• 대한방사선기술학회지:방사선기술과학
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• 제31권4호
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• pp.379-387
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• 2008

반접현상(Aliasing)을 제거하기위한 방법 중 속도범위(velocity scale)를 높이는 방법은 동일 조건하에서 속도범위를 높여줌으로써 혈류의 방향이 반대로 나타나는 현상이 점차 사라지는 것을 확인할 수 있었다. Doppler angle을 $0^{\circ}$에 가깝게 하는 실험에서는 각도의 변화에 따른 스펙트럼 파형에서 유의한 차이점을 발견을 하지 못했다. 실제 초음파 검사(Ultrasonography)를 시행할 때는 검사의 편의성과 신속성, 정확성을 고려해서 속도범위에 변화를 주어 검사함으로써 보다 정확한 검사가 시행되리라고 본다. 또한 Doppler Angle에 따라 혈류속도는 기하학적으로 증가하였으며, $70^{\circ}$ 이상에서는 측정불가능 할 정도로 수치가 급상승하여 혈류속도가 Doppler Angle에 크게 의존한다는 것을 알 수 있었다. 혈류의 방향에 따른 실험에서는 입사각이 $60^{\circ}$ 이상에서 오차범위가 증가하였고, $70^{\circ}$ 이상에서는 매우 큰 차이를 보였다. 따라서 입사각은 $60^{\circ}$ 이하가 적당하다고 보며, 사지 혈관(extremity vessel)의 혈류속도를 구하는 데 있어서 Doppler 각도는 $45^{\circ}$에서 $60^{\circ}$가 적절한 것으로 사료된다.

• 대한핵의학회지
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• 제39권3호
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• pp.151-162
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• 2005

Hemangioma is the most common benign tumor of the liver, with a prevalence estimated as high as 7%. Tc-99m red blood cell (RBC) hepatic blood pool scan with single photon omission computed tomography (SPECT) imaging is extremely useful for the confirmation or exclusion of hepatic hemangiomas. The classic finding of absent or decreased perfusion and increased blood pooling ("perfusion/blood pool mismatch") is the key diagnostic element in the diagnosis of hemangiomas. The combination of early arterial flow and delayed blood pooling ("perfusion/blood pool match") is shown uncommonly. In giant hemangioma, filling with radioactivity appears first in the periphery, with progressive central fill-in on sequential RBC blood pool scan. However, the reverse filling pattern, which begins first in the center with progressive peripheral filling, is also rarely seen. Studies with false-positive blood pooling have been reported infrequently in nonhemangiomas, including hemangiosarcoma, hepatocellular carcinoma, hepatic adenoma, and metastatic carcinomas (adenocarcinoma of the colon, small cell carcinoma of the lung, neruroendocrine carcinoma). False-negative results have been also reported rarely except for small hemagniomas that are below the limits of spatial resolution of gamma camera.

• International Journal of Vascular Biomedical Engineering
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• 제4권1호
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• pp.17-26
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• 2006

Diabetes mellitus (DM) is a metabolic disorder, characterized by varying or persistent hyperglycemia, which induces several changes in the erythrocyte membrane and its cytoplasm, leading to alteration in the deformability. Techniques applied to measure this are based on filtration of erythrocyte suspension through a membrane and to obtain diffraction pattern under sheared conditions. Ektacytometry requiring less quantity of blood with disposable flow chamber used to measure the deformability of erythrocytes obtained from patients with diabetes and also associated with nephropathy and retinopathy. A decreasing trend of deformability in these patients is observed. The shape parameter form factor, as determined by image processing procedure, increases with the increased of blood glucose levels and shows a pattern similar to filtration time of erythrocyte suspensions through cellulose membranes. Further work is suggested to detect micro-level changes in cell membrane in diabetic patients

• 한국의상디자인학회지
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• 제25권3호
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• pp.53-67
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• 2023

Blood circulation is one of the most important life support functions of our body. It is essential to maintain healthy blood circulation as problems with blood circulation can lead to numerous diseases and serious complications. This study developed women's leggings with gradual compression and soft surface heating functions to improve blood circulation, and evaluated their performance and wearability. A silicon print pattern was developed to provide gradual compression, and a flexible heating surface coated with MWCNT (multi-walled carbon nanotube) conductive ink was fabricated for comfort and thermal effect. For the design, incision lines and materials were applied in consideration of aesthetic aspects, and design lines and colors were altered using a 3D program. The developed leggings showed that blood circulation can be improved when gradual compression and heating functions are simultaneously applied. Results were confirmed through measurements of clothing pressure, blood flow, and surface temperature. In the subjective wearability evaluation, it was confirmed that wearers felt gradual pressure, and they showed high satisfaction with wearability and design.

• 대한핵의학회지
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• 제20권1호
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• pp.25-31
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• 1986

This study was performed to establish normal hepatoscintiangiographic(HSA) pattern of hepatic blood flow and to investigate dynamic differential HSA findings of primary and metastatic carcinomas and abscess of the liver. HSA was carried out after intravenous bolus injection of 10 mCi of Tc-99m-phytate by obtaining sequential anterior images of 1-second exposure for 16 seconds. Observations included (1) baseline study of normal hepatic blood flow pattern by correlating with contrast angiogram, (2) time sequence phasing of normal HSA, and (3) analysis of altered patterns in primary and metastatic carcinomas and abscesses of the liver. Materials consisted of 20 normal subjects, 28 primary hepatocellular carcinomas, 16 metastatic carcinomas and 7 liver abscesses. Results were: (1) Normal HSA demonstrated 3 distinct phases of arterialization(AP), of arterial hepatogram(AHP), and of portal venous hepatogram(PVHP). The means of each phase were 5.3, 6.3 and 8.3 seconds, respectively. Portal vein could be seen in all but one of 20 normal subjects. (2) Pattern changes in diseases groups were early start of AP in carcinomas and very early start of AP in abscesses. AP became prolonged in all disease group. (3) Distinction between AHP was sharp in metastasis and abscesses but un sharp in primary hepatoma. Cold area or areas became vascularized in primary hepatoma but not in abscess. Cold areas of metastasis were inhomogeneously vascularized in late AP and throughout AHP and became relatively vascular as PVHP began. The cold area of abscess showed rim enhancement during AH and APH. These differences in HSA pattern were very useful in differential diagnosis of the diseases studied.

• 대한한의학회지
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• 제32권5호
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• pp.50-65
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• 2011

Objectives: Moxibustion has been used for various post-stroke symptoms and has also been known to have effect on peripheral blood flow. This study investigated the effect of moxibustion on radial artery blood flow by Doppler ultrasound and on heart rate variability in post-stroke hemiplegia patients. Methods: Moxibustion was applied on the points of LI4, TE3, TE5 and LI11 on the affected side, and blood flow of the radial artery was measured using the Minimax-Doppler-K device. Blood flow velocity and pulsation index were analyzed before, during, and after moxibustion. Simultaneously LF, HF, and LF/HF as variables for HRV were measured by FM-150. Results: The mean value of blood flow velocity in all patients (n=23) showed significant increase between before and after moxibustion, but there was no significant difference in pulsation index and LF, HF, LF/HF ratio between before and after moxibustion. In Yin (n=9) and Yang (n=14) groups, both showed significant increase of blood flow velocity between before and after moxibustion, but there was no significant difference in pulsation index and LF, HF, LF/HF ratio between before and after moxibustion. In Deficiency (n=14) and Fullness (n=9) groups, only the Deficiency group showed significant increase of blood flow velocity between before and after moxibustion, while the Fullness group showed no significant difference in blood flow velocity between before and after moxibustion, and also there was no significant difference in pulsation index and LF, HF, LF/HF ratio between before and after moxibustion. Conclusions: This study suggests that moxibustion on LI4, TE3, TE5 and LI11 on the affected side of stroke patients increase the peripheral blood flow in the affected arm, which was most remarkable in those with Yin and Deficiency pattern.

• Journal of Chest Surgery
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• 제10권2호
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• pp.281-294
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• 1977

Superior vena cava to pulmonary arterial shunting operation was made between the superior vena cava and the right pulmonary artery in the fashion of end-to-end anastomosis in 20 mongrel dogs. The experimental animals were divided into three group and blood flow in the superior vena cava was occluded for 20, 30 and 60 minutes respectively, and observations were made for the changes in caval pressure and cerebrospinal fluid pressure. And pathologic examinations were also performed. On occluding the caval blood flow, the superior vena caval pressure was sharply and immediately elevated from $103.5{\pm}19.8mmH_2O$ at thoracotomy to $556.4{\pm}86.lmmH_2O$ within 2 minutes to make its plateau thereafter, and the cerebrospinal fluid pressure followed closely the changes of the superior vena caval pressure in its level and pattern being elevated from $102.0{\pm}19.9mmH_2O$ to $490.5{\pm}79.9mmH_2O$. The drops of both the caval and cerebrospinal fluid pressures were definite and marked on opening the shunt flow through the anastomosis, but these postoperative pressures retained still higher ones above their levels measured at thoracotomy. The pathological examinations of the brain and the spinal cord were also performed in six animals. Characteristic changes uniformly seen in all area and in all animals were the findings of capillary congestion and perivascular edema. On the other hand, ischemic nerve cell changes were rather evident, revealing their degrees and extents being related to the prolongation of the time of caval occlusion which has followed by the sustained high pressures in both the superior vena and the cerebrospinal fluid. The experiment suggests the safety of this surgical procedure with minimal, if any, permanent damage as long as the occlusion of the caval blood flow is not prolonged beyond the expected.

• The Korean Journal of Physiology
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• 제9권1호
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• pp.45-56
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• 1975

Various factors influencing the lymph flow from thoracic duct were investigated in an attempt to evaluate their contributing degree and the mechanisms. Sixteen mongrel dogs weighing between 10 and 16 kg were anesthetized and polyethylene catheters were inserted into the thoracic duct and femoral veins. Arterial blood pressure, heart rate, central venous pressure, lymph pressure and lymph flow were measured under various conditions. Electrical stimulation of left sciatic nerve, stepwise increase of central venous pressure, manual application of rhythmical depressions onto abdomen, injection of hypertonic saline solution and histamine infusion were employed. Measurement of cental venous pressure was performed through the recording catheter inserted into abdominal inferior vena cava. Changes in central venous pressure were made by an air-ballooning catheter located higher than the tip of the recording catheter in the inferior vena cava. Lymph flow from thoracic duct was measured directly with a graduated centrifuge tube allowing the lymph to flow freely outward through the inserted cannula. The average side pressure of thoracic lymph was $1.1\;cmH_2O$ and lymph flow was 0.40 ml/min or 1.9 ml/kg-hr. Hemodynamic parameters including lymph flow were measure immediately before and after (or during) applying a condition. Stimulation of left sciatic nerve with a square wave (5/sec, 2 msec, 10V) caused the lymph flow to increase 1.4 times. The pattern of lymph flow from thoracic duct was not continuous throughout the respiratory cycle, but was continuous only during Inspiration. Slow and deep respiration appeared to increase the lymph flow than a rapid and shallow respiration. Relationship between central venous pressure and the lymph flow revealed a relatively direct proportionality; Regression equation was Lymph Flow (ml/kg-hr)=0.09 CVP$(cmH_2O)$+0.55, r=0.67. Manual depressions onto the abdomen in accordance with the respiratory cycle caused the lymph flow to increase most remarkably, e.g,. 5.5 times. The application of manual depressions showed a fluctuation of central venous pressure superimposed on the respiratory fluctuation. Hypertonic saline solution (2% NaCl) administered Intravenously by the amount of 10 m1/kg increased the lymph flow 4.6 times. The injection also increased arterial blood pressure, especially systolic Pressure, and the central venous pressure. Slow intravenous infusion of histamine with a rate of 14-32 ${\mu}g/min$ resulted in a remarkable increase in the lymph flow (4.7 times), in spite of much decrease in the blood pressure and a slight decrease in the central venous pressure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.219-222
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• 2001

The objective of the present study is to evaluate the effects of the stenting shapes on flow velocity and wall shear stress in angulated coronary stenosis by computer simulation. Coronary angiogram and Doppler ultrasound measurement in the patients with angulated coronary stenosis were obtained. Inlet wave velocity distribution obtained from in vivo intracoronary Doppler data was used for the numerical simulation. Spatial pattern of blood flow velocity and recirculation area were drawn through out the selected segment of coronary models. Wall shear stresses in the intracoronary stent models were calculated from three-dimensional computer simulation. A negative shear stress region, which is consistent with re-circulation area on flow pattern, was noted on the inner wall of post-stenotic area of pre-stenting model. The negative shear stress was disappeared after stenting. Shear stress in the post-stenting model was markedly reduced up to about two orders of magnitude compared to that of the pre-stenting model.

• Journal of Korean Neurosurgical Society
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• 제29권12호
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• pp.1634-1641
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• 2000

Objective : The cerebrospinal fluid(CSF) pulsates within the craniospinal axis in response to rhythmic cerebral blood volume variation during the cardiac cycle. The aim of this study is to characterize the normal and abnormal CSF flow and its waveforms in the cervical spinal subarachnoid space. Methods : The magnetic resonance(MR) images were obtained with 1.5 T(GE Signa, GE Medical Systems, Milwaukee, USA) unit using the 2 dimensional cine PC(phase contrast) sequence with cardiac gating and gradient recalled echo imaging. This pulse sequence yielded 16 quantitative flow-encoded images per cardiac cycle. Sagittal and axial images of the cervical spinal CSF space were obtained, and target sites were analyzed for characteristic CSF flow (TR=50ms, TE=12.5-15ms). The region of interest(ROI) was 1mm 3 in volume. Twenty six persons were included in this study : 10 healthy volunteers and 16 patients with cervical myelopathy. The post-operative cine MR study were also done in five patients. Results : The normal CSF pulsation dynamics in the cervical spine showed discrete systolic and diastolic components. The CSF flow revealed a sine wave pattern, in which the systolic phase was shorter than the diastolic phase(ratio=2 : 3). The patient group revealed decreased amplitudes of the CSF flow and irregularly distored flow waves. The systolic phase was elongated in the ROI above the stenotic level, whereas the diastolic phase was lengthened below the level. In the postoperative images, the abnormal pattern and amplitude were found to be corrected. Conclusion : From these results, the authors believe that the CSF flow study provides valuable informations regarding the extent of cervical stenosis and may be useful for the surgical planning and post-operative evaluation.