In this paper, we demonstrate how to digitally sign a content manifest of a presentable clinical document that contains multiple clinical data with presentations. Only one signature is needed for an entire clinical document with multiple data resources, which can reduce the computation time during signing and verifying processes. In the radiology field, a report may contain text descriptions, images, and annotations that are stored separately in different data resources. The manifest signature would be a proper means for integrity checking for all the clinical data within the manifest. The manifest signature can be extended with a trusted third party to add a digital time signature for long-term verifiability. The performance of the manifest signing compared with that of a traditional digital signing was evaluated. The new manifest signature can be used for signing different types of presentable clinical documents, such HL7 CDA documents and DICOM image reports.
Security; digital signature; electronic health record (EHR); digital imaging and communication in medicine (DICOM)
Information technology teams in health care are tasked with maintaining a variety of information systems with complex support requirements. In radiology, this includes picture archive and communication systems, radiology information systems, speech recognition systems, and other ancillary systems. Hospital information technology (IT) departments are required to provide 24 × 7 support for these mission-critical systems that directly support patient care in emergency and other critical care departments. The practical know-how to keep these systems operational and diagnose problems promptly is difficult to maintain around the clock. Specific details on infrequent failure modes or advanced troubleshooting strategies may reside with only a few senior staff members. Our goal was to reduce diagnosis and recovery times for issues with our mission-critical systems. We created a knowledge base for building and quickly disseminating technical expertise to our entire support staff. We used an open source, wiki-based, collaborative authoring system internally within our IT department to improve our ability to deliver a high level of service to our customers. In this paper, we describe our evaluation of the wiki and the ways in which we used it to organize our support knowledge. We found the wiki to be an effective tool for knowledge management and for improving our ability to provide mission-critical support for health care IT systems.
Wiki; PACS; knowledge management; informatics
The aim of this study was to develop wireless Picture Archiving and Communication System (PACS) device and to analyze its effect on image transfer from portable imaging modalities to the main PACS server. Using a laptop computer equipped with wireless local area network (LAN), the authors developed a wireless PACS device with DICOM modality worklist and DICOM storage server modules. This laptop computer could be easily fixed to portable imaging modalities such as ultrasound machines. From May to August 2007, 112 portable examinations were evaluated. Of these, 62 were done with wireless LAN-based PACS device, and 50 were done without wireless PACS device. To evaluate the impact of the wireless LAN-based PACS device on productivity and workflow, we analyzed the mean time delay and standard deviations (SD) both in cases where wireless LAN-based PACS device was used and in cases where it was not used. Statistical analysis was performed using a t test. The mean time interval from image acquisition to storage in the main PACS when the wireless LAN-based PACS device was used was 342.4 s (5 min and 42.4 s, SD = 509.2 s). When the wireless PACS was not used, the mean time interval was 2,305.5 s (38 min and 25.5 s, SD = 1,371.8 s). The mean time interval was statistically different between the two groups (t test, p < 0.001). The wireless LAN-based PACS device could help in reducing the storage intervals of images obtained by portable machines and in promoting effective and rapid treatment of patients who have undergone portable imaging examinations.
Wireless LAN; portable modalities; productivity; workflow
Digital screening mammograms (DM) take longer to interpret than film-screen screening mammograms (FSM). We evaluated what part of the process takes long in our reading environment. We selected cases from those for which timed readings had been performed as part of a previous study. Readers were timed as they performed various computer manipulations on groups of DM cases and as they moved the alternator and adjusted lighting and manual shutters for FSM cases. Subtracting manipulation time from the original interpretation times yielded estimated times to reach a decision. Manipulation times for DM ranged from a low of 11 s when four-view DM were simply opened and closed in a 4-on-1 hanging protocol before moving on to the next study to 113.8 s when each view of six-view DM were brought up 1-on-1, enlarged to 100% resolution, and panned through. Manipulation times for groups of FSM ranged from 8.3 to 12.1 s. Estimated decision-making times for DM ranged from 128.0 to 202.2 s, while estimated decision-making time for FSM ranged from 60.9 to 146.3 s. Computer manipulation time partially explains the discrepancy in interaction times between DM and FSM. Radiologists also appear to spend more time looking at DM than at FSM before making a decision.
Full-field digital mammography (FFDM); mammography; image manipulation; image interpretation; screening mammography; efficiency
Teaching files are integral to radiological training. Digital Imaging and Communication in Medicine compatible digital radiological data and technological advances have made digital teaching files a desirable way to preserve and share representative and/or unusual cases for training purposes. The Medical Imaging Resource Community (MIRC) system developed by the Radiological Society of North America (RSNA) is a robust multi-platform digital teaching file implementation that is freely available. An emergency radiology training curriculum developed by the American Society of Emergency Radiology (ASER) was incorporated to determine if such an approach might facilitate the entry, maintenance, and cataloguing of interesting cases. The RSNA MIRC software was obtained from the main MIRC website and installed. A coding system was developed based on the outline form of the ASER curriculum. Weekly reports were generated tallying the number of cases in each category of the curriculum. Resident participation in the entry and maintenance of cases markedly increased after incorporation of the ASER curriculum. The coding schema facilitated progress assessment. Ultimately, 454 total cases were entered into the MIRC database, representing at least 42% of the subcategories within the ASER curriculum (161 out of 376). The incorporation of the ASER emergency radiology curriculum greatly facilitated the location, cataloguing, tracking, and maintenance of representative cases and served as an effective means by which to unify the efforts of the department to develop a comprehensive teaching resource within this subspecialty. This approach and format will be extended to other educational curricula in other radiological subspecialties.
Electronic supplementary material
The online version of this article (doi:10.1007/s10278-009-9178-8) contains supplementary material, which is available to authorized users.
Medical Imaging Resource Center (MIRC); electronic teaching file; emergency radiology; experiential; Extensible Markup Language (XML); web technology; computers in medicine; computer communication networks; data mining; database management systems; digital libraries; education; medical; image libraries; radiology teaching files; teaching
To enhance the readability, improve the structure, and facilitate the sharing of digital imaging and communications in medicine (DICOM) files, this research proposed one kind of XML-based DICOM data format. Because XML Schema offers great flexibility for expressing constraints on the content model of elements, we used it to describe the new format, thus making it consistent with the one originally defined by DICOM. Meanwhile, such schemas can be used in the creation and validation of the XML-encoded DICOM files, acting as a standard for data transmission and sharing on the Web. Upon defining the new data format, we started with representing a single data element and further improved the whole data structure with the method of modularization. In contrast to the original format, the new one possesses better structure without loss of related information. In addition, we demonstrated the application of XSLT and XQuery. All of the advantages mentioned above resulted from this new data format.
DICOM; data format; XML; XML Schema
We created our imaging center (IC) to move outpatient imaging from our busy inpatient imaging suite off-site to a location that is more inviting to ambulatory patients. Nevertheless, patients scanned at our IC still represent the depth and breadth of illness complexity seen with our tertiary care population. Thus, we protocol exams on an individualized basis to ensure that the referring clinician’s question is fully answered by the exam performed. Previously, paper based protocoling was a laborious process for all those involved where the IC business office would fax the requests to various reading rooms for protocoling by the subspecialist radiologists who are 3 miles away at the main hospital. Once protocoled, reading room coordinators would fax back the protocoled request to the IC technical area in preparation for the next day’s scheduled exams. At any breakdown in this process (e.g., lost paperwork), patient exams were delayed and clinicians and patients became upset. To improve this process, we developed a paper free process whereby protocoling is accomplished through scanning of exam requests into our PACS. Using the common worklist functionality found in most PACS, we created “protocoling worklists” that contain these scanned documents. Radiologists protocol these studies in the PACS worklist (with the added benefit of having all imaging and report data available), and subsequently, the technologists can see and act on the protocols they find in PACS. This process has significantly decreased interruptions in our busy reading rooms and decreased rework of IC staff.
Radiology workflow; workflow re-engineering; PACS
Digital radiology departments could benefit from the ability to integrate and visualize data (e.g. information reflecting complex workflow states) from all of their imaging and information management systems in one composite presentation view. Leveraging data warehousing tools developed in the business world may be one way to achieve this capability. In total, the concept of managing the information available in this data repository is known as Business Intelligence or BI. This paper describes the concepts used in Business Intelligence, their importance to modern Radiology, and the steps used in the creation of a prototype model of a data warehouse for BI using open-source tools.
Data collection; data mining; databases; data extraction; knowledge management; online analytical processing (OLAP)
We evaluated the potential utility of a newly developed liquid-crystal display (LCD), which used an independent sub-pixel drive (ISD) technique for increasing the spatial resolution of a standard LCD three times in one direction, by use of receiver operating characteristic (ROC) analysis and a two-alternative-forced-choice (2AFC) method to determine improvement in radiologists’ accuracy in the detection of clustered microcalcifications (MCLs) on digital mammograms. We used a standard LCD without and with the ISD technique, which can increase the spatial resolution of the LCD three times in one direction from three mega- to nine megapixels without changes in the size of the display. We used 60 single views of digital mammograms (30 with and 30 without clustered MCLs) for ROC studies and 60 regions of interest (ROIs) with clustered MCLs for 2AFC studies. In the ROC study, seven radiologists attempted to detect clustered MCLs without and with the ISD on the same LCD. In the 2AFC study, the same observer group compared the visibility of MCLs by use of the LCD without and with the ISD. Our institutional review board approved the use of this database and the participation of radiologists in this study. The accuracy in detecting clustered MCLs in the ROC study was improved by use of the LCD with the ISD, but the improvement was not statistically significant (p = 0.08). However, the superiority of the LCD with the ISD was demonstrated as significant (p < 0.001) in the 2AFC study. An LCD with ISD can improve the visibility of clustered MCLs when high-resolution digital mammograms are available.
Digital mammography; observer performance; display device; receiver operating characteristic curve; digital display
A temporal subtraction image, which is obtained by subtraction of a previous image from a current one, can be used for enhancing interval changes (such as formation of new lesions and changes in existing abnormalities) on medical images by removing most of the normal structures. However, subtraction artifacts are commonly included in temporal subtraction images obtained from thoracic computed tomography and thus tend to reduce its effectiveness in the detection of pulmonary nodules. In this study, we developed a new method for substantially removing the artifacts on temporal subtraction images of lungs obtained from multiple-detector computed tomography (MDCT) by using a voxel-matching technique. Our new method was examined on 20 clinical cases with MDCT images. With this technique, the voxel value in a warped (or nonwarped) previous image is replaced by a voxel value within a kernel, such as a small cube centered at a given location, which would be closest (identical or nearly equal) to the voxel value in the corresponding location in the current image. With the voxel-matching technique, the correspondence not only between the structures but also between the voxel values in the current and the previous images is determined. To evaluate the usefulness of the voxel-matching technique for removal of subtraction artifacts, the magnitude of artifacts remaining in the temporal subtraction images was examined by use of the full width at half maximum and the sum of a histogram of voxel values, which may indicate the average contrast and the total amount, respectively, of subtraction artifacts. With our new method, subtraction artifacts due to normal structures such as blood vessels were substantially removed on temporal subtraction images. This computerized method can enhance lung nodules on chest MDCT images without disturbing misregistration artifacts.
Temporal subtraction; nonlinear warping; computer-aided diagnosis; chest CT; image registration
In this paper, we compare five common classifier families in their ability to categorize six lung tissue patterns in high-resolution computed tomography (HRCT) images of patients affected with interstitial lung diseases (ILD) and with healthy tissue. The evaluated classifiers are naive Bayes, k-nearest neighbor, J48 decision trees, multilayer perceptron, and support vector machines (SVM). The dataset used contains 843 regions of interest (ROI) of healthy and five pathologic lung tissue patterns identified by two radiologists at the University Hospitals of Geneva. Correlation of the feature space composed of 39 texture attributes is studied. A grid search for optimal parameters is carried out for each classifier family. Two complementary metrics are used to characterize the performances of classification. These are based on McNemar’s statistical tests and global accuracy. SVM reached best values for each metric and allowed a mean correct prediction rate of 88.3% with high class-specific precision on testing sets of 423 ROIs.
Quantitative image analysis; feature extraction; texture analysis; chest high-resolution CT; supervised learning; support vector machines
Bronchoscopy is often performed for staging lung cancer. The recent development of multidetector computed tomography (MDCT) scanners and ultrathin bronchoscopes now enable the bronchoscopic biopsy and treatment of peripheral diagnostic regions of interest (ROIs). Because these ROIs are often located several generations within the airway tree, careful planning and interpretation of the bronchoscopic route is required prior to a procedure. The current practice for planning bronchoscopic procedures, however, is difficult, error prone, and time consuming. To alleviate these issues, we propose a method for producing and previewing reports for bronchoscopic procedures using patient-specific MDCT chest scans. The reports provide quantitative data about the bronchoscopic routes and both static and dynamic previews of the proper airway route. The previews consist of virtual bronchoscopic endoluminal renderings along the route and three-dimensional cues for a final biopsy site. The reports require little storage space and computational resources, enabling physicians to view the reports on a portable tablet PC. To evaluate the efficacy of the reporting system, we have generated reports for 22 patients in a human lung cancer patient pilot study. For 17 of these patients, we used the reports in conjunction with live image-based bronchoscopic guidance to direct physicians to central chest and peripheral ROIs for subsequent diagnostic evaluation. Our experience shows that the tool enabled useful procedure preview and an effective means for planning strategy prior to a live bronchoscopy.
Image-based reporting; image-guided surgery; 3D imaging; virtual bronchoscopy; lung cancer; bronchoscopy
Picture archiving and communication systems (PACS) for imaging studies is rapidly being adopted in hospitals throughout the UK. However, very little comparison has been made between PACS and laser hard copies for assessing the diagnostic accuracy of detecting fractures by emergency physicians. A prospective paired comparison study was undertaken looking at correct reporting of scaphoid X-rays on PACS and conventional film by emergency department medical staff. A total of 34 imaging studies were reported by 38 physicians using both PACS workstations and laser-printed films. The percentage of emergency physicians correctly reporting imaging studies was similar when comparing PACS images to laser film copies (80.7% versus 81.0%). The sensitivity and specificity of PACS for diagnosing scaphoid fractures was 79.5% and 81.6%, versus 78.1% and 83.8% for conventional films. There is no significant difference in accuracy of diagnosis between PACS and laser film copies when scaphoid X-rays are reported by emergency physicians.
PACS; PACS system performance; performance measurement
To evaluate the number of actual detections versus “accidental” detections by a computer-aided detection (CAD) system for small nodular lung cancers (≤30 mm) on chest radiographs, using two different criteria for measuring performance. A Food-and-Drug-Administration-approved CAD program (version 1.0; Riverain Medical) was applied to 34 chest radiographs with a “radiologist-missed” nodular cancer and 36 radiographs with a radiologist-mentioned nodule (a newer version 3.0 was also applied to the 36-case database). The marks applied by this CAD system consisted of 5-cm-diameter circles. A strict “nodule-in-center” criterion and a generous “nodule-in-circle” criterion were compared as methods for the calculation of CAD sensitivity. The increased sensitivities by the nodule-in-circle criterion were considered as nodules detected by chance. The number of false-positive (FP) marks was also analyzed. For the 34 radiologist-missed cancers, the nodule-in-circle criterion caused eight more cancers (24%) to be detected by chance, as compared to the nodule-in-center criterion, when using the version 1.0 results. For the 36 radiologist-mentioned nodules, the nodule-in-circle criterion caused seven more lesions (19%) to be detected by chance, as compared to the nodule-in-center criterion, when using the version 1.0 results, and three more lesions (8%) to be detected by chance when using the version 3.0 results. Version 1.0 yielded a mean of six FP marks per image, while version 3.0 yielded only three FP marks per image. The specific criteria used to define true- and false-positive CAD detections can substantially influence the apparent accuracy of a CAD system.
Lung; neoplasms; computer-aided detection; chest radiography
The purpose of this study was to study whether the benefits from introducing a picture archiving and communication systems (PACS) reported by innovators and early adopters also can be achieved by a hospital belonging to the “late majority” and to see whether such benefits are sustained, using report turnaround time (RTAT) as an indicator. Activity-related data was retrieved from the radiology information system (RIS) over a 2-year period. The median RTAT for preliminary reports was initially reduced from 12 to 2 h then increased to 3 h. For final reports, the median RTAT was initially reduced from 23 to 13 h then gradually reverted back to 22 h. Innovators and early adopters demonstrate not only that positive results can be achieved but also the importance of involving key personnel. We believe that such involvement and the focus on wider organizational concerns are important when introducing PACS to the late majority, both for achieving and sustaining positive results.
Radiology information systems (RIS); radiology reporting; radiology workflow; PACS; cost effectiveness; medical informatics applications
Successfully introducing a new technology in a health-care setting is not a walk in the park. Many barriers need to be overcome, not only technical and financial but also human barriers. In this study, we focus on the human barriers to health-care information systems’ implementation. We monitored the acceptance of a Picture Archiving and Communication System (PACS) by radiologists and hospital physicians in a large Belgian university hospital. Hereto, questionnaires were taken pre-implementation (T1) and 1 year after the radiology department stopped printing film (T2). The framework we used to perform the study was the Unified Theory of Acceptance and Use of Technology. Main findings were that both groups were positive toward PACS prior to the introduction and that each group was even more positive at T2 with extensive PACS experience. In general, the ratings of the radiologists were higher than those of the physicians, as the radiologists experienced more of the benefits of PACS and had to use PACS throughout the day. Two factors were salient for predicting users’ intention to use PACS: the usefulness of PACS (performance expectancy) and the availability of support of any kind (facilitating conditions). The results show that our approach was successful. Both radiologists and physicians give evidence of an excellent level of user acceptance. We can conclude that the implementation of PACS into our hospital has succeeded.
PACS; acceptance testing; computers in medicine; radiology workflow; UTAUT; attitude; university hospital
The study investigates the effect of a substantial dose reduction on the variability of lung nodule volume measurements by assessing and comparing nodule volumes using a dedicated semiautomated segmentation software on ultralow-dose computed tomography (ULD-CT) and standard-dose computed tomography (SD-CT) data. In 20 patients, thin-slice chest CT datasets (1 mm slice thickness; 20% reconstruction overlap) were acquired at ultralow-dose (120 kV, 5 mAs) and at standard-dose (120 kV, 75 mAs), respectively, and analyzed using the segmentation software OncoTREAT (MeVis, Bremen, Germany; version 1.3). Interobserver variability of volume measurements of 202 solid pulmonary nodules (mean diameter 11 mm, range 3.2–44.5 mm) was calculated for SD-CT and ULD-CT. With respect to interobserver variability, the 95% confidence interval for the relative differences in nodule volume in the intrascan analysis was measured with −9.7% to 8.3% (mean difference −0.7%) for SD-CT and with −12.6% to 12.4% (mean difference −0.2%) for ULD-CT. In the interscan analysis, the 95% confidence intervals for the differences in nodule volume ranged with −25.1% to −23.4% and 26.2% to 28.9% (mean difference 1.4% to 2.1%) dependent on the combination of readers and scans. Intrascan interobserver variability of volume measurements was comparable for ULD-CT and SD-CT data. The calculated variability of volume measurements in the interscan analysis was similar to the data reported in the literature for CT data acquired with equal radiation dose. Thus, the evaluated segmentation software provides nodule volumetry that appears to be independent of the dose level with which the CT source dataset is acquired.
Chest CT; lung neoplasms; segmentation; computer-aided diagnosis (CAD); radiation dose
We describe the development of software that allows and automates the routine inclusion of nondigital paper-based data directly into DICOM examinations. No human intervention is required. The software works by allowing the direct faxing of nondigital paper-based patient data directly into DICOM imaging examinations and is added as the first series in the examination. The software is effective in any typical PACS/DICOM server environment.
DICOM conversion; DICOM server; image to DICOM conversion; TIFF to DICOM; JPEG to DICOM; DICOM barcode; DICOM workflow
There are lots of work being done to develop computer-assisted diagnosis and detection (CAD) technologies and systems to improve the diagnostic quality for pulmonary nodules. Another way to improve accuracy of diagnosis on new images is to recall or find images with similar features from archived historical images which already have confirmed diagnostic results, and the content-based image retrieval (CBIR) technology has been proposed for this purpose. In this paper, we present a method to find and select texture features of solitary pulmonary nodules (SPNs) detected by computed tomography (CT) and evaluate the performance of support vector machine (SVM)-based classifiers in differentiating benign from malignant SPNs. Seventy-seven biopsy-confirmed CT cases of SPNs were included in this study. A total of 67 features were extracted by a feature extraction procedure, and around 25 features were finally selected after 300 genetic generations. We constructed the SVM-based classifier with the selected features and evaluated the performance of the classifier by comparing the classification results of the SVM-based classifier with six senior radiologists′ observations. The evaluation results not only showed that most of the selected features are characteristics frequently considered by radiologists and used in CAD analyses previously reported in classifying SPNs, but also indicated that some newly found features have important contribution in differentiating benign from malignant SPNs in SVM-based feature space. The results of this research can be used to build the highly efficient feature index of a CBIR system for CT images with pulmonary nodules.
Feature selection; content-based image retrieval; classification; CT images; lung diseases
Although accurate information on thoracolumbar bone structure is essential when computed tomography (CT) images are examined, there is no automated method of labeling all the vertebrae and ribs on a CT scan. We are developing a computer-aided diagnosis system that labels ribs and thoracolumbar vertebrae automatically and have evaluated its accuracy. A candidate bone was extracted from the CT image volume data by pixel thresholding and connectivity analysis. All non-bony anatomical structures were removed using a linear discriminate of distribution of CT values and anatomical characteristics. The vertebrae were separated from the ribs on the basis of their distances from the centers of the vertebral bodies. Finally, the thoracic cage and lumbar vertebrae were extracted, and each vertebra was labeled with its own anatomical number by histogram analysis along the craniocaudal midline. The ribs were labeled in a similar manner, based on location data. Twenty-three cases were used for accuracy comparison between our method and the radiologist’s. The automated labeling of the thoracolumbar vertebrae was concordant with the judgments of the radiologist in all cases, and all but the first and second ribs were labeled correctly. These two ribs were frequently misidentified, presumably because of pericostal anatomical clutter or high densities of contrast material in the injected veins. We are confident that this system can contribute usefully as part of a picture archiving and communication system workstation, though further technical improvement is required for identification of the upper ribs.
Computer-aided diagnosis; bone labeling; CT; PACS; ribs
Grid has emerged recently as an integration infrastructure for sharing and coordinated use of diverse resources in dynamic, distributed environment. In this paper, we present a prototype system for integration of heterogeneous medical databases based on Grid technology, which can provide a uniform access interface and efficient query mechanism to different medical databases. After presenting the architecture of the prototype system that employs corresponding Grid services and middleware technologies, we make an analysis on its basic functional components including OGSA-DAI, metadata model, transaction management, and query processing in detail, which cooperate with each other to enable uniform accessing and seamless integration of the underlying heterogeneous medical databases. Then, we test effectiveness and performance of the system through a query instance, analyze the experiment result, and make a discussion on some issues relating to practical medical applications. Although the prototype system has been carried out and tested in a simulated hospital information environment at present, the underlying principles are applicable to practical applications.
Grid; medical database; OGSA-DAI; metadata
This paper presents a radiological collaborative tool capable of direct manipulation of Digital Imaging and Communications in Medicine (DICOM) images on both sides, and also recording and reenacting of a recorded session. A special collaborative application protocol formerly developed was extended and used as basis for the development of collaborative session recording and playback processes. The protocol is used today for real-time radiological meetings through the Internet. This new standard for collaborative sessions makes possible other uses for the protocol, such as asynchronous collaborative sessions, decision regulation, auditing, and educational applications. Experimental results are given which compare this protocol with other popular collaborative approaches. Comparison of these results shows that the proposed protocol performs much better than other approaches when run under controlled conditions.
Collaborative session; session playback; session recording; telemedicine; teleradiology; DICOM workstation
Ideally, medical x-ray imaging systems should be designed to deliver maximum image quality at an acceptable radiation risk to the patient. Quality assurance procedures are employed to ensure that these standards are maintained. A quality control protocol for direct digital radiography (DDR) systems is described and discussed. Software to automatically process and analyze the required images was developed. In this paper, the initial results obtained on equipment of different DDR manufacturers were reported. The protocol was developed to highlight even small discrepancies in standard operating performance.
Quality control; direct digital radiography; automatic software; quality assurance; automated measurement; image quality analysis