• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.62-67
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• 2014

A glomerular filtration rate (GFR) study is a test that uses radioactive materials or tracers (radiopharmaceuticals) and a computer to see how well the kidneys are working. Asan Medical Center analyzed and compared data between kidney depth, acquired from kidney donors' CT image and acquired from Gates method's GFR value that are calculated by Tonnesen equation. This study was able to confirm that kidney depth measured from CT image was higher than the Gates Method's GFR value, which was calculated by Tonnessen equation; the direct relationship among pathologic results is confirmed. Particularly, kidney donor whose kidney was at the pelvic area had direct relationship with other clinical results. During the GFR test, it is necessary to confirm the location of kidney has no change with reference of CT image. If kidney depth is manually corrected using CT image when we measures GFR of deformed or horse-shoe kidney, it would be possible to acquire the compatible value which is equivalent to clinical result. There would be a possible issue of appropriateness that whether the applied GFR using CT image's kidney depth has clinical validity. In case of a pediatric patient, the GFR derived from Tonnesen was quiet underestimated while manual method and Gordon stay in normal range. Which results may be correct among them? There have been many reports about kidney depth, to be an accurate index of GFR in children. As one of the study performers, we should contemplate what the best option for pediatric patients would be.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.295-298
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• 2006

Experiments in methane-air low strain rate counterflow diffusion flames diluted with nitrogen have been conducted to study the behavior of flame extinction and edge flame oscillation in which lateral conduction heat loss in addition to radiative heat loss could be remarkable at low global strain rates. Onset conditions of edge flame oscillation and flame oscillation modes are also provided with global strain rate. It is seen that flame length is closely relevant to lateral heat loss, and this affects flame extinction and edge flame oscillation. Edge flame oscillations in low strain rate flames are categorized into three: a growing oscillation mode, a decaying oscillation mode, and a harmonic oscillation mode. The regime of flame oscillation is also provided at low strain rate flames.

• Journal of the Korean Society of Radiology
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• v.9 no.4
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• pp.235-238
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• 2015

The aims of this study were to evaluate the difference of renal uptake rate in $^{99m}Tc-DMSA$ scan on pediatrics by including the bladder. Phantom and Clinical studies were performed. In the phantom study, we put $^{99m}TcO_4{^-}$ (300uCi, 11 MBq) in 3cups filled with distilled water at the rate 1:1:0, 1:1:0.5, 1:1:1, 1:1:2 and were placed Lt kidney, Rt kidney and bladder position on the table. To acquire the image, we used Symbia-E gamma camera from Siemens with preset count method(400,000 counts). In quantitative analysis, the counts of drawing ROIs on the phantom were analyzed. In clinical studies, we analyzed the 20 pediatrics who were examined by $^{99m}Tc-DMSA$ scan. At first, the images were acquired with both kidney and bladder. Secondly we acquired images after shielding the bladder. And the data were compared using a pared t-test by SPSS(ver.22.0). As a result of renal phantom's experiment, we compared with average of uptake rate(%), 1:1:0 was Lt 43.32%, Rt 45.97%, 1:1:0.5 was Lt 35.79%, Rt 36.89%, 1:1:1 was Lt 29.68%, Rt 31.45% and 1:1:2 was Lt 22.89%, Rt 24.32%. There was no correlation between the zoom and uptake rate. The results of patient were that excluded bladder was $29.83{\pm}8.81%$(Lt), $24.29{\pm}6.66%$(Rt) and included bladder was $26.65{\pm}8.03%$(Lt, $21.78{\pm}6.24%$(Rt). This is deemed statistically significant (p<0.05). Renal uptake rate was undervalued because the counts of bladder were included in the total counts.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.627-634
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• 2003

In this paper, we consider a graph-theoretic problem,, the so-called "graph embedding problem" that maps the vertices and edges of the given guest graph model into the corresponding vertices and paths of the host graph under the condition of maintaining better performance parameters such as dilation, congestion, and expansion. We firstly propose a new mapping function which can embed the pyramid model with height N into the 3-dimensional mesh massively parallel processor system with the height $(4^{(N+1)/3}+2)/3$ and the regular 2-dimensional mesh of one side $2^{(2N-1)/3}$, and analyze the performance of the embedding in terms of the dilation parameter that reflects the number of communication steps between two adjacent vertices under the embedding. We prove that the dilation of the embedding is $2{\cdot}4^{(N-2)/3}+4)/3$. This is superior to the previous result of $4^{N+183}+2)/3$ under the same condition.condition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.275-278
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• 2006

Systematic experiments in $CH_4/Air$ counterflow diffusion flames diluted with He have been undertaken to study the oscillatory instability in which lateral heat loss could be remarkable at low global strain rate. The oscillatory instability arises for Lewis numbers greater than unity and occurs near extinction condition. The dynamic behaviors of extinction in this configuration can be classified into three modes; growing, harmonic and decaying oscillation mode near extinction. As the global strain rate decreases, the amplitude of the oscillation becomes larger. This is caused by the increase of lateral heat loss which ran be confirmed by the reduction of lateral flame size. Oscillatory edge flame instabilities at low global strain rate are shown to be closely associated with not only Lewis number but also heat loss (radiation and lateral heat loss).

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.48-56
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• 2014

Purpose $^{99m}Tc$-DTPA renal scintigraphy serves as a key indicator to measure a kidney donor's Glomerular Filtration Rate (GFR) and determine the possibility of kidney transplant. The Gates method utilized to measure GFR considers 3 variables of renal depth, injection dose, and net kidney counts. In this research, we seek to compare changes in kidney donors' GFR according to renal depth measurement methods of the 3 variables. Materials and Methods We investigated 32 kidney donors who had visited the hospital from October, 2013 to March, 2014 and received abdominal CT and $^{99m}Tc$-DTPA GFR examination. With the cross-section image of the CT and the lateral image from a gamma camera, we measured the renal depth and compared with renal depth calculation equations-Tonnesen, Taylor, and Itoh methods. Renal depth-specific GFR was calculated by using Xeleris Ver. 2.1220 of GE. Then the results were compared with MDRD (Modification of Diet Renal Disease) GFRs based on serum creatinine level. Results The renal depths measured based on the CT and gamma camera images showed high correlation. Tonessen equation gave the lowest GFR value while the value calculated by using the renal depth of CT image was the highest with a 16.62% gap. MDRD GFR showed no statistically significant difference among values calculated through Taylor, Itoh, CT and gamma camera renal depth application (P>0.05), but exhibited a statistically significant change in the value based on Tonnesen equation (P<0.05). Conclusion This research has found that, in GFR evaluation in kidney donors by utilizing $^{99m}Tc$-DTPA, Tonnesen equation-based Gates method underestimated the value than the MDRD GFR. Therefore, if a MDRD GFR value shows a huge difference from the actual examination value, using an image-based renal depth measurement, instead of Tonnesen equation applied to Gates method, is expected to give an accurate GFR value to kidney donors.

• The Korean Journal of Nuclear Medicine
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• v.38 no.4
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• pp.306-310
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• 2004

Purpose: The aim was to assess how the background site affects the Gates' glomerular filtration rate(GFR) measurement using Tc-99m-DTPA in correlation with GFR by I-125-lothalamate method. Material and methods: The study populations were 63 adults with 39 men and 24 women aged from 20 to 59 yrs (mean=37.9 yrs). The fellowing five background regions of interest were used in measurement of GFR using Gates' method: 1) lower side of each kidney(subrenal), 2) around each kidney(circumferential), 3) upper side of each kidney(suprarenal), 4) lateral side of each kidney(lateral), 5) between the two kidneys(inter-renal). We also measured GFR using I-125-iothalamate in each subject. The two studies were separated by 1 to 3 weeks. The subjects were divided into two groups by renal depth. Group 1 with renal $depth{\geq}7cm$ and group 2 with renal depth<7cm. We calculated the means and standard deviations of the GFRs measured by two studies. And we statistically analyzed the correlation and differences among GFRs by Gates' method and the GFR by iothalamate method with correlation analysis. Results: The GFRs by Gates' method using suprarenal and inter-renal background correction showed better correlation with the GFR measured by I-125-iothalamate. And GFRs measured by Gates' method showed statistically significant correlation with the GFR measured by I-125-iothalamate in the group with renal depth<7cm. But GFRs measured by Gates' method did not show statistically significant correlation with the GFR measured by I-125-iothalamate in the group with renal $depth{\geq}7cm$. Conclusion: GFRs measured with Gates' method showed higher correlation with the GFR measured by I-125-iothalamate when the regions of interest were plated over the suprarenal and inter-renal backgrounds. And GFRs measured with Gates method showed statistically significant correlation with the GFR measured by I-125-iothalamate in the group with renal depth<7cm.

• Childhood Kidney Diseases
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• v.17 no.2
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• pp.57-64
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• 2013

Purpose: In children, 24-hour urine collections are unreliable for evaluating glomerular filtration rate (GFR) because of the difficulty of regulating voiding and the daily variation of urinary creatinine up to 25%. Additionally, creatinine clearance (Ccr) based on urinary creatinine is considered inaccurate. The purpose of this study was to compare estimated GFR determined using Ccr, formulas with serum cystatin C and creatinine, and $^{99m}Tc$-mercaptoacetyltriglycine (MAG3) dynamic renal scintigraphy. Methods: This retrospective study included 101 patients (age, <18 years) who visited Chung-Ang University Hospital between July 2011 and August 2012. GFR was estimated using 24-hour urinary creatinine, five formulas with serum creatinine and cystatin C, and $^{99m}Tc$-MAG3 renal scan. Results: Of the 101 patients, glomerular renal diseases were present in 60 patients (59.4%) and non-glomerular diseases were present in 41 patients (40.6%). There was a significant correlation between estimated GFR determined using $^{99m}Tc$-MAG3 renal scan and Ccr (r=0.389, P <0.001). The correlation values between estimated GFR determined using $^{99m}Tc$-MAG3 renal scan and each formula of Schwartz, Counahan-Barratt, Cockcroft-Gault, Filler and Lepage, and Bokencamp were 0.265 (P=0.007), 0.128 (P=0.044), 0.230 (P=0.021), 0.356 (P<0.001), and 0.355 (P <0.001), respectively. $^{99m}Tc$-MAG3 renal scan was correlated with estimated-GFR by all formulas in decreased renal function. Conclusion: Estimated GFRs determined using serum creatinine and cystatin C, and $^{99m}Tc$-MAG3 renal scan correlated well with estimated GFR determined using Ccr. $^{99m}Tc$-MAG3 renal scan may be replaced for evaluation of renal function with convenience in patients with renal disease and decreased renal function in childhood.

• The Korean Journal of Nuclear Medicine
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• v.36 no.4
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• pp.271-276
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• 2002

Purpose: To measure reliable glomerular filtration rate by using the representative values of transplanted renal depths, which are measured with ultrasonography. Materials and Methods: We included 54 patients (26 men, 28 women), with having both renal scintigraphy and ultrasonography after renal transplantation. We measured GFR with Gates' method using the renal depth measured by ultrasonography, and median and mean ones in each patient. We compared GFR derived from ultrasonography-measured renal depth with GFR derived from median and mean renal depths. The correlation coefficients were obtained among GFR derived from ultrasonography-measured renal depths, median and mean renal depths under linear regression analysis. We determined whether GFR derived from median or mean renal depth could substitute GFR derived from ultrasonography-measured renal depth with Bland-Altman method. We analyze the expected errors of the GFR using representative renal depth in terms of age, sex, weight, height, creatinine value, and body surface. Results: The transplanted renal depths range from 3.20 cm to 5.96 cm. The mean value and standard deviation of renal depths measured by ultrasonography are $4.09{\pm}0.65cm$ in men, and $4.24{\pm}0.78cm$ in women. The median value of renal depths measured by ultrasonography is 4.36 cm in men and 4.14 cm in women. The GFR derived from median renal depth is more consistent with GFR derived from ultrasonography-measured renal depth than GFR derived from mean renal depth. Differences of GFR derived from median and ultrasonography-measured renal depth are not significantly different in the groups classified with creatinine value, age, sex, height, weight and body surface. Conclusion: When median value is adapted as a representative renal depth, we could obtain reliable GFR in transplanted kidney simply.

• The Monthly Diabetes
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• s.261
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• pp.24-26
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• 2011

신장이식은 국내에서 가장 많이 이루어지고 있는 장기이식수술 중 하나이다. 대한이식학회에서 발표한 자료에 따르면(2009년) 국내 신장 이식자의 5년 생존율은 85.6% 로, 최근 면역억제제의 개발에 따라 성공률이 증가하고 있다.