• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.591-602
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• 2021

Acute ischemic stroke(AIS) should be diagnosed within a few hours of onset of cerebral infarction symptoms using diagnostic radiology. In this study, we evaluated the clinical usefulness of SVD and the Bayesian algorithm to measure the volume of cerebral infarction using computed tomography perfusion(CTP) imaging and magnetic resonance diffusion-weighted imaging(MR DWI). We retrospectively included 50 patients (male : female = 33 : 17) who visited the emergency department with symptoms of AIS from September 2017 to September 2020. The cerebral infarct volume measured by SVD and the Bayesian algorithm was analyzed using the Wilcoxon signed rank test and expressed as a median value and an interquartile range of 25 - 75 %. The core volume measured by SVD and the Bayesian algorithm using was CTP imaging was 18.07 (7.76 - 33.98) cc and 47.3 (23.76 - 79.11) cc, respectively, while the penumbra volume was 140.24 (117.8 - 176.89) cc and 105.05 (72.52 - 141.98) cc, respectively. The mismatch ratio was 7.56 % (4.36 - 15.26 %) and 2.08 % (1.68 - 2.77 %) for SVD and the Bayesian algorithm, respectively, and all the measured values had statistically significant differences (p < 0.05). Spearman's correlation analysis showed that the correlation coefficient of the cerebral infarct volume measured by the Bayesian algorithm using CTP imaging and MR DWI was higher than that of the cerebral infarct volume measured by SVD using CTP imaging and MR DWI (r = 0.915 vs. r = 0.763 ; p < 0.01). Furthermore, the results of the Bland Altman plot analysis demonstrated that the slope of the scatter plot of the cerebral infarct volume measured by the Bayesian algorithm using CTP imaging and MR DWI was more steady than that of the cerebral infarct volume measured by SVD using CTP imaging and MR DWI (y = -0.065 vs. y = -0.749), indicating that the Bayesian algorithm was more reliable than SVD. In conclusion, the Bayesian algorithm is more accurate than SVD in measuring cerebral infarct volume. Therefore, it can be useful in clinical utility.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.683-690
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• 2009

The purpose of this study is to evaluate the usefulness of high-b-values diffusion weighted magnetic resonance imaging for the preoperative detection of focal rectum cancers. 60patients with diffusion weighted imaging were evaluated for the presence of rectal cancers. Forty were male and twenty were female, and their ages ranged from 38 to 71 (mean, 56) years. Used equipment was 1.5Tesla MRI((GE, General Electric Medical System, Excite HD). Examination protocols were used the fast spin echo T2, T1 weighted imaging. All examination protocols were performed by the same location with diffusion weighted imaging for accuracy detection. The b-values used in DWI were 250, 500, 750, 1000. 1500, 2000$(s/mm^2)$. The rectum, bladder to tumor contrast-to-noise ratio (CNR) of MR images were quantitativlely analyzed using GE software Functool tool, four experienced radiologists and three radiotechnologists qualitatively evaluated image quality in terms of image artifacts, lesion conspicuity and rectal wall. These data were analysed by using ANOVA and Freedman test with each b-value(p<0.05). Contrast to noise ratio of rectum, bladder and tumor in b-value 1000 were 27.21, 24.44, respectively(p<0.05) and aADC value was $0.73\times10^{-3}$. As a qualitative analysis, the conspicuity and discrimination from the rectal wall of lesions were high results as $4.0\pm0.14$, $4.4\pm0.16$ on b-value 1000(p<0.05), image artifacts were high results as $4.8\pm0.25$ on b-value 2000(p<0.05). In conclusion, DWI was provided useful information with depicting the pre-operative detection of rectal cancers, High-b-value 1000 image was the most excellent DWI value.

• Journal of radiological science and technology
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• v.32 no.1
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• pp.95-99
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• 2009

The purpose of this research is to seek SPAIR's reversal time (TI) which satisfies two conditions ; maintaining the suppression ability of fat tissue and simultaneously minimizing the inhomogeneity of fat tissue in T2 high-speed spin echo 3.0T magnetic resonance image (MRI) of the brain, and to compare SPAIR with STIR which is fat-suppression technique. The reversal times (TI) of SPAIR protocol are set to 1/2, 1/3, 1/6 and 1/12 of SPAIR TR (420 msec), namely 210 msec (8 people), 140 msec (26 people), 70 msec (26 people) and 35 msec (18 people) and STIR TI is set with 250 msec (26 people). With these parameter sets, we acquired the axis direction 104 images of the brain. In ROI ($50\;mm^2$) of output image, signal intensities of the fatty tissue, the muscular tissue, and the background were measured and the CNRs of fatty tissue and the muscular tissue were calculated. The inhomogeneity of the fatty tissue is SD/mean, where SD is the standard deviation and 'mean' is a average fatty tissue signal. Consequently, SPAIR TI is determined on either 1/3 or 1/6 of TR (420 ms) ; 140 ms or 70 ms. Because the difference of statistics in fat-suppression ability and inhomogeneity of fatty tissue is very small (p < 0.001), Selecting 140 ms seems to be better choice for the image quality. Meanwhile, Comparing SPAIR (TI : 140 ms) with STIR, the fat-suppression is not able to be considered statistically (p < 0.252), but the image quality is able to be considered statistically (p < 0.01). In conclusion, SPAIR is better than STIR in the image quality.

• Journal of Radiation Protection and Research
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• v.33 no.2
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• pp.47-51
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• 2008

Objective: This study analyzed errors due to rotation or tilt of the magnetic resonance (MR) imaging indicator during image acquisition for a stereotactic radiosurgery. The error correction procedure of a commercially available stereotactic neurosurgery treatment planning program has been verified. Materials and Methods: Software virtual phantoms were built with stereotactic images generated by a commercial programming language, Interactive Data Language (version 5.5). The thickness of an image slice was 0.5 mm, pixel size was $0.5{\times}0.5mm$, field of view was 256 mm, and image resolution was $512{\times}512$. The images were generated under the DICOM 3.0 standard in order to be used with Leksell GammaPlan$^{(R)}$. For the verification of the rotation error correction function of Leksell GammaPlan$^{(R)}$, 45 measurement points were arranged in five axial planes. On each axial plane, there were nine measurement points along a square of length 100 mm. The center of the square was located on the z-axis and a measurement point was on the z-axis, too. Five axial planes were placed at z=-50.0, -30.0, 0.0, 30.0, 50.0 mm, respectively. The virtual phantom was rotated by $3^{\circ}$ around one of x, y, and z-axis. It was also rotated by $3^{\circ}$ around two axes of x, y, and z-axis, and rotated by $3^{\circ}$ along all three axes. The errors in the position of rotated measurement points were measured with Leksell GammaPlan$^{(R)}$ and the correction function was verified. Results: The image registration errors of the virtual phantom images was $0.1{\pm}0.1mm$ and it was within the requirement of stereotactic images. The maximum theoretical errors in position of measurement points were 2.6 mm for a rotation around one axis, 3.7 mm for a rotation around two axes, and 4.5 mm for a rotation around three axes. The measured errors in position was $0.1{\pm}0.1mm$ for a rotation around single axis, $0.2{\pm}0.2mm$ for double and triple axes. These small errors verified that the rotation error correction function of Leksell GammaPlan$^{(R)}$ is working fine. Conclusion: A virtual phantom was built to verify software functions of stereotactic neurosurgery treatment planning program. The error correction function of a commercial treatment planning program worked within nominal error range. The virtual phantom of this study can be applied in many other fields to verify various functions of treatment planning programs.

• Journal of Korean Neurosurgical Society
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• v.63 no.1
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• pp.89-98
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• 2020

Objective : Ossification of posterior longitudinal ligament (OPLL) in the thoracic spine may cause chronic compressive myelopathy that is usually progressive, and unfavorable by conservative treatment. Although surgical intervention is often needed, the standard surgical method has not been established. Recently, it has been reported that posterior decompression with dekyphosis is effective surgical technique for favorable clinical outcome. The purpose of this study was to evaluate the surgical outcomes in patients with thoracic OPLL according to dekyphosis procedure and to identify predictive factors for the surgical results. Methods : A total of 25 patients with thoracic OPLL who underwent surgery for myelopathy from May 2004 to March 2017, were retrospectively reviewed. Patients with cervical myelopathy were excluded. We assessed the clinical outcomes according to various surgical approaches. The modified Japanese orthopedic association (JOA) scores for the thoracic spine (total, 11 points) and JOA recovery rates were used for investigating surgical outcomes. Results : Of the 25 patients, 10 patients were male and the others were female. The mean JOA score was 6.7±2.3 points preoperatively and 8.8±1.8 points postoperatively, yielding a mean recovery rate of 53.8±31.0%. The mean patients' age at surgery was 52.4 years and mean follow-up period was 40.2 months. According to surgical approaches, seven patients underwent anterior approaches, 13 patients underwent posterior approaches, five patients underwent combined approaches. There was no significant difference of the surgical outcomes related with different surgical approaches. Age (≥55 years) and high signal intensity on preoperative magnetic resonance (MR) image in the thoracic spine were significant predictors of the lower recovery rate after surgery (p<0.05). Posterior decompression with dekyphosis procedure was related to the excellent surgical outcomes (p=0.047). Dekyphosis did not affect the complication rates. Conclusion : In this study, our result elucidated that old age (≥55 years) and presence of intramedullary high signal intensity on preoperative MR images were risk factors related to poor surgical outcomes. In the meanwhile, posterior decompression with dekyphosis affected favorable clinical outcome. Posterior approach with dekyphosis procedure can be a recommendable surgical option for favorable results.

• Korean Journal of Applied Biomechanics
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• v.12 no.1
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• pp.233-249
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• 2002

The purpose of this study was to employing MRI in the estimation of the biomechanical body segment parameters of Korean adults. for this purpose MRI study on 19 Korean living subjects were used to measurement. All the parameters that was concerned were inertial characteristics of human body mass of each segment, center of mass of them and the length of radius of gyration of them. The cross sectional images and saggital images of every 1cm interval were got using the 0.5 Tesla MRI from the top of head to the bottom of foot, whole body. And then, by tracing the images of the film and scanning them, got the area which the several tissues occupied in the image of slice. By summing the area of slice of each segment which were calculating and by multipling the density of the tissues, got the mass of segment and other inertial characteristics. The ratios of radius of gyration in both transverse axis and longitudinal axis though the segmental mass and segment length are as follow: male A : head($0.229\pm0.0029$), neck($0.256\pm0.0095$), thorax($0.374\pm0.0059$) abdomen($0.245\pm0.0020$), pelvis($0.368\pm0.0106$), thigh($0.288\pm0.0030$) shank($0.280\pm0.0043$), foot($0.277\pm0.0195$), upperarm($0.311\pm0.0074$) forearm($0.286\pm0.0051$), hand($0.253\pm0.0095$) female A : head($0.214\pm0.0032$), neck($0.254\pm0.0112$), thorax($0.295\pm0.0061$) abdomen($0.289\pm0.0021$), pelvis($0.329\pm0.0108$), thigh($0.288\pm0.0036$) shank($0.280\pm0.0047$), foot($0.243\pm0.0206$), upperarm($0.279\pm0.0083$) forearm($0.286\pm0.0048$), hand($0.229\pm0.0097$) male B : head($0.532\pm0.0006$), neck($0.533\pm0.0006$), thorax($0.658\pm0.0008$) abdomen($1.350\pm0.0022$), pelvis($0.875\pm0.0002$), thigh($0.213\pm0.0001$) shank($0.160\pm0.0001$), foot($0.152\pm0.0002$), upperarm($0.136\pm0.0002$) forearm($0.202\pm0.0002$), hand($0.273\pm0.0006$) female B : head($0.198\pm0.0002$), neck($0.335\pm0.0011$), thorax($0.238\pm0.0001$) abdomen($0.888\pm0.0001$), pelvis($1.318\pm0.0117$), thigh($0.095\pm0.0001$) shank($0.075\pm0.0001$), foot($0.181\pm0.0006$), upperarm($0.0.062\pm0.0001$) forearm($0.083\pm0.0001$), hand($0.105\pm0.0007$).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.786-792
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• 2013

In this study was explored minimize side effects due to the additional injection of contrast medium and maintaining a high resolution imaging applied to the inspection and analysis of the contrast medium that affect the peak time biomechanics factors. Included 48 patients using the test bolus method, after measuring a patient's biomechanics factors of inspection before and during the test, correlation between contrast medium peak time and learn, matches the regression equation calculated and measured contrast medium peak time was assessed by the Bland Altman plot. Research result, inspections of SBP, HR contrast medium peak time and a significant negative correlation was, step 1, every increase, the contrast medium peak time significantly to -0.018 and -0.159 decreased, a fairly high concordance no difference between the two method. In conclusion, the regression equation using the existing methods, while maintaining excellent image quality that contrast medium is reduced to a patient, it can conclude that the alternative to the existing methods.

• The Journal of the Korea Contents Association
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• v.17 no.7
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• pp.437-442
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• 2017

Previously, studies on compensation material to increase the signal intensity have been conducted which does not affect the reading of images. However, the compensation material has a concern on patient infection as it is attached directly on the skin. Therefore, in this study, we tested an indirect attachment of the compensation material as an alternative method of the direct attachment. The silicon compensation material was fabricated in the form of a cylindrical bar and attached to each element of the 8 channel head coil. Then the signal intensities of the water phantom pre and post application of the silicon were measured. T1 and T2-weighted images were acquired using an 8-channel head coil and a 3.0T superconducting MRI. Signal intensities were measured by using an image measuring program. Paired t-test was used to verify if there were significant differences. The signal intensity before application of the silicon was significantly increased by 3.39% and 2.62% in T1 and T2 weighted images, respectively. Although the indirect attachment method had a limitation to completely replace the existing method, it was considered to be useful in patients with infectious diseases such as diabetic complications since it had a meaningful improvement in signal intensity based on the filling factor increase.

• Science of Emotion and Sensibility
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• v.14 no.2
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• pp.227-234
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• 2011

The purpose of present study was to examine brain functions associated with intention to conceal information. Kubo & Nittono(2009) and Verschuere et al.(2009) studied the intention to conceal information using P300 amplitude. On the basis of these two studies, present study attempted to identify brain area while participants were performing concealed information test. 19 healthy college students participated in fMRI-based concealed information test. Participants' name were used as concealed information. The test was performed in two conditions. In the intention condition, participants were instructed to try leaving their names undetected by suppressing their brain response to it. In the no intention condition, participants performed the test without intention to conceal. The fMRI results showed that the right anterior cingulated cortex (Rt. ACC), and left orbito-frontal cortex (Lt. OFC) activations were greater in the deceptive condition than the truth condition. These finding confirmed that ACC is area a deception-specific process as shown in the previous fMRI study. The OFC activation was also observed in the deceptive condition. The OFC is an area known as associated with emotional response such as anxiety, fear, and guilty. The anxiety induced while participants were intended to conceal information might be related to the OFC activation.

• Korean Journal of Cognitive Science
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• v.18 no.2
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• pp.159-178
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• 2007

Lee & Kang (2002) showed that simultaneous phonological rehearsal significantly delayed the performance of multiplication but not subtraction, whereas holding an image in the memory delayed subtraction but not multiplication. This result indicated that arithmetic function is related to working memory in a subsystem-specific manner. The aim of the current study was to examine the neural correlates of previous finding using fMRI. For this goal, dual task conditions that required suppression or no suppression were manipulated. In general, several areas were more activated in the interference conditions than in the less interference conditions, although both conditions were dual condition. More important finding is that the specific areas activated in the phonological suppression rendition were right inferior frontal gyrus, left angular, and inferior parietal lobule, while the areas activated in the other condition were mainly in the right superior temporal gyrus and anterior cingulate gyrus. Furthermore, the areas activated in the phonological or visual less suppression condition were right medial frontal gyrus, left middle frontal gyrus, and bilateral medial frontal gyri, anterior cingulate cortices, and parahippocampal gyri, respectively. These results revealed that sharing the processing code invokes interference, and its neural basis.