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Biomedical subjects

S K Mun

Publications and source records attributed to S K Mun.

At least 19 recordsLinked to original sources
PubMed2002

Spine needle biopsy simulator using visual and force feedback.

OBJECTIVE: Biopsy with an inserted needle is an important procedure for lesion detection in the spine, but is difficult to perform due to the presence of many critical organs near the spine. This article presents a spine needle biopsy simulator, based on visual and force feedback, which can be used to plan the optimal path of a needle and to practice the procedure without risk. MATERIALS AND METHODS: The simulator is composed of a 3D human model, a visual-feedback component, a force-feedback component, and an evaluation module. The human model is based on 3D CT data. The visual-feedback component provides an oblique section, multiplanar reformatting images, and a volume-rendered image. Of these, the oblique section display is very useful for planning a 3D path for the needle. During simulation, the force-feedback component generates and provides realistic forces acting on the biopsy needle in real time by synchronizing them to visual feedback. After each simulation, the evaluation module provides a performance analysis for the trainee. RESULTS: For an XCT abdomen volume data set of 256 x 256 x 256, the update rate of image rendering due to needle movement is over 25 Hz, with a force-feedback rate of 1 kHz. This performance proved to be good enough for the trainee to learn the relationship between visual and force feedback. CONCLUSIONS: The simulator is useful for the planning of and training in complicated 3D spine needle biopsy procedures. It may be used as an educational tool for beginners, a practice tool to increase expertise, or a test bed for new procedures.

Algorithms↗
PubMed2002

Investigating the distribution of prostate cancer using three-dimensional computer simulation.

The objective of this work was to investigate the distribution of prostate cancer using three-dimensional (3-D) computer simulation. Two hundred and eighty-one 3-D computer prostate models were constructed from radical prostatectomy specimens. An algorithm was developed which divided each model into 24 symmetrical regions, and it then detected the presence of tumor within an individual region. The distribution rate of prostate cancer was assessed within each region of all 281 prostate models, and the difference between the rates was statistically analyzed using Mantel-Haenszel methodology. There was a statistically significant higher distribution rate of cancer in the posterior half (57.2%) compared to the anterior half ( 40.5%; P=0.001). The base regions (36.8%) had a statistically significant lower distribution rate than either the mid regions (56.3%; P=0.001) or the apical regions (53.5%; P=0.001). The mid regions did have a statistically significant higher distribution rate compared to the apical regions (P=0.032). There was no statistically significant difference between the distribution rate on the left half (48.5%) compared to that on the right half (49.2%; P=0.494). The spatial distribution of prostate cancer can be analyzed using 3-D computer prostate models. The results illustrate that prostate cancer is least commonly located in the anterior half and base regions of the prostate. Through an analysis of the spatial distribution of prostate cancer, we believe that new optimal biopsy strategies and techniques can be developed.

Biopsy↗
PubMed2001

Prostate biopsy protocols: 3D visualization-based evaluation and clinical correlation.

OBJECTIVES: Systematic needle core biopsy is commonly used for the diagnosis of prostate cancer by urologists worldwide. As accurate and early diagnosis will result in more and better options for treatment, it is critical that the best possible protocols for biopsy be used clinically. In this study, we develop three-dimensional (3D) modeling and simulation technologies to evaluate most of the biopsy protocols in current clinical use, and correlate the results with those from clinical cases. MATERIALS AND METHODS: Using deformable modeling techniques, 3D computerized prostate surface models were reconstructed from step-sectioned, whole-mounted radical prostatectomy specimens with localized prostate cancer. A 3D computer simulation system was developed to accurately depict the anatomy of the prostate and all individual tumor foci. A user-friendly interface was developed in the system so that a physician can easily and interactively use it for prostate needle core biopsy. A total of 281 prostate models were reconstructed, and 18 biopsies were performed by a urologist on each model to determine the detection rates of seven different biopsy protocols. Clinical biopsies from 35 patient cases were also reviewed and correlated with the simulation results. RESULTS: The most commonly used sextant biopsy had only a 71.5% detection rate, while rates for the 10-pattern and 12-pattern protocols were much higher (96.4% and 97.2%, respectively). Even the lateral 4-pattern protocol performed better than the sextant protocol, with a detection rate of 89.3%. The lateral sextant biopsy protocol (using sites similar to, but more lateral than, those in the sextant protocol) achieved a rate of 92.5%. Although the rate of the 14-pattern biopsy was a little higher (97.5%), it used four more biopsies to achieve this increase, which, according to McNemar's test, is not statistically significant when compared to results with the 10-pattern protocol. The 5-region protocol, which uses 12 biopsies, had a detection rate of 89.7%. Transition zone and seminal vesicle biopsies did not result in a significantly increased detection rate when added to the patterns above. The clinical correlation also confirmed that the 10-pattern protocol was significantly superior to the traditional sextant biopsy pattern. CONCLUSIONS: The 10-pattern biopsy protocol was the most optimized among all the protocols evaluated. This protocol supplemented the sextant biopsy protocol with four more lateral biopsies in the mid and apical sites on both sides.

Biopsy, Needle↗
PubMed2000

Lateral biopsies added to the traditional sextant prostate biopsy pattern increases the detection rate of prostate cancer.

Urologists routinely use the systematic sextant needle biopsy technique to detect prostate cancer. However, recent evidence suggests that this technique has a significant sampling error and data based upon whole-mounted step-sectioned radical prostatectomy specimens using a three-dimensional computer-assisted prostate biopsy simulator suggests that an increased detection rate is possible using laterally placed biopsies. The simulated 10-core biopsy pattern (traditional sextant biopsy cores and four laterally placed biopsies in the right and left apex and mid portion of the prostate gland) was shown to be superior to the traditional sextant biopsy. The objective of this pilot study was to confirm the higher prostate cancer detection rate obtained using the 10-core biopsy pattern in patients. We reviewed data on 35 consecutive patients with a pathologic diagnosis of prostate cancer biopsied by a single urologist using the 10-core biopsy pattern. The frequency of positive biopsy was determined for each core. Additionally, the sextant and 10-core prostate biopsy patterns were compared with respect to prostate cancer detection rate. Of the 35 patients diagnosed with prostate cancer, 54.3%(19/35) were diagnosed by the sextant biopsy only. The 10-core pattern resulted in an additional 45.7%(16/35) of patients being diagnosed solely with the laterally placed biopsies. The laterally placed biopsies had the highest frequency of positive biopsies when compared to the sextant cores. In conclusion, biopsy protocols that use laterally placed biopsies based upon a five region anatomical model are superior to the routinely used sextant prostate biopsy pattern. Prostate Cancer and Prostatic Diseases (2000) 3, 43-46

Journal Article↗
PubMed2000

3-D computer visualization and interactive prostate biopsy simulation leads to an improved systematic technique for the detection of prostate cancer: clinical correlation.

OBJECTIVES: Urologists routinely use the systematic sextant needle biopsy technique to detect prostate cancer. However, recent evidence suggests that this technique has a significant sampling error. Recent data based upon whole-mounted step-sectioned radical prostatectomy specimens using a 3-D computer assisted prostate biopsy simulator suggests that an increased detection rate is possible using laterally placed biopsies. A new 10-core biopsy pattern was shown to be superior to the traditional sextant biopsy. This pattern includes the traditional sextant biopsy cores and four laterally placed biopsies in the right and left apex and mid portion of the prostate gland. The objective of this study is to confirm the higher prostate cancer detection rate obtained using the 10-core biopsy pattern in a small cohort of patients. METHODS: We retrospectively reviewed 35 consecutive patients with a pathologic diagnosis of prostate cancer biopsied by a single urologist using the 10-core biopsy pattern. The frequency of positive biopsy was determined for each core. Additionally, the sextant and 10-core prostate biopsy patterns were compared with respect to prostate cancer detection rate. RESULTS: Of the 35 patients diagnosed with prostate cancer, 54.3% (19/35) were diagnosed when reviewing the sextant biopsy data only. Review of the 10-core pattern revealed that an additional 45.7% (16/35) of patients were diagnosed solely with the laterally placed biopsies. The laterally placed biopsies had the highest frequency of positive biopsies when compared to the sextant cores. CONCLUSIONS: Our results suggest that biopsy protocols that use laterally placed biopsies based upon a five region anatomical model are superior to the routinely used sextant prostate biopsy pattern. Lateral biopsies in the apex and mid portion of the gland are the most important.

Biopsy, Needle↗
PubMed2000

Investigating 3D tumor distribution for optimized diagnosis of prostate cancer.

Transrectal Ultrasonography (TRUS) based systematic needle biopsy of the prostate has been widely used clinically in the diagnosis of prostate carcinoma. Current protocols for prostate biopsy, such as the Sextant Protocol, however, have been proven to be insufficient in cancer detection since these protocols were built without having accurate information on 3D distribution of prostate cancers. In this research, our goal is to optimize prostate biopsy protocols by statistically investigating spatial distributions of prostate cancers. Based on the low-resolution nature of ultrasound imaging and the current clinical conventions, we propose to divide each individual prostate gland into different zones that are can be recognized and accessed by the urologists with ultrasound images during biopsy. By calculating cancer appearance inside each of these zones using a large number of prostate samples, we get the overall distributions of prostate cancers based on which an optimal biopsy protocol can be developed.

Biopsy, Needle↗
PubMed1999

Three-dimensional computer-simulated prostate models: lateral prostate biopsies increase the detection rate of prostate cancer.

OBJECTIVES: Urologists routinely use the systematic sextant needle biopsy technique to detect prostate cancer. However, recent evidence suggests that this technique has a significant sampling error. We developed a novel three-dimensional (3D) computer-assisted prostate biopsy simulator based on whole-mounted step-sectioned radical prostatectomy specimens to compare the diagnostic accuracy of various prostate needle biopsy protocols. METHODS: We obtained digital images of 201 step-sectioned whole-mounted radical prostatectomy specimens. 3D computer simulation software was developed to accurately depict the anatomy of the prostate and all individual tumor foci. Additional peripheral devices were incorporated into the system to perform interactive prostate biopsies. We obtained 18 biopsies of each prostate model to determine the detection rates of various biopsy protocols. RESULTS: The 10- and 12-pattern biopsy protocols had a 99.0% detection rate; the traditional sextant biopsy protocol rate was only 72.6%. The 5-region biopsy protocol had a 90.5% detection rate and the 14-pattern, which includes all the biopsies used in the patterns above, only added 1 additional positive case (99.5%). Transitional zone and seminal vesicle biopsies did not result in a significantly increased detection rate when added to the patterns above. Only one positive model was obtained when the transitional zone biopsies were added. The lateral sextant pattern had a detection rate of 95.5%, and the 4-pattern lateral biopsy protocol had a 93.5% detection rate. CONCLUSIONS: Our results suggest that all the biopsy protocols that use laterally placed biopsies based on the 5-region anatomic model are superior to the routinely used sextant prostate biopsy pattern. Lateral biopsies in the mid and apical zones of the gland are the most important.

Biopsy, Needle↗
PubMed1999

Telemedicine: emerging e-medicine.

This paper reviews the emergence of telemedicine and its recent expansion and use within the healthcare industry. Through this review, several examples of telemedicine within a variety of applications provide a broad context to discuss the challenges and opportunities facing the emergence of e-medicine. These examples provide snapshots of a teleradiology system used by the military, teleconsultations used in neurosurgery and hemodialysis, and home telemedicine used in diabetes care. Based on the discussion of telemedicine's history and expansion and the examples provided, a framework is offered for understanding the evolution of telemedicine applications through four stages. These stages include: (a) development of basic technological capabilities, (b) development of relevant applications, (c) the integration of technical applications within a complex environment, and (d) transformation of the operating environment. Implications for this framework are discussed.

Biomedical Engineering↗
PubMed1999

Prostate biopsy schemes: 3-D visualization-based evaluation.

We have developed a prostate needle biopsy visualization system for the evaluation and optimization of biopsy schemes. Three-dimensional (3-D) prostate surface models have been reconstructed from the digitized whole-mount radical prostetactomy specimens with localized cancers. We have conducted evaluation of five major biopsy schemes with a total of 201 3-D prostate models. These are sextant, 10-pattern, 12-pattern, 14-pattern, and the 5-region schemes. The 10- and 12-pattern biopsy schemes had a 99.0% detection rate, while the rate of traditional sextant biopsy scheme was only 72.6%. The 5-region biopsy scheme had a 90.5% detection rate and the 14-pattern, which includes all the biopsies used in the above schemes, added only one additional positive case (99.5%). Our results suggest that biopsy schemes that use laterally placed biopsies based on the five region anatomical model are superior to the routinely used sextant biopsy scheme. Significant correlation is found between the tumor volume and the positive needle core volume for each of these five schemes. The 10-pattern scheme is the best in cancer detection among these five biopsy schemes.

Biopsy, Needle↗
PubMed1998

A telemedicine consultative service for the evaluation of patients with urolithiasis.

OBJECTIVES: A 6-month pilot teleconsultative project linking Georgetown University Medical Center (GUMC) in Washington, DC, and City Hospital in Martinsburg, West Virginia, 90 miles away, was designed to assess the effectiveness of telemedicine on the clinical decision-making process for patients with urolithiasis. METHODS: The telemedicine system designed and tested for this project was based on a PC-based platform. Videoconferencing and review of the patient's imaging studies were performed over an Integrated Service Digital Network (ISDN) with 3 Basic Rate (BRI) ISDN lines providing a 336-kilobytes/s bandwidth through an Inverse Multiplexor (IMUX). Treatment options were recorded for the clinical trial group and a simulated study group by the consulting urologist after the initial telephone consultation, after the telemedicine consultation, and after examination of those patients transferred to GUMC. RESULTS: A total of 32 telemedicine consultations were performed: 14 in the clinical trial group and 18 in the simulated study group. The recommendation of the consulting urologist at the tertiary center was altered in 12 patients (37.5%) after the telemedicine consultation compared with the recommended treatment after the initial telephone consultation. CONCLUSIONS: In the evaluation of patients with urolithiasis, this telemedicine application enhanced the clinical decision-making process by allowing for improved quality of care through immediate access and effective transfer of information between the referring urologist, the patient, and the stone center specialist.

Adult↗
PubMed1998

Experience implementing a DICOM 3.0 multivendor teleradiology network.

OBJECTIVE: The ISIS Center at Georgetown University received a grant from the U.S. Army to act as systems integrator for a project to design, develop, and implement a commercial off-the-shelf teleradiology system to support the U.S. troops in Bosnia-Herzegovina. The goal of the project was to minimize troop movement while providing primary diagnosis to military personnel. This paper focuses on Digital Imaging Communications in Medicine (DICOM) 3.0 related issues that arose from this type of teleradiology implementation. The objective is to show that using the DICOM standard provides a good starting point for systems integration but is not a plug-and-play operation. METHODS: Systems were purchased that were based on the DICOM 3.0 standard. The modalities implemented in this effort were computed radiography (CR), computed tomography (CT), film digitization (FD), and ultrasonography (US). Dry laser printing and multiple-display workstations were critical components of this network. The modalities and output devices were integrated using the DICOM 3.0 standard. All image acquisition from the modalities is directly to a workstation. The workstation distributes the images to other local and remote workstations, to the dry laser printer, and to other vendors' workstations using the DICOM 3.0 standard. All systems were integrated and tested prior to deployment or purchase. Local and wide area networking were also tested prior to implementation of the deployable radiology network. RESULTS: The results of the integration of the multivendor network were positive. Eventually, all vendors' systems did communicate. Software configuration and operational changes were made to many systems in order to facilitate this communication. Often, software fixes or patches were provided by a vendor to modify their DICOM 3.0 implementation to allow better communications with another vendor's system. All systems were commercially available, and any modifications or changes provided became part of the vendor's commercially available package. CONCLUSION: Seven DICOM interfaces were implemented for this project, and none was achieved without modification of configuration files, changes or patches in vendor software, or operational changes. Some of the problems encountered included missing or ignored required data elements, padding of data values, unique study identifiers (UID), and the use of application entity titles. The difficulties with multivendor connectivity lie in the understanding and interpretation of standards such as DICOM 3.0. The success of this network proves that these problems can be overcome and a clinically successful network implemented utilizing multiple vendors' systems.

Computer Communication Networks↗
PubMed1998

Anatomic region-based dynamic range compression for chest radiographs using warping transformation of correlated distribution.

The purpose of this paper is to investigate the effectiveness of our novel dynamic range compression (DRC) for chest radiographs. The purpose of DRC is to compress the gray scale range of the image when using narrow dynamic range viewing systems such as monitors. First, an automated segmentation method was used to detect the lung region. The combined region of mediastinum, heart, and subdiaphragm was defined based on the lung region. The correlated distributions, between a pixel value and its neighboring averaged pixel value, for the lung region and the combined region were calculated. According to the appearance of overlapping of two distributions, the warping function was decided. After pixel values were warped, the pixel value range of the lung region was compressed while preserving the detail information, because the warping function compressed the range of the averaged pixel values while preserving the pixel value range for the pixels which had had the same averaged pixel value. The performance was evaluated with our criterion function which was the contrast divided by the moment, where the contrast and the moment represent the sum of the differences between the pixel values and the averaged values of eight pixels surrounding that pixel, and the sum of the differences between the pixel values and the averaged value of all pixels in the region-of-interest, respectively. For 71 screening chest images from Johns Hopkins University Hospital (Baltimore, MD), this method improved our criterion function at 11.7% on average. The warping transformation algorithm based on the correlated distribution was effective in compressing the dynamic range while simultaneously preserving the detail information.

Humans↗
PubMed1998

Deployable teleradiology: Bosnia and beyond.

The United States military has been an effective proponent of digital imaging and teleradiology for the past 15 years [1]. A digital imaging network that eliminates the use of x-ray film makes military medicine requirements simpler. X-ray film requirements include storage of new, unexposed films, storage and use of chemicals and water for processing, and disposal of chemicals. In some deployed situations, the chemical discharge needs to be collected and shipped out of the area. Therefore, the ability to implement electronic imaging and eliminate or greatly reduce the dependence on film, chemicals, and water are intrinsically important to military medicine. In December 1995, the United States government began deployment of 20,000 United States troops to Bosnia-Herzegovina as part of NATO's peacekeeping implementation force (IFOR) operation. A full complement of military medical support facilities was established in Bosnia. An army base in Hungary was the location from which the deployment was staged. The project to deploy telemedicine and teleradiology capabilities to the medical treatment facilities (MTF) in Bosnia and Hungary became known as PrimeTime III [2]. This paper deals with the deployable teleradiology (DEPRAD) system that was installed by the Imaging Science and Information Systems (ISIS) Center, Department of Radiology, Georgetown Medical Center, Washington, DC, at a number of facilities to implement filmless radiology and teleradiology services in support of PrimeTime III.

Bosnia and Herzegovina↗
PubMed1998

Automated segmentation of anatomic regions in chest radiographs using an adaptive-sized hybrid neural network.

The purposes of this research are to investigate the effectiveness of our novel image features for segmentation of anatomic regions such as the lungs and the mediastinum in chest radiographs and to develop an automatic computerized method for image processing. A total of 85 screening chest radiographs from Johns Hopkins University Hospital were digitized to 2 K by 2.5 K pixels with 12 bit gray scale. To reduce the amount of information, the images were smoothed and subsampled to 256 by 310 pixels with 8 bit. The determination approach consists of classifying each pixel into two anatomic classes (lung and others) on the basis of several image features: (1) relative pixel address (Rx, Ry) based on lung edges extracted through image processing using profile, (2) density normalized from lungs and mediastinum density, and (3) histogram equalized entropy. The combinations of image features were evaluated using an adaptive-sized hybrid neural network consisting of an input, a hidden, and an output layer. Fourteen images were used for the training of the neural network and the remaining 71 images for testing. Using four features of relative address (Rx, Ry), normalized density, and histogram equalized entropy, the neural networks classified lungs at 92% accuracy against test images following the same rules as for the training images.

Biophysical Phenomena↗
PubMed1997

Requirements for urology and renal dialysis PC-based telemedicine applications: comparative analysis.

The Imaging Science and Information Systems (ISIS) Center of the Department of Radiology at Georgetown University Medical Center (GUMC) has been developing technical requirements for different telemedicine applications. This paper details the process through which those technical requirements are determined and shows how they may differ substantially, depending on the clinical need. This information is presented in light of two telemedicine applications being undertaken at GUMC: a urology application for the management of patients with surgical stone disease and a nephrology application for monitoring of renal dialysis patients.

Humans↗
PubMed1996

Health systems evaluation of telemedicine: a staged approach.

Telemedicine promises greater access to health care of higher quality, potentially at lower cost. The diverse applications of telemedicine technology developed to date have not been evaluated systematically in terms of their ability to achieve these goals. Furthermore, the great variety in telemedicine applications and the far-reaching consequences of new information systems for health care delivery pose challenges to traditional methods of technology assessment. Methods appropriate for mature technologies may not be suitable for emerging ones and, indeed, may risk stifling their development with premature negative conclusions. The staged approach to technology assessment proposed here matches the analysis to the technology's stage of development. It focuses on access, quality, and cost and considers the communication pathway employed in the telemedicine application. A staged approach to technology assessment can inform and foster the development of new telemedicine technology while allowing health care delivery systems to make rational decisions about adopting telemedicine.

Clinical Trials as Topic↗
PubMed1995

Teleradiology/telepathology requirements and implementation.

Teleradiology and telepathology form an integral part of the telemedicine concept. Teleradiology is becoming a mature technology because of advances in imaging technology, database design and communications infrastructure and capabilities. Telepathology has also made significant progress but more development is needed in the definition of required images, database design and standards. While the requirements of most clinical applications of teleradiology are well established, telemammography still presents some impediments. Technical difficulties in telemammography are presented in terms of the lack of a clinically accepted digital imaging system and large data volume required per image. Another important aspect in tele-imaging is the database question. Workstations constitute a window into database. Comprehensive database development is the most difficult and expensive technology for tele-imaging and operational features of such systems are discussed. Finally, we explore current examples of the use of telepathology and teleradiology in the global telemedicine context.

Computer Communication Networks↗