• Title, Summary, Keyword: Signal Intensity

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THE RELATIVE SIGNAL INTENSITY OF RETRODISCAL TISSUE IN TMJ USING A T2-WEIGHTED MRI (MRI T2강조영상에서 측두하악관절 원판 후 조직의 상대적 신호 강도에 대한 연구)

  • Ye, Young-Geun;Lee, Sang-Hwa;Yoon, Hyun-Joong
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.27 no.5
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    • pp.457-462
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    • 2005
  • The aim of this study is to evaluate the relative signal intensity of TMJ retrodiscal tissue in T2-weighted MRI as diagnostic marker of temporomandibular disorder(TMD). 58 temporomandibular joints from 29 TMD patients (14 men & 15 women) were evaluated. The relative signal intensity of retrodiscal tissue in T2-weighted MRI was referenced to brain gray matter same size of the region of interest(ROI). The collected data was compared to disc positions (normal, anterior disc displacement with reduction, anterior disc displacement without reduction), the presence of joint effusion. The relative signal intensity of retrodiscal tissue was significantly increased when the disc was displaced without reduction. And the relative signal intensity of retrodiscal tissue was significantly increased when joint effusion was present. The results suggest that evaluating the relative signal intensity of TMJ retrodiscal tissue using a T2-weighted MRI is valuable as a non-invasive tool for diagnosing the procession of TMD.

THE MRI-BASED COMPARISON OF NORMAL- AND ABNORMAL-SIDE RETRODISCAL TISSUE, AND RELATIONSHIP BETWEEN CLINICAL EXAMINATION & THE MRI FINDINGS OF RETRODISCAL TISSUE IN PATIENTS WITH UNILATERAL TMJ INTERNAL DERANGEMENT (편측 악관절 내장증 환자에서 비이환측과 이환측의 자기공명영상 소견상 원판후 조직의 비교 및 임상소견과의 관계)

  • Yoon, Hyun-Joong;Park, Chul-Hong;Kim, Jin
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.28 no.4
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    • pp.330-335
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    • 2002
  • The study was performed to investigate the comparison of relative signal intensity of normal- and abnormal-side retrodiscal tissue, and relationship between clinical examination, joint effusion and relative signal intensity of retrodiscal tissue in patients with unilateral TMJ internal derangement. The study group comprised 19 females and 9 males, with a mean age of 29 years. After measurements of the signal intensity were made on the MR imager for the T2 weighted images on retrodiscal tissue and brain gray matter, we calculated relative value and tried to find relationship between clinical examination, joint effusion and relative signal intensity on normal- and abnormal-side. The results are as follows. 1. The gray matter is an appropriate reference point. 2. The relative signal intensity is high significantly in abnormal-side retrodiscal tissue compared with normal-side retrodiscal tissue. 3. The relative signal intensity is high significantly in painful joints compared with nonpainful joints and in joints with joint effusion compared with joints without joint effusion. 4. The relative signal intensity in normal joints, joints with reduction and joints without reduction is increased in order significantly.

Hepatic Lymphoma Representing Iso-Signal Intensity on Hepatobiliary Phase, in Gd-EOB-DTPA-Enhanced MRI: Case Report

  • Ahn, Tae-Ran;Kim, Yeo-Eun;Park, Chul-Hi;Jung, Eun-Ah
    • Investigative Magnetic Resonance Imaging
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    • v.19 no.3
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    • pp.200-204
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    • 2015
  • Image findings of hepatic lymphoma have been reported as variable, ranging from single or multiple small nodules to diffuse infiltrative patterns. On MRI, most hepatic lymphomas show T1 low signal intensity, T2 high signal intensity. Dynamic imaging reveals a hypointense appearance in the arterial phase, followed by delayed enhancement in the portal venous and transitional phase. In the hepatobiliary phase using a hepatocyte-specific contrast agent (which have recently aided in increasing the access to the focal liver lesions), hepatic lymphoma is known to exhibit low signal intensity. We report a case of hepatic lymphoma, which shows iso-signal intensity on hepatobiliary phase, using gadoxetic acid (Gd-EOB-DTPA).

Magnetic resonance imaging signal intensity of temporomandibular joint disk and posterior attachment in patients with internal derangement (측두하악관절 내장 환자의 관절원판과 관절원판 후조직의 자기공명영상 신호강도)

  • Jeong Yeon-Hwa;Cho Bong-Hae
    • Imaging Science in Dentistry
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    • v.31 no.2
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    • pp.93-99
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    • 2001
  • Purpose: To analyze the possible association between magnetic resonance imaging signal intensity of temporomandibular joint disk and posterior attachment, and the type and extent of disk displacement, disk configuration, effusion and clinical signs in patients with internal derangement. Materials and Methods: Magnetic resonance images of the 132 temporomandibular joints of 66 patients with temporomandibular joint displacement were analyzed. The clinical findings were obtained by retrospective review of the patients' records. The type and extent of disk displacement, disk configuration and effusion were evaluated on the proton density MR images. The signal intensity from the anterior band, posterior band and posterior attachment were measured on MR images. The associations between the type and extent of disk displacement, disk configuration, effusion and clinical signs and the MR signal intensity of disk and posterior attachment were statistically analyzed by student's t-test. Results: Of 132 joints, 87 (65.9%) showed anterior disk displacement with reduction (ADR) and 45 (34.1%) showed anterior disk displacement without reduction (ADnR). The signals from posterior attachments were lower in joints with ADnR than those of ADR (p<0.05). The results showed statistically significant (p<0.05) association between the type and extent of disk displacement and disk configuration, and decreased signal intensity of posterior attachment. There were no statistical associations between pain, noise and limited mouth opening, and signal intensity of disk and posterior attachment. Conclusions: The average signal from posterior attachment was lower in joints with ADnR than that of ADR. The type and extent of disk displacement and disk configuration appeared to be correlated with the signal intensity from posterior attachment.

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Analysis of Distances for MRI Scan to Maintain Pptimal Signal Intensity in a Surface Coil (MRI 검사 시 코일내 최적의 신호강도를 유지할 수 있는 거리의 기준 분석)

  • Son, Soon-Yong
    • The Journal of the Korea Contents Association
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    • v.18 no.10
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    • pp.158-164
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    • 2018
  • The purpose of this study is to statistically analyze the signal intensity pattern according distance from the surface coil center and to maintain optimal signal intensity under clinical circumstances where the surface coil centers are not correctly positioned due to various causes. The cylindrical fluid phantom was placed and moved from the coil center in vertical direction with 1 cm increments. The signal intensities were measured and compared. As a result, the signal intensity showed no significant difference within 4 cm and 1 cm from in T1 weighted images while in T2 weighted images the signal intensity was maintained up to 5 cm and lower 3 cm in the upper and lower direction from the coil center. In conclusion, to maintain the optimal signal intensity the target region should be located within the reference distances proposed in this study.

A STUDY ON THE CHANGES OF MR SIGNAL INTENSITY OF POSTERIOR ATTACHMENT OF THE TEMPOROMANDIBULAR JOINT (악관절 후방부착부에 있어서 MRI 신호변화에 대한 고찰)

  • Jung, Joo-Sung;Huh, Won-Shil;Chung, Hoon
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.19 no.1
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    • pp.93-107
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    • 1997
  • Magnetic resonance imaging has been used in the temporomandibular joint(TMJ) primarily to define morphology and positional relationship of associating structures. This report examines signal intensity characteristics of the posterior attachment as they related to the severity of internal derangement. Fifty six joints in 35 patients with a history of TMJ dysfunction were imaged writ MR using $T_1$-weighted spin echo sequence. According to disk position, ability to reduction, and the presence of osteoarthritis, the joints were categorized into three groups. A group 1 was anterior disk displacement with reduction; a group 2 was anterior disk displacement without reduction; a group 3 was anterior disk displacement without reduction and condyle had osteoarthritic change. The control group was determined by the clinical absence of any signs or symptoms of current or past TMJ pain and dysfunction. Calculated the relative value of MR signal intensity in posterior attachment and disk to cerebral cortex of temporal lobe by means of computer program, we have compared them with each groups. The result showed statistically little significant difference of disk signal intensity among each groups. but, signal intensity from posterior attachment in group 2 and 3 were significantly(p<0.05) decreased than control group. this might reflect an fibrosis or hyalinization of posterior attachment, which was part of remodeling process that occurs in disk displacement without reduction. However, this study could not demonstrate histologic confirmation of the decreased signal intensity in the posterior attachment. So, further investigation could be needed to understand the association between them.

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Measurement of soot concentration in flames using laser-induced incandescence method (레이저 가열 측정법을 이용한 화염 내 매연 농도 측정)

  • Jurng, Jong-Soo
    • Journal of the Korean Society of Combustion
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    • v.1 no.1
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    • pp.75-82
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    • 1996
  • Laser induced incandescence, LII, recently developed technique for measuring soot concentration in flames, can overcome most of limitations of conventional laser extinction measurement. In this study, experiments were performed to investigate the effect of laser intensity, detection wavelength, and also laser beam quality on both LII signal at a particular position and peak-to-centerline LII signal ratio. The results of LII signal with increasing laser intensity shows its near-independence of laser intensity once threshold level of laser intensity has been reached. However, this near-independence depends on laser beam quality and the incident optical setup. The peak-to-centerline LII signal ratio slowly but continuously increases with laser power. This fact is due to the dependence of LII signal on particle mean diameter. LII signal is attenuated during it passes through the flame containing soot particles. The attenuation rate is inversely proportional to detection wavelength. In this study, LII signal at 680 nm band is 10% greater than the signal at 400 nm band.

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ESR Signal in Different Cuts of Irradiated Chicken, Pork and Beef

  • Nam, Hye-Seon;Yang, Jae-Seung;Ly, Sun-Yung
    • Nuclear Engineering and Technology
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    • v.32 no.3
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    • pp.254-260
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    • 2000
  • Electron spin resonance (ESR) spectroscopy was used to detect irradiated meat containing bones (chicken, pork and beef), to investigate the effect of irradiation dose on the ESR signal intensity and to identify the stability of radicals under 9 weeks of storage. Chicken, pork and beef were irradiated with doses 0, 1, 3, 5 and 7 kGy at room temperature using a Co-60 irradiator. Bones were pieced and dried, which were placed in a quartz tube within an Electron paramagnetic resonance (EPR) spectrometer resonator cavity. The irradiated bone presented an asymmetric absorption in shape, different from that of a non-irradiated one. The signal intensity of smaller animals are lower than larger species. Variation was observed between samples of the same species depending on the calcification status of the bone. Moreover different irradiation doses produced different signal areas that make possible to estimate the absorbed dose of treated meat. The ESR signal stability after irradiation was stable in even after a 9 week storage at room temperature.

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Carotid Intraplaque Hemorrhage Imaging: Diagnostic Value of High Signal Intensity Time-of-Flight MR Angiography Compared with Magnetization-Prepared Rapid Acquisition with Gradient-Echo Sequencing

  • Ahn, Ji-eun;Kwak, Hyo Sung;Chung, Gyung Ho;Hwang, Seung Bae
    • Investigative Magnetic Resonance Imaging
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    • v.22 no.2
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    • pp.94-101
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    • 2018
  • Purpose: To determine the value of the appearance of the high signal intensity halo sign for detecting carotid intraplaque hemorrhage (IPH) on maximum intensity projection (MIP) of time-of-flight (TOF) MR angiography (MRA), based on high signal intensity on magnetization-prepared rapid acquisition with gradient-echo (MPRAGE) sequencing. Materials and Methods: A total of 78 carotid arteries in 65 patients with magnetization-prepared rapid acquisition gradient-echo (MPRAGE) positive on carotid plaque MR imaging were included in this study. High-resolution MR imaging was performed on a 3.0-T scanner prior to carotid endarterectomy or carotid artery stenting. Fast spin-echo T1- and T2-weighted axial imaging, TOF, and MPRAGE sequences were obtained. Carotid plaques with high signal intensity on MPRAGE > 200% that of adjacent muscle on at least two consecutive slices were defined as showing IPH. Halo sign of high signal intensity around the carotid artery was found on MIP from TOF MRA. Continuous and categorical variables were compared among groups using the Mann-Whitney test and Fisher's exact tests. Results: Of these 78 carotid arteries, 53 appeared as a halo sign on the TOF MRA. The total IPH volume of patients with a positive halo sign was significantly higher than that of patients without a halo sign ($75.0{\pm}86.8$ vs. $16.3{\pm}18.2$, P = 0.001). The maximum IPH axial wall area in patients with a positive halo sign was significantly higher than that of patients without a halo sign ($11.3{\pm}9.9$ vs. $3.7{\pm}3.6$, P = 0.000). Conclusion: High signal intensity halo of IPH on MIP of TOF MRA is associated with total volume and maximal axial wall area of IPH.

Analysis of Signal Intensity in Choroid Plexuses by Diffusion Weighted Imaging (확산강조영상의 검사기법에 따른 맥락얼기의 신호강도 분석)

  • Oh, JongKap
    • Journal of the Korean Society of Radiology
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    • v.7 no.4
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    • pp.265-269
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    • 2013
  • This report aims at picturing out the clinical usefulness by analyzing the signal intensity in choroid plexuses which produce cerebrospinal fluids by diffusion weighted imaging. At first, subjects were chosen among the patients who showed high in signal intensity by diffusion weighted imaging. The subjects were taken another test by fluid attenuated inversion recovery diffusion weighted echo planer image(FLAIR-DW-EPI) the signals of fluid attenuation. And it was found that there are differences between the signal intensities of the two methods, which showed that the signal intensity in FLAIR-DW-EPI is equal to or low than, that in the Brain. By this, it is felt that it is helpful to diagnose the disease in choroid plexus by testing another more with FLAIR-DW-EPI methods the patients who showed high in signal intensity in choroid plexus by $T2^*$ diffusion weighted echo planer image($T2^*$-DW-EPI).