• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4313-4319
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• 2013

The purpose of our study is to shorten the scanning time and minimize the inconveniences of the patients in acquisition of the black blood images using the signal void effect in the fast spin echo technique while keeping the diagnostic value of the test. Thirty-two consecutive patients who underwent black blood MR imaging were examed with additional double inversion recovery (DIR) sequence and the conventional fast spin echo (FSE) sequence. Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) of the internal carotid arteries' lumen were compared in T1 and T2 weighted images to determine whether there are differences between the two techniques for depiction of the signal void effect inside the vessel wall. The FSE images showed lower SNR values than the DIR images in both of the T1 and T2 weighted images (11.49% and 13.66% respectively). While the CNR values were higher in the FSE images than in the DIR images in both of the T1 and T2 weighted images (8.69% and 7.55% respectively).There was no significant difference between the two techniques for either of the SNR or CNR (p>0.05, p>0.05 respectively). The DIR and the FSE images demonstrated almost identical imaging patterns. Therefore, it is anticipated that the use of FSE technique in acquisition of the black blood imaging could reduce the inconveniences of the patients during the scanning and minimize exam time while keeping the diagnostic value of the test.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.137-137
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• 2002

목적： 동시획득 T1/T2 강조 경사자장 펄스열을 이용하여 근골격계의 종양 관류 평가를 하고자 한다. 대상 및 방법： 근골격계 양성 및 악성 종양을 대상으로 동시획득 T1/T2 강조 경사자장 펄스열을 이용하여 시간해상도를 1.2초로 하여 1000회(약20분)를 반복하여 역동적 영상을 얻는다. 각각의 TR/TE1/TE2는 10/2/8 msec이다. 각 시기에서 서로 다른 TE를 가지고 있는 두 개의 영상을 이용하여, 수학적으로 분리하여 T1과 T2 값을 얻고, 이를 시간에 따라 배열한다. 이를 통하여, T2의 경우에는 일차효과를 이용하여 조직관류량(tissue blood volume)을 측정하고, T1에서는 2구획모델을 이용하여 투과도(permeability)를 측정한다.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.953-958
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• 2021

High-altitude cerebral edema (HACE) is a potentially fatal neurological syndrome that develops in persons traveling to a high altitude. We report the case of a 49-year-old male who had traveled to a high altitude, and lost consciousness for a few hours. Susceptibility-weighted images revealed multiple, fine black pepper like microbleeds along the corpus callosum with several microbleeds in the left frontal and parietal subcortical white matter. The T2-weighted images did not show any abnormal signal intensities along the corpus callosum. The diffusion-weighted images revealed small nodular high signal intensities in the basal ganglia. This report describes the atypical radiologic findings of HACE showing multiple microbleeds along the corpus callosum, without abnormal high-signal intensity on T2-weighted images.

• The Journal of the Korea Contents Association
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• v.20 no.2
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• pp.472-477
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• 2020

The purpose of this study is to correct the error of lower weight input method as an alternative to reduce the specific absorption rate(SAR) in MRI. In order to prove that the SAR values not change according to the weight entered into the patient information, the 50kg phantom is placed in the coil and the input weight is changed from 10 to 100 in 10kg units to compare the SAR values. As a result, T1-weighted images had a SAR rate of 0.2W/kg and T2-weighted images had an average of 0.4W/kg. In conclusions, the SAR does not change according to the weight input by the technician before the scan, a lower weight when inputting patient information cannot be an alternative to reduce the SAR.

• Investigative Magnetic Resonance Imaging
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• v.7 no.2
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• pp.132-136
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• 2003

Purpose : To evaluate the usefulness of breath-hold T2-weighted MR imaging in patients with myocardial infarction. Materials and Methods : We investigated 11 patients with myocardial infarction who shown delayed enhancement on MR imaging. Infarcted myocardium on T2-weighted MR imaging was classified as high, iso, and low signal area comparing with normal myocardium. The intensity and transmural extent of infracted myocardium was also analyzed. On the basis of clinical information, the stage of infracted myocardium on T2-weighted MR imaging was assessed. Results : It was observed high signal area in 12 segments of 5 patients, low in 12 segments of 6 patients on T2-weighted MR imaging. The high signal intensity of infarcted myocardium was shown as $175{\pm}9\%$ comparing with that of the normal myocardium, low signal intensity as $73{\pm}5\%\;(p\;<\;0.05)$. In the evaluation of transmural extent, the high signal areas on T2-weighted MR imaging were larger than infarct area on delayed enhancement imaging $(100\%\;vs.49\%{\pm}17\%)$, whereas low signal areas on T2-weighted MR imaging correlated. High signal area was visualized on T2-weighted MR imaging within 11 days, whereas low-signal area was seen after 7 months. Conclusion : Breath-hold T2-weighted MR imaging is useful in the evaluation of stage as well as edema and fibrous scar in patients with myocardial infarction.

• Investigative Magnetic Resonance Imaging
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• v.10 no.2
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• pp.121-125
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• 2006

A 48-year-old man presented with a dermatofibrosarcoma protuberans (DFSP) of the scalp associated with local recurrence. Axial T1- and T2-weighted images demonstrated a well-circumscribed hypointense and intermediate hyperintense mass in the skin and subcutaneous layer of the scalp, respectively. Contrast-enhanced T1-weighted images showed the strongly enhanced mass invasion to the skin, subcutaneous layer and adjacent galeal layer. Scalp DFSP is very uncommon but is an aggressive tumor, so MR imaging diagnosis of the extent of the lesion to underlying structures, and initial wide local resection is important to prevent recurrence.

• Investigative Magnetic Resonance Imaging
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• v.5 no.1
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• pp.43-48
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• 2001

Purpose : To evaluate changes in rabbit liver parenchyma on MR images following percutaneous Holmium-166 injection, and to correlate those changes with histologic findings. Materials and methods. Holmium-166 (10-25 mCi) was percutaneously injected into the liver of rabbit (n=12) under sonographic guidance. MR images were obtained between one to two weeks (acute phasea) after the injection in four rabbits, and between two to four weeks (subacute phase) after the injection in four rabbits. Tissue specimens of these eight rabbits were obtained immediately after MR imaging. Tissue specimens were obtained without MR imaging in four rabbits (between one to two weeks in one rabbit and between three to four weeks in three rabbits). Results : Tissue specimens showed central liquefactive necrosis and peripheral coagulative necrosis containing deposition of small particles and hemorrhage. The peripheral margin of the lesions showed formation of the granulation tissue with fibrosis, which tended to be more prominent in subacute phase. The area of the necrosis tended to correlate with the dose of the radioactive Holmium-166. On MR images, the central portion of the necrosis showed hyperintensity on 72-weighted image, hypointensity on the precontrast T1-weighted images, and no enhancement on the dynamic MR images. The peripheral portion of the necrosis showed hypointensity on T2-weighted images, iso or mild hypointensity on the T1-weighted images, and mild peripheral enhancement on the delayed dynamic MR images. The peripheral margin of the lesion showed hypointensity on both T1- and T1-weighted images with increased enhancement on the delayed phase images of the dynamic MR images. Conclusion : After percutaneous Holmium-166 injection into rabbit liver parenchyma, the central portion showed liquefactive necrosis, the peripheral portion showed coagulative necrosis with granulation, fibrosis, hemorrhage and depostition of small granules. MR imaging may be helpful in evaluation of the histological change of the liver after percutaneous Holmium-166 treatment.

• 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.6
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• pp.1613-1618
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• 2021

Primary central nervous system lymphoma is a rare form of extranodal non-Hodgkin lymphoma, and primary T-cell lymphoma of the cauda equina is extremely rare. We describe a case involving a 56-year-old female who presented with low back pain and radiating leg pain for 4 months. MRI of the lumbar spine revealed an elongated, multinodular intradural lesion of approximately 10 cm from the L4 body to the S2 body level with iso-signal intensity on T1-weighted imaging, heterogeneous iso- and high-signal intensity on T2-weighted imaging, and a heterogeneous intense enhancement on gadolinium contrast-enhanced T1-weighted imaging. A peripheral T-cell lymphoma of the cauda equina was diagnosed on the basis of immunohistochemical and T-cell receptor gamma gene rearrangement analysis after intradural biopsy of the mass.

• Investigative Magnetic Resonance Imaging
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• v.17 no.3
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• pp.192-199
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• 2013

Purpose : To retrospectively evaluate the diagnostic performance of dynamic contrast-enhanced MR imaging (DCE-MRI) in detecting recurrent prostate cancer after HIFU of clinically localized cancer, as compared with T2-weighted imaging (T2WI). Materials and Methods: Twenty-six patients with increased prostate-specific antigen levels after HIFU were included in this study. All MR examinations were performed using T2WI and DCE-MRI, followed by transrectal ultrasound-guided biopsy. MRI and biopsy results were correlated in six prostate sectors. Residual or recurrent cancer after HIFU was defined as local tumor progression if biopsy results showed any cancer foci. Two independent readers interpreted the MR images. Results: Of 156 prostate sectors, 51 (33%) were positive for cancer in 17 patients. For detecting local tumor progression, the sensitivity of DCE-MRI and T2WI was 80% and 57% for reader 1 (P < 0.001) versus 84% and 61% for reader 2 (P < 0.001), respectively. The specificity and overall accuracy between DCE-MRI and T2WI showed no statistical difference in both readers (P > 0.05). Interobserver agreement of DCE-MRI and T2WI was moderate and fair, respectively. Conclusion: For detecting local tumor progression of prostate cancer after HIFU, DCE-MRI was more sensitive than T2WI, with less interobserver variability.