• Journal of Chest Surgery
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• v.34 no.9
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• pp.662-671
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• 2001

Background: This study was aimed to assess improvement in myocardial perfusion after TMR by measuring regional myocardial blood flow(RMBF) in porcine model of chronic myocardial ischemia. Material and Method: Ameroid ring was placed around the proximal left circumflex coronary artery in fourteen pigs. After 4 weeks, the control group(7 pigs) underwent rethoracotomy only, and the TMR group(7 pigs) underwent Ho:YAG laser TMR at the circumflex territory. After another 4 weeks, the animals were sacrificed for the measurement of RMBF using colored microspheres. The ratio of RMBF between the circumflex territory and the interventricular septum was calculated and compared. Result: At 4 weeks after ameroid constriction, RMBF of the circumflex territory decreased to 46∼89% of RMBF of the interventricular septum. In five of six animals in the TMR group, RMBF of the circumflex territory at 8 weeks after ameroid constriction was higher compared with RMBF at 4 weeks after ameroid constriction. However, the improvement was statistically significant only in two animals. In three of the four animals in the control group, RMBF of the circumflex territory also increased at 8 weeks compared with RMBF at 4 weeks. The degree of increase in RMBF was not different between the control and the TMR groups. Conclusion: In porcine model of chronic myocardial ischemia, the degree of increase in RMBF of the ischemic area after Ho:YAG TMR was not different from the increase by development of native collateral circulation. Perfusion of ischemic myocardium after TMR is not thought to improve to the degree that can be demonstrated by currently available method of assessment such as radioisotope myocardial scintigraphy.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.102-109
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• 2009

Purpose: Flash 3D (pixon(R) method; 3D OSEM) was developed as a software program to shorten exam time and improve image quality through reconstruction, it is an image processing method that usefully be applied to nuclear medicine tomography. If perfoming brain diamox perfusion scan by reconstructing subtracted images by Flash 3D with shortened image acquisition time, there was a problem that SNR of subtracted image is lower than basal image. To increase SNR of subtracted image, we use LEAP collimators, and we emphasized on sensitivity of vessel dilatation than resolution of brain vessel. In this study, our purpose is to confirm possibility of application of LEAP collimators at brain diamox perfusion tomography, identify proper reconstruction factors by using Flash 3D. Materials and methods: (1) The evaluation of phantom: We used Hoffman 3D Brain Phantom with $^{99m}Tc$. We obtained images by LEAP and LEHR collimators (diamox image) and after 6 hours (the half life of $^{99m}Tc$: 6 hours), we use obtained second image (basal image) by same method. Also, we acquired SNR and ratio of white matters/gray matters of each basal image and subtracted image. (2) The evaluation of patient's image: We quantitatively analyzed patients who were examined by LEAP collimators then was classified as a normal group and who were examined by LEHR collimators then was classified as a normal group from 2008. 05 to 2009. 01. We evaluate the results from phantom by substituting factors. We used one-day protocol and injected $^{99m}Tc$-ECD 925 MBq at both basal image acquisition and diamox image acquisition. Results: (1) The evaluation of phantom: After measuring counts from each detector, at basal image 41~46 kcount, stress image 79~90 kcount, subtraction image 40~47 kcount were detected. LEAP was about 102~113 kcount at basal image, 188~210 kcount at stress image and 94~103 at subtraction image kcount were detected. The SNR of LEHR subtraction image was decreased than LEHR basal image about 37%, the SNR of LEAP subtraction image was decreased than LEAP basal image about 17%. The ratio of gray matter versus white matter is 2.2:1 at LEHR basal image and 1.9:1 at subtraction, and at LEAP basal image was 2.4:1 and subtraction image was 2:1. (2) The evaluation of patient's image: the counts acquired by LEHR collimators are about 40~60 kcounts at basal image, and 80~100 kcount at stress image. It was proper to set FWHM as 7 mm at basal and stress image and 11mm at subtraction image. LEAP was about 80~100 kcount at basal image and 180~200 kcount at stress image. LEAP images could reduce blurring by setting FWHM as 5 mm at basal and stress images and 7 mm at subtraction image. At basal and stress image, LEHR image was superior than LEAP image. But in case of subtraction image like a phantom experiment, it showed rough image because SNR of LEHR image was decreased. On the other hand, in case of subtraction LEAP image was better than LEHR image in SNR and sensitivity. In all LEHR and LEAP collimator images, proper subset and iteration frequency was 8 times. Conclusions: We could archive more clear and high SNR subtraction image by using proper filter with LEAP collimator. In case of applying one day protocol and reconstructing by Flash 3D, we could consider application of LEAP collimator to acquire better subtraction image.

• Archives of Reconstructive Microsurgery
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• v.20 no.1
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• pp.38-42
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• 2011

Purpose: To evaluate the effect of intermittent bleeding method in the distal phalanx replantation. Materials and Methods: From January 2007 through June 2009, authors have replanted 117 cases of distal phalangeal amputation in adults at Soo Hospital and Chonbuk National University Hospital. Cases of zone II were 60 cases and zone III 57 according to Allen classification. Male to female ratio was 8.7:1.3. The most common cause was machinery injury in the factory, 98 cases(83.8%), next one was belt injury of the machine, 11 cases(9.4%) and others, 8(6.8%). At least one digital artery and digital nerve were anastomosed under the operating microscope, but vein was impossible to anastomosis as unable to find out in the zone II and III. After anastomosis of one or more digital arteries and nerves, heparine(6,000-10,000 units) was kept to intravenous injection for 24 hours and at the same time fish mouth incision in 2-3 millimeter diameter was made in the distal radial and ulnar margin of the replanted distal phanlanx. From the first 30 minutes to an hour after replantation, incision site was swabbed with heparinized cotton ball for 5 minutes in every 30 to 40 minutes to make sure perfusion for 24 hours, every an hour at the second day, every two hours at the postoperative third to fifth day. Results: 92 cases(78.6%) was completely survived at average postoperative third week follow-up and satisfied with preservation of the finger nail, digit length, good range of motion of the distal interphalangeal joint and acceptable sensibility at average 1.2 years follow-up. Conclusions: Intermittant bleeding method in replantation of crushed distal phalanx impossible to anastomosis of vein at zone II and III of Allen classification was regarded as one of the notable salvage procedure.

• Progress in Medical Physics
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• v.22 no.4
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• pp.172-177
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• 2011

The purpose of this study was to analyze $^{68}Ga$-BAPEN dynamic PET image in rat myocardium to evaluate potential of this radiotracer as a perfusion imaging agent. Animal PET/CT scan was done in 9 rats during 120 minutes. Especially we synthesized $^{68}Ga$-BAPEN with kit which is simple and low cost method. PET images showed the in vivo dynamic distribution of $^{68}Ga$-BAPEN in the chest region of rats. Initially $^{68}Ga$-BAPEN PET images showed aorta and liver activities and a few minutes later, $^{68}Ga$-BAPEN moved to myocardium. Regions of interest were drawn on myocardium, liver, lung and blood pool. Time-activity curves showed significant uptake of $^{68}Ga$-BAPEN in myocardium. The contrast ratios of myocardial to blood pool, lung and liver at 60 minutes after injection were 1.66, 2.82 and 0.60. To estimate accurate kinetic parameters, 60 minutes after injection was required to PET scan as myocardium image contrast ratios reached to constant values. As a result, $^{68}Ga$-BAPEN would be suitable radiotracer for PET which can applied to diagnosis of myocardial perfusion diseases after further preclinical and clinical investigations.

• Journal of Biomedical Engineering Research
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• v.33 no.1
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• pp.39-46
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• 2012

Electrical impedance tomography(EIT) can produce functional images with conductivity distributions associated with physiological events such as cardiac and respiratory cycles. EIT has been proposed as a clinical imaging tool for the detection of stroke and breast cancer, pulmonary function monitoring, cardiac imaging and other clinical applications. However EIT still suffers from technical challenges such as the electrode interface, hardware limitations, lack of animal or human trials, and interpretation of conductivity variations in reconstructed images. We improved the KHU Mark2 EIT system by introducing an EIT electrode interface consisting of nano-web fabric electrodes and by adding a synchronized biosignal measurement system for gated conductivity imaging. ECG and respiration signals are collected to analyze the relationship between the changes in conductivity images and cardiac activity or respiration. The biosignal measurement system provides a trigger to the EIT system to commence imaging and the EIT system produces an output trigger. This EIT acquisition time trigger signal will also allow us to operate the EIT system synchronously with other clinical devices. This type of biosignal gated conductivity imaging enables capture of fast cardiac events and may also improve images and the signal-to-noise ratio (SNR) by using signal averaging methods at the same point in cardiac or respiration cycles. As an example we monitored the beat by beat cardiac-related change of conductivity in the EIT images obtained at a common state over multiple respiration cycles. We showed that the gated conductivity imaging method reveals cardiac perfusion changes in the heart region of the EIT images on a canine animal model. These changes appear to have the expected timing relationship to the ECG and ventilator settings that were used to control respiration. As EIT is radiation free and displays high timing resolution its ability to reveal perfusion changes may be of use in intensive care units for continuous monitoring of cardiopulmonary function.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.11
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• pp.897-903
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• 2015

In this paper, the contrast therapy of skin was numerically investigated by solving the conjugate heat transfer problem. A finite volume method based on the SIMPLE algorithm was adopted to solve the axisymmetric incompressible Navier-Stokes equations, coupled with an energy equation. These equations are strongly coupled with the Pennes bio-heat equation in order to consider the effect of blood perfusion rate. We investigated the thermal response of skin at some selected depths for various input temperature profiles of a stimulator for contrast therapy. From the numerical simulations, the regions with cold/hot threshold temperatures were found for five input temperature profiles. It was shown that the temperature varies mildly for different input profiles as the depth increases, owing to the Pennes effect. The input temperatures for effective hot/cold stimulation of dermis layer were found to be $47^{\circ}C$ and $7^{\circ}C$, respectively. The present numerical results will be used for finding an optimal temperature profile of a stimulator for contrast therapy.

• The Korean Journal of Nuclear Medicine
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• v.27 no.2
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• pp.155-160
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• 1993

The identification of viable myocardium in patients with coronary artery disease and left ventricular dysfunction is an issue of increasing clinical relavance in the current era of myocardial revascularization. There are at least two forms of reversible myocardial dysfunction. Early reperfusion does not always lead to immediate functional improvement; rather, the return of contractility in tissue salvaged by reperfusion is delayed for hours, days or even weeks, a phenomenon that has been termed "stunned myocardium". Some patients with coronary artery disease show myocardial dysfunction at rest which are associated with reduced perfusion, and which disappear after revascularization; this phenomenon has been termed "hibernating myocardium". Recently, cardiac imaging techniques that evaluate myocardial viability on the basis of perfusion-contraction mismatch and inotropic reserve have gained substantial popularity and clinical success. This review focus on the application of $^{201}TI$ and $^{99m}Tc-MIBI$ to address myocardial viability in patients with hibernating and stunned myocardium. It is clear that 4-hour redistribution images of $^{201}TI$ underestimate ischemia and overestimate scar. Delayed imaging and reinjection imaging have been developed for the assessment of viability. Among many protocols suggested, stress-redistribution-reinjection imaging gained most popularity. Although $^{99m}Tc-MIBI$ could identify myocardial viability, $^{201}TI$ reinjection technique was regarded as superior to it. In conclusion, $^{201}TI$ stress, 4-hr rest redistribution, and reinjection imaging technique may be the most preferable method for evaluation of myocardial viability.

• Journal of Veterinary Clinics
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• v.26 no.5
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• pp.441-444
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• 2009

Ischemia-reperfusion (I/R) injury is associated with an increased risk of acute rejection, delayed graft function and long-term changes after kidney transplantation. The reperfusion models remain unsolved complications such as vascular obstruction and blood leakage. We developed an alternative model of isolated hemoperfusion in porcine kidneys. In the present study we introduced a newly developed reperfusion method. A connector was used instead of surgical suture for the vascular anastomosis on the inguinal region in which main femoral vessels are parallel and big enough to perfuse the kidney. To assess renal perfusion quality of the modified hemoreperfusion model, we analyzed both hemodynamic values and patterns of I/R injury following a renal reperfusion. Following unilateral nephrectomy, the kidneys were preserved for 0, 24 and 48 hours at $4^{\circ}C$ with histidine-tryptophan ketogluatarate (HTK) solution and reperfused for 3 hours by vascular anastomosis connected to the femoral artery and vein in inguinal region. Histolopathological examinations were assessed on kidney biopsy specimens, taken after each cold storage and reperfusion. No differences of hemodynamic values were observed between aorta and femoral artery. The average warm ischemia time before reperfusion start was $7.0{\pm}1.1$ minutes. There were no complications including vascular obstruction and blood leakage during the reperfusion. I/R injury of the perfused kidneys in this model was dependent upon the cold ischemia time. The results support that the modified perfusion model is simple and appropriate for the study of early renal I/R injury and transplant immunology.

• Journal of Chest Surgery
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• v.43 no.1
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• pp.25-32
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• 2010

Background: Patients with vascular diseases commonly have coronary artery disease and associated cardiac problems. Therefore, their underlying heart diseases may be induced or exacerbated after vascular surgery. The effectiveness of SPECT imaging, which is a relatively simple and non-invasive imaging modality, for assessing these underlying heart diseases is still controversial. This study was performed to evaluate the clinical effect of tests and treatment based on SPECT imaging prior to vascular surgery on the development of post-operation cardiac complications. Material and Method: Sixty three patients who were treated at Inje University Pusan Paik Hospital between April 2004 and September 2007 and who underwent adenosine infusion technetium-99m (Tc-99m) tetrofosmin SPECT imaging prior to vascular surgery were selected for this study and we retrospectively reviewed their records. Result: The sensitivity and specificity of detecting a perfusion defect on SPECT to predict the development of cardiac complications was relatively low at 41.2% and 52.2%, respectively. However when coronary angiographies were done on the patients with abnormal SPECT and this was followed by aggressive treatment such as coronary artery intervention and coronary artery bypass grafting based on the angiography results, there was a tendency for lower cardiac complication rates. Conclusion: SPECT imaging shows low effectiveness as a screening test for predicting cardiac complications after vascular surgery.

• The Korean Journal of Nuclear Medicine
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• v.25 no.1
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• pp.46-52
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• 1991

Radioaerosol inhalation imaging (RII) has been used in radionuclide pulmonary studies for the past 20 years. The method is well accepted for assessing regional ventilation because of its usefulness, easy fabrication and simple application system. To evaluate its clinical utility in the study of impaired regional ventilation in bronchial asthma, we obtained and analysed RIIs in 31 patients (16 women and 15 men; age ranging 21-76 years) with typical bronchial asthma at the Department of Radiology, Kangnam St. Mary's Hospital, Catholic University Medical college, from January, 1988 to August, 1989. Scintiscans were obtained with radioaerosol produced by a BARC(Bhabha Atomic Reserch Center, India) nebulizer with 15 mCi of $^{99m}Tc-phytate$. The scanning was peformed in anterior, posterior and lateral projections following 5-minute inhalation of radioaerosol on sitting position. The scans were analyzed and correlated with the results of pulmonary function study and the findings of chest radiography. Fifteen patients had concomitant lung perfusion image with $^{99m}Tc-MAA$. Follow-up scans were obtained in 5 patients after bronchodilator therapy. The patients were divided into (1) attack type (4 patients), (2) resistant type (5 patients), (3) remittent type (10 patients) and (4) bronchitic type (12 patients). Chest radiography showed hyperinflation, altered pulmonary vascularity, thickening of the bronchial wall and accentuation of basal interstitial markings in 26 of the 31 patients. Chest radiographs were norma! in the remaining 5 patients. Regardless of type, the findings of RII were basically the same, and characterized by the deposition of radioaerosol in the central parts or in the main respiratory air ways along with mottled nonsegmental ventilation defects in the periphery. Peripheral parenchymal defects were more extensive than that of expected findings from clinical symptoms, pulmonary function test and chest radiograph. Broomstick sign was present in 17 patients. The abnormality of RII was poorly correlated with perfusion scans. In all 5 patients treated with bronchodilators, follow-up study demonstrated a decrease in the degree of radioaerosol deposition in the central air way with improved ventilation defects. This study indicates that RII is a useful technique for the evaluation of regional ventilation abnormality and the effect of treatment with bronchodilators in patients with bronchial asthma.