PURPOSE: DIR image is relatively free from susceptibility artifacts therefore, DIR image can make it possible to reliably measure cortical thickness/volume. One drawback of the DIR acquisition is the long scan time to acquire the fully sampled 3D data set. To solve this problem, we applied a parallel imaging method (GRAPPA) and verify the reliability of using the volumetric study. MATERIALS AND METHODS: Six healthy volunteers (3 males and 3 females; age 25.33+/-2.25 years) underwent MRI using the 3D DIR sequence at a 3.0T Siemens Tim Trio MRI scanner. GRAPPA simulation was performed from the fully sampled data set for reduction factor 2. Data reconstruction was performed using MATLAB R2009b. Freesurfer v.4.3.0 was used to evaluate the cortical thickness of the entire brain, and to extract white matter information from the DIR image, Analyze 9.0 was used. The global cortical thickness estimated from the reconstructed image was compared with reference image by using a T-test in SPSS. RESULTS: Although reduced SNR and blurring are observed from the reconstructed image, in terms of segmentation the effect was not so significant. The volumetric result was validated that there were no significant differences in many cortical regions. CONCLUSION: This study was performed with DIR image for a volumetric MRI study. To solve the long scan time of 3D DIR imaging, we applied GRAPPA algorithm. According to the results, fast imaging can be done with reduction factor 2 with little loss of image quality at 3.0T.
Artifacts ; Brain ; Humans ; Male

PURPOSE: DIR image is relatively free from susceptibility artifacts therefore, DIR image can make it possible to reliably measure cortical thickness/volume. One drawback of the DIR acquisition is the long scan time to acquire the fully sampled 3D data set. To solve this problem, we applied a parallel imaging method (GRAPPA) and verify the reliability of using the volumetric study. MATERIALS AND METHODS: Six healthy volunteers (3 males and 3 females; age 25.33+/-2.25 years) underwent MRI using the 3D DIR sequence at a 3.0T Siemens Tim Trio MRI scanner. GRAPPA simulation was performed from the fully sampled data set for reduction factor 2. Data reconstruction was performed using MATLAB R2009b. Freesurfer v.4.3.0 was used to evaluate the cortical thickness of the entire brain, and to extract white matter information from the DIR image, Analyze 9.0 was used. The global cortical thickness estimated from the reconstructed image was compared with reference image by using a T-test in SPSS. RESULTS: Although reduced SNR and blurring are observed from the reconstructed image, in terms of segmentation the effect was not so significant. The volumetric result was validated that there were no significant differences in many cortical regions. CONCLUSION: This study was performed with DIR image for a volumetric MRI study. To solve the long scan time of 3D DIR imaging, we applied GRAPPA algorithm. According to the results, fast imaging can be done with reduction factor 2 with little loss of image quality at 3.0T.
Artifacts ; Brain ; Humans ; Male

OBJECTIVE: This study was designed to evaluate the cause of mortality in patients with dementia, including Alzheimer's disease and multi-infarct dementia, and those without dementia. METHOD: Hospital records of geriatric patients (> or =65) in nursing home having dementia were reviewed retrospectively for 6 years. The total number of patients was 351 (the number of demented patients was 146 and those without dementia was 68). Of the ones with dementia, 146 had dementia of Alzheimer's type, 101 patients had vascular dementia, and 36 patients had non-specific dementia. This study focused on the different complications associated with Alzheimer's disease and cerebrovascular dementia. RESULT: 1) The average age at death of demented patient is higher than the non-demented population;however, there is no difference in age between Alzheimer's disease and vascular dementia. 2) There is no difference in time spent in the nursing home among the non-demented group, Alzheimer's disease and vascular dementia group from admission to death. The life expectancy of male patients with Alzheimer's disease after admission to the nursing home is significant shorter than their female counterpart. 3) Patients with vascular dementia have a higher incidence of hypertension, atherosclerotic disease, and diabetes than the Alzheimer's patients. 4) The main overall causes of the death (in nursing home patients) are infection and sepsis. In Alzheimer's disease's, sepsis is the major cause of death, while in vascular dementia, atherosclerotic disease is the number one cause. CONCLUSION: Knowledge of the causes of the death in demented patients may help the management of the possible complications associated with the different types of dementia. However, long-term research is then needed to analyze the survival rates of demented nursing home patients.
Alzheimer Disease ; Cause of Death ; Dementia* ; Dementia, Multi-Infarct ; Dementia, Vascular ; Female ; Hospital Records ; Humans ; Hypertension ; Incidence ; Life Expectancy ; Male ; Mortality* ; Nursing Homes* ; Nursing* ; Retrospective Studies ; Sepsis ; Survival Rate

PURPOSE: In-vivo conductivity reconstruction using transmit field (B1+) information of MRI was proposed. We assessed the accuracy of conductivity reconstruction in the presence of statistical noise in complex B1 + map and provided a parametric model of the conductivity-to-noise ratio value. MATERIALS AND METHODS: The B1+ distribution was simulated for a cylindrical phantom model. By adding complex Gaussian noise to the simulated B1+ map, quantitative conductivity estimation error was evaluated. The quantitative evaluation process was repeated over several different parameters such as Larmor frequency, object radius and SNR of B1+ map. A parametric model for the conductivity-to-noise ratio was developed according to these various parameters. RESULTS: According to the simulation results, conductivity estimation is more sensitive to statistical noise in B1+ phase than to noise in B1+ magnitude. The conductivity estimate of the object of interest does not depend on the external object surrounding it. The conductivity-to-noise ratio is proportional to the signal-to-noise ratio of the B1+ map, Larmor frequency, the conductivity value itself and the number of averaged pixels. To estimate accurate conductivity value of the targeted tissue, SNR of B1+ map and adequate filtering size have to be taken into account for conductivity reconstruction process. In addition, the simulation result was verified at 3T conventional MRI scanner. CONCLUSION: Through all these relationships, quantitative conductivity estimation error due to statistical noise in B1+ map is modeled. By using this model, further issues regarding filtering and reconstruction algorithms can be investigated for MREPT.
Evaluation Studies as Topic ; Magnetic Resonance Imaging ; Noise* ; Radius ; Signal-To-Noise Ratio

Visualization of the tissue loss tangent property can provide distinct contrast and offer new information related to tissue electrical properties. A method for non-invasive imaging of the electrical loss tangent of tissue using magnetic resonance imaging (MRI) was demonstrated, and the effect of loss tangent was observed through simulations assuming a hyperthermia procedure. For measurement of tissue loss tangent, radiofrequency field maps (B1+ complex map) were acquired using a double-angle actual flip angle imaging MRI sequence. The conductivity and permittivity were estimated from the complex valued B1+ map using Helmholtz equations. Phantom and ex-vivo experiments were then performed. Electromagnetic simulations of hyperthermia were carried out for observation of temperature elevation with respect to loss tangent. Non-invasive imaging of tissue loss tangent via complex valued B1+ mapping using MRI was successfully conducted. Simulation results indicated that loss tangent is a dominant factor in temperature elevation in the high frequency range during hyperthermia. Knowledge of the tissue loss tangent value can be a useful marker for thermotherapy applications.
Fever ; Hyperthermia, Induced ; Magnetic Resonance Imaging ; Magnets

An accurate assessment of the recommended calcium (Ca) intake may contribute to reducing the risk of fractures and chronic diseases, ultimately improving quality of life.This review was performed to summarize key findings of Ca studies, investigate the effect of Ca intake on health outcomes, and determine the adequacy of evidence to revise the 2015 Dietary Reference Intakes for Koreans (KDRIs) for Ca in 2020. Databases were searched for intervention studies that assessed health outcomes by providing Ca in diets or as supplements. The framework of the systematic review comprised conducting literature searches, data extraction, quality assessment of the literature, and summarizing key findings relevant to set the Estimated Average Requirement (EAR) and Tolerable Upper Intake Level (UL) for Ca for the 2020 KDRI. The final search was performed in June 2019. A total of 13,309 studies were identified through databases and manual search. Sixtyfive studies were included in the final quality assessment and were summarized according to health indicators. As bone health was used as an indicator of the EAR for Ca, literature reports on bone health were further categorized by the life-cycle stage of the participants. This systematic review did not find new evidence that could be applied to the general Korean adult population, including postmenopausal women, for defining a new EAR for Ca in the 2020 KDRIs. Evidence in most of the reviewed literature was considered weak; however, some evidence was found that could improve the criteria on how the EAR for Ca was determined in children and adolescents. A review of the literature for the 2020 KDRIs for Ca did not find strong evidence in order to change the recommended values of the 2015 KDRIs. More clinical interventions are required among Koreans to strengthen the body of evidence to warrant the revision of the KDRIs.

BACKGROUND: An association between sleep duration and a wide spectrum of diseases has been reported, but little is known about its relationship with bone mineral density (BMD). Previously conducted studies in Korea and abroad have reported results that are controversial. The present study sought to assess whether sleep duration can be considered an independent risk factor of osteoporosis. METHODS: We included participants over the age of 60 years with data on self-reported habitual sleep duration and BMD measured with dual X-ray absorptiometry. Comprehensive data on the study sample was obtained from the Korea National Health and Nutritional Survey performed from 2008 to 2010. Sex-stratified multiple regression analyses were conducted with adjustments for possible confounding factors. RESULTS: There was a significant inverse dose-dependent association between sleep duration and BMD measured at total hip, femur neck, and lumbar spine for women and total hip and femur neck for men. Sex-stratified regression analyses adjusted for age and body mass index revealed that sleep duration had a negative correlation with BMD at total hip and femoral neck for both women (beta = -0.0048; P = 0.0172 for total hip, beta = -0.0037; P = 0.0303 for femur neck) and men (beta = -0.0057; P = 0.0218 for total hip, beta = -0.0057; P = 0.0143 for femur neck). For women, the significance remained after further adjustment of confounding variables. CONCLUSION: Prolonged sleep duration appears to have a significant association with lower total hip and femur neck BMD in elderly women but not in elderly men.
Absorptiometry, Photon ; Aged* ; Asian Continental Ancestry Group ; Body Mass Index ; Bone Density* ; Confounding Factors (Epidemiology) ; Female ; Femur ; Femur Neck ; Hip ; Humans ; Korea ; Male ; Nutrition Surveys ; Osteoporosis ; Risk Factors ; Spine

BACKGROUND/AIMS: The Republic of Korea is a country where the hemodialysis population is growing rapidly. It is believed that the numbers of treatments related to vascular access-related complications are also increasing. This study investigated the current status of treatment and medical expenses for vascular access in Korean patients on hemodialysis. METHODS: This was a descriptive observational study. We inspected the insurance claims of patients with chronic kidney disease who underwent hemodialysis between January 2008 and December 2016. We calculated descriptive statistics of the frequencies and medical expenses of procedures for vascular access. RESULTS: The national medical expenses for access-related treatment were 7.12 billion KRW (equivalent to 6.36 million USD) in 2008, and these expenses increased to 42.12 billion KRW (equivalent to 37.67 million USD) in 2016. The population of hemodialysis patients, the annual frequency of access-related procedures, and the total medical cost for access-related procedures increased by 1.6-, 2.6-, and 5.9-fold, respectively, over the past 9 years. The frequency and costs of access care increased as the number of patients on hemodialysis increased. The increase in vascular access-related costs has largely been driven by increased numbers of percutaneous angioplasty. CONCLUSIONS: The increasing proportion of medical costs for percutaneous angioplasty represents a challenge in the management of end-stage renal disease in Korea. It is essential to identify the clinical and physiological aspects as well as anatomical abnormalities before planning angioplasty. A timely surgical correction could be a viable option to control the rapid growth of access-related medical expenses.
Administrative Claims, Healthcare ; Angioplasty ; Arteriovenous Fistula ; Endovascular Procedures ; Humans ; Insurance ; Insurance, Health* ; Kidney Failure, Chronic ; Korea ; Observational Study ; Renal Dialysis* ; Renal Insufficiency, Chronic ; Republic of Korea

OBJECTIVE: This study was conducted to demonstrate the temporal trends in perinatal outcomes of triplet pregnancies over the last two decades. METHODS: The medical records of patients with triplet pregnancies at two Korean tertiary-care hospitals from 1992 to 2012 were retrospectively reviewed in regard to maternal and neonatal outcomes. The study was divided into two periods for analysis: period I (1992–2001) and period II (2003–2012). RESULTS: Over a 21-year period, 65 women with triplet pregnancies and 185 neonates were analyzed. Period II, when compared with period I, was associated with improved maternal outcomes, characterized by a decreased incidence of preeclampsia (31.8% vs. 2.3%, P=0.002) and anemia (68.2% vs. 30.2%, P=0.003) during pregnancy. Regarding neonatal aspects, the composite morbidity of period II was significantly decreased compared with that of period I, as assessed with a generalized estimating equation for logistic regression (26.2% vs. 8.1%, P=0.03). Multivariable analysis revealed that the gestational age at delivery and the period were significantly associated with the composite neonatal morbidity (P<0.001 and 0.007, respectively). CONCLUSION: Improved neonatal morbidity was associated with a higher gestational age at delivery and with the more recent decade.
Anemia ; Female ; Gestational Age ; Humans ; Incidence ; Infant, Newborn ; Logistic Models ; Medical Records ; Pre-Eclampsia ; Pregnancy ; Pregnancy Outcome ; Pregnancy, Triplet ; Premature Birth ; Retrospective Studies ; Triplets

Rheumatoid arthritis (RA) is a chronic autoimmune disease that typically results in strong inflammation and bone destruction in the joints. It is generally known that the pathogenesis of RA is linked to cardiovascular and periodontal diseases. Though rheumatoid arthritis and periodontitis share many pathologic features such as a perpetual inflammation and bone destruction, the precise mechanism underlying a link between these two diseases has not been fully elucidated. Collagen-induced arthritis (CIA) mice were orally infected with Porphyromonas gingivalis (Pg) or Pg preincubated with an anti-FimA antibody (FimA Ab) specific for fimbriae that are flexible appendages on the cell surface. Pg-infected CIA mice showed oral microbiota disruption and increased alveolar bone loss and had synovitis and joint bone destruction. However, preincubation with FimA Ab led to a significant reduction in the severity of both oral disease and arthritis. Moreover, FimA Ab attenuated bacterial attachment and aggregation on human gingival and rheumatoid arthritis synovial fibroblasts. In addition, we discovered bacteria may utilize dendritic cells, macrophages and neutrophils to migrate into the joints of CIA mice. These results suggest that disrupting Pg fimbriae function by FimA Ab ameliorates RA.