• Journal of Biomedical Engineering Research
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• v.38 no.2
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• pp.82-88
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• 2017

Enlargement of the lateral ventricles have been identified as a surrogate marker of neurological disorders. Quantitative measure of the lateral ventricle from MRI would enable earlier and more accurate clinical diagnosis in monitoring disease progression. Even though it requires an automated or semi-automated segmentation method for objective quantification, it is difficult to define lateral ventricles due to insufficient contrast and brightness of structural imaging. In this study, we proposed a fully automated lateral ventricle segmentation method based on a graph cuts algorithm combined with atlas-based segmentation and connected component labeling. Initially, initial seeds for graph cuts were defined by atlas-based segmentation (ATS). They were adjusted by partial volume images in order to provide accurate a priori information on graph cuts. A graph cuts algorithm is to finds a global minimum of energy with minimum cut/maximum flow algorithm function on graph. In addition, connected component labeling used to remove false ventricle regions. The proposed method was validated with the well-known tools using the dice similarity index, recall and precision values. The proposed method was significantly higher dice similarity index ($0.860{\pm}0.036$, p < 0.001) and recall ($0.833{\pm}0.037$, p < 0.001) compared with other tools. Therefore, the proposed method yielded a robust and reliable segmentation result.

• Biomolecules & Therapeutics
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• v.26 no.1
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• pp.81-92
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• 2018

It is widely accepted that altered metabolism contributes to cancer growth and has been described as a hallmark of cancer. Our view and understanding of cancer metabolism has expanded at a rapid pace, however, there remains a need to study metabolic dependencies of human cancer in vivo. Recent studies have sought to utilize multi-modality imaging (MMI) techniques in order to build a more detailed and comprehensive understanding of cancer metabolism. MMI combines several in vivo techniques that can provide complementary information related to cancer metabolism. We describe several non-invasive imaging techniques that provide both anatomical and functional information related to tumor metabolism. These imaging modalities include: positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS) that uses hyperpolarized probes and optical imaging utilizing bioluminescence and quantification of light emitted. We describe how these imaging modalities can be combined with mass spectrometry and quantitative immunochemistry to obtain more complete picture of cancer metabolism. In vivo studies of tumor metabolism are emerging in the field and represent an important component to our understanding of how metabolism shapes and defines cancer initiation, progression and response to treatment. In this review we describe in vivo based studies of cancer metabolism that have taken advantage of MMI in both pre-clinical and clinical studies. MMI promises to advance our understanding of cancer metabolism in both basic research and clinical settings with the ultimate goal of improving detection, diagnosis and treatment of cancer patients.

• The Journal of the Korean dental association
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• v.53 no.4
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• pp.238-248
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• 2015

Sleep related breathing disorders(SRBDs) are a group of diseases accompanied by difficulties in respiration and ventilation during sleep. Central sleep apnea, obstructive sleep apnea(OSA), sleep-related hypoventilation, and hypoxemia disorder are included in this disease entity. OSA is known to be the most common SRBDs and studies show its significant correlation with general health problems including hypertension, arrhythmia, diabetes, and metabolic syndrome. The diagnostic process of OSA is composed of physical examinations of the head and neck area and also the oral cavity. Radiologic studies including cephalography, CT, MRI, and fluoroscopy assist in identifying the site of obstruction. However, polysomnography(PSG) is still considered the gold standard for the diagnosis of OSA since it offers both qualitative and quantitative recording of the events during a whole night's sleep. The dentist who is trained in sleep medicine can easily identify patients with the risk of OSA starting from simple questions and screening questionnaires. Diagnosis is the first step to treatment and considering the high rate of under-diagnosis for OSA the dentist may play a substantial role in the diagnosis and treatment of OSA which will eventually lead to the well-being of the patient as a whole person. So the objective of this article is to assist dental professionals in gaining knowledge and insight of the diagnostic measures for OSA including PSG.

• Health Policy and Management
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• v.17 no.3
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• pp.26-49
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• 2007

The purpose of this study is to analyze the equity of health care utilization by income groups in terms of both quantity and quality of care, which is measured by expenditure, type of care, and type of health care institutions. Equity in health care utilization is measured by HIwv index, based on the survey of 1,480 Gwangju-Jeonnam residents. Health care utilization in terms of the probability and quantity of outpatient and inpatient care show equitable or pro-poor inequitable distribution, whereas the distribution of health care expenditure, which can account for the quality of care, is pro-rich inequitable, implying that the better off tend to use more expensive medical care. In terms of the types of care, simple visits for basic care show equitable distribution, whereas the distribution of the utilization of traditional tonic medicine, comprehensive health examination, CT, MRI, and ultrasound is pro-rich inequitable. Utilization of general hospitals and traditional health institutions show pro-rich inequitable distribution, hospitals and dental care institutions equitable, and physician clinics and public health centers pro-poor inequitable.

• Journal of KIISE:Software and Applications
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• v.27 no.8
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• pp.846-854
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• 2000

In this paper, we propose effecient methods to extract the femoral head region in MR images. The femoral head area in MRI is approximated using Hough transform and the anatomical features of the femoral heads. Then, modified region growing method is applied to extract the femoral head region. We measured the parameters for the diagnosis of the avascular necrosis of the femoral heads from the segmented femoral head region. The proposed methods are proved very effective to extract the femoral head of healthy volunteer and of the patient having heavy avascular necrosis. The measured parameters can be used very efficiently for the quantitative analysis and the diagnosis of the avascular necrosis of the femoral heads.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.222-228
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• 2023

This study aimed to analyze the applicability of the improved median filter in positron emission tomography (PET)/magnetic resonance (MR) fusion images based on parallel imaging using generalized autocalibrating partially parallel acquisition (GRAPPA). In this study, a PET/MR fusion imaging system based on a 3.0T magnetic field and ¹⁸F radioisotope were used. An improved median filter that can set a mask of the median value more efficiently than before was modeled and applied to the acquired image. As quantitative evaluation parameters of the noise level, the contrast to noise ratio (CNR) and coefficient of variation (COV) were calculated. Additionally, no-reference-based evaluation parameters were used to analyze the overall image quality. We confirmed that the CNR and COV values of the PET/MR fusion images to which the improved median filter was applied improved by approximately 3.32 and 2.19 times on average, respectively, compared to the noisy image. In addition, the no-reference-based evaluation results showed a similar trend for the noise-level results. In conclusion, we demonstrated that it can be supplemented by using an improved median filter, which suggests the problem of image quality degradation of PET/MR fusion images that shortens scan time using GRAPPA.

• Korean Journal of Radiology
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• v.22 no.6
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• pp.880-889
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• 2021

Objective: This study aimed to investigate the regional amyloid burden and myocardial deformation using T1 mapping and strain values in patients with cardiac amyloidosis (CA) according to late gadolinium enhancement (LGE) patterns. Materials and Methods: Forty patients with CA were divided into 2 groups per LGE pattern, and 15 healthy subjects were enrolled. Global and regional native T1 and T2 mapping, extracellular volume (ECV), and cardiac magnetic resonance (CMR)-feature tracking strain values were compared in an intergroup and interregional manner. Results: Of the patients with CA, 32 had diffuse global LGE (group 2), and 8 had focal patchy or no LGE (group 1). Global native T1, T2, and ECV were significantly higher in groups 1 and 2 than in the control group (native T1: 1384.4 ms vs. 1466.8 ms vs. 1230.5 ms; T2: 53.8 ms vs. 54.2 ms vs. 48.9 ms; and ECV: 36.9% vs. 51.4% vs. 26.0%, respectively; all, p < 0.001). Basal ECV (53.7%) was significantly higher than the mid and apical ECVs (50.1% and 50.0%, respectively; p < 0.001) in group 2. Basal and mid peak radial strains (PRSs) and peak circumferential strains (PCSs) were significantly lower than the apical PRS and PCS, respectively (PRS, 15.6% vs. 16.7% vs. 26.9%; and PCS, -9.7% vs. -10.9% vs. -15.0%; all, p < 0.001). Basal ECV and basal strain (2-dimensional PRS) in group 2 showed a significant negative correlation (r = -0.623, p < 0.001). Group 1 showed no regional ECV differences (basal, 37.0%; mid, 35.9%; and apical, 38.3%; p = 0.184). Conclusion: Quantitative T1 mapping parameters such as native T1 and ECV may help diagnose early CA. ECV, in particular, can reflect regional differences in the amyloid deposition in patients with advanced CA, and increased basal ECV is related to decreased basal strain. Therefore, quantitative CMR parameters may help diagnose CA and determine its severity in patients with or without LGE.

• Sleep Medicine and Psychophysiology
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• v.28 no.2
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• pp.78-85
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• 2021

Objectives: When elderly patients show depressive symptoms, discrimination between depressive disorder and prodromal phase of Alzheimer's disease is important. We tested whether a quantitative electroencephalogram (qEEG) marker was associated with cerebral amyloid-β (Aβ) deposition in older adults with depression. Methods: Non-demented older individuals (≥ 55years) diagnosed with depression were included in the analyses (n = 63; 76.2% female; mean age ± standard deviation 73.7 ± 6.87 years). The participants were divided into Aβ+ (n = 32) and Aβ- (n = 31) groups based on amyloid PET assessment. EEG was recorded during the 7min eye-closed (EC) phase and 3min eye-open (EO) phase, and all EEG data were analyzed using Fourier transform spectral analysis. We tested interaction effects among Aβ positivity, condition (EC vs. EO), laterality (left, midline, or right), and polarity (frontal, central, or posterior) for EEG alpha band power. Then, the EC-to-EO alpha reactivity index (ARI) was examined as a neurophysiological marker for predicting Aβ+ in depressed older adults. Results: The mean power spectral density of the alpha band in EO phase showed a significant difference between the Aβ+ and Aβ- groups (F = 6.258, p = 0.015). A significant 3-way interaction was observed among Aβ positivity, condition, and laterality on alpha-band power after adjusting for age, sex, educational years, global cognitive function, medication use, and white matter hyperintensities on MRI (F = 3.720, p = 0.030). However, post-hoc analyses showed no significant difference in ARI according to Aβ status in any regions of interest. Conclusion: Among older adults with depression, increased power in EO phase alpha band was associated with Aβ positivity. However, EC-to-EO ARI was not confirmed as a predictor for Aβ+ in depressed older individuals. Future studies with larger samples are needed to confirm our results.

• The Korean Journal of Nuclear Medicine
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• v.39 no.6
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• pp.481-488
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• 2005

Purpose: Functional imaging of dopamine transporter (DAT) defines integrity of the dopaminergic system, and DAT is the target site of drugs of abuse such as cocaine and methamphetamine. Functional imaging the DAT may be a sensitive and selective indicator of neurotoxic change by the drug. The aim of the present study is to evaluate the clinical implications of qualitative/quantitative analyses of dopamine transporter imaging in methamphetamine abusers. Materials and Methods: Six detoxified methamphetamine abusers (abuser group) and 4 volunteers (control group) were enrolled in this study. Brain MRI was performed in all of abuser group. Abuser group underwent psychiatric and depression assessment using brief psychiatric rating scale (BPRS) and Hamilton depression rating scale (HAMD), respectively. All of the subjects underwent I-123 IPT SPECT (IPT SPECT). IPT SPECT image was analysed with visual qualitative method and quantitative method using basal ganglia dopamine transporter (DAT) specific/non-specific binding ratio (SBR). Comparison of DAT SBR between abuser and control groups was performed. We also performed correlation tests between psychiatric and depression assessment results and DAT SBR in abuser group. Results: All of abuser group showed normal MRI finding, but had residual psychiatric and depressive symptoms, and psychiatric and depressive symptom scores were exactly correlated (r=1.0, p=0.005) each other. Five of them showed abnormal finding on qualitative visual I-123 IPT SPECT Abuser group had lower basal ganglia DAT SBR than that of control ($2.38{\pm}0.20\;vs\;3.04{\pm}0.27$, p=0.000). Psychiatric and depressive symptoms were negatively well correlated with basal ganglia DAT SBR (r=-0.908, p=0.012, r=-0.924, p=0.009). Conclusion: These results suggest that dopamine transporter imaging using I-123 IPT SPECT may be used to evaluate dopaminergic system of the basal ganglia and the clinical status in methamphetamine abusers.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.134-141
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• 2015

The purpose on this research is quantitatively comparing and analyzing signal intensity of 1.0mol and 0.5mol contrast agent. For this study, two MR phantoms were produced. One of them is used with 1.0mol Gadobutrol. The other is used with 0.5mol Gadoteridol. These two phantoms respectively have been scanned by SE T1 sequence which is used to get a general contrast-enhanced image in 1.5T MRI and 3D FLASH sequence which is used as enhanced angio MRI. Signal intensity was measured by scanned images as per contrast agent dilution ratio. The results were as follow: RSP(Reaction Starting Point) of the two sequences(2D SE, 3D FLASH) was respectively 6.0%, 60.0% in 0.5mol contrast and 2.0%, 20.0% in 1.0mol contrast, which means in 0.5mol contrast, RSP was formed faster than the one in 1.0mol contrast. MPSI was respectively 1358.8[a.u], 1573[a.u] in 0.5mol contrast and 1374[a.u], 1642.4[a.u] in 1.0mol contrast, which means 0.5mol contrast's MPP (0.4%, 10.0%) was formed faster than 1.0mol contrast's MPP (0.16%, 1.8%). Lastly, RA as per contrast agent dilution ratio was 27.4%, 11.8% wider in 0.5mol contrast(20747.4[a.u], 23204.6[a.u]) than in 1.0mol contrast(12691.9[a.u], 20747.4[a.u]). According to the study, we are able to assure that signal reaction time of 1.0mol contrast is slower than the one of 0.5mol contrast in contrast-enhanced MRI at two different sequences(2D SE, 3D FLASH). Furthermore, owing to the fact that there are not any signal intensity differences between 1.0mol and 0.5mol contrast, it is not true that high concentration gadolinium MR contrast agent does not always mean high signal intensity in MRI.