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ABSTRACT: The purpose of this study was to assess whether gadoxetate disodium-enhanced hepatobiliary phase MRI could predict the histologic factors of hepatocellular carcinomas (HCCs).
Fifty-three HCCs histopathologically proved by surgery in 51 patients were evaluated retrospectively. All patients underwent gadoxetate disodium-enhanced MRI before surgical resection. The differences in contrast enhancement ratio of the lesions and differences in contrast-to-noise ratio (CNR) among the histologic grades of HCC were compared by using the Kruskal-Wallis test. The Spearman method was used to determine the correlations among contrast enhancement ratio, CNR, cell density ratio, and positivity for anti-hepatocyte antibody, keratin 7, and keratin 19.
Of 53 HCCs, 50 showed low signal intensity on hepatobiliary phase images, whereas three HCCs were hyperintense on hepatobiliary phase images compared with surrounding hepatic parenchyma. Although well-differentiated HCCs tended to show higher contrast enhancement, there was no statistical significance between contrast enhancement ratio of the tumors and histologic grade (p = 0.414). No significant difference was observed between CNR and histologic grade (p = 0.965). The contrast enhancement ratios of the tumors were significantly lower in the keratin 19-positive group than in the keratin 19-negative group (p = 0.015). There was no significant correlation among contrast enhancement ratio, anti-hepatocyte antibody positivity, cell density ratio, and keratin 7 positivity (p > 0.05).
The contrast enhancement ratio and CNR of HCCs were not correlated with histologic grades. The contrast enhancement ratio was significantly lower in keratin 19-positive HCCs.
American Journal of Roentgenology 08/2011; 197(2):399-405. · 2.78 Impact Factor
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ABSTRACT: This study is part of the ongoing development of treatment methods for metabolic syndrome (MS) project, which involves monitoring daily physical activity. In this study, we have focused on detecting walking activity from subjects which includes many other physical activities such as standing, sitting, lying, walking, running, and falling. Specially, we implemented an integrated solution for various physical activities monitoring using a mobile phone and PC.
We put the iPod touch has built in a tri-axial accelerometer on the waist of the subjects, and measured change in acceleration signal according to change in ambulatory movement and physical activities. First, we developed of programs that are aware of step counts, velocity of walking, energy consumptions, and metabolic equivalents based on iPod. Second, we have developed the activity recognition program based on PC. iPod synchronization with PC to transmit measured data using iPhoneBrowser program. Using the implemented system, we analyzed change in acceleration signal according to the change of six activity patterns.
We compared results of the step counting algorithm with different positions. The mean accuracy across these tests was 99.6 ± 0.61%, 99.1 ± 0.87% (right waist location, right pants pocket). Moreover, six activities recognition was performed using Fuzzy c means classification algorithm recognized over 98% accuracy. In addition we developed of programs that synchronization of data between PC and iPod for long-term physical activity monitoring.
This study will provide evidence on using mobile phone and PC for monitoring various activities in everyday life. The next step in our system will be addition of a standard value of various physical activities in everyday life such as household duties and a health guideline how to select and plan exercise considering one's physical characteristics and condition.
Healthcare informatics research. 03/2011; 17(1):76-86.
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ABSTRACT: This paper suggests the experimental guidelines to evaluate the electro-mechanical safety of belt type equipment. The electro-mechanical safety was determined by using the International Electrotechnical Commission guidelines, which are widely used as important factors for assessing the electro-mechanical safety of belt type equipment. However, the local guidelines on wearable healthcare sensors are currently not well-established. Therefore, safety guidelines suited for the actual circumstances in Korea are required, and this paper attempts to try a new experimental safety test procedure of the wearable healthcare sensor.
This belt type device measures the electrocardiogram (ECG) and heart rates by attaching to the chest. Examination lists were selected by analyzing the common standards ofelectro-mechanical safety (IEC 60601-1) and environment tests (IEC 60068-1, IEC 60068-2) of home-healthcare equipment.
The essential electrical safety, which was required for the RS300G3 as a medical device, was evaluated, and most of the examination lists were selected by considering the circumstances of the users. The device passed all the selected examinable lists that are applicable to the Korean environment.
This study has limitations to estimate and to conduct electro-mechanical safety experiments because our study focused on the belt type of heart-rates equipment. We are not taking into account the overall electro-mechanical home-healthcare measurements. According to industrial and technological development, there are infinite possibilities for the advancement of home-healthcare equipment, so more examination lists for safety are being added in addition to what we have done.
Healthcare informatics research. 03/2010; 16(1):30-5.
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ABSTRACT: Soft-computing techniques are commonly used to detect medical phenomena and to help with clinical diagnoses and treatment. The purpose of this paper is to analyze the single electroencephalography (EEG) signal with the chaotic methods in order to identify the sleep stages.
Data acquisition (polysomnography) was performed on four healthy young adults (all males with a mean age of 27.5 years). The evaluated algorithm was designed with a correlation dimension and Lyapunov's exponent using a single EEG signal that detects differences in chaotic characteristics.
The change of the correlation dimension and the largest Lyapunov exponent over the whole night sleep EEG was performed. The results show that the correlation dimension and largest Lyapunov exponent decreased from light sleep to deep sleep and they increased during the rapid eye movement stage.
These results suggest that chaotic analysis may be a useful adjunct to linear (spectral) analysis for identifying sleep stages. The single EEG based nonlinear analysis is suitable for u-healthcare applications for monitoring sleep.
Healthcare informatics research. 03/2010; 16(1):46-51.
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Bung-Chul Chang,
Nam-Hyun Kim,
Young-A Kim,
Jee Hea Kim,
Hae Kyung Jung,
Eun Hae Kang,
Hee Suk Kang,
Hyung Il Lee,
Yong Ook Kim, Sun Kook Yoo,
Ilnam Sunwoo,
Seo Yong An,
Hye Jeong Jeong
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ABSTRACT: The purpose of this study was to review an implementation of u-Severance information system with focus on electronic hospital records (EHR) and to suggest future improvements.
Clinical Data Repository (CDR) of u-Severance involved implementing electronic medical records (EMR) as the basis of EHR and the management of individual health records. EHR were implemented with service enhancements extending to the clinical decision support system (CDSS) and expanding the knowledge base for research with a repository for clinical data and medical care information.
The EMR system of Yonsei University Health Systems (YUHS) consists of HP integrity superdome servers using MS SQL as a database management system and MS Windows as its operating system.
YUHS is a high-performing medical institution with regards to efficient management and customer satisfaction; however, after 5 years of implementation of u-Severance system, several limitations with regards to expandability and security have been identified.
Healthcare informatics research. 03/2010; 16(1):60-4.
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Lecture Notes in Engineering and Computer Science. 01/2009;
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ABSTRACT: It is important to consider electrocardiogram (ECG) data compression that does not sacrifice diagnostic quality significantly before applying ECG data compression to mobile telecardiology applications. In this paper, we assessed the reconstructed ECG quality after compression with a wavelet-based low-delay algorithm, using both subjective and objective indices. We included diverse ECG databases including both normal and abnormal ECG data, and evaluated the relationship between the subjective and objective indices, paying close attention to specific cases in which there was a large discrepancy between the objective and subjective quality. Based on our observations, an empirically determined compression ratio can be applied to compress continuous ECG signals in limited-bandwidth mobile telecardiology applications.
Telemedicine and e-Health 04/2008; 14(2):156-63. · 1.42 Impact Factor
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ABSTRACT: The authors describe the continuance of the growth of the distracted cranium after the reshaping of the cranium by distraction osteogenesis (DO) in children with simple symmetric and asymmetric craniosynostosis. From 2000 until 2002, 9 children with simple craniosynostosis underwent cranial reshaping by gradual distraction using an external distraction device. Four patients have symmetric deformities caused by bicoronal and sagittal craniosynostosis, and 5 patients have asymmetric deformities caused by unicoronal and unilambdoidal craniosynostosis. The distraction device was developed and applied by the author. Preoperative simulation surgery was done on the three-dimensional rapid prototyped model and on the three-dimensional computerized tomography scan to determine the favorable osteotomy line. The distraction rate was from 1 to 1.5 mm/d, and the latency period was from 1 to 5 days. The extent of distraction was determined on the basis of the results of simulation surgery and the change of external appearance. Evaluation of the growth of reshaped cranium was processed from the data of the reconstructed three-dimensional computerized tomography scans before operation, immediate end of distraction, and the last follow-up time. The anteroposterior length and bitemporal width were measured in symmetric synostosis cases, and the distance from supratrochlear notch to occiput was measured in asymmetric synostosis cases. The results showed that the immediate morphologic changes of cranium after DO were maintained in both symmetric and asymmetric synostosis up to the last follow-up without evidence of relapse. Cases of asymmetric deformity also showed that the affected side and the unaffected side had grown with the maintenance of the symmetry that was corrected at the immediate end of the distraction. The cranium modified by the DO was well maintained with the children's growth without any signs of recurrent restricted growth of the original disease. The corrected symmetry of asymmetric deformity was well maintained during a long-term follow-up period as well.
Journal of Craniofacial Surgery 02/2008; 19(1):45-55. · 0.82 Impact Factor
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Cooperative Design, Visualization, and Engineering, 4th International Conference, CDVE 2007, Shanghai, China, September 16-20, 2007, Proceedings; 01/2007
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Ubiquitous Computing Systems, Third International Symposium, UCS 2006, Seoul, Korea, October 11-13, 2006, Proceedings; 01/2006
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ABSTRACT: As part of an ongoing investigation into the development of a dental digital radiographic (DDR) system using a complementary metal-oxide semiconductor (CMOS) sensor, this study developed hardware and software with a graphical user interface to acquire and display intra-oral images from a prototype DDR system. The aim of this study was to develop a DDR system using a CMOS sensor and evaluate its characteristics. Electrical signals that were generated by the CMOS sensor were transformed into digital images by a control computer equipped using a USB board. The distance between the X-ray tube and the CMOS sensor was adjusted within the range of 10-40 cm to provide the optimal image quality. In order to evaluate the image quality according to variations in the dose, phantom images (60 kVp, 7 mA) were obtained at exposure times of 0.03, 0.05, 0.08, 0.10, and 0.12 s, and the signal-to-noise ratio (SNR) was calculated from the phantom image data. The modulation transfer function (MTF) was obtained from a Fourier transform of the line spread function, which was itself derived from the edge spread function of a sharp edge image acquired using the exposure conditions of 60 kVp, 7 mA, and 0.08 s exposure time. The best contrast and focus were obtained at 20 cm. The SNR level was found to increase with increasing exposure time ranging from 0.03 to 0.08 s. The results obtained at 10% of the MTF showed that the resolution of the DDR system was approximately 6.2 line pairs per millimeter. The characteristics of the prototype DDR system have potential applications in intra-oral dental radiographic imaging. The fully developed DDR system can be used for making a clinical diagnosis with further improvements in the acquisition time and spatial resolution.
IEEE Transactions on Nuclear Science 03/2005; · 1.45 Impact Factor
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Advances in Natural Computation, First International Conference, ICNC 2005, Changsha, China, August 27-29, 2005, Proceedings, Part I; 01/2005
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ABSTRACT: The image display is an important component of the Picture Archiving and Communication System (PACS) and of digital imaging in general. In this paper, we assess the display performance of 32 different flat panel LCD devices, in terms of their reflection, luminance response, luminance uniformity, resolution, noise, veiling glare and color uniformity included in the tentative guidelines of the AAPM TG18 document version 8.1. We also report on the angular dependencies of luminance and contrast, which constitute one of the miscellaneous tests. The tools used included a telescopic photometer, which was also used as a colorimeter, an illuminance meter, light sources for the reflection assessment, light-blocking devices, and digital TG18 test patterns. The luminance ratio (LR), maximum luminance difference (ALmax) and deviation of contrast response with respect to that of DICOM GSDF were 379.2+/-61.0, 1.6+/-1.1%, and 4.84+/-0.58%, respectively. The maximum luminance nonuniformity was 9.2+/-3.9% for the 10% luminance of the TG18-UNL10 test pattern. In the luminance-based resolution test, the percent luminance difference (deltaL) at the center was 0.78+/-0.42%. In all cases of noise testing, the rectangular target in each square in the three quadrants was visible, as were all 15 targets, except for the smallest one, in each corner pattern and the center pattern. The glare ratio (GR) was 2350+/-1460. The average color uniformity parameter, delta(u',v'), across the display area of each display device was 0.002+/-0.001. Nevertheless, not all of the color uniformity parameters of the display devices associated with a workstation met the acceptance criteria. For 7 selected flat panel displays, the mean specular and diffuse reflection coefficients were 0.0061+/-0.0010 and 0.0017+/-0.0005 cd/m2 per lux, respectively. All of the test results conformed to the criteria recommended by AAPM TG18, indicating that the displays were fully acceptable for diagnostic image interpretation. The maximum viewing angle conforming to the DICOM 3.14 standard luminance responses with a 10% tolerance was found to be approximately 50 degrees in both directions along the vertical axis, 10 degrees in the upper direction and 20 degrees in the lower direction along the horizontal axis, and 20 degrees in the upper direction and 10 degrees in the lower direction along the diagonal axis. Therefore, a radiologist should interpret a displayed image by considering the physical characteristics of the narrow viewing angle of the AMLCD displays. The acceptance testing protocol described herein demonstrates the successful clinical implementation of the guidelines for the viewing conditions of medical displays, and if implemented with a QC program, can be used to determine when LCD devices used for diagnostic interpretation need to be upgraded.
Medical Physics 08/2004; 31(7):2155-64. · 2.83 Impact Factor
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ABSTRACT: This study evaluated the migration to full-PACS of medical image data archived using mini-PACS at two hospitals of the Yonsei University Medical Center, Seoul, Korea. A major concern in the migration of medical data is to match the image data from the mini-PACS with the hospital OCS (Ordered Communication System). Prior to carrying out the actual migration process, the principles, methods, and anticipated results for the migration with respect to both cost and effectiveness were evaluated. Migration gateway workstations were established and a migration software tool was developed. The actual migration process was performed based on the results of several migration simulations. Our conclusions were that a migration plan should be carefully prepared and tailored to the individual hospital environment because the server system, archive media, network, OCS, and policy for data management may be unique.
Journal of Digital Imaging 07/2004; 17(2):100-8. · 1.25 Impact Factor
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ABSTRACT: It is clinically important to examine the effect of the heart rate and its variation on the image quality and selection of the optimized window in coronary angiography using multidetector row CT (MDCT). This study performed contrast-enhanced coronary angiography using MDCT on 83 patients. Fifty-two cases with information on the heart rate available were enrolled in this study. The effect of heart rate and its variation were systemically analyzed. Two radiologists rated the image quality as follows: 4-excellent; 3-good; 2-fair; 1-bad. Cardiac cycle windows at 40% and 70% were routinely selected for image reconstruction. The optimized window was rated as 1 when a 40% reconstruction had a better quality than the 70% reconstruction, as 2 when the 40% reconstruction was the same as the 70% reconstruction, and as 3 when the 70% reconstruction was better than the 40% reconstruction. The image quality was more affected by a variation of the heart rate than by the high heart rate. The selection of the optimized reconstruction window for a good image quality was mostly affected by the heart rate and there was a tendency for the 40% phase reconstruction to have a better image quality than the 70% reconstruction at higher heart rates.
IEEE Transactions on Nuclear Science 03/2004; · 1.45 Impact Factor
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ABSTRACT: It is clinically important to study the effect of heart rate and its variation on image quality, and selection of optimized window in coronary angiography using multi-detector row CT (MDCT). We performed contrast-enhanced coronary angiography using MDCT in 83 patients. Sixty cases with available information of heart rate were enrolled in this study. We systemically analyzed the effect of heart rate and its variation. Two radiologists rated image quality as follows: 4, excellent; 3, good; 2, fair; 1, bad. Cardiac cycle windows at 70 and 40% were routinely selected for image reconstruction. Both of 40% and 70% reconstructed images were available only to fifty-seven cases. Optimized window was rated as 1 when 40% reconstruction was better quality than 70%, as 2 when 40% reconstruction was the same as 70%, and as 3 when 70% reconstruction was better than 40%.
Nuclear Science Symposium Conference Record, 2002 IEEE; 12/2002
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ABSTRACT: The efficient compression of radiographic images is of importance for improved storage and network utilization in support of picture archiving and communication systems (PACS) applications. The DICOM Working Group 4 adopted JPEG2000 as an additional compression standard in Supplement 61 over the existing JPEG. The wavelet-based JPEG2000 can achieve higher compression ratios with less distortion than the Discrete Cosine Transform (DCT)-based JPEG algorithm. However, the degradation of JPEG2000-compressed computed radiography (CR) chest images has not been tested comprehensively clinically. The authors evaluated the diagnostic quality of JPEG2000-compressed CR chest images with compression ratios from 5:1 to 200:1. An ROC (receiver operating characteristic analysis) and t test were performed to ascertain clinical performance using the JPEG2000-compressed images. The authors found that compression ratios as high as 20:1 can be utilized without affecting lesion detectability. Significant differences between the original and the compressed CR images were not recognized up to compression ratio of 50:1 within a confidence level of 99%.
Journal of Digital Imaging 07/2002; 15(2):78-83. · 1.25 Impact Factor
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ABSTRACT: This paper presents a dual AC-3 and MPEG-2 audio decoder which can
decode both bit-streams. MPEG-2 synthesis filtering is modified by the
32-point FFT to share the common data path with the AC-3's. The
architecture of the decoder consists of a programmable DSP core and a
hardwired common synthesis filter. The DSP core was designed suitable
for audio processing. The common filter design adopts the suggested
MPEG-2 modified synthesis filtering. The proposed system was synthesized
with 0.6 μm technology and proven to be cost-effective
IEEE Transactions on Consumer Electronics 09/1998; · 0.94 Impact Factor
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ABSTRACT: Audio codec (coding/decoding) algorithms are complex, of several
coding techniques, and can be divided into DSP tasks, controller tasks
and mixed tasks. The traditional DSP processor has been designed for
fast processing of DSP tasks only, but not for controller and mixed
tasks. This paper presents a new architecture that achieves high
throughput on both controller and mixed tasks of such algorithms while
maintaining high performance for DSP tasks. The proposed processor:
YSP-3, operates four functional units (multiplier, two ALUs, load/store
unit) in parallel via 4-issue super-scalar instruction structure. The
performance evaluation of YSP-3 has been done through the implementation
of the common DSP algorithms and the AC-3 decoder
Acoustics, Speech and Signal Processing, 1998. Proceedings of the 1998 IEEE International Conference on; 06/1998 · 4.63 Impact Factor
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ABSTRACT: The authors present a design for cycle saving hardware components
that enable real-time operation of audio coder-decoders. To determine
the key components of audio coding algorithms, the MPEG2 audio algorithm
is analysed, which is an international standard and uses a mixture of
several coding strategies. Through the analysis, some components are
selected that significantly contribute to the total number of cycles,
and corresponding hardware accelerators that complete assigned tasks in
a single cycle are designed. By incorporating these accelerators, a
simple processor can reduce the number of cycles for assigned tasks by
up to 72.2%
Electronics Letters 05/1998; · 0.96 Impact Factor
