• Journal of Korea Multimedia Society
• /
• v.15 no.9
• /
• pp.1075-1085
• /
• 2012

In clinical research using medical images, the image segmentation is one of the most important processes. Especially, the hippocampal atrophy is helpful for the clinical Alzheimer diagnosis as a specific marker of the progress of Alzheimer. In order to measure hippocampus volume exactly, segmentation of the hippocampus is essential. However, the hippocampus has some features like relatively low contrast, low signal-to-noise ratio, discreted boundary in MRI images, and these features make it difficult to segment hippocampus. To solve this problem, firstly, We selected region of interest from an experiment image, subtracted a original image from the negative image of the original image, enhanced contrast, and applied anisotropic diffusion filtering and gaussian filtering as preprocessing. Finally, We performed an image segmentation using two level set methods. Through a variety of approaches for the validation of proposed hippocampus segmentation method, We confirmed that our proposed method improved the rate and accuracy of the segmentation. Consequently, the proposed method is suitable for segmentation of the area which has similar features with the hippocampus. We believe that our method has great potential if successfully combined with other research findings.

• Proceedings of the KSMRM Conference
• /
• 2003.10a
• /
• pp.20-20
• /
• 2003

Purpose： To investigate the difference of fractional anisotropy (FA) values between 6- and 25-direction diffusion tensor images (DTI) in normal adult brain. Materials and Methods： DTI was peformed in 28 normal subjects (15 subjects with 6-direction, 13 subjects with 25-direction) in a 1.5 T MR system. DTI was done with SE-EPI sequence with TR/TE/NEX 10000/84/1, 5mm slice thickness and b=1000 s/mm2. FA values were measured from 8 different anatomical locations which included both cerebral peduncles, both posterior limbs of the internal capsules, both corona radiata, genu and splenium of the corpus callosum. Statistical difference of FA was tested between 6-and 25-direction DTI.

• Investigative Magnetic Resonance Imaging
• /
• v.16 no.2
• /
• pp.184-188
• /
• 2012

Anoperineal tuberculosis is a rare extrapulmonary form of the disease and may present as abscess. We report a case of anoperineal tuberculous abscess, which showed low signal intensity on T1-weighted images, high signal intensity on T2-weighted images and diffusion restriction on diffusion weighted images.

• Journal of the Korean Society of Radiology
• /
• v.2 no.2
• /
• pp.31-38
• /
• 2008

Line scan diffusion weighted imaging (LSDI) pulse sequence for 0.32 T magnetic resonance imaging (MRI) system was developed. In the LSDI pulse sequence, the imaging volume is formed by the intersection of the two perpendicular planes selected by the two slice-selective $\pi$/2-pulse and $\pi$-pulse and two diffusion sensitizing gradients placed on the both side of the refocusing $\pi$-pulse and the standard frequency encoding readout was followed. Since the maximum gradient amplitude for the MR system was 15 mT/m the maximum b value was $301.50s/mm^2$. Using the developed LSDI pulse sequence, the diffusion weighted images for the aqueous NaCl solution phantom and triacylglycerol solution phantom calculated from the line scan diffusion weighted images gives the same results within the standard error range (mean diffusivities = $963.90{\pm}79.83({\times}10^{-6}mm^2/s)$ at 0.32 T, $956.77{\pm}4.12({\times}10^{-6}mm^2/s)$ at 1.5 T) and the LSDI images were insensitive to the magnetic susceptibility difference and chemical shift.

• Journal of the Korean Society of Radiology
• /
• v.10 no.4
• /
• pp.241-246
• /
• 2016

The purpose of this study was to investigate the problems of low signal-to-noise ratio(SNR) of single-shot turbo spin echo(SS-TSE) by quantifying numerically decreased signal to noise ratio. Thirty five patients without brain disease underwent diffusion MRI in 3T scanner from July to October in 2015. Single shot echo planar imaging(SS-EPI) which is conventionally used in MRI was taken to compared SS-TSE in SNR of medulla oblongata. As a result, SNR of SS-TSE diffusion(b0=$314.41{\pm}42.96$, b1000=$117.33{\pm}14.04$) is than SS-EPI diffusion(b0=$514.84{\pm}48.97$, b=$208.65{\pm}25.70$) lower in b=0 image(38.9%) and b=1,000 image(43.8%). Thus, diffusion MR using SS-EPI of MS-EPI should be taken for diagnosis of disease in brain stem due to decreased SNR of diffusion using SS-TSE.

• Journal of radiological science and technology
• /
• v.34 no.3
• /
• pp.239-244
• /
• 2011

In this study, we evaluated diffusion weighted imaging (DWI) to investigate whether the DWI parameters can predict characteristic parameters on pathologic specimens of tumor or not. CFPAC-1 was injected subcutaneously on the back flank of athymic nude mice (n=13) then two tumors were initiated on each mouse (2${\times}$13=26 tumors). The mice were sacrificed to make specimen immediately after initial MR imaging then were compared with the MR image. A dedicated high-field (7T) small-animal MR scanner was used for image acquisitions. A T1 and T2 weighted axial image using RARE technique was acquired to measure the T2 values and tumor size. DWI MR was performed for calculating ADC values. To evaluate tumor cellularity and determine the levels of MVD, tumor cells were excised and processed for H-E staining and immunostaining using CD31. T2 values and ADC values were computed and analyzed for each half of the tumors and compared to the correlated specimens slide. Median ADC within each half of mass was compared to the cellularity and MVD in the correlated area of pathologic slide. The mean of ADC value is $0.7327{\times}10^{-3}$ $mm^2/s$ and standard deviation is $0.1075{\times}10^{-3}$ $mm^2/s$. There is a linear relationship between ADC value and tumor necrosis (R2=0.697, p< 0.001). DW image parameters including the ADC values can be utilized as surrogate markers to assess intratumoral neoangiogenesis and change of the internal structure of tumor cells.

• Investigative Magnetic Resonance Imaging
• /
• v.7 no.2
• /
• pp.116-123
• /
• 2003

Purpose : The present study was undertaken to evaluate the usefulness of cerebral diffusion (DWI) and perfusion MR imaging (PWI) in rabbit models with hyperacute cerebral ischemic infarction. Materials and Methods : Experimental cerebral infarction were induced by direct injection of mixture of Histoacryl glue, lipiodol, and tungsten powder into the internal cerebral artery of 6 New-Zealand white rabbits, and they underwent conventional T1 and T2 weighted MR imaging, DWI, and PWI within 1 hour after the occlusion of internal cerebral artery. The PWI scan for each rabbit was obtained at the level of lateral ventricle and 1cm cranial to the basal ganglia. By postprocessing using special imaging software, perfusion images including cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) maps were obtained. The detection of infarcted lesion were evaluated on both perfusion maps and DWI. MTT difference time were measured in the perfusion defect lesion and symmetric contralateral normal cerebral hemisphere. Results : In all rabbits, there was no abnormal signal intensity on T2WI. But on DWI, abnormal high signal intensity, suggesting cerebral infarction, were detected in all rabbits. PWI (rCBV, CBF and MTT map) also showed perfusion defect in all rabbits. In four rabbits, the calculated square of perfusion defect in MTT map is larger than that of CBF map and in two rabbits, the calculated size of perfusion defect in MTT map and CBF map is same. Any rabbits do not show larger perfusion defect on CBF map than MTT map. In comparison between CBF map and DWI, 3 rabbits show larger square of lesion on CBF map than on DWI. The others shows same square of lesion on both technique. The size of lesion shown in 6 MTT map were larger than DWI. In three cases, the size of lesion shown in CBF map is equal to DWI. But these were smaller than MTT map. The calculated square of lesion in CBF map, equal to that of DWI and smaller than MTT map was three. And in one case, the calculated square of perfusion defect in MTT map was largest, and that of DWI was smallest. Conclusion : DWI and PWI may be useful in diagnosing hyperacute cerebral ischemic infarction and in e-valuating the cerebral hemodynamics in the rabbits.

• Journal of radiological science and technology
• /
• v.32 no.3
• /
• pp.313-323
• /
• 2009

Diffusion-weighted imaging (DWI) has been demonstrated to be a practical method for the diagnosis of various brain diseases such as acute infarction, brain tumor, and white matter disease. In this study, we used two techniques to examine the average signal intensity (SI) and apparent diffusion coefficient (ADC) of the brains of patients who ranged in age from 10 to 60 years. Our results indicated that the average SI was the highest in amygdala (as derived from DWI), whereas that in the cerebrospinal fluid was the lowest. The average ADC was the highest in the cerebrospinal fluid, whereas the lowest measurement was derived from the pons. The average SI and ADC were higher in $T_2^*$-DW-EPI than in FLAIR-DW-EPI. The higher the b-value, the smaller the average difference in both imaging techniques; the lower the b-value, the greater the average difference. Also, comparative analysis of the brains of patients who had experienced cerebral infarction showed no distinct lesion in the general MR image over time. However, there was a high SI in apparent weighted images. Analysis of other brain diseases (e.g., bleeding, acute, subacute, chronic infarction) indicated SI variance in accordance with characteristics of the two techniques. The higher the SI, the lower the ADC. Taken together, the value of SI and ADC in accordance with frequently occurring areas and various brain disease varies based on the b-value and imaging technique. Because they provide additional useful information in the diagnosis and treatment of patients with various brain diseases through signal recognition, the proper imaging technique and b-value are important for the detection and interpretation of subacute stroke and other brain diseases.

• Investigative Magnetic Resonance Imaging
• /
• v.17 no.2
• /
• pp.101-109
• /
• 2013

Objective: To investigate roles of dynamic contrast enhanced magnetic resonance (DCE MR) and diffusion-weighted (DW) imaging in preoperative prediction of underestimation of ductal carcinoma in situ (DCIS) ${\geq}2cm$ on US guided core needle biopsy. Materials and Methods: Twenty two patients with DCIS on US-guided 14 gauge core needle biopsy were included. Patients were divided into a group with and without DCIS underestimation based on histopathology. MR images including DCE and DW imaging were obtained with a 3.0-T MR. The lesion type (mass or non-mass), enhancement pattern, peak enhancement, and apparent diffusion coefficient (ADC) values of proven malignant masses were generated using software of CADstream and compared between two groups using Fisher's exact test and Mann Whitney test. Results: Eight patients were in the group with underestimation and 14 patients were in the group without underestimation. The lesion type and enhancement pattern were not different between two groups (P values = 1.000 and 0.613, respectively). The median peak enhancement of lesions with underestimation was 159.5%, higher than 133.5% of those without underestimation, but not significant (P value = 0.413). The median ADC value of lesions with underestimation was $1.26{\times}10^{-3}mm^2/sec$, substantially lower than $1.35{\times}10^{-3}mm^2/sec$ of those without underestimation (P value = 0.094). Conclusion: ADC values had the potential to preoperatively predict DCIS underestimation on US-guided core needle biopsy, although a large prospective series study should be conducted to confirm these results.

• Journal of Korean Neurosurgical Society
• /
• v.54 no.1
• /
• pp.19-24
• /
• 2013

Objective : The purpose of this study was to retrospectively evaluate and compare the incidence of diffusion-weighted image (DWI) lesions between the Guglielmi detachable coil (GDC) and the Target coil for treating unruptured intracranial aneurysm. Methods : From 2010 to 2011, consecutive 222 patients with an intracranial aneurysm underwent coil embolization. Inclusion criterias were : 1) unruptured intracranial aneurysm, 2) one or more GDC or Target coils used with or without other coils, 3) DWI examination within 24 hours after coiling, and 4) coiling performed without a balloon or stent. Results : Ninety patients (92 cases) met the inclusion criteria. DWI lesions were detected in 55 (61.1%) of 90 patients. In the GDC group (n=44), DWI lesions were detected in 31 (70.5%). The average number of DWI lesions was $5.0{\pm}8.7$ (mean${\pm}$SD; range, 1-40) in aneurysm-related territory. In the Target coil group (n=48), DWI lesions were detected in 24 (50.0%). The number of DWI lesion was $2.1{\pm}5.4$ (range, 1-32) in aneurysm-related territory. There was no significant correlation between a number of coils and DWI lesions. No significant differences were also observed in the number of DWI lesions in each group. Conclusion : The GDC and Target coils, which have an electrolytic detachable system, showed no differences in the incidence of DWI lesion.