devices, offline media readers such as compact disks and digital videodisks, and speech recognition and voice activation). Use of 3D techniques in designing other parts of the radiology department (eg, examination rooms, technologists' areas, physicians' offices) could greatly improve and facilitate the design and implementation of complex settings in these work areas.

Contemporary cardiac imaging: an overview

Comprehensive cardiac assessment embraces virtually every imaging modality and includes information about coronary vascular anatomy as well as cardiac morphology, function, perfusion, metabolism, and tissue characterization. Through sophisticated computer processing and image analysis, newer imaging technologies such as computed tomography (CT), magnetic resonance (MR), MR spectroscopy, and positron emission tomography now provide quantitative information that may obviate more invasive angiographic assessment. Currently, no single imaging technology realizes all questions relating to cardiac form and function, and many of the technologies overlap in the content and quality of information they provide. This overview seeks to provide a broad perspective on current cardiac imaging, articulating the benefits of various technologies and their limitations.

Detection and quantification of valvular heart disease with dynamic cardiac MR imaging

Magnetic resonance (MR) imaging is rapidly gaining acceptance as an accurate, reproducible, noninvasive method for optimal assessment of structural and functional parameters in patients with valvular heart disease. The severity of valvular regurgitation can be evaluated with cine gradient-echo MR imaging, which allows measurement of the area of the signal void corresponding to the abnormal flow jet. Alternatively, this modality can be used to obtain ventricular volumetric measurements and calculate the regurgitant fraction, or velocity-encoded cine (VEC) MR imaging can be used to quantify regurgitant blood flow. The severity of valvular stenosis can be determined by evaluating the flow jet and associated findings with either modality or by using VEC MR imaging to calculate the transvalvular pressure gradient and valve area. Dynamic MR imaging allows accurate assessment of ventricular function and comprehensive evaluation of pathophysiologic changes. In addition, good interstudy reproducibility suggests a role for VEC MR imaging in assessing the effects of therapeutic intervention and monitoring regurgitant fraction, thereby helping in surgical planning and the prevention of ventricular dysfunction. With greater cost-effectiveness and the increasing availability of new hardware and more advanced techniques, MR imaging will become a routine procedure in valvular heart disease.

The exchange of radiotherapy data as part of an electronic patient-referral system

PURPOSE

To describe the implementation and use of an electronic patient-referral system as an aid to the efficient referral of patients to a remote and specialized treatment center.

METHODS AND MATERIALS

A system for the exchange of radiotherapy data between different commercial planning systems and a specially developed planning system for proton therapy has been developed through the use of the PAPYRUS diagnostic image standard as an intermediate format. To ensure the cooperation of the different TPS manufacturers, the number of data sets defined for transfer has been restricted to the three core data sets of CT, VOIs, and three-dimensional dose distributions. As a complement to the exchange of data, network-wide application-sharing (video-conferencing) technologies have been adopted to provide methods for the interactive discussion and assessment of treatments plans with one or more partner clinics.

RESULTS

Through the use of evaluation plans based on the exchanged data, referring clinics can accurately assess the advantages offered by proton therapy on a patient-by-patient basis, while the practicality or otherwise of the proposed treatments can simultaneously be assessed by the proton therapy center. Such a system, along with the interactive capabilities provided by video-conferencing methods, has been found to be an efficient solution to the problem of patient assessment and selection at a specialized treatment center, and is a necessary first step toward the full electronic integration of such centers with their remotely situated referral centers.

Update on digital image management and PACS

Information technology is becoming a vital component of all health care enterprises, from managed care services to large hospital networks, that provides the basis of electronic patient records and hospital-wide information. The rationale behind such systems is deceptively simple: physicians want to sit down at a single workstation and call up all information, both clinical data and medical images, concerning a given patient. Picture archiving and communication systems (PACS) are responsible for solving the problem of acquiring, transmitting, and displaying radiologic images. The major benefit of PACS resides in its ability to communicate images and reports to referring physicians in a timely and reliable fashion. With the changes in economics and the shift toward managed and capitated care, the teleradiology component of PACS is rapidly gaining momentum. In allowing remote coverage of multiple sites by the same radiologists and remote consultations and expert opinion, teleradiology is in many instances the only option to maintain economically viable radiologic settings. The technical evolution toward more integrated systems and the shift toward Web-based technology is rapidly merging the two concepts of PACS and teleradiology in global image management and communication systems.

Web-based video for real-time monitoring of radiological procedures

A web-based video transmission of images from CT and MRI consoles was implemented in an Intranet environment for real-time monitoring of ongoing procedures. Images captured from the consoles are compressed to video resolution and broadcast through a web server. When called upon, the attending radiologists can view these live images on any computer within the secured Intranet network. With adequate compression, these images can be displayed simultaneously in different locations at a rate of 2 to 5 images/s through a standard local-area network. While the quality of the images was insufficient for diagnostic purposes, our users survey showed that they were suitable for supervising a procedure, positioning the imaging slices, and for routine quality checking before completion of a study. The system was implemented at UCLA to monitor nine CT's and six MRI's distributed in four different buildings. This system significantly improved the radiologists productivity by saving valuable time spent in trips between reading rooms and examination rooms. It also improved patient care and throughput by reducing the time spent waiting for the radiologists to check a study before removing the patient from the scanner.

Morphologic and functional evaluation of congenital heart disease by magnetic resonance imaging

Magnetic resonance imaging (MRI) has evolved sufficiently to be recognized as a useful complementary noninvasive method to echocardiography in the evaluation of congenital heart disease (CHD). In some cases, MRI is superior to other imaging modalities, particularly in the evaluation of thoracic aortic anomalies and in defining the anatomy of central pulmonary arteries; it is also the procedure of choice in the postoperative follow-up of patients with CHD. Recent technological advances permit not only morphological evaluation (provided by spin-echo and MR angiographic techniques) but functional and flow information (provided by fast cine-GE and velocity-encoded sequences), causing it to be recognized by pediatric cardiologists and cardiac surgeons as an unavoidable technique for pre- and postoperative evaluation of some CHD. This review describes the various techniques used in the evaluation of CHD with emphasis on recent developments as well as recognized clinical applications. J. Magn. Reson. Imaging 1999;10:639-655.

A hospital-wide distributed PACS based on intranet

A hospital-wide Picture Archiving and Communication System (PACS) is currently under development at the University Hospital of Geneva. After a first implementation including two oneterabyte optical libraries, the system is expanded to integrate all the imaging modalities of the hospital. The new storage requirement is 10 terabytes to cover three year archive. A large distributed image archive has been designed including new archive servers for long-term storage and display servers for medium-term storage. The acquisition, archive and distribution cycles are performed using separated networks combining Fast Ethernet and Ethernet. Image files are distributed to the wide-hospital using a prefetching strategy or an Intranet server, RADIOLAB. The first mode takes advantage of the fully integrated hospital information system DIOGENE 2 to allow the automatic retrieval of studies in advance. The second mode provides a convivial study selection from any conventional WWW (World Wide Web) browser. Image files are then transmitted to the user's display station using HTTP (HyperText Transfer Protocol) and handled by OSIRIS software, which acts as a helper or viewer. Such a system is expected to meet the time requirement, which is less than three seconds per image.

Teleradiology in the operating room of the future

Recent advances in magnetic resonance imaging (MRI) are rapidly making this modality the imaging method of choice for image-guided neurosurgical operations. However, to be ready for its prime time in the operating room (OR), utilization of MRI in the OR requires development of better techniques for image-guided navigation, as well as interactive real-time teleradiologic methods that will allow tele-collaboration between the surgeon and the radiologist. This presentation describes our work in progress toward achievement of teleradiology in the OR.

Design of a cooperative teleradiology system

The article describes a teleradiology system intended to provide a user-friendly environment for exchanging images and working cooperatively on them. With the development of a hospital-wide picture archiving and communication system (PACS), the University Hospital of Geneva and several other health institutions in the region became interested in teleradiology. Because of the heterogeneous needs of the potential participants, the following requirements were identified: (1) remote consultation and interpretation of images; and (2) cooperative interpretation of medical images, allowing real-time interaction between physicians. To satisfy these needs, a multipoint teleradiology system has been implemented that incorporates an innovative image display and manipulation software program known as OSIRIS, which supports the full spectrum of imaging modalities. Images and data are transmitted over the public telecommunications Integrated Services Digital Network (ISDN). To accommodate different computing environments at the various locations, platform-independent software has been designed that has the same "look and feel" for PC-Windows, Macintosh, and UNIX-X11 work-stations. The teleradiology system can be used in two modes: synchronous (cooperative) or asynchronous. Special efforts have been made in the development of the synchronous mode. Within the European Telemed Project, a specific protocol has been designed to allow cooperative work between remotely located workstations.

Multimedia image and data navigation workstation

World Wide Web (WWW) standards have been established for the transmission of and remote consultation on medical information and records, including medical images, extracted from an existing hospital information system. A software package called Osiris is being used for the display and manipulation of medical images in a hospital-based picture archiving and communication system. Recent extensions of Osiris, through the integration of WWW navigational tools, allow easy access to a variety of clinical data from patient records. A special interface allows access to radiologic images, laboratory results, and related textual information through public-domain software programs. These technologic advances offer medical professionals the convenience and ease of use that have made WWW and Internet navigation so popular in the academic community.

Three- to five-dimensional biomedical multisensor imaging for the assessment of neurological (dys) function

This report describes techniques and protocols implemented at the Geneva Canton University Hospitals (HUG) for the combination of various biomedical imaging modalities and sensors including electromagnetic tomography, to study, assess, and localize neurological (dys) function. The interest for this combination stems from the broad variety of information brought out by (functional) magnetic resonance imaging, magnetic resonance spectroscopy, computed tomography, single-photon emission tomography, positron emission tomography, and electromagnetic tomography. Combining these data allows morphology, metabolism, and function to be studied simultaneously, the complementary nature of the information from these modalities becoming evident when studying pathologies reflected by metabolic or electrophysiologic dysfunctions. Compared with other current multimodality approaches, the one at the HUG is totally compatible with both clinical and research protocols, and efficiently addresses the multidimensional registration and visualization issues. It also smoothly integrates electrophysiology and related data as fully featured modalities.

In-house access to PACS images and related data through World Wide Web

The development of a hospital wide PACS is in progress at the University Hospital of Geneva and several archive modules are operational since 1992. This PACS is intended for wide distribution of images to clinical wards. As the PACS project and the number of archived images grow rapidly in the hospital, it was necessary to provide an easy, more widely accessible and convenient access to the PACS database for the clinicians in the different wards and clinical units of the hospital. An innovative solution has been developed using tools such as Netscape navigator and NCSA World Wide Web server as an alternative to conventional database query and retrieval software. These tools present the advantages of providing a user interface which is the same, independent of the platform being used (e.g. Mac, Windows, UNIX), and an easy integration of different types of documents (e.g. text, images). A strict access control has been added to this interface. It allows user identification and access rights checking, as defined by the in-house hospital information system, before allowing the navigation through patient data records.

Standard views in cardiac multimodality tomographic imaging

In cardiology, it is often necessary to acquire more than one type of image to investigate a given clinical problem of a single patient. Images obtained from different imaging modalities are usually recorded and displayed in different orientations, at different positions, and at different scale factors. It is then necessary for the physician to mentally integrate the image information from the different imaging modalities. This phenomenon is particularly true with tomographic imaging techniques that allow complete freedom of the acquisition plane. In particular, when comparing images obtained from ultrasound, computed tomography, magnetic resonance imaging, positron-emission tomography, and single-photon emission computed tomography. The purpose of this article is to propose a standard set of slice orientations that could be easily applied to all modalities. Such common views could greatly facilitate the user's perception of the regional abnormalities observed in the different imaging modalities. This standardization is certainly useful for clinical application but also for every research study that requires a comparative evaluation of the different imaging modalities. Although exact registration of the images from the different modalities requires sophisticated computer programs, the simple reference method in plane positioning proposed here based on plane orientation according to the cardiac geometry can certainly provide a practical and convenient method for the reasonably accurate image registration required for visual comparative studies.

Osiris: a medical image-manipulation system

We designed a general-purpose computer program, Osiris, for the display, manipulation, and analysis of digital medical images. The program offers an intuitive, window-based interface with direct access to generic tools. Characterized by user-friendliness, portability, and extensibility, Osiris is compatible with both Unix-based and Macintosh-based platforms. It is readily modified and can be used to develop new tools. It is able to monitor the entries made during a work session and thus provide data on its use. Osiris and its source code are being distributed, free of charge, to universities and research groups around the world.

[Architecture and organization of PACS workstations: a critical overview]

The development and implementation of a workstation capable of handling medical images and data from different imaging modalities require a particular user-interface design so that it is easily accessible by clinical and non-computer-oriented users. Appropriate management of medical images from different imaging modalities is the first step toward the integration of multimedia information in a coherent computerized medical record. It is also the most challenging part because the amount of data obtained in the form of images is much greater than the text, graphic or sound elements. The proportion of clinical investigations based on imaging modalities is also constantly increasing. The goal of this paper is to review some important design concepts of imaging workstations and to explore the needs and requirements of medical image display and manipulation.

PAPYRUS 3.0: DICOM-compatible file format

This paper describes the PAPYRUS 3.0 file format based on the new DICOM 3.0 Standard which addresses the open interchange of medical images in files or on removable storage media. This specific implementation of the DICOM standard is intended as a generic solution for interchange of multi-modality medical images on removable media. It can also be used for convenient exchange of image data between different computer systems through industry standard file transfer mechanisms. Finally it can also be used for storage and archiving of medical image data in a DICOM-compatible format.

Image analysis and computer vision in medicine

Multimedia lives with images; medical images are born from digital imaging. A physician's multimedia workstation cannot exist without tools for manipulating images, performing measurements and, generally speaking, extracting and collecting pieces of information from the available data. Image analysis and computer vision constitute a wide and rapidly evolving field. This paper is intended as an introductory document for medical imaging researchers and practitioners wishing an overview of recent developments and trends. The major lines of activities in the domain are presented, under the common framework of a processing pipeline. After a presentation of the various stages of this pipeline, current subjects of research are indicated.

Digital image management and communication in medicine

With the rapid development of digital imaging modalities in medicine, there is an increasing need for an efficient management and archival of medical images in digital form. Picture Archiving and Communication Systems (PACS) are becoming an essential component of medical imaging equipment, allowing for medical images to be accessed and stored directly in digital form. This paper describes a hospital-wide PACS currently under development at the University Hospital of Geneva, based on an open architecture, regrouping equipment from different vendors in a distributed topology. The image archival is organized in multiple locations geographically distributed in the hospital. The PACS database is fully integrated with the concurrent Radiology Information System (RIS) and Hospital Information System (HIS). A standard image storage format called the PAPYRUS format was developed for the storage of medical images from a variety of imaging modalities. To provide a more uniform user interface on a variety of different workstations, a common platform for image display and manipulation called OSIRIS was developed.

Object-oriented design of medical imaging software

A special software package for interactive display and manipulation of medical images was developed at the University Hospital of Geneva, as part of a hospital wide Picture Archiving and Communication System (PACS). This software package, called Osiris, was especially designed to be easily usable and adaptable to the needs of noncomputer-oriented physicians. The Osiris software has been developed to allow the visualization of medical images obtained from any imaging modality. It provides generic manipulation tools, processing tools, and analysis tools more specific to clinical applications. This software, based on an object-oriented paradigm, is portable and extensible. Osiris is available on two different operating systems: the Unix X-11/OSF-Motif based workstations, and the Macintosh family.

From multimodality digital imaging to multimedia patient record

The constant improvement in computer power and performance nowadays offers convenient and efficient means of manipulating images, graphics, and movies on off-the-shelf workstations. With this improvement the trend toward integration of multimodality clinical documents from patient records comes naturally. Images and graphs are certainly the most important part of the complementary information that must accompany the text and numerical data. It is, however, possible to include sounds and voice messages together with all the other modalities. In medicine that could certainly help conveying hart murmur or sounds, but could also offer a convenient way of including vocal messages and comments. These new possibilities will certainly change the way physicians use workstations for direct communication. The computer industry will soon offer means of interactive communication between remote users through computer workstations. That alone will open a completely new era in cooperative computing and remote consultation scenarios in medicine. More than the technology itself, a complete change in behavior and work habits can be expected in the medical community.