• Title, Summary, Keyword: MRI

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Results of MRI Evaluation for the Fatty Masses (지방 종괴의 진단에 대한 MRI의 판별 능력)

  • Seo, Jae-Sung;Ahn, Jong-Chul;Kim, Jeong-Rae;Choi, Jun-Hyuk;Cho, Kil-Ho;Shin, Duk-Seop
    • The Journal of the Korean bone and joint tumor society
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    • v.11 no.1
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    • pp.25-31
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    • 2005
  • Purpose: This study was designed to know the usefulness of the MRI to distinguish lipoma and well differentiated liposarcoma (WDL). Materials and methods: 47 lipomatous tumors with MRI were reviewed among the 107 lipomatous tumors operated in our department. MRI examinations and their corresponding pathology reports were compared to determine sensitivity, specificity, diagnostic ability, positive predictable value and negative predictable value. Statistical analysis was performed to know the relationship between malignancy of the tumor (WDL) with the age and gender of the patients, and location, depth, size and the enhancement of tumors in MRI. Results: Among 28 lipoma in MRI examinations, 26 were proved as lipoma in pathology, and only 6 were WDL from 19 suspicious lesions in MRI, and others were proved as lipoma variants mostly. The varieties of lipoma variants were fibrolipoma, angiolipoma, spindle cell lipoma, lipoblastoma and angiomyolipoma. The sensitivity, specificity, diagnostic ability, positive predictable value and negative predictable value of MRI were 100%, 68 %, 72%, 31% and 100% in WDL, and 90%, 89%, 89%, 93% and 84% in lipoma. Among the variants to distinguish WDL and lipoma, the size of tumor and enhancement in MRI were significant statistically (p<0.05). Conclusion: MRI was highly sensitive in detection of WDL and highly specific in detection of simple lipoma. The size of tumor and enhancement in MRI were significant variants to distinguish WDL and lipoma. When MRI finding is non-specific, it is more likely to represent one of lipoma variants.

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PSNR Appraisal of MRI Image (MRI 영상의 PSNR 평가)

  • Kang, Kwang-Soo;Lee, Jun-Haeng
    • Journal of the Korean Society of Radiology
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    • v.3 no.4
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    • pp.13-21
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    • 2009
  • The Magnetic Resonance Imaging (MRI) systems consist of various parameters. Among them, the image quality can be arguably the most important part of the systems. As the other components in MRI systems have been developed and evolved, the MRI image quality has been advanced remarkably. And, the radiation imaging system is being converted from the Film to the digital method, which drives the computerization of many hospitals. The management of the tremendous radiation images becomes more critical. The data compression is used to store such large data in a network server. When the image files are compressed, the image quality degrades comparing to its original images. Even slight quality degradation of a medical image could cause an erroneous diagnosis, so the images must be handled carefully. This thesis studied the image assessment methods of comparing the quality of the compressed image to its original, and the quality of the original and the displayed images of the MRI systems via PSNR with actual medical images used in hospitals. As a result, no noticeable quality degradation was found comparing the compressed images with various digital compression methods and the original images. However, it was a different story comparing the original images and the displayed images on MRI monitors. Some noise or image distortion was visible using any regular CRT or LCD monitors were used while the special monitors designed for the MRI imaging and medical images displayed high definition images.

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Multiparametric MRI of Prostate Cancer after Biopsy: Little Impact of Hemorrhage on Tumor Staging

  • Choi, Moon Hyung;Jung, Seung Eun;Park, Yong Hyun;Lee, Ji Youl;Choi, Yeong-Jin
    • Investigative Magnetic Resonance Imaging
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    • v.21 no.3
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    • pp.139-147
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    • 2017
  • Purpose: To evaluate differences in staging accuracy of prostate cancer according to the extent of hemorrhage on multiparametric MRI performed after biopsy. Materials and Methods: We enrolled 71 consecutive patients with biopsy-proven prostate cancer. Patients underwent MRI followed by a prostatectomy at our institution in 2014. Two radiologists reviewed the MRI to determine the tumor stage. Correlation between biopsy-MRI interval and extent of hemorrhage was evaluated. Regression analyses were used to determine factors associated with accuracy of tumor staging. Results: The mean interval between biopsy and MRI was $17.4{\pm}10.2days$ (range, 0-73 days). The interval between prostate biopsy and MRI and the extent of hemorrhage were not significantly correlated (P = 0.880). There was no significant difference in the accuracy rate of staging between the small and large hemorrhage groups. Conclusion: Biopsy-induced hemorrhage in the prostate gland is not sufficiently absorbed over time. The extent of hemorrhage and the short interval between biopsy and MRI may not impair tumor detection or staging on multiparametric MRI.

Compressed Sensing Based Dynamic MR Imaging: A Short Survey (Compressed Sensing 기법을 이용한 Dynamic MR Imaging)

  • Jung, Hong;Ye, Jong-Chul
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.46 no.5
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    • pp.25-31
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    • 2009
  • The recently developed sampling theory, "compressed sensing" is gathering huge interest in MR reconstruction area because of its feasibility of high spatio-temporal resolution of dynamic MRI which has been limited in conventional methods based on Nyquist sampling theory. Since dynamic MRI usually has high redundant information along temporal direction, this can be very sparsely represented in most of cases. Therefore, compressed sensing that exploits the sparsity of unknown images can be effectively applied in most of dynamic MRI. This review article briefly introduces currently proposed compressed sensing based dynamic MR imaging algorithms and other methods exploiting sparsity. By comparing them with conventional methods, you may have insight how the compressed sensing based methods can impact nearly every area of clinical dynamic MRI.

Active Noise Control for Target Point Inside Bore Using Property of MRI Noise (MRI 소음의 특성을 이용한 공동 내부 목표점의 능동소음 제어)

  • Lee, Nokhaeng;Park, Youngjin;Park, Youn-Sik
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.1
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    • pp.62-68
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    • 2014
  • Recently, MRI(magnetic resonance imager) scanner is continually used for medical diagnosis and many biomedical researches. When it operates, however, intense noise is generated. The SPL(sound pressure level) of the noise approaches 130 dB especially in 3 T(Tesla) MRI. Meanwhile, more than 3 T MRI scanners have been developed to get higher-resolution images, so louder noise is expected in the future. The intense noise makes patients feel nervous and uncomfortable. Moreover, it could possibly cause hearing loss to patient in extreme cases. For this reason, some active noise control systems have been researched. One of them used feedback Filtered-X LMS(FXLMS) algorithm which is able to control only narrowband noises and possible to diverge in severe case. In this paper, we determine the property of MRI noise. Using the property, we applied a method of open-loop and adaptive control for reducing MRI noise at target point inside bore. We verified performance of the method with computer simulation and preliminary experiment. The results demonstrate that the method can effectively reduce MRI noise at target point.

Factors Influencing the Background Parenchymal Enhancement in Follow-Up Breast MRI after Adjuvant Endocrine Therapy

  • Youk, Ji Hyun;Son, Eun Ju;Kim, Jeong-Ah
    • Investigative Magnetic Resonance Imaging
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    • v.19 no.2
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    • pp.99-106
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    • 2015
  • Purpose: To investigate factors influencing the evaluation of background parenchymal enhancement (BPE) at follow-up breast magnetic resonance imaging (MRI) after adjuvant endocrine therapy. Materials and Methods: One hundred twelve women with breast cancer and MRI of the contralateral unaffected breast before and after endocrine therapy were identified. Two readers in consensus performed blinded side-by-side comparison of BPE (minimal, mild, moderate, and marked) before and after therapy with categorical scales. Age, body mass index, menopausal status, treatment regimen (selective estrogen receptor modulator or aromatase inhibitor), chemotherapy, follow-up duration, BPE at baseline MRI, MRI field strength before and after therapy, and recurrence were analyzed for their influences on decreased BPE. Results: Younger age, premenopausal status, treatment with selective estrogen receptor modulator, MRI field strength, and moderate or marked baseline BPE were significantly associated with decreased BPE. In multivariate analysis, MRI field strength and baseline BPE showed a significant association. Conclusion: MRI field strength and baseline BPE before and after therapy .were associated with decreased BPE at post-therapy, follow-up MRI.

CT and MRI image fusion reproducibility and dose assessment on Treatment planning system (치료계획시스템에서 전산화단층촬영과 자기공명영상의 영상융합 재현성 및 선량평가)

  • Ahn, Byeong Hyeok;Choi, Jae Hyeok;Hwang, Jae ung;Bak, Ji yeon;Lee, Du hyeon
    • The Journal of Korean Society for Radiation Therapy
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    • v.29 no.2
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    • pp.33-41
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    • 2017
  • Objectives: The aim of this study is to evaluate the reproducibility and usefulness of the images through the fusion of CT(Computed tomography) and MRI(Magnetic resonance imaging) using a self-manufactured phantom. We will also compare and analyze the target dose from acquired images. Materials and Methods: Using a self-manufactured phantom, CT images and MRI images are acquired by 1.5T and 3.0T of different magnetic fields. The reproducibility of the size and volume of the small holes present in the phantom is compared through the image from CT and 1.5T and 3.0T MRI, and dose changes are compared and analyzed on any target. Results: 13 small hole diameters were a maximum 31 mm and a minimum 27.54 mm in the CT scan and the were measured within an average of 29.28 mm 1 % compared to actual size. 1.5 T MRI images showed a maximum 31.65 mm and a minimum 24.3 mm, the average is 28.8 mm, which is within 1 %. 3.0T MRI images showed a maximum 30.2 mm and a minimum 27.92 mm, the average is 29.41 mm, which is within 1.3 %. The dose changes in the target were 95.9-102.1 % in CT images, 93.1-101.4 % in CT-1.5T MRI fusion images, and 96-102 % in CT-3.0T MRI fusion images. Conclusion: CT and MRI are applied with different algorithms for image acquisition. Also, since the organs of the human body have different densities, image distortion may occur during image acquisition. Because these inaccurate images description affects the volume range and dose of the target, accurate volume and location of the target can prevent unnecessary doses from being exposed and errors in treatment planning. Therefore, it should be applied to the treatment plan by taking advantage of the image display algorithm possessed by CT and MRI.

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Effective of Body Temperature Increasing during Brain MRI scan (MRI 검사 시 체온상승 효과: 1.5 T vs 3.0 T)

  • Kim, Myeong Seong;Lee, Jongwoong;Jung, Jaeeun
    • Journal of the Korean Society of Radiology
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    • v.11 no.1
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    • pp.49-54
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    • 2017
  • As the Radiofrequency(RF) increases with the magnetic field strength, the wavelength of the RF excitation field becomes smaller, which leads to more the thermal effect in the human-body placed in the electric field. MRI scanner used was GE signa 1.5T, HDx 3.0T and Philips 3.0T with same routine clinical sequence protocol. Therefore temperature was measured before and after each scan. Taken the temperatures in the ear with ear infra-red type thermometer(Braun co). 3.0T were temperature increases more than $0.15^{\circ}C$ and GE 3.0T MRI equipment about $0.14^{\circ}C$ higher than the Philips 3.0T MRI(p<0.012). Psychogenic status was investigated by the survey respondents about their status can not just answer therefore, a little different from the expected. In our study of Thermal effect of clinical MRI with clinical protocol sequence, we found that the 3.0T in the body-temperature rise was greater than the 1.5T. Therefore, in clinical 3.0T examine the dangerous situation caused by the temperature rise occurred (burns, impaired thermoregulatory mechanism in patients with high-temperature damage, exhaustion occurs due to excessive sweating), not to appear the more watched the patient's condition with procedure.

Image Evaluation Via $SUV_{LBM}$ for Normal Regions of VOI by Using Whole Body Images Obtained from PET/MRI and PET/CT (F-18 FDG PET/MRI와 PET/CT 전신 영상에서 VOI를 이용한 정상부위의 $SUV_{LBM}$-최대치에 의한 영상평가)

  • Park, Jeong-Kyu;Kim, Sung-Kyu;Cho, Ihn-Ho;Kong, Eun-Jung;Park, Meyong-Hwan
    • Progress in Medical Physics
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    • v.24 no.1
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    • pp.68-75
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    • 2013
  • The purpose of this research is to compare and analyze $SUV_{LBM}$-maximum of normal regions using VOI (the volume of interest) in order to enhance the diagnostic level in whole body images of PET/CT and PET/MRI for 26 health check-up participants. In particular, we try to set up $SUV_{LBM}$-maximum data that can be used in synchronous evaluation for PET/CT and PET/MRI without contrast media. The evaluation of $SUV_{LBM}$-maximum for normal regions of whole body PET/CT and whole body PET/MRI shows that the image of PET/MRI differs very significantly from the reference image of PET/CT (p<0.0001). However, they exhibit high correlations in view of statistics (R>0.8). From this research, we suggest that the decision in the evaluation of $SUV_{LBM}$-maximum for PET/MRI should be made with the reduction of about 26.3%, while one should decide with the reduction of about 29.3% when the contrast media is used. It is helpful to interpret all image of PET/CT and PET/MRI using $SUV_{LBM}$-maximum for convenience and efficiency.

MRI Diagnosis of the Tear Pattern of Menisci (반월상 연골판 파열 양상의 자기공명영상 진단)

  • Ahn, Jin Hwan;Ha, Chul Won;Ahn, Joong Mo;Kim, Sang Hyun
    • Journal of the Korean Arthroscopy Society
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    • v.2 no.2
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    • pp.151-154
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    • 1998
  • In the diagnosis of the meniscal tear of the knee, the high accuracy of the MRI diagnosis is well-known, but the accuracy of the MRI in the diagnosis of the very pattern of the tear of menisci is not well-established. The purpose of this study is to give some informations to consider in the diagnosis and therapeutic planning of torn menisci. The authors performed a retrospective study comparing the MRI and arthroscopic findings of 141 knees which had undergone arthroscopic surgery from Mar. 1997 to Mar. 1998. The results are as follows. In the diagnosis of tear of the menisci, MRI had sensitivity of 91%, specificity of 96%, accuracy of 95%. The mismatch of the tear patterns of the menisci between MRI and arthroscopic findings was identified in 59%, especially high in flap tear(100%), complex tear(84%), peripheral tear(55%). In conclusion, MRI is very accurate in the diagnosis of the tear of menisci, but the tear patterns of the menisci cannot be accurately determined by MRI. In the cases of flap tears, complex tears and peripheral tears, it is more difficult to determine the tear patterns of the menisci by MRI. False-negative rate of MRI was especially high(44%) in the peripheral tear type. So, other clinical correlations should be made in determination of the presence of the tear in the diagnosis of peripheral tear of the menisci.

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