• The Korean Journal of Nuclear Medicine
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• v.34 no.6
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• pp.497-507
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• 2000

Purpose: We have examined the utility of $^{99m}Tc$-MAG3 perfusion indices for assessing renal graft function in early post-transplantation period. Materials and Methods: Our study included 80 renal transplant recipients (48 men and 32 women, mean age: 40.3 years). Diagnosis was based on biopsy, laboratory data and clinical course. Renal scintigraphy (RS) was obtained using 100 MBq of $^{99m}Tc$-MAG3 from 11 days to 23 days of kidney transplantation. We measured 5 indices in whole-kidney (WK) and cortical (C) renograms; Hilson's perfusion index (PI), transplant perfusion index (TP) and transplant function index (TF) as perfusion parameter, and the time to peak activity (Tmax) and the ratio of renal counts at 20 min to that at 3 min (K20/3) as functional parameter. Results: The diagnoses at the day of RS were normal graft (NG) in 44, acute rejection (AR) in 14, acute tubular necrosis (ATN) in 10, and Cyclosporine A nephrotoxicity (CsA) in 12. TP and TF were significantly decreased in AR, ATN and CsA, compared to those in NG. K20/3 of AR and ATN wore significantly greater than that of NG. WK-Tmax of AR was significantly longer than that of NG. K20/3 of AR and C-K20/3 of ATN were significantly prolonged relative to those of CsA. There were no statistically significant perfusion indices among complication groups. Conclusion: TP and TF reflecting microperfusion and initial tubular extraction are reliable in assessing graft function. However, it is required to correlate perfusion indices with functional indices and clinical course in differentiating from one another among complication groups.

• Journal of Chest Surgery
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• v.32 no.12
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• pp.1065-1077
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• 1999

Background : Ventricular assist devices(VADs) are being used for patients in postcvardiotomy cardiogenic shock status bridge to cardiac transplant settings and in post-myocardial infarction cardiogenic shock. The VAD which was developed at the Deparment of medical engineering in Dankook University College of Medicine was a pneumatically driven device and can maintain pulsatile flow. The goal of this study is to develop animal experimental models using the VAD and to clarify the reliability and hemodynamic property adequacy of end organ perfusion durability and severity of thrombotic-hemolytic tendency of the device. Material and Method : The pneumatic VAD was applied to 8 adult female lambs, We examined some hemodynamic parameters such as arterial blood pressure pulmonary capillary wedge pressure(pcwp) pulmonary artery pressure(PAP) left atrial pressure hour urine output cardiac index VAD flow EKG to determine the reliability of the VAD and hemodynamic compatibility of the experimental animals within 24 hours of experiment. We also observed the end organ perfusion durability of the VAD and thrombotic-hemolytic property of the VAD after 24 hours of VAD insertion. Result: We could monitor all hemodynamic parameters including pcwp PAP cardiac index EKG, adn hour urine as true clinical settings. We observed that the reliability of the VAD was excellent and the hemodynamic property of the experimental animal and end organ perfusion were adequate within 24 hours of experiment. In four lambs surviving 24 hours after insertion the reliability of the VAD and end organ perfusion were excellent and no thrombotic-hemolytic tendency was noted. However after 15 days of experiment the diaphragm of the VAD was torn and it was recommende that the durability of the VAD should be extended. Conclusion : e conclude that the pneumatic VAD developed at Dankook University Biomedical Engineering has good hemodynamic property and low thromboembolic tendency and presents adequate end organ perfusion but we noted that the durability of the device should be expanded further. It will be possible to do more reliable experiment in the future according to the animal experimental method developed in this study especially with the heart failure models.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.276-286
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• 2013

SVD-based deconvolution algorithm has been known as the most effective technique for CT perfusion image analysis. In this algorithm, in order to reduce noise effects, SVD coefficients smaller than a certain threshold are removed. As the truncation threshold, either a fixed value or a variable threshold yielding a predetermined OI (oscillation index) is frequently employed. Each of these two thresholding methods has an advantage to the other either in accuracy or efficiency. In this paper, we propose a Monte Carlo simulation method to evaluate the accuracy of the two methods. An extension of the proposed method is presented as well to measure the effects of image smoothing on the accuracy of the thresholding methods. In this paper, after the simulation method is described, experimental results are presented using both simulated data and real CT images.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.4
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• pp.280-286
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• 2009

Purpose: The aim of this study was to evaluate the hemodynamic changes after endovascular stenting in patients with unilateral middle cerebral artery (MCA) stenosis using statistical probabilistic anatomical mapping (SPAM) analysis of basal/acetazolamide (ACZ) Tc-99m ECD brain perfusion SPECT. Materials and Methods: Eight patients (3 men and 5 women, 64.8$\pm$10.5 years) who underwent endovascular stenting for unilateral MCA stenosis were enrolled. Basal/ACZ Tc-99m ECD brain perfusion SPECT studies were performed by one-day protocol before and after stenting. Using SPAM analysis, we compared basal cerebral perfusion (BCP) counts and cerebrovascular reserve (CVR) index of the MCA territory before stenting with those after stenting. Results: After stenting, no patient had any complication nor additional stroke. In SPAM analysis, 7 out of the 8 patients had improved BCP counts of the MCA territory and 7 out of the 8 patients had improved CVR index of the MCA territory after stenting. Before stenting, the mean BCP counts and CVR index in the affected MCA territory were 47.1$\pm$2.2 ml/min/100 g and -2.1$\pm$2.9%, respectively. After stenting, the mean BCP counts and CVR index in the affected MCA territory were improved significantly (48.3$\pm$2.9 ml/min/100 g, p =0.025 and 0.1$\pm$1.3%, p =0.036). Conclusion: This study revealed that SPAM analysis of basal/ACZ brain perfusion SPEG would be helpful to evaluate hemodynamic efficacy of endovascular stenting in unilateral MCA stenosis.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.88-89
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• 2002

Traditionally, kinetics of brain influx of drugs has been evaluated by a number of experimental techniques. Brain uptake index and in situ brain perfusion study have been used for the determination of the kinetics; However, these methods generally focus on the accuracy of the uptake rate into the brain rather than the speed of the determination. In addition, application of radiolabelled substrates (e.g., $_{14}$C-labelled sucrose) further impedes the wide spread acceptance of these techniques for the application of high throughput screening system. (omitted)

• The Korean Journal of Nuclear Medicine
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• v.28 no.1
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• pp.22-30
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• 1994

Encephalo-duro-arterio-synangiosis (EDAS) is a relatively new surgical procedure for treatment of childhood moyamoya disease. We assessed regional cerebral perfusion in moyamoya patients before (1.3 mo) and after (6.8 mo) EDAS with $^{99m}Tc$-HMPAO brain SPECT. A total of 21 EDAS operations in 17 moyamoya patients was included. Preoperative CT or MRI showed cerebral infarction in 14 patients and carotid angiography showed Suzuki grade I to V stenosis in 6%, 9%, 62%, 12% and 12% of the hemispheres respectively. Preoperative SPECT showed regional hypoperfusion in all patients, bilateral frontal and temporal lobes being the most frequently involved site. $4{\times}4$ pixel sized ROIs were applied on the frontotemporal cortex in 3 slice averaged transverse tomographic images. An index of regional perfusion was measured as: PI (%)=average F-T activity/average cerebellar activity${\times}100$ Pre-EDAS ipsilateral PI ranged from 23.7 to 98.4% (mean: $74.3{\pm}17%$) and increased significantly after operation ($81.4{\pm}17%$, p<0.001). Individual post-EDAS PI improved in 15/21 cases, showed no significant change in 5 and was slightly aggravated in 1. The amount of clinical improvement (${\Delta}CI$) was graded with a scale of 0 to 4 based on frequency and severity of TIA attacks. When patients were grouped according to pre-EDAS PI, group II (PI 70-89) showed a significantly higher ${\Delta}CI$ (3.3) compared to group I (PI< 70, 1.57) or group III (PI >90, 0.5) (P< 0.001). The amount of perfusion improvement (${\Delta}PI$) showed significant correlation with ${\Delta}CI$ (r=0.42, p=0.04). ${\Delta}PI$ did not, however, correlate with the amount of neovascularization assessed angiographically in 8 patients. Serial HMPAO SPECT is an useful noninvasive study for assessing perfusion improvement after EDAS in childhood moyamoya patients.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.2
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• pp.144-152
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• 2016

Carotid-artery stenosis may reduce cerebral perfusion, and affect cerebral neuronal activities. We examined the question of whether the recovery of cerebral-perfusion reserve after carotid-artery stenting (CAS) can affect the EEG power-spectrum. Nineteen candidates for CAS were initially recruited. Subtraction imaging of single photon emissary computerized tomography (SPECT) and an electroencephalogram (EEG) were taken twice, before and 1 month after CAS. At each time point, the EEGs were recorded before and after injection of acetazolamide (pre-ACZ EEG and post-ACZ EEG). Finally, 7 patients were enrolled after exclusion of incomplete studies. We obtained the spectral ratio (SR) of each hemisphere. SR was defined as the divided value of the power-spectrum sum of fast activities by that of slow activities. The power-spectrum values between hemispheres were compared using the inter-hemispheric index of spectral ratio (IHISR), and we examined the correlation between the power-spectrum and the cerebral-perfusion reserve. Cerebral-perfusion reserve improved after CAS on the stent side in 6 of 7 patients. In 3 patients with unilateral carotid-artery stenosis, CAS increased SR on the pre-ACZ EEGs, and IHISR on the post-ACZ EEGs. The increases of SR and IHISR were concordant with the increment of cerebral-perfusion reserve. In contrast, the results in the other patients with bilateral stenosis showed complex patterns. The SR of pre-ACZ EEGs and IHISR of post-ACZ EEGs may be useful electrophysiological markers for the blood-flow reserve after CAS in patients with unilateral carotid-artery stenosis, but not in those with bilateral stenosis.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.5
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• pp.386-394
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• 2009

Purpose: We aimed to assess the myocardial velocity on gated myocardial perfusion SPECT (gated MPS), to compare myocardial velocity between patients without coronary artery disease (CAD) and CAD patients and to assess the correlation of myocardial velocity and perfusion and wall thickening on CAD group. Materials and Methods: Seventeen patients without CAD (M:F=9:8, mean age $61.8{\pm}11.1$ yrs: group A) and thirty-nine patients with CAD (M:F=18:21, mean age $66.9{\pm}8.1$ yrs : group B) had undergone one-day adenosine stress gated MPS. In twenty segment model, 12 segments (except apical and basal segments) of each patient were included. We obtained systolic and diastolic gate ratio in left ventricular volume curve by eight frames per cardiac cycle on gated MPS. Using the systolic and diastolic gate ratio and R-R time of each patient, we obtained systolic and diastolic time ratio. The myocardial velocity was defined as wall thickening over systolic or diastolic time. Results: We presented normal range of myocardial velocities according segments and territories of coronary artery. The myocardial velocity of group B was significantly lower than group A (p=0.00). There was no significant difference between the myocardial velocity of group B with preserved EF and group A. The stress systolic velocity significantly correlated with regional myocardial perfusion in group B with preserved EF (p=0.00) as well as decreased EF (p=0.01). In group B, stress perfusion of segments which had decreased wall thickening and decreased myocardial velocity was significantly lower than segments which had decreased wall thickening and preserved myocardial velocity (p=0.01). Conclusion: The new functional index of velocity will be used as an useful of gated MPS.

• Journal of radiological science and technology
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• v.45 no.1
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• pp.41-47
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• 2022

The purpose of this study is to apply a deep learning model that can distinguish lung perfusion and lung ventilation images in nuclear medicine, and to evaluate the image classification ability. Image data pre-processing was performed in the following order: image matrix size adjustment, min-max normalization, image center position adjustment, train/validation/test data set classification, and data augmentation. The convolutional neural network(CNN) structures of VGG-16, ResNet-18, Inception-ResNet-v2, and SE-ResNeXt-101 were used. For classification model evaluation, performance evaluation index of classification model, class activation map(CAM), and statistical image evaluation method were applied. As for the performance evaluation index of the classification model, SE-ResNeXt-101 and Inception-ResNet-v2 showed the highest performance with the same results. As a result of CAM, cardiac and right lung regions were highly activated in lung perfusion, and upper lung and neck regions were highly activated in lung ventilation. Statistical image evaluation showed a meaningful difference between SE-ResNeXt-101 and Inception-ResNet-v2. As a result of the study, the applicability of the CNN model for lung scintigraphy classification was confirmed. In the future, it is expected that it will be used as basic data for research on new artificial intelligence models and will help stable image management in clinical practice.

• Tuberculosis and Respiratory Diseases
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• v.44 no.4
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• pp.889-898
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• 1997

Pulmonary Embolism can develop in variable conditions, and presents with nonspecific symptoms and signs. If diagnosis is delayed, it can be resulted in catastrophic results. Therefore, early diagnosis and adequate treatment is crucial in Pulmonary Embolism. Lung Perfusion Scan is useful screening test. Negative result can exclude pulmonary embolism. But, perfusion defects don't always mean pulmonary embolism. To find the better methods of interpretation of lung perfusion scan and To evaluate the clinical course and outcomes of the patients, in whom pulmonary embolism was suspected by lung perfusion scan, we reviewed the clinical records of 49 cases suspected by lung perfusion scan at Seoul National University Hospital during the period of January, 1995 to July, 1996. The results are as follows. First impression of cases in which PE was present at time of admission were pulmonary embolism (63%), heart diseases (26%), and pneumonia (11%) in orders. Underlying diseases of cases in which PE developed during admission were malignancy (36.5%), ICH (22.7%), sepsis (13.7%), and SLE (9.1%) in orders. The predisposing factors were operation (20%), cancer (16%), immobility (16%), connective tissue disease (16%), heart dis. (10%), old age (10%), and preg/pelvic dis. (8%) The results, of lung perfusion scan were HPPE 40 cases(26.8 %), IPPE 21 cases(14.1%), LPPE 88 cases (59.1%), and cases(%) of treatment in these cases were HPPE 34 cases(85%), IPPE 9 cases(42.9%), LPPE 0 case(0.0%). Treatments were heparin and warfarin (69.5%), heparin alone (8.2%), warfarin alone (2.0%), embolectomy (4.1%), thrombolytics (2.0%), IVC filter (2.0%), and no treatment (12.2%) In 34 cases (69.4%), follow up could be done, and 5 cases were recurred (10.2%). The causes of recurrence was incomplete anticoagulant therapy (3 cases) and recurrence of predisposing factor (2 cases). Expired case due to pulmonary embolism was one who was expired just before trial of thrombolytic therapy. Conclusion : Efforts should be made to shorten the interval from onset of Sx to Dx, ie, high index of suspision.