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At least 145 records · Page 8Linked to original sources
PubMed2005

Digital image DNA cytometry: a useful tool for the evaluation of malignancy in biliary strictures.

BACKGROUND: Cytologic evaluation of the biliary tract strictures is nowadays widely used for distinguishing between benign and malignant lesions but remains a challenge for some problematic cases. Digital Image cytometry (DNA-cytometry) helps cytopathologists to resolve some unclear situations. METHODS: We have analysed 41 specimens of bile duct brushings obtained from patients during ERCP (11 benign cases, 7 suspicious for malignancy cases and 23 malignant cases) by DNA-cytometry and correlated them with the histological biopsy counterpart. RESULTS: All eleven cytological and histological benign cases were DNA-diploid and among 22 patients with malignant cytological and histological diagnosis 21 were DNA-aneuploid. One case considered malignant by the cytopathologist revealed DNA-aneuploid but malignancy could not be confirmed by histology. The analysis of the suspicious for malignancy cases revealed that all DNA-aneuploid cases were malignant and all DNA-diploid cases were benign referring to the follow-up of the patients. The comparison between cytology alone and cytology combined with DNA-cytometry related to the histological diagnosis (gold standard) resulted in a sensitivity of 100% and a specificity of 79% for cytology alone; a specificity of 94% and a sensitivity 92% for DNA-cytometry and a specificity of 93% and a sensitivity of 100% with combined analyses. The positive predictive value was 90% for cytology, 96% for DNA-cytometry and for both analyses. The negative predictive value showed 100% for cytology, 89% for DNA-cytometry and 100% for combined studies. CONCLUSIONS: Despite the limited number of patients involved in the study, the results obtained indicate an increased of specificity and of positive predictive value using DNA-cytometry. These results confirm the pertinence of these method for challenging cases, in conjunction with other available diagnostic tools.

Adult↗
PubMed2006

Automated tool for the detection of cell nuclei in digital microscopic images: application to retinal images.

PURPOSE: To develop an automated tool that provides reliable, consistent, and accurate results for counting cell nuclei in tissue sections. METHODS: We propose a novel method based on an image processing algorithm to analyze large sets of digital micrographs. The nucleus detector design is based on a Laplacian of Gaussian filter. We use the leave-one-out cross validation method for estimating the generalization error, which is then used to choose the model and parameters of the proposed nucleus detector with both fluorescent and dye stained images. We also evaluate the performance of a nucleus detector by comparing the results with manual counts. RESULTS: When our nucleus detector is applied to previously unanalyzed images of feline retina, it correctly counts nuclei within the outer nuclear layer (ONL) with an average error of 3.67% ranging from 0 to 6.07%, and nuclei within the inner nuclear layer (INL) with an average error of 8.55% ranging from 0 to 13.76%. Our approach accurately identifies the location of cell bodies. Even though we have a relatively large error in the INL due to the large intra-observer variation, both manual counting and nucleus detector result in the same conclusion. This is the first time that cell death in the INL in response to retinal detachment is analyzed quantitatively. We also test the proposed tool with various images and show that it is applicable to a wide range of image types with nuclei varying in size and staining intensity. CONCLUSIONS: The proposed method is simple and reliable. It also has widespread applicability to a variety of sample preparation and imaging methods. Our approach will be immediately useful in quantifying cell number in large sets of digital micrographs and from high-throughput imaging. The tool is available as a plug-in for Image J.

Algorithms↗
PubMed2004

Audience response made easy: using personal digital assistants as a classroom polling tool.

Both teachers and students benefit from an interactive classroom. The teacher receives valuable input about effectiveness, student interest, and comprehension, whereas student participation, active learning, and enjoyment of the class are enhanced. Cost and deployment have limited the use of existing audience response systems, allowing anonymous linking of teachers and students in the classroom. These limitations can be circumvented, however, by use of personal digital assistants (PDAs), which are cheaper and widely used by students. In this study, the authors equipped a summer histology class of 12 students with PDAs and wireless Bluetooth cards to allow access to a central server. Teachers displayed questions in multiple-choice format as a Web page on the server and students responded with their PDAs, a process referred to as polling. Responses were immediately compiled, analyzed, and displayed. End-of-class survey results indicated that students were enthusiastic about the polling tool. The surveys also provided technical feedback that will be valuable in streamlining future trials.

California↗
PubMed1983

Intravenous digital subtraction angiography as used in a general hospital: a toy or a tool?

Although the exact role of digital subtraction angiography (DSA) in diagnostic radiology has not yet been determined, DSA appears to occupy a key position in diagnosing various vascular disorders. The examinations have been performed in a general, nonacademic, nonspecialized hospital for a period of 10 months. No clinical trials or comparative studies have been performed. The number of conventional angiograms has decreased by 43% in comparison to a year ago.

Angiography↗
PubMed2004

Digital radiograph registration and subtraction: a useful tool for the evaluation of the progress of chronic apical periodontitis.

The purpose of this study was to evaluate the suitability of a digital radiograph registration and subtraction software for a sensitive and reliable assessment of the progress of chronic apical periodontitis. Ninety cases of teeth with chronic apical periodontitis have been studied. In each case, a preoperative radiograph was taken, root canals were prepared, and a Ca(OH)2 paste was placed in the root canals. Radiographic control and replacement of Ca(OH)2 paste took place at 15-day intervals. The root canals were obturated 1.5 months after the first appointment. Recall radiographs were taken 0.5, 1.5, 3, 6, and 12 months after the obturation. All radiographs were taken for each case under constant conditions by using a direct digital radiography system. In each case, the preoperative, postoperative, and control and recall radiographs were digitally registered and pairwise subtracted. The resulting images were further processed by using contrast enhancement and pseudocoloring methods. Changes to the periapical tissue structure were easily detectable by using the above-mentioned methodology, even during short time intervals.

Calcium Hydroxide↗
PubMed1995

Picture archiving and communications systems in radiation oncology (PACSRO): tools for a physician-based digital image review system.

Digital imaging is becoming more and more important in the diagnosis, staging, and treatment of patients in radiation oncology. In order to facilitate the most efficient interface of this technology to physicians and other users of this information, a medical image display system (MID) has been developed at the Fox Chase Cancer Center (FCCC). The system runs on 20 personal computers situated in physicians offices as well as a modified system located in the radiation oncology conference room. Access to CT, MRI, and EPID information is achieved through an Ethernet connection to the hospital picture archiving and communications system (PACS). Over a 1-year period a total of 503 patients and 3845 images have been stored on the system. Physician approval using the MID system (without conventional films) was performed on 106 patients. Of these, 22%, 16%, 11%, 10%, and 9% consisted of breast, prostate, pelvic, lung, and head and neck patients, respectively. Digital images sent from a variety of image sources to the MID system take up to 15 s to process and format while image access and display can take 2-5 s, dependent upon image size and speed of the host computer.

Adult↗
PubMed2001

A simple tool for teaching flap design with digital images.

BACKGROUND: Defects created by excision or Mohs micrographic surgery must be analyzed and surgical options including flaps must be considered. Teaching flap design to dermatology trainees is often done at the bedside of the patient with the trainee describing or marking a proposed flap. Open discussion of the options in this way is sometimes unnerving for the patient. Blackboard discussions or drawings are limited in their realism. OBJECTIVE: To describe a rapid, simple method using commonly available software to allow a trainee to draw and redraw a proposed flap on a digital image of the defect without the time and cost of printing. METHODS: We describe a feature in the widely used presentation program Microsoft PowerPoint which can be used to draw on an imported digital image in various colors. RESULTS: A digital photograph taken at the bedside can quickly be loaded into PowerPoint and viewed as a full-screen picture on a computer. Using an electronic pen, multiple lines can be drawn and erased on the picture, allowing surgical planning and teaching away from the bedside. CONCLUSION: Design and analysis of potential incision lines for a flap can be done quickly using a digital image and commonly available software, allowing a new option for teaching flap design.

Dermatology↗
PubMed2005

Prospective evaluation of digital non-stereo color fundus photography as a screening tool in age-related macular degeneration.

PURPOSE: To evaluate mydriatic, non-stereo digital color fundus photographs as a screening tool for identifying and classifying exudative age-related macular degeneration (AMD). DESIGN: Prospective case series. METHODS: Digital color fundus photographs were obtained from patients seen in the AMD screening clinic over a 9-month period at the Ivey Eye Institute in London, Ontario. Photographs for eligible patients were separated by eye, cataloged, blinded, and randomly labeled before interpretation by an experienced vitreoretinal surgeon. Exact agreement, sensitivity, specificity, positive predictive value, and negative predictive value of the fundus photographs in diagnosing, classifying, and managing cases of suspected exudative AMD were then calculated against gold standard clinical examination and fluorescein angiography. RESULTS: A total of 223 images were used from 118 eligible patients. Exact agreement between photographic evaluation and gold standard ranged from 89.2% (presence of pigment epithelial detachment (PED)) to 82.5% (evidence of retinal pigment epithelium geographic atrophy). Sensitivities ranged from 89.2% (presence of choroidal neovascular membrane (CNVM)) to 40.0% (presence of PED). Specificities ranged from 94.1% (presence of PED) to 86.8% (presence of retinal pigment epithelium geographic atrophy). Positive predictive value ranged from 86.1% (presence of CNVM) to 40.0% (presence of PED). Negative predictive value ranged from 94.1% (presence of PED) to 88.9% (presence of CNVM). As a screening tool for high-risk dry changes and active exudative changes, overall sensitivity specificity, positive predictive value, and negative predictive value were 82.1%, 79.1%, 70.4%, and 88.0%, respectively. CONCLUSIONS: Digital, non-stereo color fundus photographs are highly sensitive and have high negative predictive value as a screening tool. Very few treatable lesions are missed using telemedicine in age-related macular degeneration.

Aged↗
PubMed2000

Automated detection of microaneurysms in digital red-free photographs: a diabetic retinopathy screening tool.

AIMS: To develop a technique to detect microaneurysms automatically in 50 degrees digital red-free fundus photographs and evaluate its performance as a tool for screening diabetic patients for retinopathy. METHODS: Candidate microaneurysms are extracted, after the image has been modified to remove variations in background intensity, by algorithms that enhance small round features. Each microaneurysm candidate is then classified according to its intensity and size by the application of a set of rules derived from a training set of 102 images. RESULTS: When 3,783 individual images were analysed and the results compared with the opinion of a clinical research fellow examining the same images, the program achieved a sensitivity of 81% and a specificity of 93% for the detection of images containing microaneurysms. Nine hundred and twenty-five sets of 4 images per patient were then analysed and the total number of microaneurysms detected compared with the overall patient retinopathy grade derived by the clinician examining the same images. In this context, intended to mimic a screening situation, the program achieved a sensitivity of 85% and a specificity of 76% for the detection of patients with (any) retinopathy (positive predictive value 0.71, negative predictive value 0.88). CONCLUSIONS: An automated technique was developed to detect retinopathy in digital red-free fundus images that can form part of a diabetic retinopathy screening programme. It is believed that it can perform a useful role in this context identifying images worthy of closer inspection or eliminating 50% or more of the screening population who have no retinopathy.

Algorithms↗
PubMed2000

Image processing tools for dental applications.

Digital image processing has seen a wide variety of applications in dental radiography. Examples of operations from any of the fundamental classes can be found in the literature, and the increasing role of digital technology in dental imaging will promote new developments and clinical applications. Further progress is not limited by a lack of available image processing tools; rather, improvement of our understanding of the various components of diagnostic imaging will facilitate the meaningful use of new imaging technologies in dentistry. Image processing cannot be separated from other aspects of the diagnostic imaging chain. Its diagnostic value fundamentally depends on image acquisition as well as on aspects of vision and cognition. If used properly, image processing can help to improve diagnostic outcomes and provide insight into other aspects of the imaging process that may be limiting the diagnostic yield. Although novelty is still a powerful force driving some scientific endeavors, advances in dental imaging will be based on the purposeful, goal-oriented development and application of new technology. Specifications for useful image processing operations need to be defined with the diagnostic problem in mind as well as the final outcome for the patient.

Humans↗
PubMed2006

Identification and classification of human cytomegalovirus capsids in textured electron micrographs using deformed template matching.

BACKGROUND: Characterization of the structural morphology of virus particles in electron micrographs is a complex task, but desirable in connection with investigation of the maturation process and detection of changes in viral particle morphology in response to the effect of a mutation or antiviral drugs being applied. Therefore, we have here developed a procedure for describing and classifying virus particle forms in electron micrographs, based on determination of the invariant characteristics of the projection of a given virus structure. The template for the virus particle is created on the basis of information obtained from a small training set of electron micrographs and is then employed to classify and quantify similar structures of interest in an unlimited number of electron micrographs by a process of correlation. RESULTS: Practical application of the method is demonstrated by the ability to locate three diverse classes of virus particles in transmission electron micrographs of fibroblasts infected with human cytomegalovirus. These results show that fast screening of the total number of viral structures at different stages of maturation in a large set of electron micrographs, a task that is otherwise both time-consuming and tedious for the expert, can be accomplished rapidly and reliably with our automated procedure. Using linear deformation analysis, this novel algorithm described here can handle capsid variations such as ellipticity and furthermore allows evaluation of properties such as the size and orientation of a virus particle. CONCLUSION: Our methodological procedure represents a promising objective tool for comparative studies of the intracellular assembly processes of virus particles using electron microscopy in combination with our digitized image analysis tool. An automated method for sorting and classifying virus particles at different stages of maturation will enable us to quantify virus production in all stages of the virus maturation process, not only count the number of infectious particles released from un infected cell.

Algorithms↗
PubMed2005

Radiographic alveolar bone change as an outcome measure for therapies that inhibit bone loss or foster bone gain.

Periodontal clinical trials rely on signs of gingival inflammation, periodontal probing methods, and intra-oral radiographic methods to measure outcomes of therapies that inhibit bone loss or foster bone gain. A single radiograph can provide information on the accumulation of past disease, and sequential radiographs can determine regeneration or progression of periodontal destruction. However, the precision achieved with a radiograph is associated with the actual exposure of the film and the subsequent analysis. A film exposed using standardized geometry and standardized processing has many advantages over non-standardized conventional film. If the patient population for a study is a small, selective group, or if one needs to identify the smallest amount of bone loss in the shortest time, standardized films may be used. Conversely, in a large-scale trial, the use of standardized films may prove to be impractical. Since the advent of personal computer-based image-processing workstations, digital-image analysis has also become a practical tool for clinical trials. Digital subtraction radiography is a highly precise and accurate technique for assessing bony changes associated with periodontal disease. Therefore, advanced digital-imaging systems may be more cost-effective in a clinical trial because the level of precision will have an effect on study length and sample size.

Alveolar Bone Loss↗
PubMed2001

Restructuring the electronic medical record to incorporate full digital signature capability.

The security of Electronic Medical Records can be enhanced by the addition of digital signatures that guarantee data integrity, authenticate the signer, and establish non-repudiation through the use of public key encryption. The task is complicated by the contribution of multiple providers to an encounter and the entry of data at multiple points in time Dividing encounters into an episode of care and redesigning the data model of the EMR will facilitate full signature capabilities. Generation of digital signatures is best accomplished using microprocessors on smart cards that control visibility of the private keys and assist in user authentication. The Java Programming Language including cryptography extensions and a smart card API is a useful tool for adding digital signature to an EMR. Inter-operability of signatures and continuity of signature will require attention to standards and preservation of cryptography and authentication certificate archives. Digital signatures will need to accommodate changes in data storage formats when information is transported between EMR systems using XML or other transaction standards because the original signatures will not validate if the data storage format changes. The costs of adding digital signature to EMR mandates serious examination of the business case for digital signature within an EMR as compared with transactions such as electronic prescriptions. At present, there is no regulatory requirement for digital signature of an EMR.

Computer Security↗
PubMed1999

Staging of malignant cutaneous wounds: a pilot study.

PURPOSE/OBJECTIVES: To determine the color, size, hydration, and general appearance of malignant cutaneous wounds (MCWs); the effectiveness of using digital imagery to quantify wound characteristics; and the feasibility of an MCW staging system. DESIGN: Descriptive pilot study. SETTING: A university-affiliated, comprehensive cancer center. METHODS: Assessment of each subject's wound (N = 13) using the Hopkins Wound Assessment Tool (HWAT) and digital analysis of photographs. Development of an MCW staging system from grouping and classifying the assessment data. A panel of experts used the assessment data and MCW staging system to determine each subject's wound stage and the feasibility of a staging system. Visual HWAT data and digital photographic assessment data were compared for consistency in size, color, and hydration status. MAIN RESEARCH VARIABLES: Characteristics and stages of MCW; digital imagery. FINDINGS: Investigators identified four stages of MCW using the wound characteristics. Digitally assessed wound measurements of size, color, and hydration status were consistent, reflecting the ability of this method to accurately capture malignant wound characteristics. CONCLUSIONS: An MCW staging system is feasible. Wound color, hydration status, the absence or presence of nodules, drainage, pain, odor, and tunneling indicate the stage of malignant wound progression. The two stages identified are distinctly different from pressure or diabetic wound progression. Stage 1N is characterized by fibrous desmoplasia (hard fibrous nodule) of cancer metastasis, and stage 4 is characterized by destruction of the basement membrane. Data comparisons indicate that digital assessment has potential for more accurately recording wound assessment indices. IMPLICATIONS FOR NURSING PRACTICE: Nurses can improve their assessment and management of a patient's MCW by understanding the wounds' stages and using a digital imaging protocol. Further research is needed to establish the reliability and validity of the MCW staging system and the digital assessment and quantification protocol.

Adult↗
PubMed1997

Benchmark test cases for evaluation of computer-based methods for detection of setup errors: realistic digitally reconstructed electronic portal images with known setup errors.

PURPOSE: The purpose of this investigation was to develop methods and software for computing realistic digitally reconstructed electronic portal images with known setup errors for use as benchmark test cases for evaluation and intercomparison of computer-based methods for image matching and detecting setup errors in electronic portal images. METHODS AND MATERIALS: An existing software tool for computing digitally reconstructed radiographs was modified to compute simulated megavoltage images. An interface was added to allow the user to specify which setup parameter(s) will contain computer-induced random and systematic errors in a reference beam created during virtual simulation. Other software features include options for adding random and structured noise, Gaussian blurring to simulate geometric unsharpness, histogram matching with a "typical" electronic portal image, specifying individual preferences for the appearance of the "gold standard" image, and specifying the number of images generated. The visible male computed tomography data set from the National Library of Medicine was used as the planning image. RESULTS: Digitally reconstructed electronic portal images with known setup errors have been generated and used to evaluate our methods for automatic image matching and error detection. Any number of different sets of test cases can be generated to investigate setup errors involving selected setup parameters and anatomic volumes. This approach has proved to be invaluable for determination of error detection sensitivity under ideal (rigid body) conditions and for guiding further development of image matching and error detection methods. Example images have been successfully exported for similar use at other sites. CONCLUSIONS: Because absolute truth is known, digitally reconstructed electronic portal images with known setup errors are well suited for evaluation of computer-aided image matching and error detection methods. High-quality planning images, such as the visible human CT scans from the National Library of Medicine, are essential for producing realistic images. Sets of test cases with systematic and random errors in selected setup parameters and anatomic volumes are suitable for use as standard benchmarks by the radiotherapy community. In addition to serving as an aid to research and development, benchmark images may also be useful for evaluation of commercial systems and as part of a quality assurance program for clinical systems. Test cases and software are available upon request.

Computer Simulation↗
PubMed2002

Biological data integration: wrapping data and tools.

Nowadays scientific data is inevitably digital and stored in a wide variety of formats in heterogeneous systems. Scientists need to access an integrated view of remote or local heterogeneous data sources with advanced data accessing, analyzing, and visualization tools. Building a digital library for scientific data requires accessing and manipulating data extracted from flat files or databases, documents retrieved from the Web as well as data generated by software. We present an approach to wrapping web data sources, databases, flat files, or data generated by tools through a database view mechanism. Generally, a wrapper has two tasks: it first sends a query to the source to retrieve data and, second builds the expected output with respect to the virtual structure. Our wrappers are composed of a retrieval component based on an intermediate object view mechanism called search views mapping the source capabilities to attributes, and an eXtensible Markup Language (XML) engine, respectively, to perform these two tasks. The originality of the approach consists of: 1) a generic view mechanism to access seamlessly data sources with limited capabilities and 2) the ability to wrap data sources as well as the useful specific tools they may provide. Our approach has been developed and demonstrated as part of the multidatabase system supporting queries via uniform object protocol model (OPM) interfaces.

Algorithms↗