• Korean Journal of Radiology
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• v.22 no.4
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• pp.559-567
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• 2021

Objective: To evaluate the impact of multiparametric magnetic resonance imaging (mpMRI) before confirmatory prostate biopsy in patients under active surveillance (AS). Materials and Methods: This retrospective study included 170 patients with Gleason grade 6 prostate cancer initially enrolled in an AS program between 2011 and 2019. Prostate mpMRI was performed using a 1.5 tesla (T) magnetic resonance imaging system with a 16-channel phased-array body coil. The protocol included T1-weighted, T2-weighted, diffusion-weighted, and dynamic contrast-enhanced imaging sequences. Uroradiology reports generated by a specialist were based on prostate imaging-reporting and data system (PI-RADS) version 2. Univariate and multivariate analyses were performed based on regression models. Results: The reclassification rate at confirmatory biopsy was higher in patients with suspicious lesions on mpMRI (PI-RADS score ≥ 3) (n = 47) than in patients with non-suspicious mpMRIs (n = 61) and who did not undergo mpMRIs (n = 62) (66%, 26.2%, and 24.2%, respectively; p < 0.001). On multivariate analysis, presence of a suspicious mpMRI finding (PI-RADS score ≥ 3) was associated (adjusted odds ratio: 4.72) with the risk of reclassification at confirmatory biopsy after adjusting for the main variables (age, prostate-specific antigen density, number of positive cores, number of previous biopsies, and clinical stage). Presence of a suspicious mpMRI finding (adjusted hazard ratio: 2.62) was also associated with the risk of progression to active treatment during the follow-up. Conclusion: Inclusion of mpMRI before the confirmatory biopsy is useful to stratify the risk of reclassification during the biopsy as well as to evaluate the risk of progression to active treatment during follow-up.

• Clinical and Experimental Pediatrics
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• v.52 no.4
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• pp.488-493
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• 2009

Purpose : The aim of this study was to assess the efficacy and safety of recent-generation patent ductus arteriosus (PDA) closure devices applied by a new selection strategy according to the characteristics of each PDA. Methods : From February 2003 to January 2006, 138 patients underwent transcatheter closure of PDA (study group). According to the size and morphology of each ductus, a COOK Detachable Coil or 'flex' PFM Nit-Occlud was used for a small ductus (group 1, n=43); 'medium' PFM Nit-Occlud (group 2, n=49) for a moderate ductus; and an Amplatzer Duct Occluder (group 3, n=46) for a large ductus. The 83 patients who underwent transcatheter closure of PDA from February 2000 to January 2003 were defined as the comparison group. The Qp/Qs ratio, pulmonary/aorta pressure ratio, and MD of the ductus were compared. Immediate and follow-up results including residual shunts and complications were also evaluated and compared among groups. Results : In all 138 patients, complete occlusions were confirmed without major complications, while procedure failure (n=2, 2.2%), device embolization (n=1, 1.1%), and persistent residual shunt (n=4, 4.5%) were documented in the comparison group. Total complication rates were lower in the study group than in the comparison group (study group, 1.4%; comparison group, 9.0%; P<0.05). Conclusion : A novel strategy adopting the merits of various recent-generation devices for transcatheter closure of PDA provides excellent clinical results with minimal risk.

• Investigative Magnetic Resonance Imaging
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• v.16 no.1
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• pp.67-75
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• 2012

Purpose : We studied enhanced method to view the vessels in the brain using Magnetic Resonance Angiography (MRA). Noticing that Maximum Intensity Projection (MIP) image is often used to evaluate the arteries of the neck and brain, we propose a new method for view brain vessels to stereo image in 3D space with more superior and more correct compared with conventional method. Materials and Methods: We use 3T Siemens Tim Trio MRI scanner with 4 channel head coil and get a 3D MRA brain data by fixing volunteers head and radiating Phase Contrast pulse sequence. MRA brain data is 3D rotated according to the view angle of each eyes. Optimal view angle (projection angle) is determined by the distance between eye and center of the data. Newly acquired MRA data are projected along with the projection line and display only the highest values. Each left and right view MIP image is integrated through anaglyph imaging method and optimal stereoscopic MIP image is acquired. Results: Result image shows that proposed method let enable to view MIP image at any direction of MRA data that is impossible to the conventional method. Moreover, considering disparity and distance from viewer to center of MRA data at spherical coordinates, we can get more realistic stereo image. In conclusion, we can get optimal stereoscopic images according to the position that viewers want to see and distance between viewer and MRA data. Conclusion: Proposed method overcome problems of conventional method that shows only specific projected image (z-axis projection) and give optimal depth information by converting mono MIP image to stereoscopic image considering viewers position. And can display any view of MRA data at spherical coordinates. If the optimization algorithm and parallel processing is applied, it may give useful medical information for diagnosis and treatment planning in real-time.

• Investigative Magnetic Resonance Imaging
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• v.17 no.2
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• pp.133-143
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• 2013

Purpose : To evaluate and compare the accuracy of magnetic resonance imaging (MRI) and ultrasound (US) for detection and estimation of invasion depth of colorectal carcinoma (CRC) by correlation with histopathologic findings in vitro, and to find out the best MR pulse sequence for accurate delineation of tumor from surrounding normal tissue. Materials and Methods: Resected specimens of CRC from 45 patients were examined about tumor detectability and invasion depth of US using high frequency (5-17 MHz) linear transducer in a tube filled with normal saline and MRI in a 8-channel quadrate head coil. The institutional review board approved this study and informed consent was waived. MRI with seven pulse sequences of in- and out-of-phases gradient echo T1 weighted images, fast spin echo T2 weighted image and its fat suppression image, fast imaging employing steady-state acquisition (FIESTA) and its fat suppression image, and diffusion weighted image (DWI) were performed. In each case, both imaging findings of MRI and US were evaluated independently for detection and estimation of invasion depth of tumor by consensus of two radiologists and were compared about diagnostic accuracy according to the histopathologic findings as reference standard. Seven MR pulse sequences were evaluated on the point of accurate delineation of tumor from surrounding normal tissue in each specimen. Results: In specimens of CRC, both imaging modalities of MRI (91.1%) and US (86.7%) showed relatively high diagnostic accuracy to detect tumor and evaluate invasion depth of tumor. In early CRC, diagnostic accuracy of US was 87.5% and that of MRI was 75.0%. There was no statistically significant difference between two imaging modalities (p > 0.05). The best pulse sequence among seven MR sequences for accurate delineation of tumor from surrounding normal tissue in each specimen of CRC was fast spin echo T2 weighted image. Conclusion: MRI and US show relatively high diagnostic accuracy to detect tumor and evaluate invasion depth of resected specimen of CRC. The most excellent pulse sequence of MRI for accurate delineation of tumor from surrounding normal tissue in CRC is fast spin echo T2 weighted image.

• The korean journal of orthodontics
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• v.36 no.4
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• pp.242-250
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• 2006

Objective: Periodontal ligament fibroblasts have an ectomesenchymal origin and are thought to play a crucial role for not only homeostasis of periodontal tissues but also bone remodeling, wound healing and regeneration of tissues. Recently, it has been reported that UNC-50 is not expressed in gingival fibroblasts but in PDL fibroblasts. The purpose of this study was to examine the expression of UNC-50 and osteocalcin in the periodontium after application of intermittent force. Methods: Twelve rats had 40 grams of mesially-directed force applied at the upper molar for 1 hour/day. Four rats were sacrificed at 1, 3 and 5 days. Immunohistochemical localization of UNC-50 and osteocalcin antibody was carried out. The results showed apposition of new cellular cementum and a slight increase in periodontal space at the tension side. Results: Strong UNC-50 expression was observed in the differentiating cementoblasts close to PDL fibroblasts in the tension side whereas it was barely expressed at the compression side. Expression was strong at day 3, and decreased at day 5. Osteocalcin immunoreactivity expression was strong in differentiating cementoblasts at the tension side. Conclusion: It can be suggested that UNC-50 is related to the differentiation of cementoblasts, and may be responsible for the molecular event in PDL cells under mechanical stress.

• Investigative Magnetic Resonance Imaging
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• v.13 no.2
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• pp.161-170
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• 2009

Purpose : A parallel imaging method provides us to improve temporal resolution to obtain three-dimensional (3D) MR images. The objective of this study was to optimize three 3D MRI techniques by adjusting 2D SESNE factors of the parallel imaging method in phantom and human brain. Materials and Methods : With a 3 Tesla MRI system and an 8-channel phase-array sensitivity-encoding (SENSE) coil, three 3D MRI techniques of 3D T1-weighted imaging (3D T1WI), 3D T2-weighted imaging (3D T2WI) and 3D fluid attenuated inversion recovery (3D FLAIR) imaging were optimized with adjusting SESNE factors in a water phantom and three human brains. The 2D SENSE factor was applied on the phase-encoding and the slice-encoding directions. Signal-to-noise ratio(SNR), percent signal reduction rate(%R), and contrast-to-noise ratio(CNR) were calculated by using signal intensities obtained in specific regions-of-interest (ROI). Results : In the phantom study, SENSE factor = 3 was provided in 0.2% reduction of signals against without using SENSE with imaging within 5 minutes for 3D T1WI. SENSE factor = 2 was provided in 0.98% signal reduction against without using SENSE with imaging within 5 minutes for 3D T2WI. SENSE factor = 4 was provided in 0.2% signal reduction against without using SENSE with imaging around 6 minutes for 3D FLAIR. In the human brain study, SNR and CNR were higher with SENSE factors = 3 than 4 for all three imaging techniques. Conclusion : This study was performed to optimize 2D SENSE factors in the three 3D MRI techniques that can be scanned in clinical time limitations with minimizing SNR reductions. Without compromising SNR and CNR, the optimum 2D SENSE factors were 3 and 4, yielding the scan time of about 5 to 6 minutes. Further studies are necessary to optimize 3D MRI techniques in other areas in human body.

• Progress in Medical Physics
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• v.20 no.4
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• pp.235-243
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• 2009

The purpose of this experiment is to know the relation of the detection and characterization of liver's diseases as comparison of finding at MR imaging using a Ferucarbotran (SPIO) and Gd-EOB-DTPA (Primovist) agents in diffuse liver disease. A total of 50 patients (25 men and 25 women, mean age: 50 years) with liver diseases were investigated at 3.0T machine (GE, General Electric Medical System, Excite HD) "with 8 Ch body coil for comparison of diseases and contrast's uptake relation, which used the LAVA, MGRE." All images were performed on the same location with before and after Ferucarbotran and Gd-EOB-DTPA administrations (p<0.05). Contrast to noise ratio of Ferucarbotran and Gd-EOB-DTPA in the HCC were $3.08{\pm}0.12$ and $7.00{\pm}0.27$ with MGRE and LAVA pulse sequence, $3.62{\pm}0.13$ and $2.60{\pm}0.23$ in the hyper-plastic nodule, $1.70{\pm}0.09$ and $2.60{\pm}0.23$ in the meta, $2.12{\pm}0.28$ and $5.86{\pm}0.28$ in the FNH, $4.45{\pm}0.28$ and $1.73{\pm}0.02$ in the abscess and ANOVA test was used to evaluate the diagnostic performance of each disease (p<0.05). In conclusions, two techniques were well demonstrated with the relation of the detection and characterization of liver's diseases.

• The Korean Journal of Nuclear Medicine
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• v.35 no.1
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• pp.75-80
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• 2001

Purpose: There was little evidence that Tc-99m labeled ciprofloxacin (Infecton) located inside of bacteria. Antimicrobial activity of Infecton could be an indirect evidence of its location. We compared in vitro antimicrobial activities of Infecton and ciprofloxacin. Materials and methods: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Infecton and ciprofloxacin against three standard strains of bacteria, Staphylococcus aureus ATCC 29213, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 were measured using modified broth macrodilution techniques and pour plate methods, respectively. Data were expressed as mean${\pm}$SE (range). Results: MICs of Infecton and ciprofloxacin were $1.12{\pm}0.20\;(0.8{\sim}1.6){\mu}g/ml\;and\;0.35{\pm}0.04\;(0.2{\sim}0.4){\mu}g/ml$ for S. aureus, $0.03{\pm}0.005\;(0.025{\sim}0.05){\mu}g/ml\;and\;0.011{\pm}0.001\;(0.006{\sim}0.012){\mu}g/ml$ for E. coil, and $0.96{\pm}0.16\;(0.8{\sim}1.6){\mu}g/ml)\;and\;0.56{\pm}0.098\;(0.4{\sim}0.8){\mu}g/ml$ for P. aeruginosa, respectively. MBCs of Infecton and ciprofloxacin were $2.56{\pm}0.39\;(1.6{\sim}3.2){\mu}g/ml\;and\;0.88{\pm}0.2\;(0.4{\sim}1.6){\mu}g/ml$ for S. aureus, $0.04{\pm}0.05\;(0.025{\pm}0.05){\mu}g/ml\;and\;0.02{\pm}0.01\;(0.025{\sim}0.05)\;{\sim}g/ml$ for E coli, and $2.24{\pm}0.39\;(1.6{\sim}3.2){\mu}g/ml\;and\;1.44{\pm}0.16\;(0.8{\sim}1.6){\mu}g/ml$ for P. aeruginosa, respectively. Conclusion: Although both MICs and UBCs of Infecton were higher than those of ciprofloxacin, all three standard bacterial strains were sensitive to Infecton. It could be an indirect evidence that Tc-99m Infecton be a specific imaging agent for bacterial infection.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.103-107
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• 1997

Purpose: To investigate the localization and functional lateralization of the supplementary motor area (SMA) in motor activation tests in comparison to that of the primary motor area. Materials and Methods: Seven healthy volunteers obtained echoplanar imaging blood oxygen level dependent technique. This study was carried on 1.5T Siemens Magnetom Vision system with the standard head coil. Parameters of EPI were followed as; TR/TE : 1.0/66.0msec, flip angle: $90^{\circ}$, field of view: $22cm{\times}22cm,{\;}matrix:{\;}128{\times}128$, slice number/slice thickness/gap: 1O/4mm/0.8mm with fat suppression technique. Motor task as finger opposition in each hand consisted of 3 sets of alternative rest and activation periods. Postprocessing were done on Stimulate 5.0 by using cross-correlation statistics. To compare the functional lateralization of the SMA in the right and left hand tests, each examination was evaluated for the percent change of signal intensity and the number of activated voxels both in the SMA and in the pri¬mary motor area. Hemispheric asymmetry was defined as difference of summation of the activted voxels between each hemisphere. Results: Percent change of signal intensity in the SMA (2.49 -3.06%) is lower than that of primary motor area(4.4 -7.23%). Percent change of signal intensity including activated voxels were observed almost equally in the right and left SMA. As for summation of activated voxels, primary motor area had significant difference between each hemisphere but not did the SMA. Conclusion: Preferred contralateral dominant hemisphere and hemispheric asymmetry were detected in the primary motor area but not in the SMA.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.114-118
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• 1997

Purpose: Functional MR imaging is the method of demonstrating changes in regional cerebral blood flow produced by sensory, motor, and any other tasks. Functional MR of visual cortex is performed as a patient stares a photic stimulation, so adaptable photic stimulation is necessary. The purpose of this study is to evaluate whether the size of photic stimulator can affect the degree of visual cortex activation. Materials and Methods: Functional MR imaging was performed in 5 volunteers with normal visual acuity. Photic stimulator was made by 39 light-emitting diodes on a plate, operating at 8Hz. The sizes of photic stimulator were full field, half field and focal central field. The MR imager was Siemens 1.5-T Magnetom Vision system, using standard head coil. Functional MRI utilized EPI sequence (TR/TE= 1.0/51. Omsec, matrix $No.=98{\times}128$, slice thickness=8mm) with 3sets of 6 imaging during stimulation and 6 imaging during rest, all 36 scannings were obtained. Activation images were obtained using postprocessing software(statistical analysis by Z-score), and these images were combined with T-1 weighted anatomical images. The activated signals were quantified by numbering the activated pixels, and activation a index was obtained by dividing the pixel number of each stimulator size with the sum of the pixel number of 3 study using 3 kinds of stimulators. The correlation between the activation index and the stimulator size was analysed. Results: Mean increase of signal intensities on the activation area using full field photic stimulator was about 9.6%. The activation index was greatest on full field, second on half field and smallest on focal central field in 4. The index of half field was greater than that of full field in 1. The ranges of activation index were full field 43-73%(mean 55%), half field 22-40 %(mean 32%), and focal central field 5-24%(mean 13%). Conclusion: The degree of visual cortex activation increases with the size of photic stimulator.