• Imaging Science in Dentistry
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• 제49권1호
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• pp.53-58
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• 2019

Purpose: To present characteristic findings of Tc-99m hydroxymethylene diphosphonate (HMDP) scintigraphy, computed tomography (CT), and magnetic resonance (MR) imaging for osteonecrosis in the mandible, especially osteoradionecrosis(ORN) and medication-related osteonecrosis of the jaw(MRONJ). Materials and Methods: Thirteen patients with MRONJ and 7 patients with ORN in the mandible underwent Tc-99m HMDP scintigraphy, CT, and MR imaging (T1-weighted images[T1WI], T2-weighted images[T2WI], short inversion time inversion recovery images[STIR]), diffusion-weighted images[DWI], and apparent diffusion coefficient [ADC] mapping). The associations of scintigraphy, CT, and MR imaging findings with MRONJ and ORN were analyzed using the chi-square test with the Pearson exact test. Results: Thirteen patients with MRONJ and 7 patients with ORN in the mandible showed low signal intensity on T1WI and ADC mapping, high signal intensity on STIR and DWI, and increased uptake on scintigraphy. Periosteal bone proliferation on CT was observed in 69.2% of patients with MRONJ(9 of 13) versus 14.3% of patients with ORN(1 of 7)(P=0.019). Conclusion: This study presented characteristic imaging findings of MRONJ and ORN on scintigraphy, CT, and MR imaging. Our results suggest that CT can be effective for detecting MRONJ and ORN.

• Imaging Science in Dentistry
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• 제52권4호
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• pp.393-398
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• 2022

Purpose: This study proposed a generative adversarial network (GAN) model for T2-weighted image (WI) synthesis from proton density (PD)-WI in a temporomandibular joint(TMJ) magnetic resonance imaging (MRI) protocol. Materials and Methods: From January to November 2019, MRI scans for TMJ were reviewed and 308 imaging sets were collected. For training, 277 pairs of PD- and T2-WI sagittal TMJ images were used. Transfer learning of the pix2pix GAN model was utilized to generate T2-WI from PD-WI. Model performance was evaluated with the structural similarity index map (SSIM) and peak signal-to-noise ratio (PSNR) indices for 31 predicted T2-WI (pT2). The disc position was clinically diagnosed as anterior disc displacement with or without reduction, and joint effusion as present or absent. The true T2-WI-based diagnosis was regarded as the gold standard, to which pT2-based diagnoses were compared using Cohen's ĸ coefficient. Results: The mean SSIM and PSNR values were 0.4781(±0.0522) and 21.30(±1.51) dB, respectively. The pT2 protocol showed almost perfect agreement(ĸ=0.81) with the gold standard for disc position. The number of discordant cases was higher for normal disc position (17%) than for anterior displacement with reduction (2%) or without reduction (10%). The effusion diagnosis also showed almost perfect agreement(ĸ=0.88), with higher concordance for the presence (85%) than for the absence (77%) of effusion. Conclusion: The application of pT2 images for a TMJ MRI protocol useful for diagnosis, although the image quality of pT2 was not fully satisfactory. Further research is expected to enhance pT2 quality.

• Journal of Korean Dental Science
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• 제8권1호
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• pp.16-27
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• 2015

Purpose: The purpose of this study was to evaluate the correlation between the clinical symptoms of temporomandibular disorder and findings in the magnetic resonance imaging (MRI). Materials and Methods: Clinical data and MRI images were collected from a total of 240 German patients. Clinical symptoms were briefed as joint clicking, crepitus and pain. MRI findings were further defined according to the condyle position, condyle degeneration, disc positon, disc degeneration and the presence of osteophyte/sclerosis/synovitis. Hypermobility was separately recorded. Correlation analysis between parameters was performed. Result: Joint clicking had a positive correlation with unilateral disc degeneration, osteophyte, sclerosis and synovitis. Crepitus had a significant correlation with bilateral osteophyte. Pain was not correlated with any MRI findings except hypermobility. Conclusion: Selective correlations between the MRI findings and clinical symptoms were elucidated. The results of this study imply that condyle-disc deformities could be advanced without pain, and that joint clicking and crepitus could be clinical symptoms of condyle-disc degeneration.

• The Korean Journal of Pain
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• 제23권3호
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• pp.202-206
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• 2010

Magnetic resonance image (MRI) is the most sensitive imaging test of the spine in routine clinical practice. Unlike conventional x-ray examinations and computed tomography scans, high-quality magnetic resonance images can be assured only if patients are able to remain perfectly still. However, some patients find it uncomfortable to remain still because of pain. In that condition, interlaminar cervical epidural injections can reduce pain and allow the procedure. When using air with the "loss of resistance" technique in epidural injections to identify the epidural space, there is the possibility of injected excessive air epidurally to mimic a herniated disc. We describe a case report of epidural air artifact in a cervical MRI after cervical epidural injections.

• Investigative Magnetic Resonance Imaging
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• 제23권1호
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• pp.1-16
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• 2019

Dynamic contrast enhanced (DCE) magnetic resonance (MR) imaging plays an important role in non-invasive detection and characterization of primary and metastatic lesions in the liver. Recently, efforts have been made to improve spatial and temporal resolution of DCE liver MRI for arterial phase imaging. Review of recent publications related to arterial phase imaging of the liver indicates that there exist primarily two approaches: breath-hold and free-breathing. For breath-hold imaging, acquiring multiple arterial phase images in a breath-hold is the preferred approach over conventional single-phase imaging. For free-breathing imaging, a combination of three-dimensional (3D) stack-of-stars golden-angle sampling and compressed sensing parallel imaging reconstruction is one of emerging techniques. Self-gating can be used to decrease respiratory motion artifact. This article introduces recent MRI technologies relevant to hepatic arterial phase imaging, including differential subsampling with Cartesian ordering (DISCO), golden-angle radial sparse parallel (GRASP), and X-D GRASP. This article also describes techniques related to dynamic 3D image reconstruction of the liver from golden-angle stack-of-stars data.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1890-1894
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• 2012

Vascular endothelial growth factor (VEGF) and its receptor (VEGFR) have been implicated in the pathogenesis of rheumatoid arthritis, which is angiogenesis dependent. Antibody-based molecular imaging improves targeting, and antibody radiolabeling is useful for monitoring biological events $in$ $vivo$ $via$ PET or SPECT. We investigated the potential of molecular imaging to diagnose arthritis with VEGFR-2 $in$ $vivo$. The $^{123}I$-VEGFR-2 antibody was prepared by the iodogen tube method. The radioligand was injected into arthritic mice, and micro SPECT/CT was performed. The arthritic mice were examined by 4.7-T MRI and immunohistochemistry. The $^{123}I$-VEGFR-2 antibody showed high uptake in the arthritic region at 1 h postinjection on SPECT/CT but no uptake in the control animals after radioligand injection. In MR images, the arthritic tissue of the mice was correlated with regions labeled by the $^{123}I$-VEGFR-2 antibody. Immunohistochemical localization showed markedly increased expression of VEGFR-2 in the endothelial cells, fibroblasts, and macrophages of the arthritic mice.

• Journal of Veterinary Science
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• 제22권1호
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• pp.2.1-2.10
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• 2021

Background: Diseases related to cerebrospinal fluid flow, such as hydrocephalus, syringomyelia, and Chiari malformation, are often found in small dogs. Although studies in human medicine have revealed a correlation with cerebrospinal fluid flow in these diseases by magnetic resonance imaging, there is little information and no standard data for normal dogs. Objectives: The purpose of this study was to obtain cerebrospinal fluid flow velocity data from the cerebral aqueduct and subarachnoid space at the foramen magnum in healthy beagle dogs. Methods: Six healthy beagle dogs were used in this experimental study. The dogs underwent phase-contrast and time-spatial labeling inversion pulse magnetic resonance imaging. Flow rate variations in the cerebrospinal fluid were observed using sagittal time-spatial labeling inversion pulse images. The pattern and velocity of cerebrospinal fluid flow were assessed using phase-contrast magnetic resonance imaging within the subarachnoid space at the foramen magnum level and the cerebral aqueduct. Results: In the ventral aspect of the subarachnoid space and cerebral aqueduct, the cerebrospinal fluid was characterized by a bidirectional flow throughout the cardiac cycle. The mean ± SD peak velocities through the ventral and dorsal aspects of the subarachnoid space and the cerebral aqueduct were 1.39 ± 0.13, 0.32 ± 0.12, and 0.76 ± 0.43 cm/s, respectively. Conclusions: Noninvasive visualization of cerebrospinal fluid flow movement with magnetic resonance imaging was feasible, and a reference dataset of cerebrospinal fluid flow peak velocities was obtained through the cervical subarachnoid space and cerebral aqueduct in healthy dogs.

• Investigative Magnetic Resonance Imaging
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• 제12권2호
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• pp.197-200
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• 2008

관절강내 및 관절주위 연골종은 큰 관절 중 주로 슬관절에 생기는 드문 양성 종양이다. 저자들은 동통을 동반한 만져지는 슬개골하 종괴를 주소로 내원한 15세 여자 환자에서 Hoffa씨 지방층에 발생한 관절강내 및 관절주위 연골종을 경험하였다. 이학적 검사에서 슬개골하 부위에 단단하고 이동성이 있는 종괴가 만져졌으며 자기공명영상에서 이 종괴는 국소 석회화를 동반한 경계가 좋은 연조직 종괴였다.

• Investigative Magnetic Resonance Imaging
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• 제18권2호
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• pp.171-175
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• 2014

간문맥으로 파열된 췌장 가성낭종은 매우 드문 합병증이며, 자기공명영상으로 확진된 경우는 3예만 보고되어 있다. 저자들은 50세 남자 환자에서 가성낭종과 간문맥 사이에 형성된 누공을 자기공명영상을 이용하여 비침습적으로 확진한 증례를 보고한다. T2강조영상 및 자기공명 담체관조영술에서 간문맥, 상장간막정맥, 그리고 비장정맥 내에 액체신호가 보였으며, 가성낭종과 간문맥이 직접 연결된 소견을 보였다.

• Investigative Magnetic Resonance Imaging
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• 제17권4호
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• pp.308-311
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• 2013

심부실비우스열뇌수막종은 뇌수막종의 드문 형태이다. 본 증례를 합하여 한국에서 총 4증례가 보고 되었다. 이전 병력이 없던 43세 남자가 경련발작을 주소로 본원에 내원하였다. 자기공명영상에서 오른 심부실비우스열에 테두리가 조영증강되는 종괴가 발견되었고 경막과의 연결성은 없었다. 수술적 제거 후 심부실비우스뇌수막종으로 진단되었다.