• Journal of radiological science and technology
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• v.32 no.1
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• pp.101-106
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• 2009

Purpose of this study is to compare the signal intensity (SI) and CNR with T1 weighted image using FLASH at 3T abdominal MRI by varying flip angle (FA). Totally 20 patients (male : 12, female : 8, Age : $28{\sim}63$ years with mean : 51) were examined by 3 Tesla MR scanner (Magnetom Tim Trio, SIEMENS, Germany) with 8 channel body array coil between september and October 2008. Imaging parameters were as follows : FLASH sequence, TR : 120 ms, TE : minimum, FOV (field of view) : $360{\times}300\;mm$, Matrix : $256{\times}224$, slice : 6 mm, scan time : 15 sec and Breath-hold technique. Abdominal image, with a 50 ml syringe filled with water placed in the FOV measuring the water signal, were acquired with varying FA through $10^{\circ}$ to $90^{\circ}$ with $10^{\circ}$ interval. SI's were measured three times at liver parenchyme, water, spleen and background and averaged. The CNR's were measured between the ROIs (region of interest). Statistic analysis was performed with ANOVA test using SPSS software (version 17.0). Less than FA $30^{\circ}$, abdominal images were severely inhomogeneity. Especially, T1 effect of water signal was weak. As the flip angle increased, the signal intensity decreased at all the regions. Especially, flip angle of the highest signal intensity was observed with $40^{\circ}$ at the liver parenchyme, $20^{\circ}$ at water, $30^{\circ}$ at the spleen, respectively. The CNR between liver and water was -60.92 at FA $10^{\circ}$ and 15.16 at FA $80^{\circ}$. The CNR between liver and spleen was -3.18 at FA $10^{\circ}$ and 9.65 at $80^{\circ}$. In conclusion, FA $80^{\circ}$ is optimal for T1 weighted effect using FLASH pulse sequence at 3.0 T abdominal MRI.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.12 no.2
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• pp.256-262
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• 2001

Objective：The enlargement of the lateral ventricle is well established finding in adult-onset schizophrenia, but in the patients with early-onset psychotic disorder(EOPD) is still controversal. To identify structural abnormalities of the lateral ventricle in patients with EOPD and difference of the brain developmental course in EOPD group, planimetrical assessment of the lateral ventricle was conducted by means of retrospective quantitative neuroimaging. Methods：The brain MR images of 14 patients with EOPD(mean age $14.0{\pm}2.1$ years) who met the DSM-III-R diagnostic criteria for schizophrenia and bipolar disorder and 24 control subjects with simple headache(mean age $10.0{\pm}2.1$ years) were collected. Single best view for the lateral ventricle, one axial slice was selected for analysis. MR images were redigitalized with flatbed scanner and data were analyzed with NIH IMAGE software. Results：In the patients with EOPD, there were significant correlations between aging and lateral ventricular sizes and between aging and ventricular brain ratio(VBR). The statistical significance of normal asymmetry of the lateral ventricle was not observed for the EOPD group. The EOPD group had larger lateral ventricular sizes and VBR than control group, but these results were not statistically significant. Conclusion：These findings suggest that the brain abnormalities in patients with EOPD progress from the earlier course of the disorders and the course of brain development in EOPD group is different from control group.

• The Korean Journal of Nuclear Medicine
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• v.36 no.3
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• pp.166-176
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• 2002

Purpose: The purpose of this study is to investigate the effects of visual activation and quantitative analysis of regional cerebral blood flow. Visual activation was known to increase regional cerebral blood flow in the visual cortex in occipital lobe. We evaluated that change in the distribution of $^{99m}Tc-HMPAO$ (Hexamethyl propylene amine oxime) to reflect in regional cerebral blood flow. Materials and Methods: The six volunteers were injected with 925 MBq (mean ages: 26.75 years, n=6, 3men, 3women) underwent MRI and $^{99m}Tc-HMPAO$ SPECT during a rest state with closed eyes and visual stimulated with 8 Hz LED. We delineate the legion of interest and calculated the mean count per voxel in each of the fifteen slices to quantitative analysis. The ROI to whole brain ratio and regional index was calculated pixel to pixel subtraction visual non-activation image from visual activation image and constructed brain map using a statistical parameter map (SPM99). Results: The mean regional cerebral blood flow was increased due to visual stimulation. The increase rate of the mean regional cerebral blood flow which of the activation region in primary visual cortex of occipital lobe was $32.50{\pm}5.67%$. The significant activation sites using a statistical parameter of brain constructed a rendering image and image fusion with SPECT and MRI. Conclusion: Visual activation was revealed significant increase through quantitative analysis in visual cortex. Activation region was certified in Talairach coordinate and primary visual cortex (Ba17),visual association area (Ba18,19) of Brodmann.

• Progress in Medical Physics
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• v.21 no.2
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• pp.153-164
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• 2010

To determine the clinical target volumes considering vascularity and cellularity of tumors, the software was developed for mapping of the analyzed biological clinical target volumes on anatomical images using regional cerebral blood volume (rCBV) maps and apparent diffusion coefficient (ADC) maps. The program provides the functions for integrated registrations using mutual information, affine transform and non-rigid registration. The registration accuracy is evaluated by the calculation of the overlapped ratio of segmented bone regions and average distance difference of contours between reference and registered images. The performance of the developed software was tested using multimodal images of a patient who has the residual tumor of high grade gliomas. Registration accuracy of about 74% and average 2.3 mm distance difference were calculated by the evaluation method of bone segmentation and contour extraction. The registration accuracy can be improved as higher as 4% by the manual adjustment functions. Advanced MR images are analyzed using color maps for rCBV maps and quantitative calculation based on region of interest (ROI) for ADC maps. Then, multi-parameters on the same voxels are plotted on plane and constitute the multi-functional parametric maps of which x and y axis representing rCBV and ADC values. According to the distributions of functional parameters, tumor regions showing the higher vascularity and cellularity are categorized according to the criteria corresponding malignant gliomas. Determined volumes reflecting pathological and physiological characteristics of tumors are marked on anatomical images. By applying the multi-functional images, errors arising from using one type of image would be reduced and local regions representing higher probability as tumor cells would be determined for radiation treatment plan. Biological tumor characteristics can be expressed using image registration and multi-functional parametric maps in the developed software. The software can be considered to delineate clinical target volumes using advanced MR images with anatomical images.

• Radiation Oncology Journal
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• v.12 no.1
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• pp.81-90
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• 1994

Purpose : The aim of this study is to analyze the clinical results of thermo-irradiation treatment for surgically unresectable advanced hepatoma with or without hepatic arterial chemo-embolization (HACE), chemotherapy (CT) and interferon (IFN) therapy. Materials and Methods : Between February 1990 and December 1992, 45 Patients with surgically unresectable advanced hepatomas were treated by thermo-irradiation with or without hepatic arterial chemo-embolization and other treatment modalities. Among them, We analyzed retrospectively 25 patients who received more than three times of hyperthermias. Mean age was 50 years (range : 18-71 years) and male to female ratio was 20 : 5. In the study, treatment was administered as follows : 3 patients received radiation therapy(RT) and hyperthermia (HT). 3 received RT+HT+CT. 3 received RT+HT+HACE. 1 received RT+HT+CT+HACE. 2 received RT+HT+CT+IFN. 10 received RT+HT+HACE+IFN. 3 received RT+HT+CT+HACE+IFN. Radiation therapy was done by a 6 MV linear accelerator Patients were treated with daily fractions of 180 cGy to doses of 11Gy-50Gy (median 30Gy). Local hyperthermia was done by HEH-500C(Omron Co. Japan), 30-45 min/session, 2 sessions/wk and the number of HT sessions ranged from 3 to 17 (median 7 times). 15 patients of 25 were followed by abdominal CT scan or abdominal ultra-sonogram. The following factors were analyzed :Age, histologic grade, sex. number of hyperthermia, total RT dose, hepatic arterial chemo-embolization. Results : Of 25 patients. there were observed tumor regression (partial response and minimal response) in 6 (24$ \% $), no response in 8 (32$ \% $), progression in 1 (4$ \% $) and not evaluable ones in 10 (40$ \% $) radiographically. The over all 1-year survival was 25$ \% $, with a mean survival of 33 weeks. The treatment modes of partial and minimal responsive patients (PR+MR)were as follows : Two were treated with RT+HT+HACE, 2 were done with RT+HT+HACE+IFN Remaining 2 were treated with RT+HT+CT+HACE+IFN. The significant factor affecting the survival rate were RT dose (more than 25 Gy), HACE, number of HT (above 6 times), responsiveness after treatment (PR + MR). Age, sex, histologic differentiation, chemotherapy, interferon therapy were not statistically significant factors affecting the survival rate. Conclusion : Although follow-up duration was short, the thermo-irr3diBtion with/without hepatic arterial chemo-embolization was well tolerated and there were no serious complicatons. In future, it is considered the longer follow up and prospective, well controlled trials should be followed to evaluate the efficacies of survival advantage.

• Progress in Medical Physics
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• v.14 no.2
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• pp.124-130
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• 2003

Currently, as a consequence of PACS (Picture Archiving Communication System) implementation many hospitals are replacing conventional film-type interpretations of diagnostic medical images with new digital-format interpretations that can also be saved, and retrieve However, the big limitation in PACS is considered to be the lack of mobility. The purpose of this study is to determine the optimal communication packet size. This was done by considering the terms occurred in the wireless communication. After encoding medical image using JPGE2000 image compression method, This method embodied auto-error correction technique preventing the loss of packets occurred during wireless communication. A PC class server, with capabilities to load, collect data, save images, and connect with other network, was installed. Image data were compressed using JPEG2000 algorithm which supports the capability of high energy density and compression ratio, to communicate through a wireless network. Image data were also transmitted in block units coeded by JPEG2000 to prevent the loss of the packets in a wireless network. When JPGE2000 image data were decoded in a PUA (Personal Digital Assistant), it was instantaneous for a MR (Magnetic Resonance) head image of 256${\times}$256 pixels, while it took approximately 5 seconds to decode a CR (Computed Radiography) chest image of 800${\times}$790 pixels. In the transmission of the image data using a CDMA 1X module (Code-Division Multiple Access 1st Generation), 256 byte/sec was considered a stable transmission rate, but packets were lost in the intervals at the transmission rate of 1Kbyte/sec. However, even with a transmission rate above 1 Kbyte/sec, packets were not lost in wireless LAN. Current PACS are not compatible with wireless networks. because it does not have an interface between wired and wireless. Thus, the mobile JPEG2000 image viewing system was developed in order to complement mobility-a limitation in PACS. Moreover, the weak-connections of the wireless network was enhanced by re-transmitting image data within a limitations The results of this study are expected to play an interface role between the current wired-networks PACS and the mobile devices.

• Journal of the Korean Magnetics Society
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• v.26 no.3
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• pp.92-98
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• 2016

To aim of this study was to assess the full scan and half scan of imaging with half scan factor. Patients without a cerebral vascular disease (n = 30) and were subject to the full scan half scan, and set a region of interest in the cerebral artery from the three regions (C1, C2, C3) in the range of 7 to 8 mm. MIP (maximum intensity projection) to reconstruct the images in signal strength SNR (signal to noise ration), PSNR (peak signal noise to ratio), RMSE (root mean square error), MAE (mean absolute error) and calculated by paired t-test for use by statistics were analyzed. Scan time was half scan (4 minutes 53 seconds), the full scan (6 minutes 04 seconds). The mean measurement range (7.21 mm) of all the ROI in the brain blood vessel, was the SNR of the first C1 is completely scanned (58.66 dB), half-scan (62.10 dB), a positive correlation ($r^2=0.503$), for the second C2 SNR is completely scanned (70.30 dB), half-scan (74.67 dB) the amount of correlation ($r^2=0.575$), third C3 of a complete scan SNR (70.33 dB), half scan SNR (74.64 dB) in the amount of correlation between the It was analyzed with ($r^2=0.523$). Comparative full scan with half of SNR ($4.75{\pm}0.26dB$), PSNR ($21.87{\pm}0.28dB$), RMSE ($48.88{\pm}1.61$), was calculated as MAE ($25.56{\pm}2.2$). SNR is also applied to examine the half-scans are not many differences in the quality of the two scan methods were not statistically significant in the scan (p-value > .05) image takes less time than a full scan was used.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.403-410
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• 2015

The purpose of this study was to investigate the problems of a signal to noise ratio measurement using a two region measurement method that is conventionally used when using a multi-channel coil and a parallel imaging technique. As a research method, after calculating the standard SNR using a single channel head coil of which coil satisfies three preconditions when using a two region measurement method, we made comparisons and evaluations after calculating an SNR by using a two region measurement method of which method is problematic because it is used without considering the methods recommended by reputable organizations and the preconditions at the time of using a multi-channel coil and a parallel imaging technique. We found that a two region measurement method using a multi-channel coil and a parallel imaging technique shows the highest relative standard deviation, and thus shows a low degree of precision. In addition, we found out that the difference of SNR according to ROI location was very high, and thus a spatial noise distribution was not uniform. Also, 95% confidence interval through Blend-Altman plot is the widest, and thus the conformity degree with a two region measurement method using the standard single channel head coil is low. By directly comparing an AAPM method, which serves as a standard of a performance evaluation test of a magnetic resonance imaging device under the same image acquisition conditions, an NEMA method which can accurately determine the noise level in a signal region and the methods recommended by manufacturers of a magnetic resonance imaging device, there is a significance in that we quantitatively verified the inaccurate problems of a signal to noise ratio using a two region measurement method when using a multi-channel coil and a parallel imaging technique of which method does not satisfy the preconditions that researchers could overlook.

• Economic and Environmental Geology
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• v.48 no.3
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• pp.261-271
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• 2015

Toxicity results of metals, nanoparticles (NPs), and soils contaminated with metals were introduced on this review. Following methods were used: seed germination, bioluminescence, enzyme activity, and mutation. In general, different sensitivities were observed, depending on types of bioassays and pollutants. Among tested seeds, sensitivities of Lactucus and Raphanus were greater than others. Of single metal exposure, effect by As(III) was greater than others, and high revertant mutation ratio (5.1) was observed at 1 mg/L arsenite, indicating high mutagenicity. No general pattern was observed on the effect of metal mixture, but synergistic effect was observed with seeds. In case of soils, no correlation was observed between total metal contents and toxicity. Toxicity of NPs was observed as follows: CuO > ZnO > NiO > $TiO_2$, $Fe_2O_3$, $Co_3O_4$. Especially, no considerable effects were observed by $TiO_2$, $Fe_2O_3$, and $Co_3O_4$ under tested concentration (max. 1,000 mg/L). The evaluation results of interactive toxic effects using various bioassays may comprise a useful tool for the bioassessment of various environmental pollutants.

• The Korean Journal of Nuclear Medicine
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• v.26 no.1
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• pp.14-25
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• 1992

Thallium-201 $(^{201}T1)$ SPECT studies were performed on a normal volunteer and 12 patients with intracerebral lesions: 3 patients with gliomas, 3 patients with meningiomas, 1 patient each with metastatic tumor, brain abscess, and cerebral infarction, and 3 postirradiation patients. (2 with metastatic tumors, 1 with lymphoma). A $^{201}T1$ index, based on the ratio of $^{201}T1$ uptake in the brain lesion versus the homologous contralateral brain, was calculated and compared with tumor histology and CT/MRI findings. The SPECT $^{201}T1$ scan showed minimal uptake of tracer in a normal brain. There was substantial uptake of $^{201}T1$ in high-grade gliomas (index>1.5) with little uptake in low-grade lesions. A previously irradiated patient with recurrent astrocytoma, in whom MRI study was unable to distinguish tumor recurrence from necrosis, showed the lesions with high $^{201}T1$ indices in both hemispheric regions (2.50/1.93), suggesting tumor recurrence. Two meningiomas and a metastatic tumor showed varying degrees of $^{201}T1$ uptake (index $1.71\sim8.15$), revealing that $^{201}T1$ uptake is not exclusive to high-grade gliomas. In 2 postirradiation patients with metastatic tumors, no abnormal $^{201}T1$ uptake was found in the cerebral lesions, shortly after the initiation of radiation therapy or despite the persistence of enhancing lesions-though improved-on MR images, suggesting that $^{201}T1$ uptake may reflect the metabolic and possibly clonogenic activities of tumors and the brain $^{201}T1$ SPECT imaging might be valuable for the evaluation of tumor responsiveness to the therapy and for early detection of tumor recurrence. A patient with brain abscess on antibiotic treatment, showig increased uptake of $^{201}T1$ in the resolving lesions (index 2.87/1.52) is discussed. In a patient with cerebral infarction, there was no abnormal uptake of $^{201}T1$ in infarcted tissue. When using a threshold index of 1.5, correlation rate between $^{201}T1$ uptake and contrast enhancement of the cerebral lesions on CT/MRI was 73% (8/11). In conclusion, the brain $^{201}T1$ SPECT imaging may be useful for assessment of tumor response to the therapy and to predict low-or high-grade lesions.