• Journal of Biomedical Engineering Research
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• v.31 no.4
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• pp.285-291
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• 2010

Recently, advance on various modalities of diagnosing, prostate volume estimation became possible not only by the existing two-dimension medical images data but also by the three-dimensional medical images data. In this study, magnetic resonance image (MRI), computer tomography (CT) and ultrasound (US) were employed to evaluate prostate phantom volume measurements for estimation, comparison and analysis. For the prostate phantoms aimed at estimating the volume, total of 17 models were developed by using devils-tongue jelly and changing each of the 5ml of capacity from 20ml to 100ml. For the volume estimation through 2D US, the calculation of the diameter with C9-5Mhz transducer was conducted by ellipsoid formula. For the volume estimation through 3D US, the Qlab software (Philips Medical) was used to calculate the volume data estimated by 3D9-3Mhz transducer. Moreover, the images by 16 channels CT and 1.5 Tesla MRI were added by the method of continuous cross-section addition and each of imaginary prostate model's volume was yielded. In the statistical analysis for comparing the availability of volume estimation, the correlation coefficient (r) was more than 0.9 for all indicating that there were highly correlated, and there were not statistically significant difference between each of the correlation coefficient (p=0.001). Therefore, the estimation of prostate phantom volume using three-dimensional modalities of diagnosing was quite closed to the actual estimation.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2459-2463
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• 2005

Optical coherence tomography (OCT) is high resolution medical imaging system which is obtaining image inside biological objects with non-destructive method. OCT system is based on Michelson interferometer with a reciprocating mirror in the reference arm and a biological object in the sample arm. The obtained OCT image suffers from a granular or mottled image, called speckle. Speckle is caused by random interferences between reflected coherence waves. In this paper, we propose effective speckle reduction method that uses wavelet transform. With wavelet domain image, sub-windowing and thresholding are performed. Finally, speckle reduction experiments for Misgurnus mizolepis skin and rat eye images are shown.

• Journal of Biomedical Engineering Research
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• v.34 no.2
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• pp.91-96
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• 2013

In this study, we developed an integrated optical coherence tomography - photoacoustic microscopy (OCT-PAM) system to simultaneously provide optical absorption and scattering information. Two different laser sources, such as a pulsed laser for PAM and a superluminescent diode for OCT, were employed to implement the integrated OCT-PAM system. The performance of the OCT-PAM system was measured by imaging carbon fibers. We then imaged black and white hairs to demonstrate the simultaneous OCT-PAM imaging capabilities. As a result, OCT can produce 3-D images of both black and white hairs, whereas PAM is only able to image the black hair due to strong optical absorption of black hair.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.227-229
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• 1997

A new phased-array quadrature RF coil for one or two RF acquisition channels is developed for spine MR imaging. Quadrature RF coils for MRI have been useful to improve the signal-to-noise ratio (SNR) by $"\sqrt{2}"$ using two orthogonal RF coils in combination [1]. More recently, the phased-array RF coil has been proposed for more improvement of SNR by using an array of RF coil elements with a reduced size and coverage for each element. Two new schemes are proposed for the new phased-array quadrature RF coil as follows : (1) Proper overlapping of two quadrature RF coils thus removing the mutual inductance and (2) Attaching preamplifiers right after the coil section and combining the signal with proper phase delays. The coil has been implemented for receive- only mode. It has been tested through phantom and volunteer imaging. The experimental results show the utility of the proposed RF coil.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.764-770
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• 2014

It is expected that the techniques of optical imaging through turbid media enables non-invasive imaging through human skin and biological tissues. In recent years, many researches have shown that imaging through turbid media can be made possible by measuring the transmission matrix (TM) of the turbid medium and utilizing it for image recovery. However, this TM based image recovery requires a huge amount of data acquisition and post signal processing of them. Very recently, there were new results that this problem of huge data acquisition and processing can be resolved by using the compressed sensing (CS) framework. CS is a relatively new signal acquisition and reconstruction framework which makes possible to recover the signal of interest correctly with significantly smaller number of signal measurements. In this paper, the TM-based image recovery in imaging through turbid media is reviewed and the recent progress made by using CS is introduced.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.132-138
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• 2007

MR(magnetic resonance) image of moving organ such as heart shows serious distortion of MR image due to motion itself. To eliminate motion artifacts, MRI(magnetic resonance imaging) scan sequences requires a trigger pulse like ECG(electro-cardiography) R-wave. ECG-gating using cardiac cycle synchronizes the MRI sequence acquisition to the R-wave in order to eliminate image motion artifacts. In this paper, we designed ECG/PPG(photo-plethysmography) gating system which is for eliminating motion artifacts due to moving organ. This system uses nonmagnetic carbon electrodes, lead wire and shield case for minimizing RF(radio-frequency) pulse and gradient effect. Also, we developed a ECG circuit for preventing saturation by magnetic field and a finger plethysmography sensor using optic fiber. And then, gating pulse is generated by adaptive filtering based on NLMS(normalized least mean square) algorithm. To evaluate the developed system, we measured and compared MR imaging of heart and neck with and without ECG/PPG gating system. As a result, we could get a clean image to be used in clinically. In conclusion, the designed ECG/PPG gating system could be useful method when we get MR imaging of moving organ like a heart.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.4
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• pp.364-370
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• 2006

Optical coherence tomography (OCT) is high resolution medical imaging system which is obtaining image inside biological objects with non-destructive method. OCT system is based on Michelson interferometer with a reciprocating mirror in the reference arm and a biological object in the sample arm. The obtained OCT image suffers from a granular or mottled image, called speckle. Speckle is caused by random interferences between reflected coherence waves. In this paper, we propose effective speckle reduction method that uses wavelet transform. With wavelet domain image, sub-windowing and thresholding are performed. Finally, speckle reduction experiments for Misgurnus mizolepis skin and rat eye images are shown.

• Journal of Biomedical Engineering Research
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• v.40 no.5
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• pp.189-196
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• 2019

We investigated differences in ventricular and hippocampal volumes between CSF tap test (CSFTT) responders and non-responders in idiopathic normal-pressure hydrocephalus (INPH) patients and compared these parameters in INPH patients with that of age- and gender-matched healthy controls. We also evaluated relationships between ventricular and hippocampal volumes and clinical profiles in INPH patients. We enrolled 48 patients with INPH and 29 healthy controls. Ventricular and hippocampal volumes were measured on MRI, including 3-dimensional volumetric images. INPH patients, when compared to healthy controls, had significantly larger ventricular and smaller hippocampal volumes. No difference in ventricular and hippocampal volumes was found between CSFTT responders and non-responders in INPH patients. And hippocampal volumes showed significant negative correlations with Clinical Dementia Rating Scale scores, INPH grading scale cognitive scores, Timed Up and Go Test scores, and Unified Parkinson's Disease Rating Scale motor scores in INPH patients. Volumetric assessment of ventricular and hippocampal regions may have no predictive value in differentiating between CSFTT responders and non-responders in INPH patients. Our findings may help us understand the potential pathophysiology of unique symptoms associated with INPH.

• Korean Journal of Biological Psychiatry
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• v.23 no.3
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• pp.69-79
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• 2016

Frontotemporal dementia (FTD) is a degenerative disease characterized by the selective frontal and temporal lobe atrophy, and progressive deficits in behavior, executive function, or language. The prevalence and incidence of FTD are 15-22/100000 and 2.7-4.1/100000, respectively, in midlife. Hereditary is an important risk factor for FTD. Although there is some controversy regarding the further syndromatic subdivision of the different types of FTD, FTD is clinically classified into behavioral variant of frontotemporal dementia, semantic dementia and progressive nonfluent aphasia. FTD can be misdiagnosed as many psychiatric disorders because of similarity of the prominent behavioral features. Advances in clinical, imaging, and molecular characterization have increased the accuracy of FTD diagnosis, thus developing for the accurate differentiation of these syndromes from psychiatric disorders. We also discuss about therapeutic strategies for symptom management of FTD. Medications such as serotonin reuptake inhibitors, antipsychotics, and other novel treatments have been used in FTD with various rates of success. Further advanced research should be directed at understanding and developing new diagnostic and therapeutic modalities to improve the FTD patients' prognosis and quality of life.

• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.798-802
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• 2007

The synthetic focusing in the ultrasonic imaging systems has been formed in the way that one element transmits a circular wave and receives an echo signal. The amplitude of the signal transmitted from one element is too small to propagate a long distance so that the SNR(Signal to Noise Ratio) is very low in an image obtained by the synthetic focusing. To solve this problem, a defocusing method which uses several elements has been proposed. In this method, the SNR is improved due to using several elements to transmit the circular wave. But if the number of transmitting elements increases, the phase distortion is severe in the defocusing method. In this paper, we propose a new method that can generate a circular wave using a lot of elements without phase distortion. At first, we generate limited plane waves with different propagation angles and then superpose them to make a circular wave. We show that the circular wave can be used to improve SNR in the real-time 3D ultrasonic imaging as well as the synthetic focusing through computer simulation and experiments.