• Investigative Magnetic Resonance Imaging
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• v.11 no.1
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• pp.10-19
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• 2007

Conventional MRI methods using T1-, T2-, diffusion-, perfusion-weighting, and functional imaging rely on characterizing the physical and functional properties of the tissue. In this review, we introduce an imaging modality based on measured the mechanical properties of soft tissue, namely magnetic resonance elastography (MRE). The use of palpation to identify the stiffness of tissue remains a fundamental diagnostic tool. MRE can quantify the stiffness of the tissue thereby providing a objective means to measure the mechanical properties. To accomplish a successful clinical setting using MRE, hardware and software techniques in the area of transducer, pulse sequence, and imaging processing algorithm need to be developed. Transducer, a mechanical vibrator, is the core of MRE application to make wave propagate invivo. For this reason, considerations of the frame of human body, pressure and friction of the interface, and high magnetic field of a MRI system needs to be taken into account when designing a transducer. Given that the wave propagates through human body effectively, developing an appropriate pulse sequence is another important issue in obtaining an optimal image. In this review paper, we introduce the technical aspects needed for MRE experiments and introduce several applications of this new field.

• Clinical and Experimental Pediatrics
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• v.49 no.2
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• pp.212-216
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• 2006

Neurocutaneous melanosis is a rare congenital syndrome characterized by the presence of large or multiple congenital melanocytic nevi and benign pigment cell tumors of the leptomeninges. Neurocutaneous melanosis is thought to represent an error in the morphogenesis of embryonal neuroectoderm. We experienced a neonate who presented with giant, dark colored pigmented nevi covering chest, abdomen, neck and arms, with satellite lesions. Magnetic resonance image showed a nodular hyperintense lesion in the amygdala of the right temporal lobe, and T1-weighted images showed hyperintensities in the adjacent leptomeninges. We report a rare case of neurocutaneous melanosis with a brief review of related literature.

• Investigative Magnetic Resonance Imaging
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• v.11 no.1
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• pp.39-48
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• 2007

Purpose : To determine the diagnostic accuracy of four different sequences : moderately T2 weighted, two heavily T2-weighted single shot turbo spin-echo sequence and breath-hold axial-2D balanced turbo field-echo sequence(bFFE) for characterization of focal lesions. Materials and Methods : During the 3-month period between June and August 2005, seventy-six patients were proved to have ninety-three focal hepatic lesions on MR imaging. The patients consisted of 49 men and 27 women (age range, 15-75 years; mean age, 56.23 years). All MR images were acquired on a 1.5-T MR using the following sequences: 1. A breath-hold axial T2-weighted single shot turbo spin-echo sequence, 2. a breath-hold axial-2D balanced turbo field-echo sequence. Two radiologists performed quantitative analysis. Another radiologist measured the lesion-to-liver contrast-to-noise ratio at the region-of-interest in the four sequences. Results : There was no significant difference in inter-observer variability between the four sequences. The accuracy for both cyst and malignancy of moderate T2 weighted MRI (echo time: 80 msec) was also highest. There was significant difference for lesion characterization between moderate T2 weighted MRI and balanced steady state procession (p-value: 0.004) in the second reader. For longer echo time, the CNR of cystic lesions were markedly increased in comparison to lesions of other component. Conclusion : The accuracy and inter-observer variability of single shot turbo spin echo T2 weighted sequence was higher than bFFE. Although there was no statically significant difference, moderate T2 weighted MRI (echo time: 80 msec) was more accurate than heavily T2 weighted sequence (echo time: 300 msec). If the results for lesion characterization is equivocal in TE 80, the addition of heavily T2 weighted MRI (echo time: 180 msec) can be helpful.

• Korean Journal of Digital Imaging in Medicine
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• v.11 no.2
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• pp.51-57
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• 2009

The purpose of this study would evaluate if having clinical effects on diffusion image with quantitative analysis through ADC values of brain's normal tissue and lesions before and after contrast injections using a 3.0T. From November in 2007 until December in 2008, a total of 32 patient was performed on 3.0T(Signa Excite, GE Medical System, USA) with the normal or lesions in the patient who requests diffusion weighted image with 8channel head coil. The pulse sequence was used with spin echo EPI(TR: 10000msec, TE: 72.2 msec, Matrix: 128*128, FOV: 240 mm, NEX: 1, diffusion direction: 3, b-value: 1000). Measurement results of ADC values on lesions, CSF, white matter, gray matter, lesions after contrast injection were measured less 75% than before contrast injection, infarction: 100%, CSF: 78%(high), white matter: 71.4%(low), gray matter: 50%(high, low). The results of paired t-test on the deference of ADC values which statically is significant in three(lesions, CSF, white matter)regions except for white matter(p<0.05). Quantitative analysis of lesions, CSF, white matter, gray matter have difference on all regions. ADC values were low in lesions and white matter, normal CSF after contrast injection commonly is high than before contrast injection, ADC values which white matter were high and low (50:50) after contrast injection. 3.0T diffusion weighted image clinically supposed that performing DWI examination after contrast injection was not desirable because of having effects on brain tissue.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.1005-1010
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• 2021

We report a case of Immunoglobulin G4 (IgG4) related disease involving the pterygoplataine fossa. A 83-year-old male presented with left ocular pain and visual disturbance. CT showed an isodense soft tissue lesion in the left pterygopalatine fossa with bony sclerotic changes and erosion. MRI revealed an infiltrative soft tissue mass in the left pterygopalatine fossa as a T2 slightly low signal intensity and heterogeneous enhancement. The patient underwent left ethmoidectomy, and biopsy of the mass was conducted. The histopathological diagnosis was IgG4-related disease. In this case, it was difficult to differentiate invasive aspergillosis, which is common in immunocompromised patients, considering the patient's clinical history of diabetes mellitus. This report describes the imaging findings of IgG4-related disease mimicking invasive sinusitis such as invasive aspergillosis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5299-5304
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• 2012

MRI signals are significantly reduced by the magnetic field inhomogenity result from human body itself being consisted of various materials like air, fat, muscle, bone and blood vessels. In this study we used silicon which is tissue equivalent to compensate wound body shapes. Objects were eight adults who do not have any special symptoms. Feet were scanned because of their complicated structures and consequently signal reduction occurs a lot. Thirty images were acquired from the middle of arcus pedis longitudinalis including five distal phalanges parallel to the line connecting metatarsal bone and phalanges. SNR data from bones and soft tissues were compared before and after sticking silion between toes and paired t test was performed. It was came out that SNR data from bone and soft tissue were both significantly higher after applying silicon on both T1 and T2 weighted images and it was statistically meaningful having positive corelation. As a result, this study dramatically increases SNR without affecting object by increasing the object volume inside the surface coil.

• Journal of radiological science and technology
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• v.32 no.1
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• pp.95-99
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• 2009

The purpose of this research is to seek SPAIR's reversal time (TI) which satisfies two conditions ; maintaining the suppression ability of fat tissue and simultaneously minimizing the inhomogeneity of fat tissue in T2 high-speed spin echo 3.0T magnetic resonance image (MRI) of the brain, and to compare SPAIR with STIR which is fat-suppression technique. The reversal times (TI) of SPAIR protocol are set to 1/2, 1/3, 1/6 and 1/12 of SPAIR TR (420 msec), namely 210 msec (8 people), 140 msec (26 people), 70 msec (26 people) and 35 msec (18 people) and STIR TI is set with 250 msec (26 people). With these parameter sets, we acquired the axis direction 104 images of the brain. In ROI ($50\;mm^2$) of output image, signal intensities of the fatty tissue, the muscular tissue, and the background were measured and the CNRs of fatty tissue and the muscular tissue were calculated. The inhomogeneity of the fatty tissue is SD/mean, where SD is the standard deviation and 'mean' is a average fatty tissue signal. Consequently, SPAIR TI is determined on either 1/3 or 1/6 of TR (420 ms) ; 140 ms or 70 ms. Because the difference of statistics in fat-suppression ability and inhomogeneity of fatty tissue is very small (p < 0.001), Selecting 140 ms seems to be better choice for the image quality. Meanwhile, Comparing SPAIR (TI : 140 ms) with STIR, the fat-suppression is not able to be considered statistically (p < 0.252), but the image quality is able to be considered statistically (p < 0.01). In conclusion, SPAIR is better than STIR in the image quality.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.142-147
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• 1997

Purpose: To compare the effectiveness of the in-phase (IP) sequence and the opposed-phase (Op) sequence in the detection of focal hepatic lesions in the single breath-hold hepatic MR imaging with fast gradient T1-weighted pulse sequences. Materials and Methods: IP and OP T1-weighted breath-hold imaging was performed using fast gradient echo sequences in 45 patients referred for known focal hepatic lesions, in which 78 lesions were detected. Three blind readers independently reviewed the images for lesion detectability. The signal-to-noise ratio (SNR) of the liver, the lesion-to-liver contrast-to-noise ratio (CNR) and the liver-to-spleen CNR were also compared. A consensus was reached by three readers to determine which sequence is better in image quality. Results: On OP images, 61(78%), 61(78%), and 63(89%) lesions were correctly identified for reader 1, 2 and 3, respectively. On IP images, 66(85%), 65(83%), and 65(93%) lesions were detected for each reader, respectively. When two image sets were combined, 71(91 %), 69(88 %), and 76(97%) lesions respectively were detected for each reader. In cases of hepatocellular carcinoma, liver-to-Iesion CNR was greater on the OP images(p (0.05), but in other lesions significant difference was not demonstrated. Liver-to-spleen CNR was higher on OP images(p ( 0.1), but the SNR of the liver was higher on the IP images. Conclusion: Use of both IP and OP imaging can be helpful to avoid erroneous missing of some focal hepatic lesions.

• Journal of the Korean Arthroscopy Society
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• v.16 no.2
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• pp.140-146
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• 2012

Purpose: The objective of this study was to assess the clinical outcome of arthroscopic release of the extensor carpi radialis brevis (ECRB) tendon in chronic recalcitrant lateral epicondylitis and tried to determine any prognostic factors. Materials and Methods: A retrospective review of 24 patients with lateral epicondylitis treated by arthroscopic ECRB release was performed. Outcome measures included a patient self rating and visual analog scale (VAS). Functional evaluation was made with Quick-disabilities of the arm, shoulder and hand (DASH) score system to identify preoperative factors that might be associated with the outcomes. Results: Twenty one (88%) elbows received benefit from the procedure. A mean preoperative VAS pain score and the mean Quick-DASH were significantly improved at final follow up. Age, sex, dominant arm and duration of symptom, presence of capsular tear or calcification did not correlate significantly with the clinical outcome. Three of four patients without T2-weighted high signal focus of the ECRB origin on preoperative magnetic resonance imaging (MRI) showed higher Quick-DASH score. Conclusion: Arthroscopic release of the ECRB is an effective option for chronic recalcitrant lateral epicondylitis. Lack of high signal focus on preoperative MRI is significantly associated with a poor surgical outcome and a considerable factor for the proper surgical indication.

• Journal of Yeungnam Medical Science
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• v.16 no.2
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• pp.296-301
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• 1999

Background: Generally, it is difficult to differentiate uterine malignant mixed M$\ddot{u}$ llerian tumor(MMMT) from endometrial carcinom in radiological and clinical aspects. Our purpose is to investigate MR findings that distinguishes MMMT from endometrial carcinoma. Materials and Methods: We retrogradely evaluated the magnetic resonance imaging findings of pathologically proven 5 cases of malignant mixed M$\ddot{u}$llerian tumor(MMMT) and 14 endometrial carcinomas to know the differential points of these two tumors originating in the endometrial cavity. The size of the mass, presence or absence of myometrial or uterine cervical invasion, growth pattern of the mass, signal intensity and degree and pattern of contrast enhancement were analyzed and compared. Results: The length of the long axis of the MMMT was 1.5-9.0cm(average, 5.7cm) but that of the endometrial carcinoma was 0.5-6.0cm(average, 2.5cm). Invasion of uterine cervix which was found in 3 MMMT cases, dilated the endometrial cavity and the lumen of the uterine cervix and showed the pattern of growing into the external os. Invasion of uterine cervix was found in only one case of endometrial carcinoma. The presence or absence of myometrial invasion, the signal intensity and homogeneity on T1- and T2-weighted images, and the degree and patterns of contrast enhancement showed no significant difference. Conclusion: Any specific finding to differentiate MMMT from endometrial carcinoma was not ascertained. However, MMMT can be suspected if the size of the endometrial mass is greater than 5cm and if the mass dilates the enocervical canal and invades the uterine cervix.