• Title/Summary/Keyword: Magnetic resonance imaging (MR)

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Three-Dimensional Dosimetry Using Magnetic Resonance Imaging of Polymer Gel (중합체 겔과 자기공명영상을 이용한 3차원 선량분포 측정)

  • Oh Young-Taek;Kang Haejin;Kim Miwha;Chun Mison;Kang Seung-Hee;Suh Chang Ok;Chu Seong Sil;Seong Jinsil;Kim Gwi Eon
    • Radiation Oncology Journal
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    • v.20 no.3
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    • pp.264-273
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    • 2002
  • Purpose : Three-dimensional radiation dosimetry using magnetic resonance imaging of polymer gel was recently introduced. This dosimetry system is based on radiation induced chain polymerization of acrylic monomers in a muscle equivalent gel and provide accurate 3 dimensional dose distribution. We planned this study to evaluate the clinical value of this 3-dimensional dosimetry. Materials and Methods: The polymer gel poured into a cylindrical glass flask and a spherical glass flask. The cylindrical test tubes were for dose response evaluation and the spherical flasks, which is comparable to the human head, were for isodose curves. T2 maps from MR images were calculated using software, IDL. Dose distributions have been displayed for dosimetry. The same spherical flask of gel and the same irradiation technique was used for film and TLD dosimetry and compared with each other. Results : The R2 of the gel respond linearly with radiation doses in the range of 2 to 15 Gy. The repeated dosimetry of spherical gel showed the same isodose curves. These isodose curves were identical to dose distributions from treatment planning system especially high dose range. In addition, the gel dosimetry system showed comparable or superior results with the film and TLD dosimetry. Conclusion : The 3-dimensional dosimetry for conformal radiation therapy using MRI of polymer gal showed stable and accurate results. Although more studies are needed for convenient clinical application, it appears to be a useful tool for conformal radiation therapy.

Semi-Quantitative Scoring of Late Gadolinium Enhancement of the Left Ventricle in Patients with Ischemic Cardiomyopathy: Improving Interobserver Reliability and Agreement Using Consensus Guidance from the Asian Society of Cardiovascular Imaging-Practical Tutorial (ASCI-PT) 2020

  • Cherry Kim;Chul Hwan Park;Do Yeon Kim;Jaehyung Cha;Bae Young Lee;Chan Ho Park;Eun-Ju Kang;Hyun Jung Koo;Kakuya Kitagawa;Min Jae Cha;Rungroj Krittayaphong;Sang Il Choi;Sanjaya Viswamitra;Sung Min Ko;Sung Mok Kim;Sung Ho Hwang;Nguyen Ngoc Trang;Whal Lee;Young Jin Kim;Jongmin Lee;Dong Hyun Yang
    • Korean Journal of Radiology
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    • v.23 no.3
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    • pp.298-307
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    • 2022
  • Objective: This study aimed to evaluate the effect of implementing the consensus statement from the Asian Society of Cardiovascular Imaging-Practical Tutorial 2020 (ASCI-PT 2020) on the reliability of cardiac MR with late gadolinium enhancement (CMR-LGE) myocardial viability scoring between observers in the context of ischemic cardiomyopathy. Materials and Methods: A total of 17 cardiovascular imaging experts from five different countries evaluated CMR obtained in 26 patients (male:female, 23:3; median age [interquartile range], 55.5 years [50-61.8]) with ischemic cardiomyopathy. For LGE scoring, based on the 17 segments, the extent of LGE in each segment was graded using a five-point scoring system ranging from 0 to 4 before and after exposure according to the consensus statement. All scoring was performed via web-based review. Scores for slices, vascular territories, and total scores were obtained as the sum of the relevant segmental scores. Interobserver reliability for segment scores was assessed using Fleiss' kappa, while the intraclass correlation coefficient (ICC) was used for slice score, vascular territory score, and total score. Inter-observer agreement was assessed using the limits of agreement from the mean (LoA). Results: Interobserver reliability (Fleiss' kappa) in each segment ranged 0.242-0.662 before the consensus and increased to 0.301-0.774 after the consensus. The interobserver reliability (ICC) for each slice, each vascular territory, and total score increased after the consensus (slice, 0.728-0.805 and 0.849-0.884; vascular territory, 0.756-0.902 and 0.852-0.941; total score, 0.847 and 0.913, before and after implementing the consensus statement, respectively. Interobserver agreement in scoring also improved with the implementation of the consensus for all slices, vascular territories, and total score. The LoA for the total score narrowed from ± 10.36 points to ± 7.12 points. Conclusion: The interobserver reliability and agreement for CMR-LGE scoring for ischemic cardiomyopathy improved when following guidance from the ASCI-PT 2020 consensus statement.

Lumbar Angiomatous Meningioma in a Dog (개에서 발생한 요추 혈관종성수막종 증례)

  • Sohn, Jung-Min;Kim, Bo-Eun;Jung, Sun-Young;Ji, Seo-Yeoun;Yoon, Dae-Young;Kweon, Oh-Kyeong;Kim, Dae-Yong;Choi, Min-Cheol;Yoon, Junghee
    • Journal of Veterinary Clinics
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    • v.31 no.2
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    • pp.152-155
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    • 2014
  • An 11-year-old castrated Schnauzer presented with paraplegia for the last two weeks, initially developed pelvic limb ataxia 6 months ago and left pelvic limb paresis 3 months ago. On neurological examination, paraplegia and postural reaction deficits were noted in the pelvic limbs with no deep pain sensation, and the dog showed exaggerated spinal reflexes and involuntary urination. Magnetic resonance (MR) images of thoracolumbar spinal cord were obtained with a 0.3 Tesla magnet. A mass with a broad base to the dorsal and left dural margins was identified at the level of L2, causing marked spinal cord compression. The mass showed isointensity to the spinal cord on T1-weighted (T1W) precontrast images, hyperintensity on T2-weighted images, marked homogeneous contrast enhancement with well-defined margins and the "dural tail" sign on T1W postcontrast images. An intradural-extramedullay tumor was considered, most likely, meningioma was highly suggestive. Left-sided hemilaminectomy and dorsal laminectomy were performed. An intradural mass partially adherent to dura mater was compressing the spinal cord, and the mass was completely removed with the attached dura mater. A histopathologic diagnosis of angiomatous subtype meningioma was made.

Idiopathic Vestibular Disease in a Beagle Dog: Clinical Findings and Outcome (비글 견에서 발생한 특발성 전정계 질병 증례: 임상적 발견과 결과)

  • Kang, Byeong-Teck;Jung, Dong-In;Park, Chul;Gu, Su-Hyun;Jeon, Hyo-Won;Park, Hee-Myung
    • Journal of Veterinary Clinics
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    • v.23 no.3
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    • pp.340-343
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    • 2006
  • A 10-year-old, intact female Beagle dog was presented for examination of acute onset of right-sided head tilt and moderate ataxia. Clinical signs were acutely presented 12 days ago and had been progressively alleviated until the admission day. The dog was bright, alert, and responsive. On neurological examinations, mild head tilt to the right and mild ataxia were noted, thus vestibular disorders were suspected. Central vestibular disease was ruled out based on the clinical signs, magnetic resonance imaging(MRI), and cerebrospinal fluid(CSF) analysis. Otoscopic examination showed that the tympanic membranes were intact and normal in appearance. On radiographic and MR examinations, abnormalities were not found in the tympanic bulla and the petrous portion of the temporal bone. Hypothyroidism was ruled out by thyroid-stimulation hormone(TSH) stimulation test. Clinical signs were completely disappeared at 2 weeks after discharge without any therapy. Thus, the dog was definitively diagnosed as idiopathic vestibular disease based on the clinical signs, excluding other causes of vestibular dysfunction, and the alleviation of clinical signs with time.

Hearing Outcome after Gamma Knife Stereotactic Radiosurgery in Vestibular Schwannoma Patients with Serviceable Hearing

  • Cho, Jae-Hoon;Paek, Sun-Ha;Chung, Hyun-Tai;Jeong, Sang-Soon;Jung, Hee-Won;Kim, Dong-Gyu
    • Journal of Korean Neurosurgical Society
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    • v.40 no.5
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    • pp.336-341
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    • 2006
  • Objective : The authors conducted a retrospective study to evaluate the preservation rates of serviceable hearing and to determine its prognostic factors after gamma knife stereotactic radiosurgery[GK SRS] in the patient with vestibular schwannomas. Methods : Between December 1997 and March 2005, 54 patients with a sporadic vestibular schwannoma and serviceable hearing [Gardner Robertson grade I-II] were enrolled in this study. Electronic database of medical records and radiological examinations before and after GK SRS were investigated to the last follow up. The mean marginal dose was $12.3{\pm}0.7Gy$. The mean maximum dose delivered to the tumor center was 24.7Gy [$22{\sim}30Gy$]. The median tumor volume was 2cc [$0.1{\sim}9.1cc$]. The median follow-up period of magnetic resonance[MR] imaging was 31 months [$6{\sim}99\;months$], and the mean follow-up period of audiometry was 24 months [$4{\sim}70\;months$]. Results : The tumor control rate was 100% in the patients with the follow up period more than 2 years. The trigeminal and facial nerve preservation rates were 98% and 100%, respectively. Twenty-eight [52%] of the 54 patients preserved serviceable hearing and 16 [30%] patients retained their pre-GK G-R grade level after GK SRS. In the univariate and multivariate analysis, there was no significant prognostic factor in preservation of the serviceable hearing. Conclusion : The hearing preservation rate is still unsatisfactory compared with the results of other cranial nerve preservation and tumor control in the treatment of vestibular schwannoma by GK SRS. More sophisticated strategy during and after GK SRS is necessary to improve long-term hearing preservation.

Evaluation of Automatic Image Segmentation for 3D Volume Measurement of Liver and Spleen Based on 3D Region-growing Algorithm using Animal Phantom (간과 비장의 체적을 구하기 위한 3차원 영역 확장 기반 자동 영상 분할 알고리즘의 동물팬텀을 이용한 성능검증)

  • Kim, Jin-Sung;Cho, June-Sik;Shin, Kyung-Sook;Kim, Jin-Hwan;Jeon, Ho-Sang;Cho, Gyu-Seong
    • Progress in Medical Physics
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    • v.19 no.3
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    • pp.178-185
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    • 2008
  • Living donor liver transplantation is increasingly performed as an alternative to cadaveric transplantation. Preoperative screening of the donor candidates is very important. The quality, size, and vascular and biliary anatomy of the liver are best assessed with magnetic resonance (MR) imaging or computed tomography (CT). In particular, the volume of the potential graft must be measured to ensure sufficient liver function after surgery. Preoperative liver segmentation has proved useful for measuring the graft volume before living donor liver transplantations in previous studies. In these studies, the liver segments were manually delineated on each image section. The delineated areas were multiplied by the section thickness to obtain volumes and summed to obtain the total volume of the liver segments. This process is tedious and time consuming. To compensate for this problem, automatic segmentation techniques have been proposed with multiplanar CT images. These methods involve the use of sequences of thresholding, morphologic operations (ie, mathematic operations, such as image dilation, erosion, opening, and closing, that are based on shape), and 3D region growing methods. These techniques are complex but require a few computation times. We made a phantom for volume measurement with pig and evaluated actual volume of spleen and liver of phantom. The results represent that our semiautomatic volume measurement algorithm shows a good accuracy and repeatability with actual volume of phantom and possibility for clinical use to assist physician as a measuring tool.

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3-Dimensional Computed Tomography of Atlantoaxial Instability in Three Dogs (개에서 컴퓨터단층영상의 3차원 재구성을 통한 환축추골 아탈구 진단 3례)

  • Ahn, Se-Joon;Choi, Soo-Young;Lim, Soo-Ji;An, Ji-Young;Lee, In;Kwon, Young-Hang;Choi, Ho-Jung;Lee, Young-Won
    • Journal of Veterinary Clinics
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    • v.26 no.5
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    • pp.490-494
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    • 2009
  • A 2-year-old Maltese and a 5-month-old Yorkshire terrier were presented with ataxia. Tetraparesis was observed in a 9-year -old Yorkshire terrier. The localizations of the lesions suggested brain or cervical spinal cord by the neurological examination, and the following images was achieved: radiography, axial images of computed tomography (CT), reconstruction image of CT such as multi-planar reformation(MPR) and 3-dimensional(3D) reconstruction and magnetic resonance imaging (MRI). On radiography, the misalignment between atlas (C1) and axis (C2), absent dens of axis, and increased space between the dorsal arch of C1 and spinous process of C2 were found. The discontinuation between dens and body of C2 was identified through axial CT images, and the fragmentation of dens separated from axis was observed through MPR and 3D image in all case. The hyperintense lesions and the spinal cord compression on T2-weighted MR images were represented in a dog with tetraparesis, the others represented only spinal cord compression. Three dogs were diagnosed as atlantoaxial instability (AAI) by dens fracture of C2. The dog with tetraparesis was euthanized due to guarded prognosis. The others were recovered completely. It is difficult to differentiate dens fracture of C2 from abnormal dens such as agenesis and hypoplasia. We thought that CT is very useful to evaluate the dens of C2 and differentiate the causes of AAI, and the reconstruction images of CT such as MPR and 3D make the translation of the fragmented dens or axis of AAI more precisely evaluate.

Lumbar Herniated Disc Resorption of 78 Patients after Korean Medicine Treatment (요추 추간판 탈출증 환자 78명의 한방치료 후 디스크 재흡수 증례 보고)

  • Jung, Bum-Hwan;Jo, Joo-Hyun;Yoon, Yong-Il;Park, Sang-won;Kim, Sung-Moon;Go, Ung;Jung, Jin-soo;Kim, Jung-Hoon;Huh, Suk-Won;Kim, Ji-Won;Kim, Moon-Hwi
    • Journal of Korean Medicine Rehabilitation
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    • v.26 no.1
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    • pp.87-93
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    • 2016
  • Objectives To analyze the resorption of herniated lumbar intervertebral disc on MRI in patients who were treated with Korean Medicine. Methods 78 patients with lumbar disc herniation were included, 47 males and 32 females. Patients' diagnosis was based on magnetic resonance imaging (MRI). All of the patients were only treated with Korean Medicine for 6 months treatment, and underwent MRI examination twice, pre-treatment and post-treatment. MR images were assessed by reduction in diameter of T2-weighted image between pre-treatment and post-treatment, and analyzed by differences in sex, age and disc type. Results 91.2% (71 people) of total patients had extrusion type. Korean medicine treatment reduced lumbar disc herniation diameter of all the patients from 7.11 mm to 3.67 mm on average (p<0.001). The reduction of diameter in the male group was 3.52 mm on average. The reduction of diameter in the female group was 3.32 mm on average. The reduction of diameter was 3.28 mm in the group below age 29, 3.88 mm in the 30~39 age group, 3.39 mm in the 40~49 age group, and 2.71 mm in the above 50 age group on average. Conclusions The MRI results suggest that lumbar herniated disc can resorb with Korean Medicine treatment. The likelihood of lumbar disc resorption was higher at extrusion type. but there was not a significant difference between the sexes and between ages.

Software development for the visualization of brain fiber tract by using 24-bit color coding in diffusion tensor image

  • Oh, Jung-Su;Song, In-Chan;Ik hwan Cho;Kim, Jong-Hyo;Chang, Kee-Hyun;Park, Kwang-Suk
    • Proceedings of the KSMRM Conference
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    • 2002.11a
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    • pp.133-133
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    • 2002
  • Purpose: The purpose of paper is to implement software to visualize brain fiber tract using a 24-bit color coding scheme and to test its feasibility. Materials and Methods: MR imaging was performed on GE 1.5 T Signa scanner. For diffusion tensor image, we used a single shot spin-echo EPI sequence with 7 non-colinear pulsed-field gradient directions: (x, y, z):(1,1,0),(-1,1,0),(1,0,1),(-1,0,1),(0,1,1),(0,1,-1) and without diffusion gradient. B-factor was 500 sec/$\textrm{mm}^2$. Acquisition parameters are as follows: TUTE=10000ms/99ms, FOV=240mm, matrix=128${\times}$128, slice thickness/gap=6mm/0mm, total slice number=30. Subjects consisted of 10 normal young volunteers (age:21∼26 yrs, 5 men, 5 women). All DTI images were smoothed with Gaussian kernel with the FWHM of 2 pixels. Color coding schemes for visualization of directional information was as follows. HSV(Hue, Saturation, Value) color system is appropriate for assigning RGB(Red, Green, and Blue) value for every different directions because of its volumetric directional expression. Each of HSV are assigned due to (r,$\theta$,${\Phi}$) in spherical coordinate. HSV calculated by this way can be transformed into RGB color system by general HSV to RGB conversion formula. Symmetry schemes: It is natural to code the antipodal direction to be same color(antipodal symmetry). So even with no symmetry scheme, the antipodal symmetry must be included. With no symmetry scheme, we can assign every different colors for every different orientation.(H =${\Phi}$, S=2$\theta$/$\pi$, V=λw, where λw is anisotropy). But that may assign very discontinuous color even between adjacent yokels. On the other hand, Full symmetry or absolute value scheme includes symmetry for 180$^{\circ}$ rotation about xy-plane of color coordinate (rotational symmetry) and for both hemisphere (mirror symmetry). In absolute value scheme, each of RGB value can be expressed as follows. R=λw|Vx|, G=λw|Vy|, B=λw|Vz|, where (Vx, Vy, Vz) is eigenvector corresponding to the largest eigenvalue of diffusion tensor. With applying full symmetry or absolute value scheme, we can get more continuous color coding at the expense of coding same color for symmetric direction. For better visualization of fiber tract directions, Gamma and brightness correction had done. All of these implementations were done on the IDL 5.4 platform.

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Evaluation of Tendency for Characteristics of MRI Brain T2 Weighted Images according to Changing NEX: MRiLab Simulation Study (자기공명영상장치의 뇌 T2 강조 영상에서 여기횟수 변화에 따른 영상 특성의 경향성 평가: MRiLab Simulation 연구)

  • Kim, Nam Young;Kim, Ju Hui;Lim, Jun;Kang, Seong-Hyeon;Lee, Youngjin
    • Journal of the Korean Society of Radiology
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    • v.15 no.1
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    • pp.9-14
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    • 2021
  • Recently, magnetic resonance imaging (MRI), which can acquire images with good contrast without exposure to radiation, has been widely used for diagnosis. However, noise that reduces the accuracy of diagnosis is essentially generated when acquiring the MR images, and by adjusting the parameters, the noise problem can be solved to obtain an image with excellent characteristics. Among the parameters, the number of excitation (NEX) can acquire images with excellent characteristics without additional degradation of image characteristics. In contrast, appropriate NEX setting is required since the scan time increases and motion artifacts may occur. Therefore, in this study, after fixing all MRI parameters through the MRiLab simulation program, we tried to evaluate the tendency of image characteristics according to changing NEX through quantitative evaluation of brain T2 weighted images acquired by adjusting only NEX. To evaluate the noise level and similarity of the acquired image, signal to noise ratio (SNR), contrast to noise ratio (CNR), root mean square error (RMSE) and peak signal to noise ratio (PSNR) were calculated. As a result, both noise level and similarity evaluation factors showed improved values as NEX increased, while the increasing width gradually decreased. In conclusion, we demonstrated that an appropriate NEX setting is important because an excessively large NEX does not affect image characteristics improvement and cause motion artifacts due to a long scan.