• The Korean Journal of Nuclear Medicine
• /
• v.34 no.1
• /
• pp.10-21
• /
• 2000

Purpose: Episodic memory is described as an 'autobiographical' memory responsible for storing a record of the events in our lives. We performed functional brain activation study using ${H_2}^{15}O$ PET to reveal the neural basis of the encoding and the retrieval of episodic memory in human normal volunteers. Materials and Methods: Four repeated ${H_2}^{15}O$ PET scans with two reference and two activation tasks were performed on 6 normal volunteers to activate brain areas engaged in encoding and retrieval with verbal materials. Images from the same subject were spatially registered and normalized using linear and nonlinear transformation. Using the means and variances for every condition which were adjusted with analysis of covariance, t-statistic analysis were performed voxel-wise. Results: Encoding of episodic memory activated the opercular and triangular parts of left inferior frontal gyrus, right prefrontal cortex, medial frontal area, cingulate gyrus, posterior middle and inferior temporal gyri, and cerebellum, and both primary visual and visual association areas. Retrieval of episodic memory activated the triangular part of left inferior frontal gyrus and inferior temporal gyrus, right prefrontal cortex and medial temporal area, and both cerebellum and primary visual and visual association areas. The activations in the opercular part of left inferior frontal gyrus and the right prefrontal cortex meant the essential role of these areas in the encoding and retrieval of episodic memory. Conclusion: We could localize the neural basis of the encoding and retrieval of episodic memory using ${H_2}^{15}O$ PET, which was partly consistent with the hypothesis of hemispheric encoding/retrieval asymmetry.

• Neonatal Medicine
• /
• v.17 no.1
• /
• pp.64-74
• /
• 2010

Purpose : The aim of this study was to determine the risk factors, clinical characteristics and prognosis for the development of periventricular leukomalacia (PVL) in preterm infants according to the extent and site of the PVL. Methods : The medical records of infants (under 36 weeks of gestational age) delivered from January 1999 to December 2008 were reviewed. Twenty-five preterm infants with were PVL were diagnosed by brain magnetic resonance imaging (MRI) and an addition 50preterm infants with no brain lesions were enrolled in this study. The perinatal and neonatal risk factors for the development of PVL was determine in these infants. Mental and Psychomotor Developmental Indices (MDI, PDI) were assessed by a clinical psychologist using the Bayley Scales of Infant Development II. We compared the differences of the clinical characteristics and prognosis according to brain MRI findings. Results : Maternal fever, young maternal age, extended oxygen use, hypotension within the first week of birth, use of inotropics within the first week of birth, and respiratory distress syndrome were the risk factors associated with PVL (P <0.05). In the multivariate analysis, maternal fever and extended oxygen use were statistically significant independent risk factors (P <0.05). The mean MDI and PDI scores of the PVL group (74.4$\pm$ 27.8 and 58.0$\pm$17.7) were significantly lower than those of the control group (103.5$\pm$8.9 and 101.7$\pm$16.1, P <0.05). Conclusion : Maternal fever and extended oxygen use were independent risk factors for PVL. We should pay attention to infants who had the risk factors and follow them up closely by brain imaging study and Bayley Scales of Infant Development II.

• The Korean Journal of Nuclear Medicine
• /
• v.30 no.1
• /
• pp.145-151
• /
• 1996

Pathways both mediated by and independent of transferrin(Tf) and the TfR have been described for the accumulation of iron. Although it is not clear whether the same systems take up iron and gallium, these pathways may suggest the contention that uptake of Ga-67 can, in fact, occur by both Tf-independent and Tf-dependent systems and may share with Fe-59 in part the same mechanism for uptake. The predominant system by which uptake of both radiometals occurs may be different in the degree of the transformation of tumor. Transformed(MMSV/3T3) and untransformed(BALB/3T3) cells were incubated with luM of Ga-67-citrate of Fe-59-chloride for 15 min. at $37^{\circ}C$ in either the presence or absence of Tf. After then, the monolayers were washed with HBSS or PBS, and the cells were solubilized in 1% SDS for gamma well counting and protein determinations. There were similarities, as well as differences, in the pattern of uptake of Fe-59 and Ga-67 presented both in ionic from and as bound to Tf. Both radiometals appeared gain to cells in either ionic or Tf-bound forms. Transformed cells appeared to accumulate more radiometal, either Ga-67 or Fe-59 in the presence of Tf than do the their untransforemd counterparts. Conversly the presentation of either radiometal in ionic form resulted in significantly greater accumulation of metal by the untransformed cells than those transformed. The efficiency for uptake of Ga-67 or Fe-59 in the absence of Tf was greater than for uptake of the Ga-Tf or Fe-Tf. However, the magnitude of difference in efficiency of uptake was greater for Fe-59(10-fold) than for Ga-67 (3-fold). Our results Supports the theory that both Tf-independent and Tf-dependent systems for the uptake of Ga-67 both systems operate oppositely between transformed cells and those untransformed, with uptake by the predominating in transformed cells by the Tf-mediated system and in untransformed cells by the Tf-independent. The uptake of Ga-67 by tumor may share with Fe-59 in part the same mechanism.

• The Journal of Korean Orthopaedic Ultrasound Society
• /
• v.5 no.2
• /
• pp.61-65
• /
• 2012

Purpose: The aim of this study was to evaluate the effectiveness of ultrasound-guide steroid injection according to Morton's neuroma size. Materials and Methods: From October 2008 to September 2011, 17 patients (23 cases) diagnosed with Morton's neuroma were investigated. All cases were female and mean age was 52.6 years old. Neuroma were measured by the horizontal and longitudinal length of the mass and underwent ultrasound-guided steroid (5 mg dexamethasone) injection. The efficacy of the injection was determined by Visual Analogue Scale pain score and patient satisfaction(subdivided 4 group-much improved, improved, not improved, aggrevation) Results: 7 of 23(30.4%) cases showed much improved and improved satisfaction and mean longitudinal and horizontal length were $0.71{\pm}0.39cm$ and $0.47{\pm}0.24cm$, respectively. 16 of 23(69.6%) cases showed not improved and aggrevation satisfaction and mean longitudinal and horizontal length were $0.83{\pm}0.42cm$ and $0.54{\pm}0.14cm$, repectively. There was a significant difference in VAS and patient satisfaction in case longitudinal and horizontal length were smaller than 0.5 cm and 0.4 cm. (p<0.05) Conclusion: The ultrasonography is a important modality in diagnosis and treatment of morton's neuroma. Ultrasound-guide steroid injection is effective in case longitudinal and horizontal length were smaller than 0.5 cm and 0.4 cm, respectively.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.17 no.1
• /
• pp.271-278
• /
• 1987

The purpose of the present study was to investigate associations between periapical and bitewing techniques by assessing the crestal alveolar bone. This article also reports the ability of these two techniques to correctly detect evidence of interproximal dental caries, and comparison between the interproximal overlapping of teeth. Bitewing and periapical radiographs were used from posterior quardants of 243 dental students in Seoul National University. The distance from cemento-enamel junction to the alveolar crest (CEJ-AC) was measured for each proximal surface from the distal of cuspid to the distal of second molar. Data were arranged according to the proximal surface examined, and bitewing and periapical measurements were compared using paired tests. The obtained results were as follows: 1. In maxilla, a significant t ratio with a P value of 0.05 or less reached for 100% and in mandible, reached for 94%. 2. The anatomic limitations imposed on periapical radiographic technique, most often result in somewhat foreshortened radiographic images. This situation would tend to be accentuated by the anatomical restrictions of the hard palate. 3. Consequently, since the significant differences frequently exist between measurements obtained from bitewing and periapical techniques, it is important to define which technique is used. 4. The number of the interproximal overlapping was the largest medial side of the maxillary second molar, while the smallest at the distal side of the mandibular second premolar. And the overall number of the interproximal overlapping was more (538) in the periapical technique than in the bitewing technique (372). 5. The interproximal dental carious lesions were detected more (74) on the bitewing films than on the periapical ones (23). The fact was resulted from the small number of interproximal overlapping and relative easi- ness of obtaining horizontal angulation in taking the bitewing radiographs.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.1
• /
• pp.183-192
• /
• 2005

This study compared cerebral lateralization index based on the area of neural activation with that based on the intensity of neural activation. For this purpose, 8 right-handed male college students (the mean age - 23.5 years) and 10 right-handed male college students (the mean age - 25.1 years) participated respectively in researches on visuospatial and verbal task brain function. Functional brain images were taken from 3T MRI using the single-shot EPI method. The result of measuring cerebral lateralization index based on the area of neural activation suggested that the right hemisphere is dominant in visuospatial tasks and the left one is in verbal tasks. However, the dominance is not sufficient to locate the exact part of the brain for these tasks. When cerebral lateralization index was computed based on the intensity of neural activation, it was derived that the area of cerebral lateralization closely related to visuospatial tasks is the superior parietal lobe, and the area of cerebral lateralization closely related to verbal tasks is the inferior and middle frontal lobes. Thus, cerebral lateralization index by area based on the intensity of neural activation as proposed by this study can determine the dominance of the cerebrum by area, so is helpful for accurate and quantitative determination of cerebral lateralization.

• Journal of Korean Neurosurgical Society
• /
• v.29 no.1
• /
• pp.101-107
• /
• 2000

Objectives : The evaluation of peripheral nerve injuries has traditionally relied on a clinical history, physical examination, and electrodiagnostic studies. The purpose of the present study was to examine serial magnetic resonance image(MRI) changes following acute muscle denervation under experimental conditions and to identify potential advantages and disadvantages of this use of MRI. Methods : An experimental transection of right sciatic nerve on Spargue-Dawley rats was performed. MRI was performed with T1-weighted spin-echo and STIR sequences. The imaging findings were compared with EMG in order to determine its sensitivity relative to this standard procedure. A simultaneous histopathological study provided information about the morphological basis of the imaging findings. Signal intensities were expressed as a ratio of abnormal to normal. Results : The signal intensity ratio of muscles with the STIR sequence was increased significantly at 2 weeks after sciatic nerve transection(p<0.05), although definite signal change was seen as early as 4 days postdenervation in one. EMG revealed significant denervation potential from 3 days after nerve transection. Diffuse cell atrophy was revealed hostologically at 2 weeks after transection, which was at the same time of significant signal change in MRI. Conclusion : MRI signal changes in denervated muscles secondary to nerve injury correlate with the degree of muscle atrophy on histologic examination. In addition to EMG, MRI can document the course of muscle atrophy and mesenchymal abnormalities in denervation. These results indicate that MRI can play a complementary role in the evaluation of patients with denervation.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.27 no.1
• /
• pp.231-241
• /
• 1997

The aneurysmal bone cyst is a nonmalignant reactive bone lesion. Developing rarely in the craniofacial region, and more commonly affecting the long bones and the spine, the lesion has variable etiopathogenic characteristics. The authors diagnosed a 33-year-old female as aneurysmal bone cyst after undergoing clinical, radiological and histological examinations. The characteristics were as followed: 1. The patient complained of pain and swelling of the right preauricular area. 2. The conventional radiograms showed a relatively well defined radiolucent lesion with partially scalloping margin. The cortical bone of the right condyle was thinned and expanded by the lesion. 3. Bone scintigraphy with ~c demonstrated ring-like or doughnut-pattern accumulation of radioactivity. 4. On Tl-weighted imaging of MRI, the lesion on the right condyle had middle signal intensity. T2-weighted MRI demonstrated multiple high signal intensities seperated by septa which had low signal intensity. Finger in balloon appearance was seen. 5. Histologically, the lesion was composed of large sinusoidal blood spaces lined by fibroblasts and histiocytes. Its fibrous stroma consisted of fibroblstic element, multinucleated giant cells, extravasated erythrocytes and focal hemosiderin pigmentation. New bone formation was also observed around larger sinusoidal spaces.

• Imaging Science in Dentistry
• /
• v.42 no.1
• /
• pp.25-33
• /
• 2012

Purpose : This study was performed to determine the accuracy of linear measurements on three-dimensional (3D) images using multi-detector computed tomography (MDCT) and cone-beam computed tomography (CBCT). Materials and Methods : MDCT and CBCT were performed using 24 dry skulls. Twenty-one measurements were taken on the dry skulls using digital caliper. Both types of CT data were imported into OnDemand software and identification of landmarks on the 3D surface rendering images and calculation of linear measurements were performed. Reproducibility of the measurements was assessed using repeated measures ANOVA and ICC, and the measurements were statistically compared using a Student t-test. Results : All assessments under the direct measurement and image-based measurements on the 3D CT surface rendering images using MDCT and CBCT showed no statistically difference under the ICC examination. The measurements showed no differences between the direct measurements of dry skull and the image-based measurements on the 3D CT surface rendering images (P>.05). Conclusion : Three-dimensional reconstructed surface rendering images using MDCT and CBCT would be appropriate for 3D measurements.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.4
• /
• pp.221-226
• /
• 2016

Since arterial disease in the upper extremity is less common than that in the lower extremity, experimental and numerical investigations related to upper extremity have been rarely performed. We created a three-dimensional model of the arteries, larger than approximately 1 mm, in a Korean adult's left hand (from brachial to digital arteries), from 3T magnetic resonance imaging (MRI) data. For the first time, a three-dimensional computational fluid dynamic method was employed to investigate blood flow velocity, blood pressure variation, and wall shear stress (WSS) on this complicated artery system. Investigations were done on physiological blood flows near the branches of radial and deep palmar arch arteries, and ulnar and superficial palmar arch arteries. The flow is assumed to be laminar and the fluid is assumed to be Newtonian, with density and viscosity properties of plasma.