• Nuclear Medicine and Molecular Imaging
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• v.41 no.3
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• pp.194-200
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• 2007

Purpose: $^{13}N$-ammonia is a well known radiopharmaceutical for the measurement of a myocardial blood flow (MBF) non-invasively using PET-CT. In this study, we investigated a correlation between MBF obtained from dynamic imaging and myocardial perfusion score (MPS) obtained from static imaging for usefulness of cardiac PET study. Methods: Twelve patients (11 males, 1 female, $57.9{\pm}8.6$ years old) with suspicious coronary artery disease underwent PET-CT scan. Dynamic scans (6 min: $5\;sec\;{\times}\;12,\;10\;sec\;{\times}\;6,\;20\;sec\;{\times}\;3,\;and\;30\;sec\;{\times}\;6$) were initiated simultaneously with bolus injection of 11 MBq/kg $^{13}N-ammonia$ to acquire rest and stress image. Gating image was acquired during 13 minutes continuously. Nine-segment model (4 basal walls, 4 mid walls, and apex) was used for a measurement of MBF. Time activity curve of input function and myocardium was extracted from ROI methods in 9 regions for quantification. The MPS were evaluated using quantitative analysis software. To compare between 20-segment model and 9-segment model, 6 basal segments were excluded and averaged segmental scores were used. Results: There are weak correlation between MBF (rest, 0.18-2.38 ml/min/g; stress, 0.40-4.95 ml/min/g) and MPS (rest 22-91%, stress, 14-90%), however the correlation coefficient between corrected MBF and MPS in rest state was higher than stress state (rest r=0.59; stress r=0.80). As a thickening increased, correlation between MBF and MPS also showed good correlation at each segments. Conclusions: Corrected and translated MPS as its characteristics using $^{13}N$-ammonia showed good correlation with absolute MBF measured by dynamic image in this study. Therefore, we showed MPS is one of good indices which reflect MBF. We anticipate PET-CT could be used as useful tool for evaluation of myocardial function in nuclear cardiac study.

• 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.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.284-291
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• 2013

The importance of ultrasound examination in the field of medical imaging has been emphasized and the interest in sonographic image evaluation is growing. However image evaluations by the non-standardized criteria and methods, so establishment of legal provisions and objective evaluation criteria are needed. In this study, we used SNR to find out more quantitative way and supplement the limitations of the existing phantom image evaluation. The results of acquired 8 images using ATS-539 multipurpose phantom were compared in SNR of sensitivity and gray-scale dynamic range. In the result of the experiment, excellent equipment of existing phantom images are G1, S1 and G2 in regular sequence. In SNR of sensitivity, G1, S1 and G2 and in SNR of gray-scale dynamic range, S1 G1 and G2 in order. In the conclusion, all the experiment results did not show big difference and regular pattern neither. Therefore, the new evaluation measures should be used with the existing phantom image evaluation method for more objective and quantitative evaluation of the ultrasound imaging device.

• Journal of Digital Convergence
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• v.15 no.8
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• pp.333-340
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• 2017

Timelapse is an imaging technique that captures motion at regular intervals and then projects it at normal speed. We looked at Timelapse advertising images of global brands and presented a model for analyzing components and expression methods of Timelapse, a new image technique. In previous research, literature research, Internet data survey, and YouTube data were investigated. Continuous photography has been developed as an imaging technique, and we have examined the current production status applied to domestic and foreign documentary, domestic and foreign drama, film, and advertisement. In 2015-2016, I will analyze the techniques of iPhones (2016), Ralph Lauren Polo Ads (2015), and Canon EOS (2013) videos that use Timelapse techniques in their recent advertisements. The results show that the Timelapse component is a static element, the static motif is mainly an artificial structure, the place is outdoor, the color is taken at a time showing the characteristics of the place, and the layout is all centered. The dynamic motif is a moving object. The dynamic line consists of a story based on the object. The time is about 11-15 seconds, the longest is about 1 minute and 30 seconds, and the editing is mainly focused on the product with the brand logo emphasized. In conclusion, it is the role of the image to pay attention to the advertisement and catch the eye. In order to motivate the buyer's mind, it is necessary to direct and edit such as Timelapse, which stimulates the emotions inherent in the mind and stimulates the non-verbal symbols. Future research is likely to reveal various attempts at temporal editing of images.

• Investigative Magnetic Resonance Imaging
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• v.22 no.3
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• pp.158-167
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• 2018

Purpose: To investigate the surgical, perfusion, and molecular characteristics of glioblastomas which influence long-term survival after treatment, and to explore the association between MR perfusion parameters and the presence of MGMT methylation and 1p/19q deletions. Materials and Methods: This retrospective study was approved by our institutional review board. A total 43 patients were included, all with pathologic diagnosis of glioblastoma with known MGMT methylation and 1p/19q deletion statuses. We divided these patients into long-term (${\geq}60\;months$, n = 7) and short-term (< 60 months, n = 36) survivors, then compared surgical extent, molecular status, and rCBV parameters between the two groups using Fisher's exact test or Mann-Whitney test. The rCBV parameters were analyzed according to the presence of MGMT methylation and 1p/19q deletions. We investigated the relationship between the mean rCBV and overall survival using linear correlation. Multivariable linear regression was performed in order to find the variables related to overall survival. Results: Long-term survivors (100% [7 of 7]) demonstrated a greater percentage of gross total or near total resection than short-term survivors (54.5% [18 of 33]). A higher prevalence of 1p/19q deletions was also noted among the long-term survivors (42.9% [3 of 7]) than the short-term survivors (0.0% [0 of 36]). The rCBV parameters did not differ between the long-term and short-term survivors. The rCBV values were marginally lower in patients with MGMT methylation and 1p/19q deletions. Despite no correlation found between overall survival and rCBV in the whole group, the short-term survivor group showed negative correlation ($R^2=0.181$, P = 0.025). Multivariable linear regression revealed that surgical extent and 1p/19q deletions, but not rCBV values, were associated with prolonged overall survival. Conclusion: While preoperative rCBV and 1p/19q deletion status are related to each other, only surgical extent and the presence of 1p/19q deletion in GBM patients may predict long-term survival.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup1
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• pp.55-60
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• 2001

Objective : The purpose of the present study was to examine neurologic changes, fusion rate and degree of kyphosis from the surgical results of those patients who underwent multi-level anterior interbody fusion and internal fixation. Methods : Among 63 cases of the patients who received multi-level anterior interbody fusion and internal fixation in 5 years between 1995 to 1999 at the neurosurgery department, we performed a retrospective study in 52 cases that could be followed up with dynamic view imaging ; the results were compared and analyzed. The analysis was based on the results of history taking, physical findings and radiologic findings, and Odom criteria were used to classify those cases with neurologic changes. Results : Among those 52 cases in whom the follow-up was possible for at least a year and dynamic view imaging was possible, bone fusion was seen in 93% of the trauma cases and 95% in the non-trauma cases and overall bone fusion was observed in 94% of the cases. Bone fusion was seen in 93% of the autobone cases, 95% of the allobone cases, and 94% of the Mesh cases. Radiologic changes were observed by comparing the lateral view after surgery ; kyphosis was seen in 53% of the autobone cases, in 70% of the allobone cases, and in 35% of Mesh cases ; in 45% and 60% of the non-trauma cases and trauma cases, respectively ; and in 55% of the 2 level fusion cases and 46% of the 3 level fusion cases. Neurologic changes classified according to Odom criteria showed excellent result in 48% of all the cases, good in 23%, fair in 4%, and poor in 25%. Conclusion : Even those cases with multi-level fusion, a high fusion rate could be obtained by performing anterior interbody fusion and internal fixation ; those cases with kyphosis were related more with the presence or absence of posterior compartment injury rather than the fusion level ; and those trauma cases showed not much difference in the fusion rate compared with non-trauma cases but had a high possibility of kyphosis.

• Journal of Yeungnam Medical Science
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• v.26 no.1
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• pp.30-37
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• 2009

Purpose : To radiologically differentiate renal oncocytoma from other renal solid tumors, we analyzed and characterized, retrogradely, radiologic findings of renal oncocytomas. Materials and Methods : Radiologic findings of pathologically proven renal oncocytoma were analyzed in 9 patients. CT was performed in all patients, ultrasonography in 4 patients and MRI in 3 patients.(51) Results : On ultrasonography, the echogenicity of the mass was slightly more hyperechoic than normal renal parenchyma in all 4 cases. Two cases were homogeneous and the remaining two cases were relatively homogeneous. On CT, all 8 cases showed iso-density to slightly low density compared to normal renal parenchyma and 5 cases were homogeneous but the central portion of the mass was of a slightly lower density than the peripheral portion in 3 cases. All six cases had an arterial phase scan and were heterogeneously enhanced. An irregular, lower-enhancing portion was found in the central portion of the mass. Segmental inversion of contrast enhancement was found in 5 of 6 cases that had a dynamic enhancement study. On MR T1-weighted imaging, the mass was of iso-signal intensity to normal renal parenchyma and the central portion of the mass had a slightly hypo-signal intensity than the peripheral portion. On T2-weighted imaging, 2 cases were heterogeneous; the peripheral portion was of low signal intensity and central portion was of higher signal intensity than normal renal parenchyma. One case was relatively homogeneous and showed a slightly lower signal intensity than that of normal parenchyma, except for a central small portion showing high signal intensity. For 2 cases that had a dynamic study, a segmental inversion of contrast enhancement was noted. Conclusion : Renal oncocytoma is seen as a well-marginated solid mass lesion. On enhanced scans it is heterogeneously enhanced and segmental inversion of contrast enhancement may be seen. The possibility of oncocytoma can be suggested in cases showing these radiologic findings.

• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.757-763
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• 2019

Recently, Following the recent development of flat panel detector with wide dynamic ranges, increasing numbers of healthcare providers have begun to use digital radiography. As a result, filter thickness standards should be reestablished, as current clinical practice requires the use of thicknesses recommended by the National Council on Radiation Protection and Measurements, which are based on information, acquired using conventional analog systems. Here we investigated the possibility of minimizing dose creep and optimizing patient dose using Al filters in digital radiography. The use of thicker Al filters resulted in a maximum 19.3% reduction in the entrance skin exposure dose when medical images with similar sharpness values were compared. However, resolution, which is a critical factor in imaging, had a significant change of 1.01 lp/mm. This change in resolution is thought to be due to the increased amount of scattered rays generated from the object due to the X-ray beam hardening effect. The increase in the number of scattered rays was verified using the scattering degradation factor. However, the FPD, which has recently been developed and is widely used in various areas, has greater response to radiation than analog devices and has a wide dynamic range. Therefore, the FPD is expected to maintain an appropriate level of resolution corresponding to the increase in the scattered-ray content ratio, which depends on filter thickness. Use of the FPD is also expected to minimize dose creep by reducing the exposure dose.

• Korean Journal of Radiology
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• v.24 no.11
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• pp.1081-1092
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• 2023

Objective: To investigate the incidence of microvascular myocardial ischemia in diabetic patients without obstructive coronary artery disease (CAD) and its relationship with angina. Materials and Methods: Diabetic patients and an intermediate-to-high pretest probability of CAD were prospectively enrolled. Non-diabetic patients but with an intermediate-to-high pretest probability of CAD were retrospectively included as controls. The patients underwent dynamic computed tomography-myocardial perfusion imaging (CT-MPI) and coronary computed tomography angiography (CCTA) to quantify coronary stenosis, myocardial blood flow (MBF), and extracellular volume (ECV). The proportion of patients with microvascular myocardial ischemia, defined as any myocardial segment with a mean MBF ≤ of 100 mL/min/100 mL, in patients without obstructive CAD (Coronary Artery Disease-Reporting and Data System [CAD-RADS] grade 0-2 on CCTA) was determined. Various quantitative parameters of the patients with and without diabetes without obstructive CAD were compared. Multivariable analysis was used to determine the association between microvascular myocardial ischemia and angina symptoms in diabetic patients without obstructive CAD. Results: One hundred and fifty-two diabetic patients (mean age: 59.7 ± 10.7; 77 males) and 266 non-diabetic patients (62.0 ± 12.3; 167 males) were enrolled; CCTA revealed 113 and 155 patients without obstructive CAD, respectively. For patients without obstructive CAD, the mean global MBF was significantly lower for those with diabetes than for those without (152.8 mL/min/100 mL vs. 170.4 mL/min/100 mL, P < 0.001). The mean ECV was significantly higher for diabetic patients (27.2% vs. 25.8%, P = 0.009). Among the patients without obstructive CAD, the incidence of microvascular myocardial ischemia (36.3% [41/113] vs. 10.3% [16/155], P < 0.001) and interstitial fibrosis (69.9% [79/113] vs. 33.3% [8/24], P = 0.001) were significantly higher in diabetic patients than in the controls. The presence of microvascular myocardial ischemia was independently associated with angina symptoms (adjusted odds ratio = 3.439, P = 0.037) in diabetic patients but without obstructive CAD. Conclusion: Dynamic CT-MPI + CCTA revealed a high incidence of microvascular myocardial ischemia in diabetic patients without obstructive CAD. Microvascular myocardial ischemia is strongly associated with angina.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.889-902
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• 2021

Purpose To assess the diagnostic performance of contrast-enhanced ultrasound (CEUS) for additional MR-detected enhancing lesions and to determine whether or not kinetic pattern results comparable to dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) of the breast can be obtained using the quantitative analysis of CEUS. Materials and Methods In this single-center prospective study, a total of 71 additional MR-detected breast lesions were included. CEUS examination was performed, and lesions were categorized according to the Breast Imaging-Reporting and Data System (BI-RADS). The sensitivity, specificity, and diagnostic accuracy of CEUS were calculated by comparing the BI-RADS category to the final pathology results. The degree of agreement between CEUS and DCE-MRI kinetic patterns was evaluated using weighted kappa. Results On CEUS, 46 lesions were assigned as BI-RADS category 4B, 4C, or 5, while 25 lesions category 3 or 4A. The diagnostic performance of CEUS for enhancing lesions on DCE-MRI was excellent, with 84.9% sensitivity, 94.4% specificity, and 97.8% positive predictive value. A total of 57/71 (80%) lesions had correlating kinetic patterns and showed good agreement (weighted kappa = 0.66) between CEUS and DCE-MRI. Benign lesions showed excellent agreement (weighted kappa = 0.84), and invasive ductal carcinoma (IDC) showed good agreement (weighted kappa = 0.69). Conclusion The diagnostic performance of CEUS for additional MR-detected breast lesions was excellent. Accurate kinetic pattern assessment, fairly comparable to DCE-MRI, can be obtained for benign and IDC lesions using CEUS.