• Investigative Magnetic Resonance Imaging
• /
• v.22 no.2
• /
• pp.102-109
• /
• 2018

Purpose: The purpose of this study is to compare the performance of the T1 3D subtraction technique and the conventional 2D dynamic contrast enhancement (DCE) technique in diagnosing Cushing's disease. Materials and Methods: Twelve patients with clinically and biochemically proven Cushing's disease were included in the study. In addition, 23 patients with a Rathke's cleft cyst (RCC) diagnosed on an MRI with normal pituitary hormone levels were included as a control, to prevent non-blinded positive results. Postcontrast T1 3D fast spin echo (FSE) images were acquired after DCE images in 3T MRI and image subtraction of pre- and postcontrast T1 3D FSE images were performed. Inter-observer agreement, interpretation time, multiobserver receiver operating characteristic (ROC), and net benefit analyses were performed to compare 2D DCE and T1 3D subtraction techniques. Results: Inter-observer agreement for a visual scale of contrast enhancement was poor in DCE (${\kappa}=0.57$) and good in T1 3D subtraction images (${\kappa}=0.75$). The time taken for determining contrast-enhancement in pituitary lesions was significantly shorter in the T1 3D subtraction images compared to the DCE sequence (P < 0.05). ROC values demonstrated increased reader confidence range with T1 3D subtraction images (95% confidence interval [CI]: 0.94-1.00) compared with DCE (95% CI: 0.70-0.92) (P < 0.01). The net benefit effect of T1 3D subtraction images over DCE was 0.34 (95% CI: 0.12-0.56). For Cushing's disease, both reviewers misclassified one case as a nonenhancing lesion on the DCE images, while no cases were misclassified on T1 3D subtraction images. Conclusion: The T1 3D subtraction technique shows superior performance for determining the presence of enhancement on pituitary lesions compared with conventional DCE techniques, which may aid in diagnosing Cushing's disease.

• Investigative Magnetic Resonance Imaging
• /
• v.23 no.4
• /
• pp.328-340
• /
• 2019

Purpose: To generate phase images with free of motion-induced artifact and susceptibility-induced distortion using 3D radial ultrashort TE (UTE) MRI. Materials and Methods: The field map was theoretically derived by solving Laplace's equation with appropriate boundary conditions, and used to simulate the image distortion in conventional spin-warp MRI. Manufacturer's 3D radial imaging sequence was modified to acquire maximum number of radial spokes in a given time, by removing the spoiler gradient and sampling during both rampup and rampdown gradient. Spoke direction randomly jumps so that a readout gradient acts as a spoiling gradient for the previous spoke. The custom raw data was reconstructed using a homemade image reconstruction software, which is programmed using Python language. The method was applied to a phantom and in-vivo human brain and abdomen. The performance of UTE was compared with 3D GRE for phase mapping. Local phase mapping was compared with T₂* mapping using UTE. Results: The phase map using UTE mimics true field-map, which was theoretically calculated, while that using 3D GRE revealed both motion-induced artifact and geometric distortion. Motion-free imaging is particularly crucial for application of phase mapping for abdomen MRI, which typically requires multiple breathold acquisitions. The air pockets, which are caught within the digestive pathway, induce spatially varying and large background field. T₂* map, that was calculated using UTE data, suffers from non-uniform T₂* value due to this background field, while does not appear in the local phase map of UTE data. Conclusion: Phase map generated using UTE mimicked the true field map even when non-zero susceptibility objects were present. Phase map generated by 3D GRE did not accurately mimic the true field map when non-zero susceptibility objects were present due to the significant field distortion as theoretically calculated. Nonetheless, UTE allows for phase maps to be free of susceptibility-induced distortion without the use of any post-processing protocols.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.30 no.6
• /
• pp.572-576
• /
• 2008

Gorham-Stout disease is a rare skeletal disease which is progressive and spontaneous and idiopathic resorption of whole body bone. In the initial stage, the osteolytic site is replaced by histologically benign vascular proliferation without new bone formation and finally by dense fibrous tissues. We encountered with a patient involving the mandible with attention by the clinical, radiographic, scintigraphic, angiographic, and computed tomography. We resected the mandibular lesion which was reconstructed with a fibular free flap. We report literature review with a mandibular lesion involved with Gorham-Stout disease.

• Journal of Oral Medicine and Pain
• /
• v.23 no.3
• /
• pp.289-294
• /
• 1998

본 증례는 측두하악관절의 퇘행성 변화를 보이는 환자에서 악교정 수술의 시행 전에 중심위교합장치를 통해 측두하악관절의 안정화를 유도하고, 또한 골스캔을 이용하여 장치의 치료효과를 평가한 임상증례이다. 환자는 24세의 여성으로 5년 전부터 전치부 개교합이 발생되기 시작하였고, 고형식 저작시 좌측 전이부에 간헐적인 통증이 발생한다는 주소로 본원에 내원하였다. 임상검사상 촉진시 양측 관절낭 후방부에 압통을 호소하였으며, 각각 50, 45mm의 최대개구량 및 최대무통성 개구량을 보였다. 좌측 악관절부에서 단순 관절 잡음, 우측 악관절부에서 염발음이 청취되었으며, 저항검사 및 부하 검사에서는 특기할 반응을 보이지 않았다. 약 7mm의 전치부 개교합의 소견을 보였으며, 파노라마 사진과 횡두개 방사선 사진 소견상 양측 과두의 크기 및 하악지의 높이가 다소 작은 소견이 관찰되었고 자기공명영상 소견상 양측성 비정복성 관절원판의 전방전위가 관찰되었다. 1997년 10월 27일 첫 번째 골스캔 소견상 양측성 비정복성 관절원판의 전방위가 관찰되엇다. 골스캔의 전방 사진에서 Densitometer를 이용하여 좌, 우측 과두부위와 상악 골부위의 가장 어두운 부분의 흑화도를 측정하였다. 각각 3회씩 구하여 평균을 구하고 좌, 우측 과두 대 상악골의 흑화도의 비율을 계산하였다. 첫번째 골스캔의 평균 흑화도는 우측 과두, 좌측과두, 상악골이 각각 0.88, 0.81, 1.32 였다. 1997년 11월 4일 중심위교합장치를 장착하였고 지속적인 물리치료를 시행하였다. 1997년 12월 10일 두 번째 골 스캔을 평균 흑화도는 우측 과두, 좌측 과두, 상악골이 각각 0.33, 0.37, 088 이었다. 1998년 1월 30일 세 번째 골스캔 소견상 두 번째 골스캔과 비교하여 활성도가 감소된 소견을 보였다. 임상검사시 무통이었다. 1998년 2월 25일 술 전 교정 위해 중심위교합장치의 장작을 중지시켰다. 1998년 6월 5일 네 번째 골스캔 소견상 이전 검사들과 비교시 흡수가 감소된 소견을 보였다. 네 번째 골스캔의 평균 흑화도는 우측 과두, 좌측 과두, 상악골이 각각 0.24, 0.19, 0.85 였다. 현재 지속적인 관찰 중이며 본원 교정과에서 악교정수술 위한 술 전 교장을 시행중이다. 결국 첫 번째 골스캔의 과두 대 상악골의 평균 흑화도의 비율은 우측과 좌측이 각각 0.66, 0.61이었고 두 번째 골스캔에서는 우측과 좌측이 각각 0.37, 0.42였고, 네번째 골스캔에서는 우측과 좌측이 각각 0.28, 0.23 이었다. 각 골스캔의 과두 대 상악골의 평균 흑화도의 비율 사이에 유의한 차이가 있는지 검증하기 위해 Standard t-test 와 ANOVA를 시행하였다. 이상의 결과에서 첫 번째, 두 번째, 네 번째 골스캔으로 갈수록 좌, 우측 과두 대 상악골의 흑화도의 비율이 유의하게 감소했음을 알 수 있었다. 결론적으로 본 증례에서는 전치부 개교합이 발생되어 악교정수술이 필요한 환자에게 측두하악관절의 안정화를 위해 중심위교합장치를 사용함으로써 퇴행성 관절질환의 진행을 억제시킬 수 있고, 퇴행성 관절질환의 활성도에 대한 평가시 골스캔이 유용할 수 있음을 보여주었다고 사료된다.

• Tuberculosis and Respiratory Diseases
• /
• v.43 no.2
• /
• pp.236-242
• /
• 1996

Intracranial tuberculoma results from hematogenous spread of pulmonary, intestinal or urogenital tuberculosis. However, it might be caused by pulmonary tuberculosis, mainly. Clinically, symptoms of intracranial tuberculoma are headache and seizure, its symptoms are simillar to intracranial tumor. A 25-year-old-unmarried shopgirl was visited to this hospital because of headache, dizziness and visual disturbance for couple weeks in Sep. 1995. She had been treated with anti-tuberculosis agents of miliary tuberculosis during past nine months period. Brain MRI revealed intracranial tuberculoma and brain edema but not involved optic nerve. Ophthalmic examination revealed severe papilledema and splinter hemorrhage with bitemporal hemianopsis and central scotoma. This finding was strongly suggested of optic disc tuberculoma. Her symptoms became much better following repeated retrobulbar steroid injection with continuous anti-tuberculosis agents. We report a interesting case with intracranial tuberculoma and optic disc tuberculoma associated by miliary tuberculosis during anti-tuberculous treatment.

• Tuberculosis and Respiratory Diseases
• /
• v.55 no.3
• /
• pp.280-286
• /
• 2003

Background : $^{99m}Technetium$ methylene diphosphonates($^{99m}Tc$ MDP) bone scintigraphy is current method of choice for the detection of bone metastases, but whole body $^{18}F$-fluoro-deoxy-D-glucose positron emission tomography($^{18}FDG$ PET) offers superior spatial resolution and improved sensitivity. So we compared whole body $^{18}FDG$ PET with $^{99m}Tc$ MDP bone scintigraphy in patients with skeletal metastases from lung cancer. Patients and Methods : Ninety-two patients with lung cancer taken $^{18}FDG$ PET together with a $^{99m}Tc$ MDP bone scintigraphy within 1 month between March 2000 and March 2003 were investigated retrospectively. Results : The sensitivity, specificity and accuracy of the $^{99m}Tc$ MDP bone scintigraphy versus $^{18}FDG$ PET for the detection of bone metastases in lung cancers were 59% vs 82%, 71% vs 94%, and 68% vs 91%, respectively. In the diagnosis of bone metastases from lung cancer, $^{18}FDG$ PET was statistically superior to $^{99m}Tc$ MDP bone scintigraphy in its specificity and accuracy(p<0.0001). Conclusions : Whole body $^{18}FDG$ PET may be useful in detecting bone metastases among patients with lung cancer.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.34 no.1
• /
• pp.32-38
• /
• 2018

Purpose: The purpose of present study was to retrospectively analyze the survival rate of narrow diameter implant less than 3.6 mm by initial stability and radiographic measurements. Materials and Methods: In total, 24 patients who received 38 narrow diameter implants (${\leq}3.6mm$ in diameter, ${\geq}7mm$ in length) were enrolled in this retrospective study. The cumulative survival rate was calculated and various factors were investigated according to the implant platform diameter, body diameter, length, position, concomitant use of guided bone regeneration in implant placement and final prosthesis type. Initial stability was investigated with implant stability quotient (ISQ) value. The mesial and distal marginal bone level (MBL) change was calculated with radiography. Results: The overall survival rate was 92.11%. Mean ISQ value and MBL change of survival implants was 66.26 and $0.14{\pm}0.31mm$, respectively. None of the implants with platform diameters larger than the body diameter failed. Conclusion: In conclusion, the findings of present study suggest that narrow diameter implant could be predictable treatment in narrow alveolar ridge.

• Journal of Gifted/Talented Education
• /
• v.22 no.2
• /
• pp.317-332
• /
• 2012

We investigated brain activity during the performance of the intelligence task by a science high school student group (n=8) and a foreign language high school student group (n=5). Both groups scored in the top 1% on intelligence tests (science high school group: RAPM mean score=34.0, WAIS mean IQ=139.6; foreign language high school group: RAPM mean score=33.8, WAIS mean IQ=147.2). Analysis of brain activity during the performance of the intelligence task showed that both groups had brain activity in certain areas, including the left and right prefrontal cortex, parietal cortex, and anterior cingulate. The science high school group showed the highest activity in the right parietal cortex, which is related to visuo-spatial working memory, whereas the foreign language high school group showed the highest activity in the left prefrontal cortex, which is related to verbal working memory. The foreign language high school group showed higher brain activity than the science high school group in the left precentral gyrus which is related to the motion of the tongue and lips. These results show that the science high school group utilized the visuo-spatial area, whereas the foreign language high school group utilized the verbal area during the performance of the intelligence task. This suggests that the major thinking process differs depending on the gifted students' primary field of study, although they are doing the same task.

• Journal of Biomedical Engineering Research
• /
• v.18 no.3
• /
• pp.243-251
• /
• 1997

In this paper, we have reported two interesting flow effects arising in the TRFGE sequence using water flow phantom. First, we have shown that the TRFGE sequence is indeed not affected by "in-flow" effect from the unsaturated spins flowing into the imaging slice. Second, the enhancement of "in-plane flow" signal in the readout gradient direction was observed when the TRFGE sequence was used without flow compensation. These two results have many interesting applications in MR imaging other than fMRI. Results obtained were also compared with the results obtained by the conventional gradient echo(CGE) imaging. Experiments were performed at 4.7T MRI/S animal system (Biospec, BRUKER, Switzerland). A cylindrical phantom was made using acryl and a vinyl tube was inserted at the center(Fig. 1). The whole cylinder was filled with water doped with $MnCl_2$ and the center tube was filled with saline which flows in parallel to the main magnetic field along the tube. Tailored RF pulse was designed to have quadratic ($z^2$) phase distribution in slice direction(z). Imaging parameters were TR/TE = 55~85/10msec, flip angle = $30^{\circ}$, slice thickness = 2mm, matrix size = 256${\times}$256, and FOV= 10cm. In-flow effect : Axial images were obtained with and without flow using the CGE and TRFGE sequences, respectively. The flow direction was perpendicular to the image slice. In-plane flow : Sagittal images were obtained with and without flow using the TRGE sequence. The readout gradient was applied in parallel to the flow direction. We have observed that the "in-flow" effect did not affect the TRFGE image, while "in-plane flow" running along the readout gradient direction enhanced the signal in the TRFGE sequence when flow compensation gradient scheme was not used.

• Journal of KIISE:Software and Applications
• /
• v.31 no.4
• /
• pp.411-419
• /
• 2004

When the imaging object rotates in image plane during MRI scan, its rotation causes phase error and non-uniform sampling to MRI signal. The model of the problem including phase error non-uniform sampling of MRI signal showed that the MRI signals corrupted by rotations about an arbitrary center and the origin in image plane are different in their phases. Therefore the following methods are presented to improve the quality of the MR image which includes the artifact. The first, assuming that the angle of 2-D rotational motion is already known and the position of 2-D rotational center is unknown, an algorithm to correct the artifact which is based on the phase correction is presented. The second, in case of 2-D rotational motion with unknown rotational center and unknown rotational angle, an algorithm is presented to correct the MRI artifact. At this case, the energy of an ideal MR image is minimum outside the boundary of the imaging object to estimate unknown motion parameters and the measured energy increases when the imaging object has an rotation. By using this property, an evaluation function is defined to estimate unknown values of rotational angle at each phase encoding step. Finally, the effectiveness of this presented techniques is shown by using a phantom image with simulated motion and a real image with 2-D translational shift and rotation.