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Biomedical subjects

H K Huang

Publications and source records attributed to H K Huang.

At least 19 recordsLinked to original sources

A HIPAA-compliant architecture for securing clinical images.

The Health Insurance Portability and Accountability Act (HIPAA, instituted April 2003) Security Standards mandate health institutions to protect health information against unauthorized use or disclosure. One approach to addressing this mandate is by utilizing user access control and generating audit trails of the various authorized as well as unauthorized user access of health data. Although most current clinical image systems [e.g., picture archiving and communication system (PACS)] have components that generate log files for application debugging purposes, there is a lack of methodology to obtain and synthesize the pertinent data from the large volumes of log data generated by these multiple components within a PACS. We have designed a HIPAA-compliant architecture specifically for tracking and auditing the image workflow of clinical imaging systems such as PACS. As an initial first step, we developed HIPAA-compliant auditing system (H-CAS) based on parts of this HIPAA-compliant architecture. H-CAS was implemented within a test-bed PACS simulator located in the Image Processing and Informatics lab at the University of Southern California. Evaluation scenarios were developed where different user types performed legal and illegal access of PACS image data within each of the different components in the PACS simulator. Results were based on whether the scenarios of unauthorized access were correctly identified and documented as well as on normal operational activity. Integration and implementation pitfalls were also noted and included.

California↗

Computer-assisted bone age assessment: graphical user interface for image processing and comparison.

The current study is part of a project resulting in a computer-assisted analysis of a hand radiograph yielding an assessment of skeletal maturity. The image analysis is based on features selected from six regions of interest. At various stages of skeletal development different image processing problems have to be addressed. At the early stage, feature extraction is based on Lee filtering followed by the random Gibbs fields and mathematical morphology. Once the fusion starts, wavelet decomposition methods are implemented. The user interface displays the closest neighbors to each image under consideration. Results show the sensitivity of different regions to both stages of development and certain feature sensitivity within each region. At the early stage of development, the distal features are more reliable indicators, whereas at the stage of epiphyseal fusion, a larger dynamic range of middle features makes them more sensitive. In the current study, a graphical user interface has been designed and implemented for testing the image processing routines and comparing the results of quantitative image analysis with the visual interpretation of extracted regions of interest. The user interface may also serve as a teaching tool. At the later stage of the project it will be used as a classification tool.

Adolescent↗

A continuous available (CA) server for medical imaging applications.

RATIONALE AND OBJECTIVES: The trend of medical imaging research and application is toward large database management and manipulation, which requires a robust image server to receive image data from sources and to deliver them to users reliably and in a timely fashion. This article describes the design, implementation, and clinical applications of a continuous available (CA) image server for these purposes. MATERIALS AND METHODS: The design of the CA image server is based on the concept of a triple modular redundancy server with three redundant server modules. Coupled with a majority voting mechanism in the three modules and failover software, the triple modular redundancy server takes care of all single points of failure hardware components in the CA image server automatically to achieve fault tolerance. Methods and procedures of evaluating the fault tolerance system reliability caused by network connectivity, motherboard, and disk storage failures are described. RESULTS: Thorough experimental results in laboratory and clinical environments verify that the image server achieves 99.999% hardware up time (or 5 minutes/year down time), satisfying the industrial terminology of hardware continuous availability. Performance of failover of the CA image server is automatically tabulated during these procedures. CONCLUSION: Applications of CA image server are extensive. Two examples are given including Picture Archiving and Communication System, and off-site back-up archive using the Application Service Provider model. As designed, the CA image server is portable, scalable, affordable, easy to install, and requires no human intervention during failover and system recovery.

Computer Communication Networks↗

Concept of a PACS and imaging informatics-based server for radiation therapy.

Radiation Therapy (RT) is an image-based treatment. It requires images from projection X-rays, computed tomography, magnetic resonance, positron emission tomography, Linear Accelerator for tumor localization, treatment planning and verification of treatment plans. During the treatment process, patient's images are transmitted to every necessary station in the RT department. However, images of the same patient are generally scattered and there is no permanent home base for them due to the nature and traditional organization of the RT department. The advance in diagnostic picture archiving and communication system and the establishment of RT DICOM Standard provide an opportunity to define and design an RT server as a means to organize RT images and related data. This paper describes the RT workflow and the concept of the DICOM RT server. An example of RT treatment of nasopharyngeal carcinoma based on the RT server concept is given.

Diagnostic Imaging↗

Medical image security in a HIPAA mandated PACS environment.

Medical image security is an important issue when digital images and their pertinent patient information are transmitted across public networks. Mandates for ensuring health data security have been issued by the federal government such as Health Insurance Portability and Accountability Act (HIPAA), where healthcare institutions are obliged to take appropriate measures to ensure that patient information is only provided to people who have a professional need. Guidelines, such as digital imaging and communication in medicine (DICOM) standards that deal with security issues, continue to be published by organizing bodies in healthcare. However, there are many differences in implementation especially for an integrated system like picture archiving and communication system (PACS), and the infrastructure to deploy these security standards is often lacking. Over the past 6 years, members in the Image Processing and Informatics Laboratory, Childrens Hospital, Los Angeles/University of Southern California, have actively researched image security issues related to PACS and teleradiology. The paper summarizes our previous work and presents an approach to further research on the digital envelope (DE) concept that provides image integrity and security assurance in addition to conventional network security protection. The DE, including the digital signature (DS) of the image as well as encrypted patient information from the DICOM image header, can be embedded in the background area of the image as an invisible permanent watermark. The paper outlines the systematic development, evaluation and deployment of the DE method in a PACS environment. We have also proposed a dedicated PACS security server that will act as an image authority to check and certify the image origin and integrity upon request by a user, and meanwhile act also as a secure DICOM gateway to the outside connections and a PACS operation monitor for HIPAA supporting information.

California↗

Enterprise PACS and image distribution.

Around the world now, because of the need to improve operation efficiency and better cost effective healthcare, many large-scale healthcare enterprises have been formed. Each of these enterprises groups hospitals, medical centers, and clinics together as one enterprise healthcare network. The management of these enterprises recognizes the importance of using PACS and image distribution as a key technology in cost-effective healthcare delivery in the enterprise level. As a result, many large-scale enterprise level PACS/image distribution pilot studies, full design and implementation, are underway. The purpose of this paper is to provide readers an overall view of the current status of enterprise PACS and image distribution. reviews three large-scale enterprise PACS/image distribution systems in USA, Germany, and South Korean. The concept of enterprise level PACS/image distribution, its characteristics and ingredients are then discussed. Business models for enterprise level implementation available by the private medical imaging and system integration industry are highlighted. One current system under development in designing a healthcare enterprise level chest tuberculosis (TB) screening in Hong Kong is described in detail.

Computer Communication Networks↗

Some historical remarks on picture archiving and communication systems.

This Special Issue contains one Editorial and 15 papers. The Editorial reviews some key events, conferences, and publications which propel PACS to its current status. The fifteen papers describe current and future PACS research and development trends grouped in four categories: system-wide trends and clinical experience, tools, key technologies, and PACS-based applications. We see that PACS has gradually become a necessary tool for daily clinical operation, its future trends will be in the development of research methods to fully utilize its large image database for better healthcare delivery.

Diffusion of Innovation↗

Interactive instruction of cellular physiology for remote learning.

The biomedical sciences are a rapidly changing discipline that have adapted to innovative technological advances. Despite these many advances, we face two major challenges: a) the number of experts in the field is vastly outnumbered by the number of students, many of whom are separated geographically or temporally and b) the teaching methods used to instruct students and learners have not changed. Today's students have adapted to technology--they use the web as a source of information and communicate via email and chat rooms. Teaching in the biomedical sciences should adopt these new information technologies (IT), but has thus far failed to capitalize on technological opportunity. Creating a "digital textbook" of the traditional learning material is not sufficient for dynamic processes such as cellular physiology. This paper describes innovative teaching techniques that incorporate familiar IT and high-quality interactive learning content with user-centric instruction design models. The Virtual Labs Project from Stanford University has created effective interactive online teaching modules in physiology (simPHYSIO) and delivered them over broadband networks to their undergraduate and medical students. Evaluation results of the modules are given as a measure of success of such innovative teaching method. This learning media strategically merges IT innovations with pedagogy to produce user-driven animations of processes and engaging interactive simulations.

Biology↗

Nitrate reduction by Citrobacter diversus under aerobic environment.

A new aerobic denitrifier, Citrobacter diversus, was isolated from both nitrification and denitrification sludge. To monitor the variation in the concentration of nitrogen oxides, aerobic denitrification by C. diversus was carried out in a batch reactor. When the nitrate concentration was greater than 180 mg N l(-1), the nitrate reduction rate became stable. The effect of the C/N ratio on the denitrification activity was also investigated. The results showed that the optimum denitrification activity was obtained when the C/N ratio was 4-5. The range of the C/N ratio was higher than that for traditional anoxic denitrification. The effect of the dissolved oxygen concentration was further studied; and it was found that the range of dissolved oxygen concentrations, both for specific growth rates and for specific denitrification rates, was 2-6 mg(-1). From these results, it can be concluded that both the concentration of dissolved oxygen and the C/N ratio are key factors in the aerobic denitrification by C. diversus.

Aerobiosis↗

Computer automated approach to the extraction of epiphyseal regions in hand radiographs.

Epiphyseal region is the most sensitive region to developmental changes of the skeletal system. Extraction of this area is the very first step in any computerized image analysis. In this report a fully automated analysis of a hand radiograph resulting in extraction of distal and middle regions of the II, III, and IV phalanx is presented. The processing is performed in 3 stages. First, the trend of background is removed from radiograph to obtain a binary hand mask. At this stage a labeling procedure is necessary to eliminate artifacts (markers). Then, II, III, and IV phalanges are identified in the binary image, and the phalangeal axes are drawn. Finally, the intensity profile along each phalangeal axis is analyzed, and, on its basis, distal and middle regions are located. The presented procedure is designed as a part of currently developed system for automatic bone age assessment; however, it also can be as a preprocessing step in other diseases the diagnoses of which may require a computer assistance.

Adolescent↗

Computer-assisted bone age assessment: image preprocessing and epiphyseal/metaphyseal ROI extraction.

Clinical assessment of skeletal maturity is based on a visual comparison of a left-hand wrist radiograph with atlas patterns. Using a new digital hand atlas an image analysis methodology is being developed. To assist radiologists in bone age estimation. The analysis starts with a preprocessing function yielding epiphyseal/metaphyseal regions of interest (EMROIs). Then, these regions are subjected to a feature extraction function. Accuracy has been measured independently at three stages of the image analysis: detection of phalangeal tip, extraction of the EMROIs, and location of diameters and lower edge of the EMROIs. Extracted features describe the stage of skeletal development more objectively than visual comparison.

Adolescent↗

Authenticity and integrity of digital mammography images.

Data security becomes more and more important in telemammography which uses a public high-speed wide area network connecting the examination site with the mammography expert center. Generally, security is characterized in terms of privacy, authenticity and integrity of digital data. Privacy is a network access issue and is not considered in this paper. We present a method, authenticity and integrity of digital mammography, here which can meet the requirements of authenticity and integrity for mammography image (IM) transmission. The authenticity and integrity for mammography (AIDM) consists of the following four modules. 1) Image preprocessing: To segment breast pixels from background and extract patient information from digital imaging and communication in medicine (DICOM) image header. 2) Image hashing: To compute an image hash value of the mammogram using the MD5 hash algorithm. 3) Data encryption: To produce a digital envelope containing the encrypted image hash value (digital signature) and corresponding patient information. 4) Data embedding: To embed the digital envelope into the image. This is done by replacing the least significant bit of a random pixel of the mammogram by one bit of the digital envelope bit stream and repeating for all bits in the bit stream. Experiments with digital IMs demonstrate the following. 1) In the expert center, only the user who knows the private key can open the digital envelope and read the patient information data and the digital signature of the mammogram transmitted from the examination site. 2) Data integrity can be verified by matching the image hash value decrypted from the digital signature with that computed from the transmitted image. 3) No visual quality degradation is detected in the embedded image compared with the original. Our preliminary results demonstrate that AIDM is an effective method for image authenticity and integrity in telemammography application.

Computer Security↗

Skeletal age determinations in children of European and African descent: applicability of the Greulich and Pyle standards.

This study assesses the value of the Greulich and Pyle method in determining the skeletal ages of healthy American children of European and African descent born after the year 1980. The hand and wrist radiographs of 534 children (265 boys, 269 girls; 260 European-Americans [EA], 274 African-Americans [AA]), ages 0 to 19 y, were analyzed by two experienced pediatric radiologists blinded to the chronological age of the subjects. A difference score was calculated for each subject by subtracting chronological age from the mean bone ages scores provided by the two raters. One group t-tests were performed to verify the hypothesis that the mean difference score was equal to zero. Skeletal age determinations by the two radiologists showed a high degree of agreement by intraclass correlation coefficient (r = 0.994). The range of values for differences in skeletal and chronological ages was very wide, indicating great individual variability. Comparisons between skeletal and chronological age only reached statistical significance in EA prepubertal girls, whose skeletal ages were delayed, on average, by three months (t = -2.9; p = 0.005). Mean difference between skeletal and chronological age in prepubertal children of African descent was 0.09 +/- 0.66 y, while that in children of European descent was -0.17 +/- 0.67 y; (t = 3.13; p = 0.0019). On average, the bone ages of 10% of all prepubertal AA children were 2 SD above the normative data in the Greulich and Pyle atlas, while the bone ages of 8% of all prepubertal EA children were 2 SD below. In contrast to the racial differences observed in prepubertal children, EA postpubertal males had significantly greater values for bone age than AA postpubertal males (t = 2.03; p = 0.05). In conclusion, variations in skeletal maturation in prepubertal children are greater than those reflected in the Greulich and Pyle atlas; prepubertal American children of European descent have significantly delayed skeletal maturation when compared with those of African descent; and, postpubertal EA males have significantly advanced skeletal maturation when compared with postpubertal AA males. New standards are needed to make clinical decisions that require reliable bone ages and to accurately represent a multiethnic pediatric population.

Adolescent↗

Isolation and characterization of the Pin1/Ess1p homologue in Schizosaccharomyces pombe.

Pin1/Ess1p is a highly conserved WW domain-containing peptidyl-prolyl isomerase (PPIase); its WW domain binds specifically to phospho-Ser/Thr-Pro sequences and its catalytic domain isomerizes phospho-Ser/Thr-Pro bonds. Pin1 PPIase activity can alter protein conformation in a phosphorylation-dependent manner and/or promote protein dephosphorylation. Human Pin1 interacts with mitotic phosphoproteins, such as NIMA, Cdc25 and Wee1, and inhibits G(2)/M progression in Xenopus extracts. Depletion of Pin1 in HeLa cells and deletion of ESS1 in S. cerevisiae result in mitotic arrest. In addition, Pin1/Ess1p play roles in transcription in S. cerevisiae and in mammalian somatic cells. The S. pombe genome sequence has an open reading frame (ORF) that has 47% identity with Pin1. Expression of this ORF rescued the growth defect caused by ess1 deletion in S. cerevisiae, indicating that S. pombe Pin1p is a functional Pin1 homologue. Overexpression of pin1(+) in S. pombe caused slow growth and a G(1) delay. Deletion of pin1(+) (pin1 Delta) did not affect cell cycle progression or cell growth, but increased sensitivity to the cyclophilin inhibitor, cyclosporin A, suggesting that cyclophilin family PPIases have overlapping functions with the Pin1p PPIase. Deletion of pin1(+) did not affect the DNA replication checkpoint, but conferred a modest increase in UV sensitivity. Furthermore, the pin1 Delta allele caused a synthetic growth defect when combined with either cdc25-22 or wee1-50 but not the cdc24-1 temperature-sensitive mutant. The pin1 Delta strain showed increased sensitivity to the PP1/PP2A family phosphatase inhibitor, okadaic acid, suggesting that Pin1p plays a role in protein dephosphorylation as a result of its ability to increase the population of phospho-Ser/Thr-Pro peptide bonds in the trans conformation that is required for PP2A-mediated dephosphorylation. Our genetic data also suggest that Pin1p might function as a positive regulator of Cdc25p and Wee1p.

Amino Acid Sequence↗

Phosphorylation and spindle pole body localization of the Cdc15p mitotic regulatory protein kinase in budding yeast.

Cdc15p is an essential protein kinase and functions with a group of late mitotic proteins that includes Lte1p, Tem1p, Cdc14p and Dbf2p/Dbf20p to inactivate Cdc28p-Clb2p at the end of mitosis in budding yeast [1] [2]. Cdc14p is activated and released from the nucleolus at late anaphase/telophase to dephosphorylate important regulators of Cdc28p-Clb2p such as Hct1p/Cdh1p, Sic1p and Swi5p in a CDC15-dependent manner [3] [4] [5] [6] [7]. How Cdc15p itself is regulated is not known. Here, we report that both the phosphorylation and localization of Cdc15p are cell cycle regulated. The extent of phosphorylation of Cdc15p gradually increases during cell-cycle progression until some point during late anaphase/telophase when it is rapidly dephosphorylated. We provide evidence suggesting that Cdc14p is the phosphatase responsible for the dephosphorylation of Cdc15p. Using a Cdc15p fusion protein coupled at its carboxyl terminus to green fluorescent protein (GFP), we found that Cdc15p, like its homologue Cdc7p [8] in fission yeast, localizes to the spindle pole bodies (SPBs) during mitosis. At the end of telophase, a portion of Cdc15p is located at the mother-bud neck, suggesting a possible role for Cdc15p in cytokinesis.

Cell Cycle↗

Network latency and operator performance in teleradiology applications.

Teleradiology applications often use an interactive conferencing mode with remote control mouse pointers. When a telephone is used for voice communication, latencies of the data network can create a temporal discrepancy between the position of the mouse pointer and the verbal communication. To assess the effects of this dissociation, we examined the performance of 5 test persons carrying out simple teleradiology tasks under varying simulated network conditions. When the network latency exceeded 400 milliseconds, the performance of the test persons dropped, and an increasing number of errors were made. This effect was the same for constant latencies, which can occur on the network path, and for variable delays caused by the Nagle algorithm, an internal buffering scheme used by the TCP/IP protocol. Because the Nagle algorithm used in typical TCP/IP implementations causes a latency of about 300 milliseconds even before a data packet is sent, any additional latency in the network of 100 milliseconds or more will result in a decreased operator performance in teleradiology applications. These conditions frequently occur on the public Internet or on overseas connections. For optimal performance, the authors recommend bypassing the Nagle algorithm in teleradiology applications.

Algorithms↗

Teleconferencing with dynamic medical images.

Dynamic images, a sequence of static images displayed in rapid succession and perceived as a continuous motion by the human eye, are widely used in medicine. One of the primary objectives of telemedicine is the transmission of such images to a distant location to manage clinical problems remotely. A broad variety of methods is available to acquire, store, transmit, and display these images. However, the context of the clinical problem determines which of these methods can be deployed in a telemedicine solution. This paper discusses the advantages and disadvantages of the different technologies and presents an example of a teleconferencing system for interventional cardiology. This system acquires cardiac angiography and intravascular ultrasound images and transmits them over an existing Internet connection to a distant location. It is specifically optimized for clinical conferencing, where time is limited for each case presentation during the conference, compared to the relatively long time available for the conference preparation. The system takes advantage of this characteristic by transmitting the images well in advance of the clinical conference and displaying them synchronously in both locations during the conference. This allows for the preservation of the original image quality.

Blood Vessels↗