• Journal of Korea Multimedia Society
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• v.25 no.8
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• pp.1233-1241
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• 2022

Tumors of the brain are the deadliest, with a life expectancy of only a few years for those with the most advanced forms. Diagnosing a brain tumor is critical to developing a treatment plan to help patients with the disease live longer. A misdiagnosis of brain tumors will lead to incorrect medical treatment, decreasing a patient's chance of survival. Radiologists classify brain tumors via biopsy, which takes a long time. As a result, the doctor will need an automatic classification system to identify brain tumors. Image classification is one application of the deep learning method in computer vision. One of the deep learning's most powerful algorithms is the convolutional neural network (CNN). This paper will introduce a novel deep learning structure and image gradient to classify brain tumors. Meningioma, glioma, and pituitary tumors are the three most popular forms of brain cancer represented in the Figshare dataset, which contains 3,064 T1-weighted brain images from 233 patients. According to the numerical results, our method is more accurate than other approaches.

• Journal of Korean Neurosurgical Society
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• v.41 no.3
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• pp.177-179
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• 2007

Most of intradural epidermoid cyst arise as slowly growing extraaxial lesions but purely intracerebral epidermoid cysts are rare. A 39-year-old female presented with a headache during several months. Brain computed tomography [CT] scan showed a mass lesion in the both frontal lobe with heterogenous density approximately $5{\times}5cm$ in size. Magnetic resonance imaging [MRI] revealed a mass of heterogenous signal intensity on T1, T2-weighted image and faint enhancement with gadolinium [Gd]. Through the both interhemispheric approach, mass was removed subtotally except the calcified portion tightly attached to the corpus callosum. The patient discharged without neurological deficit. The authors report a case of epidermoid cyst in the corpus callosum and discuss the pathogenesis of the intraparenchymal epidermoid cyst.

• 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.

• Journal of the Korean Society of Radiology
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• v.82 no.5
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• pp.1218-1230
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• 2021

Purpose To compare the per-patient diagnostic performance of simulated abbreviated MRI (AMRI) to that of conventional MRI (CMRI) with full-sequence dynamic gadoxetic acid (GA) enhancement for early-stage hepatocellular carcinoma (HCC) screening in high-risk patients. Materials and Methods A total of 201 consecutive patients at high-risk for HCC, who underwent 3T liver MRI, were included in this retrospective study. The AMRI protocol comprised T2-weighted imaging, hepatobiliary phase imaging after GA injection, and diffusion-weighted imaging. For each patient, two AMRI and CMRI image sets were independently reviewed by two radiologists. Inter-reader agreement was assessed using Cohen's kappa value. A composite reference standard was used to determine the diagnostic performance of each image set for each reader. Results A total of 93 HCCs were detected in 79 patients. The inter-reader agreement was almost perfect for both image sets (κ = 0.839, 0.948). In AMRI, the per-patient sensitivity and negative predictive values (NPV) were 94.9% and 96.4%, respectively. In CMRI, the per-patient sensitivity and NPV were 96.2% and 97.5%, respectively. Conclusion AMRI, using only three sequences, had a comparable diagnostic performance to CMRI in screening early-stage HCC. AMRI could be an alternative HCC screening tool for high-risk HCC patients.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.187-198
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• 1990

Examinations of the temporomandibular joints were performed on a 1.5 Tesla magnetic resonance (MR) system. An MR surface receiver coil 3 inch in diameter was placed on plastic frame, the patient's head being placed in the frame so that the coil was pressed against the temporal region. In taking advantage of the magnetic resonance imaging that has been studied briskly till now, author obtained the images of parasagittal and paracoronal planes about the temporomandibular joint by using MPGR (Multi-Planar Gradient Recalled), GRASS (Gradient Recalled Acquisition in the Steady State), and CSMEMP (Contiguous Slice Multiple Echo, Multi-Planar), that differ from the Spin Echo pulse sequence which the previous authors used. Five subjects with no symptoms of temporomandibular joint pain and dysfunction were studied. The plane images obtained by these methods were compared with those by Spin Echo pulse sequence. The results were as follows: 1. The optimal repetition times (TR) and echo times (TE) for T.M.J. image were; a. 400 msec and 18 msec in PMGR pulse sequence. b. 40 msec and 12 msec in GRASS pulse sequence. c. 700 msec and 30 msec in CSMEMP pulse sequence. d. 500 msec and 20 msec in Spin Echo pulse sequence. 2. When the MPGR pulse sequence was using, T2-weighted image was obtained in very short time. On the image of the paracoronal plane by GRASS pulse sequence, meniscus showed the moderate signal intensity, and the meniscus and its anteromedial, posterolateral attachments were observed definitely with gray color. 4. The signal intensity of Spin Echo pulse sequence was equal to that of CSMEMP pulse sequence, but the image by CSMEMP pulse sequence showed relatively lower level in its resolution.

• Progress in Medical Physics
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• v.5 no.1
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• pp.3-12
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• 1994

Purporse : It is known that detection of calcification by MRI is difficulty in intracranial calcified lesions, but author tried to evaluate the signal intensity image of calcification by MR with experimental model. Subjects & Methods : Author analyzed and compared with values of calcium carbonate and hydroxyapatite phantoms by each concentration (10, 20, 30, 40, 50%) and size(1-10mm), measured ROI attenuating from CT and MRI(TlWI & T2WI). Results : The high concentration of calcium carbonate is, the lower the signal intensity of calcium carbonate phantom is both T1 & T2WI. For concentration of Hydroxyapatite of up to 30% by weight the signal intensity on standard T1 weighted images increased but subsequently decreased. Hyperintensity does not preclude calcification as a cause of the signal alteration-an observation that all radiologists interpreting MR images need to be aware of. Conclusion: The signal intensity of intracranial calcification is various on MR imaging in concerning with components, concentration, & size of calcification, and especially high signal intensity of intracranial calcification noted differencial diagnosis.

• Investigative Magnetic Resonance Imaging
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• v.8 no.2
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• pp.100-108
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• 2004

Purpose : Early degeneration of articular cartilage is accompanied by a loss of glycosaminoglycan (GAG) and the consequent change of the integrity. The purpose of this study was to biochemically quantify the loss of GAG, and to evaluate the $Gd(DTPA)^{2-}$-enhanced, and T1, T2, rho relaxation map for detection of the early degeneration of cartilage. Materials and Methods : A cartilage-bone block in size of $8mm\;\times\;10mm$ was acquired from the patella in each of three pigs. Quantitative analysis of GAG of cartilage was performed at spectrophotometry by use of dimethylmethylene blue. Each of cartilage blocks was cultured in one of three different media: two different culture media (0.2 mg/ml trypsin solution, 1mM Gd $(DTPA)^{2-}$ mixed trypsin solution) and the control media (phosphate buffered saline (PBS)). The cartilage blocks were cultured for 5 hrs, during which MR images of the blocks were obtained at one hour interval (0 hr, 1 hr, 2 hr, 3 hr, 4 hr, 5 hr). And then, additional culture was done for 24 hrs and 48 hrs. Both T1-weighted image (TR/TE, 450/22 ms), and mixed-echo sequence (TR/TE, 760/21-168ms; 8 echoes) were obtained at all times using field of view 50 mm, slice thickness 2 mm, and matrix $256\times512$. The MRI data were analyzed with pixel-by-pixel comparisons. The cultured cartilage-bone blocks were microscopically observed using hematoxylin & eosin, toluidine blue, alcian blue, and trichrome stains. Results : At quantitation analysis, GAG concentration in the culture solutions was proportional to the culture durations. The T1-signal of the cartilage-bone block cultured in the $Gd(DTPA)^{2-}$ mixed solution was significantly higher ($42\%$ in average, p<0.05) than that of the cartilage-bone block cultured in the trypsin solution alone. The T1, T2, rho relaxation times of cultured tissue were not significantly correlated with culture duration (p>0.05). However the focal increase in T1 relaxation time at superficial and transitional layers of cartilage was seen in $Gd(DTPA)^{2-}$ mixed culture. Toluidine blue and alcian blue stains revealed multiple defects in whole thickness of the cartilage cultured in trypsin media. Conclusion : The quantitative analysis showed gradual loss of GAG proportional to the culture duration. Microimagings of cartilage with $Gd(DTPA)^{2-}$-enhancement, relaxation maps were available by pixel size of $97.9\times195\;{\mu}m$. Loss of GAG over time better demonstrated with $Gd(DTPA)^{2-}$-enhanced images than with T1, T2, rho relaxation maps. Therefore $Gd(DTPA)^{2-}$-enhanced T1-weighted image is superior for detection of early degeneration of cartilage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.103-108
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• 2016

This study examined the effectiveness of the multitransmit parallel technique on the MRI scan time reduction by removing the dielectric effect. The T1 and T2 weighted images of the patients' hip joint were acquired with and without a multitransmit technique. The ROIs were located in the head of femur and iliopsoas muscle. The SNR, CNR and scan time were measured and compared. There was no difference in the images with and without multitransmit. In contrast, the acquisition time was decreased by 42.8% in T1WI and 49.7% in T2WI. In conclusion, this study demonstrated that significant scan time reductions can be accomplished without any differences in the image quality in hip joint MRI by applying the multitransmit parallel technique. Furthermore, the multitranstmit technique is useful in other body parts to resolve the long scan time of an MRI examination.

• Journal of Veterinary Clinics
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• v.26 no.1
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• pp.104-108
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• 2009

Global cerebral ischemia occurs commonly in patients who have a variety of clinical conditions including cardiac arrest and shock. Cerebral ischemia results in a rapid depletion of energy stores that triggers resulting in excitotoxic death. Imaging studies of the brain with computed tomography(CT) or magnetic resonance imaging(MRI) are necessary to confirm the clinical neurolocalization, identify any associated mass effect, and rule out other causes of focal brain disorders. Cardiopulmonary arrest was occurred by propofol anesthesia in a 1 year old, intact female Beagle dog. After successful cardiopulmonary resuscitation was performed within 5 minutes, clinical signs such as vocalization, paddling, opisthotonus and seizure were represented. At the 12th day, CT and MRI examinations of the brain were performed to evaluate the brain. After euthanasia, histopathologic examination was performed. On transverse image of CT, lesions appeared as a hypodense in the right dorsal surface of the frontal lobe and level of optic canal, and dorsomedial surface of occipital lobe of cerebrum. No contrast enhancement was represented following intravenous contrast administration. On MR images of brain, the lesions were seen as a hyperintense on T2-weighted(T2W) images and a isointense or mild hypointense on T1-weighted(T1W) images. Hyperintense lesions both T2W and T1W images were observed at the surrounding cerebral sulcus. There was no significant signal changes on contrast T1WI. Histopathologic examination after euthanasia revealed that the lesion was necrosis of the cerebral cortex caused by cerebral ischemia.

• Investigative Magnetic Resonance Imaging
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• v.15 no.2
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• pp.146-153
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• 2011

Purpose : To describe normal anatomy and compare the differences of external genital organs and urethra on MR imaging in pre- and postmenopausal women. Materials and Methods : A total of 19 pre- and 18 postmenopausal healthy women underwent pelvis MR imaging at 1.5 T. Two radiologists retrospectively scored and compared the image quality of female external genitalia and urethra on axial T2-weighted images (T2WI) and axial fat-suppressed contrast-enhanced T1-weighted images (FSCE-T1WI) by using Wilcoxon signed ranks test. The radiologists compared the wall thickness or size of external genital organs and urethra on FSCE-T1WI between two groups by using Student t test. Results : Image quality was better with FSCE-T1WI than with T2WI in all subjects (p < 0.05). The vestibular bulb, clitoris and labium minor were more clearly visualized on FSCE-T1WI in premenopausal subjects rather than in postmenopausal subjects (p < 0.05). The urethra had a target-like appearance with three layers in premenopausal and postmenopausal subjects. Postmenopausal subjects were observed to have significantly smaller vaginal wall thickness, urethral wall thickness and vestibular bulb width than premenopausal subjects (p < 0.05). Conclusion : The anatomy and morphologic changes of female external genital organs and urethra were well discernible on FSCE-T1WI.