• Tunnel and Underground Space
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• v.27 no.5
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• pp.333-342
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• 2017

In this study, the heterogeneity of internal structure of various igneous rocks acquired in Korea was quantified and correlated with the seismic velocity and the point load strength. Three-dimensional X-ray Computed Tomography (CT) was used to obtain information on the internal structure of the rock specimen, and the representative unit length (LR) was calculated by applying a statistical technique to the CT images. We also proposed an estimation equation to predict the mechanical properties of rocks from the relationship between LR, acoustic velocity and point load strength. In the proposed method, it is shown that the characterization of internal structure of rocks could be utilized as an indirect index to account for the mechanical behavior of rocks by substituting physical laboratory testing for non-destructive test.

• Investigative Magnetic Resonance Imaging
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• v.12 no.2
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• pp.188-196
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• 2008

Purpose : To describe the clinical, MR imaging, and pathologic findings of pediatric meningiomas. Materials and Methods : The authors retrospectively reviewed the medical records and MR images of 16 pediatric patients with pathologically proven meningioma. Mean patient age at diagnosis was 14 years (range, 3-18). MR images were reviewed for details of lesion sizes, locations, signal intensity (SI), marginal characteristics, internal architectures, enhancements, and dural and parenchymal changes. The findings of other imaging modalities and of pathological examinations were also analyzed. Results : Mean tumor size was 5.24 cm (range, 1.3-18.1 cm) and locations were supratentorial in 12 and infratentorial in 4. SI of masses were variable, that is, high in 9, iso in 4, and low in 3 on T2 weighted images (T2WI), and low (n=11), iso (n=4), or high (n=1) on T1WI images. All lesions were visualized as well-demarcated enhancing masses. Five of the tumors were heterogeneous with cystic or necrotic components. Dural attachment was observed in 11 patients and adjacent brain edema in 10. Tumors exhibited hyperdense (n=6) or isodense (n=4) on non-enhanced CT scans, and 3 of the 7 angiograms demonstrated blood supply from the internal carotid artery. Pathologic examinations revealed the following subtypes; transitional cell (n=4), meningotheliomatous (n=4), chordoid (n=2), fibrous (n=2), clear cell (n=1), hyalinized (n=1), rhabdoid papillary (n=1), and atypical (n=1). Conclusion : Pediatric meningiomas occur usually in teenagers, have diverse pathological types, and may produce atypical imaging findings, such as, a heterogeneous internal content or findings suggestive of intraaxial tumors.

• Investigative Magnetic Resonance Imaging
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• v.12 no.1
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• pp.1-7
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• 2008

Purpose : To compare Multi Echo Data Image Combination (MEDIC) and fast SE T2-weighted images with fat saturation (T2FS) to suggest more accurate evaluation of the histologic components of soft-tissue tumors. Materials and Methods : The experimental group included 25 histologic tissues (5 vascular, 4 neural, 4 fibrous, 4 hypercellular, 2 hemorrhagic necroses, 2 cystic, 2 lipoid, 1 myxoid stroma, and 1 thrombus) in 10 patients who had pathologically confirmed schwannoma (n = 3), hemangioma (n = 2), lipoma (n = 1), angiokeratoma (n = 1), synovial sarcoma (n = 1), liposarcoma (n = 1), and malignant fibrous histiocytoma (n = 1). The inhomogeneity values were measured using the standard deviation value (SD) divided by the mean value as SD presents an error amount similar to that of imaging heterogeneity. Results : The inhomogeneity values of 25 histologic components were lower on MEDIC than those on T2FS (p < .001). Conclusion : We conclude that MEDIC is more accurate than T2FS for evaluating the tissue components of soft-tissue tumors using digitalized data because MEDIC images have far lower inhomogeneity.

• Journal of the Korean Society of Radiology
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• v.83 no.6
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• pp.1385-1393
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• 2022

Metaplastic carcinoma of the breast is a heterogeneous group of neoplasms with mixed epithelial and mesenchymal differentiation. Metaplastic carcinoma of the breast is a rare and aggressive malignancy, with high recurrence and metastasis. Metaplastic carcinoma with chondroid differentiation is an uncommon subtype that tends to have a relatively good prognosis than that of other subtypes. We report the imaging features of three cases of pathologically proven metaplastic carcinoma with chondroid differentiation as follows: a high-density mass with amorphous or coarse heterogeneous calcifications on mammography; a microlobulated or partially indistinct, complex cystic, and solid mass on sonography; and a relatively circumscribed or partially indistinct, irregular mass with heterogeneous T2 high-signal intensity and heterogeneous or rim enhancement with initial fast enhancement and delayed washout on MRI.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.2
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• pp.461-466
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• 1994

신경초종은 신경초에서 발생되는 성장이 느린 양성 종양으로 단발성이며 드물다. 이 종양은 말초 신경,자율 신경,뇌신경의 Schwann세포에서 발생된다. 두경부 영역의 두개외 신경성 종양은 드물며 특히 타액선에서 발생되는 예는 드물다. 저자들은 20세 여자 환자에서 아래와 같은 소견을 나타내는 신경초종을 경험하였기에 보고하는 바이다. 1.주소는 좌측 악하선 부위의 종창이었으며 촉진시 3×4㎝의 단단한 종괴가 만져졌으나 동통이나 림프절병증은 없었다. 2. 일반방사선사진에서 종괴와 관련된 골변화는 없었으나 초음파 영상에서는 불균질한 반사 양상을 보이는 종괴가 좌측 악하선 영역에서 관찰되었다. 3. 자기공명영상으로 병소의 정확한 위치를 확인할 수 있었다. 병소의 경계는 명확하였으나 신호 강도는 균일하지 않았으며 T1 강조 영상에서는 근육과 유사한 신호 강도를 보였으나 T2 강조 영상에서는 근육보다 높은 신호 강도를 나타냈다. 4. 조직 병리학적으로 Antoni type B 부위보다는 A 부위가 지배적이었으며 Verocay body도 나타났다. 종양 세포는 anti-S-100 염색에 양성으로 반응하였다.

• Investigative Magnetic Resonance Imaging
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• v.6 no.2
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• pp.152-157
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• 2002

Purpose : The differential diagnosis between Modic type I degenerative spine and infectious spondylitis sometimes is difficult, because the affected bone marrows in both disease show similar signal intensity on conventional MR imaging. We evaluate the usefulness of diffusion-wighted MR imaging for differential diagnosis between Modic type I degenerative spine and infectious spondylitis. Materials and methods : The spin-echo and diffusion-weighted MR images of eight patients with Modic type I degenerative spines and 14 patients with infectious spondylitis diagnosed by clinical findings or CT-guided biopsies we re analyzed. The diffusion-weighted imaging sequence was based on reversed fast imaging with steady-state precession (PSIF). Signal intensity changes of the vertebral bone marrow on conventional spin-echo and diffusion-weighted MR imaging were compared between degenerative spine and infectious spondylitis. Results : On T1-weighte d images, the affeted bone marrow in both disease showed hypointense signals. On T 2-weighted images, all of type I degenerative spine and 11 of infectious spondylitis showed hyperintensity, and three of infectious spondylitis showed heterogeneo us mixed signal intensity. On diffusion-weighted MR images, all of type I degenerative spine were hypointense with peripheral high signal intensity to normal vertebral body, but infectious spondylitis was hyperintense (n = 11) and hypointense (n=3). Conclusion : Diffusion-weighted MR imaging is useful to differentiate Modic type I degenerative spine from infectious spondylitis. On diffusion-weighted images, the high singal intensity of bone marrow suggests infectious spondylitis, whereas the low signal intensity of bone marrow with peripheral focal high signal intensity suggests type I degenerative spine.

• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.83-88
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• 1998

Purpose : Authors correlated the three-dimensional time-of-flight MRA signal intensity characteristics and flow profile simulated by computer in an experimental flow phantom model. Materials and Methods : The three-dimensional time-of-flight MRA was performed in a fusiform flow phantom and analyzed the flow signal. computer assisted flow simulation was performed in same flow geometry. The MRA signal intensity and flow velocity distribution and direction was compared. Results : The flow was depicted as homogeneous signal internsity in inlet and outlet area and inhomogeneous signal intensity in fusiform area. Typically, the flow was depicted as target appearance in transition area to outlet. Whereas mean signal internsity decreased slowly in fusiform area, it rapidly dropped and resumed in transition area to outlet. In computer assisted flow simulation, Whereas there were flow velocity decrease and flow direction change to peripheral in entrance to fusiform area, ther were rapid flow velocity resuming and flow direction change to central in transition area to outlet. Conclusion : The signal loss and target appearance in transition area to outlet is characteristic of fusiform flow. These signal changes correlate with abrupt flow velocity and direction change well.

• Journal of radiological science and technology
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• v.42 no.1
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• pp.39-46
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• 2019

This study conducted a comparative analysis of differences between cartesian trajectory in a linear rectangular coordinate system and MultiVane trajectory in a nonlinear rectangular coordinate system axial T1 and axial T2 images using an American College of Radiology(ACR) phantom. The phantom was placed at the center of the head coil and the top-to-bottom and left-to-right levels were adjusted by using a level. The experiment was performed according to the Phantom Test Guidance provided by the ACR, and sagittal localizer images were obtained. As shown in Figure 2, slices # 1 and # 11 were scanned after placing them at the center of a $45^{\circ}$ wedge shape, and a total of 11 slices were obtained. According to the evaluation results, the image intensity uniformity(IIU) was 93.34% for the cartesian trajectory, and 93.19% for the MultiVane trajectory, both of which fall under the normal range in the axial T1 image. The IIU for the cartesian trajectory was 0.15% higher than that for the MultiVane trajectory. In axial T2, the IIU was 96.44% for the cartesian trajectory, and 95.97% for the MultiVane trajectory, which fall under the normal range. The IIU for the cartesian trajectory was by 0.47% higher than that for the MultiVane trajectory. As a result, the cartesian technique was superior to the MultiVane technique in terms of the high-contrast spatial resolution, image intensity uniformity, and low-contrast object detectability.

• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.113-119
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• 1998

Purpose : Because adenocarcinomas of the uterine cervix have lower 5-year survival rate than squamous cell carcinomas due to early lymph node metastasis and local extension, scrutiny of lymph node metastasis and local extension by radiologic examination is necessary in case of clinically diagnosed or suspected adenocarcinomas. The purpose of this study is to evaluate whether there are specific findings of these tumors, compared with squamous cell carcinomas, through the analysis of magnetic resonance (MR) imaging findings. Materials and Methods : Of 21 pathologically proven cervical adenocarcinomas, MR imaging findings of 18 tumors (histologic staging : two Ib, four IIa, two IIb, one IIIa, and one IIIb) were retrospectively analyzed and compared with those of 40 wquamous cell carcinoma in consecutive patients as a control group. T1-wetighted and fast spin echo T2-weighted images were obtained on the axial and sagittal planes, using a 1.5-T MR scanner. The largest diameter, location, signal intensity and degree of contrast enhancement contour, shape and longitudinal extent of the tumor and associated findings on MR image were analyzed. Results : The largest diameters of cervical adenocarcinomas ranged from 0.8 to 4.1 cm(mean, 2.2 cm). Of 18 adenocarcinomas, nine were of endocervical type. All adenocarcinomas were isointense to surrounding cervical stroma on T1-weighted images and hyperintense(homogeneous in ten, inhomogeneous in eight) on fast spin echo T2-weighted images. Adenocarcinomas enhanced on contrast study in all patients (homogeneous in six, inhomogeneous in 12 with hyperintese enhnacing rim in two). Eight adenocarcinomas had smooth contours and ten had irregular ones. The shape of adenocarcinoma was irregular in eight patients, barrel shape in six, papillary/polypod in three, and nodular in one. All adenocarcinomas involved lower half of the uterine cervix and six tumors extended up to the upper half. Pelvic lymph nodes of more than 1.5cm in diameter in two adenocarcinomas pateints and no detectable small pelvic lymph nodes on MR imaging in one patient were pathologically positive. Hydrometra was associated in two adenocarcinomas patients, and hematometra in one patient. Compared with squamous cell carcinomas, more frequent MR findings of endocervical type and barrel shape in cervical adenocarcinomas were statistically significant. Conclusion : Cervical adenocarcinomas had more frequent MR findings of endocervical type and barrel shape, compared with wquamous cell carcinomas. Adenocarcinoma of the uterine cervix may be suspected on MR imaging, when a cervical carcinoma is of barrel shape along the endocervical canal and tends to involve lymth nodes in earlier stages.

• Investigative Magnetic Resonance Imaging
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• v.17 no.1
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• pp.59-62
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• 2013

There are various types of foreign body reactions, such as inflammation, edema, fluid collection, hematoma, infection, abscess and granulomas. There are various imaging findings according to types of foreign bodies and depending on the lapse of time. Therefore, correct diagnosis of a foreign body reaction is difficult and easily confused with soft tissue neoplasm. The MRI is ideal for the detection of foreign bodies regardless of radiolucency or acoustic impedance. It is especially very useful in the evaluation of the surrounding tissue reaction. The authors report a case of a 26-year-old female patient with both forearm swelling due to self-injection of a mixture of powdered tablets and saline. The lesion shows numerous internal T1 and T2 dark signal intensity micro-spots with surrounding fluid collection, which are diagnosed as foreign bodies with surrounding inflammatory changes during an operation.