• The Journal of the Korea Contents Association
• /
• v.19 no.11
• /
• pp.445-450
• /
• 2019

This study proves that syringe reuse of automated injection system entails a risk of contrast media reflux and saline solution contamination which are pumped by a piston into the patients' venous cannula in the dynamic MR images, we will be aware of the serious problem. To quantify the contrast media contamination effect on the saline solution, identical volume of the saline solution was collected before and after the contrast injection to the patients' venous cannula following T1 weighted image scanning to verify whether signal intensities differences are observed. The signal intensity of saline solution after the contrast injection was significantly higher than that of saline before injection by 523.43%. This result is due to the backflow that contaminates the saline solution on the opposite side when the contrast agent is injected. In conclusion, the syringe used to inject contrast medium. causes cross-contamination due to contrast reflux. Therefore, even if the same patient's examination is used for quantitative analysis, the error should be avoided by changing the acquisition sequence or replacing the syringe.

• Investigative Magnetic Resonance Imaging
• /
• v.17 no.1
• /
• pp.1-7
• /
• 2013

Purpose : The purpose of this study is to correlate the imaging findings and the clinical findings in patients with transient splenial lesions (TSL). Materials and Methods: Total of 7 patients (M: F = 4: 3; age range 11 - 38 years, mean age 25.5 years) were studied between November 2006 and April 2011. The MRI findings and clinical findings in all patients were retrospectively reviewed. The location, MR signal intensity, restricted diffusion, enhancement pattern and reversibility from the follow up images were reviewed. Clinical features were reviewed with respect to the presented symptoms, signs, treatment and outcome. Results: The lesions were located in the splenium of corpus callosum in all patients. All lesions showed high signal intensity on diffusion weighted imaging (DWI), and six patients showed restricted diffusion on the apparent diffusion coefficient (ADC) map. ADC map was not available in one patient. All lesions (n = 7) showed high signal intensity on the T2 weighted image (T2WI). Five of the patients (71.4%) with follow up images (range 7 - 34 days) showed complete resolution of focal high signal intensity on DWI, with recovery of ADC values as well as T2WI. After contrast media administration, none of the lesions showed any enhancements. All lesions with various etiologies including TB medication were developed in younger age patients and showed reversibility after the acceptable period of minimum 7 days with conservative treatment. Conclusion: All TSL showed nonspecific imaging findings, including restricted diffusion on DWI and ADC map on the initial images. However, reversibility of the lesions and the young age preference can be a characteristic finding of TSL with acceptable period of minimum 7 days. In addition, to keep it in mind that various etiologies including TB medication may cause TSL, is important for radiologists as well as clinicians.

• Investigative Magnetic Resonance Imaging
• /
• v.14 no.1
• /
• pp.31-40
• /
• 2010

Purpose : To compare the relative values of various fast breath-hold imaging sequences for superparamagnetic iron-oxide (SPIO)-enhanced hepatic MRI for the assessment of solid focal lesions with a 3T MRI unit. Materials and Methods : 102 consecutive patients with one or more solid malignant hepatic lesions were evaluated by spoiled gradient echo (GRE) sequences with three different echo times (2.4 msec [GRE_2.4], 5.8 msec [GRE_5.8], and 10 msec [GRE_10]) for $T2^*$-weighted imaging in addition to T2-weighted turbo spin echo (TSE) sequence following intravenous SPIO injection. Image qualities of the hepatic contour, vascular landmarks and artifacts were rated by two independent readers using a four-point scale. For quantitative analysis, contrast-to-noise ratio (CNR) was measured in 170 solid focal lesions larger than 1 cm (107 hepatocellular carcinomas, nine cholangiocarcinomas and 54 metastases). Results : GRE_5.8 showed the highest mean points for hepatic contour, vascular anatomy and imaging artifact presence among all of the subjected sequences (p<0.001) and was comparable (p=0.414) with GRE_10 with regard to lesion conspicuity. The mean CNRs were significantly higher (p<0.001) in the following order: GRE_10 ($24.4{\pm}14.5$), GRE_5.8 ($14.8{\pm}9.4$), TSE ($9.7{\pm}6.3$), and GRE_2.4 ($7.9{\pm}6.4$). The mean CNRs of CCCs and metastases were higher than those of HCCs for all imaging sequences (p<0.05). Conclusion : Regarding overall performances, GRE using a moderate echo time of 5.8 msec can provide the most reliable data among the various fast breath-hold SPIO-enhanced hepatic MRI sequences at 3T unit despite the lower CNR of GRE_5.8 compared to that of GRE_10.

• Journal of Korean Neurosurgical Society
• /
• v.59 no.6
• /
• pp.584-589
• /
• 2016

Objective : A rare subtype of meningioma, sclerosing meningioma is not included in the current World Health Organization classification of meningiomas and is classified into the category of other morphological variation subtypes. Sclerosing meningioma is often misdiagnosed to other non-benign meningioma or malignant neoplasm, so it is important to diagnose sclerosing type correctly. We analyzed the radiological and clinical characteristics of a series of sclerosing meningiomas. Methods : Twenty-one patients who underwent surgery in one institute with a histopathologically proven sclerosing meningioma were included from 2006 to 2014. Eighteen tumors were diagnosed as a pure sclerosing-type meningioma, and 3 as mixed type. Magnetic resonance image was taken for all patients including contrast enhancement image. Computed tomography (CT) scan was taken for 16 patients. One neuroradiologist and 1 neurosurgeon reviewed all images retrospectively. Results : In the all 16 patients with preoperative CT images, higher attenuation was observed in the meningioma than in the brain parenchyma, and calcification was observed in 11 (69%). In 15 of the 21 patients (71%), a distinctive very low signal intensity appeared as a dark color in T2-weighted images. Nine of these 15 tumors (60%) exhibited heterogeneous enhancement, and 6 (40%) exhibited homogeneous enhancement that was unlike the homogeneous enhancing pattern shown by conventional meningiomas. Ten patients had a clear tumor margin without peritumoral edema. Conclusion : Although these peculiar radiological characteristics are not unique to sclerosing meningioma, we believe that they are distinctive features that may be helpful for distinguishing sclerosing meningioma from other subtypes.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.43 no.4 s.310
• /
• pp.1-8
• /
• 2006

This paper proposes an improved FCM(Fuzzy C-means) algorithm using intercluster and entropy-based weight in gray image. The fuzzy clustering methods have been extensively used in the image segmentation since it extracts feature information of the region. Most of fuzzy clustering methods have used the FCM algorithm. But, FCM algorithm is still sensitive to noise, as it does not include spatial information. In addition, it can't correctly classify pixels according to the feature-based distributions of clusters. To solve these problems, we applied a weight and intercluster to the traditional FCM algorithm. A weight is obtained from the entropy information based on the cluster's number of neighboring pixels. And a membership for one pixel is given based on the information considering the feature-based intercluster. Experiments has confirmed that the proposed method was more tolerant to noise and superior to existing methods.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.22 no.1
• /
• pp.15-22
• /
• 2018

Purpose Respiratory motion during PET/MRI acquisition may result in image blurring and error in measurement for volume and quantification of lesion. The aim of this study was to evaluate changes of quantitative accuracy, tumor size and image quality by applying MR based respiratory motion correction technique (MBRMCT) using integrated PET/MR scanner. Materials and Methods Data of 30 patients (aged $62.5{\pm}10.2y$) underwent $^{18}F-FDG$ liver PET/MR (Biograph mMR 3.0T, Siemens) study were collected. PET listmode data for 7 minutes was simultaneously acquired with maximum average gate (MAG), minimum time gate (MTG) and non gate (NG) T1 weighted MR images. Gated PET reconstruction was performed using mu-maps generated from MAG and MTG by setting 35% of efficiency window. Maximum SUV ($SUV_{max}$), peak SUV ($SUV_{peak}$), tumor size and full width at half maximum (FWHM) in the z-axis direction of MAG, MTG and NG PET images were evaluated. Results Compared to NG, mean $SUV_{max}$ and $SUV_{peak}$ were increased in MAG 13.15%(p<0.0001), 8.66%(p<0.0001), MTG 13.27%(p<0.0001), 8.80%(p<0.0001) and mean tumor size and FWHM were decreased in MAG 14.47%(p<0.0001), 15.49%(p=0.0004), MTG 14.89%(p<0.0001), 15.79%(p=0.0003) respectively. Mean $SUV_{max}$ and $SUV_{peak}$ of MTG were increased by 0.07%(p=0.8802), 0.13%(p=0.7766). Mean tumor size and FWHM of MTG were decreased by 0.49%(p=0.2786), 0.36%(p=0.2488) compared to MAG. There was no statistically significant difference between MAG and MTG which increase total scan time for about 7 and 2 minutes. Conclusion SUV, accuracy of tumor size and spatial resolution were improved in both of MAG and MTG by applying MBRMCT without installing additional hardware in liver PET/MR study. More accurate information can be provided with the increase of 2 minutes scan time if applying MTG of MBRMCT to various abdominal PET/MR studies affected by respiratory motion.

• Radiation Oncology Journal
• /
• v.26 no.2
• /
• pp.126-130
• /
• 2008

Avascular necrosis(AVN) is a disease characterized by the temporary or permanent loss of the blood supply to the bones, resulting from many possible causes, including radiation therapy. The femoral head is known to be the most common site of AVN. The authors encountered two cases of AVN of the femoral head among 557 patients with cervical cancer treated with whole pelvic radiation therapy at the Samsung Medical Center. AVN of the femoral head was presented with a sclerotic density change in a plain roentgenography and a decreased signal intensity lesion on the T1 and T2 weighted phases of a magnetic resonance image(MRI). Although it is a very rare complication after whole pelvic radiation therapy, AVN of the femoral head should be considered when characteristic imaging findings appear on follow-up examinations.

• Journal of the Korean Society of Radiology
• /
• v.10 no.4
• /
• pp.241-246
• /
• 2016

The purpose of this study was to investigate the problems of low signal-to-noise ratio(SNR) of single-shot turbo spin echo(SS-TSE) by quantifying numerically decreased signal to noise ratio. Thirty five patients without brain disease underwent diffusion MRI in 3T scanner from July to October in 2015. Single shot echo planar imaging(SS-EPI) which is conventionally used in MRI was taken to compared SS-TSE in SNR of medulla oblongata. As a result, SNR of SS-TSE diffusion(b0=$314.41{\pm}42.96$, b1000=$117.33{\pm}14.04$) is than SS-EPI diffusion(b0=$514.84{\pm}48.97$, b=$208.65{\pm}25.70$) lower in b=0 image(38.9%) and b=1,000 image(43.8%). Thus, diffusion MR using SS-EPI of MS-EPI should be taken for diagnosis of disease in brain stem due to decreased SNR of diffusion using SS-TSE.

• Investigative Magnetic Resonance Imaging
• /
• v.7 no.2
• /
• pp.100-107
• /
• 2003

Purpose : To assess the usefulness of cardiac MR imaging (MRI) in the diagnosis of acute myocardial infarction and in the assessment of myocardial viability in comparision with T1-201 SPECT. Materials and Methods : We retrospectively studied 17 patients who complained of chest pain and dyspnea with cardiac MRI . The patients were evaluated for the presence or absence of high signal intensity on T2-weighted image (T2wI), abnormal wall motion on 2D-FIESTA, perfusion defect on Gd-DTPA enhanced T1WI, and delayed myocardial enhancement on 15-minutes delay Gd-DTPA enhanced T1WI. The results were correlated with the images on T1-201 SPECT, taken at rest and stress, through which reversibility of perfusion defect was assessed. Results : Both cardiac MRI and T1-201 SPECT proved to be useful methods for diagnosing acute myocardial infarction. In order of decreasing correspondence, T2WI, T1-201 SPECT, delayed enhancement study, and wall motion images all showed significant statistical correlation with the clinical diagnosis of myocardial infarction. Perfusion MRI, on the other hand, showed no significant statistical difference was found between T1-201 SPECT and cardiac MRI. The results on T2WI showed high accordance with those on Tl-201 SPECT, while delayed myocardial enhancement and wall motion studies showed no agreement with Tl-201 SPECT. Conclusion : Cardiac MRI is useful method for diagnosis of acute myocardiac infarction. With respect to the assessment of myocardial viability, the results obtained on cardiac MRI showed high agreement with those on Tl-201 SPECT. However, further study is necessary at this point for standardization and establishment of the methods for assessing myocardial viability on cardiac MRI.

• The Journal of the Korea Contents Association
• /
• v.10 no.8
• /
• pp.249-256
• /
• 2010

To the detect of SPIO-labelled hMSC, in vitro study on various cell concentration and in vivo molecular magnetic resonance imaging(MRI) technique using T2, $T2^*$ and SWI are compared with pathology. Cell concentration was $1.56{\times}10^4$, $3.13{\times}10^4$, $6.25{\times}10^4$, $1.25{\times}10^5$, $2.5{\times}10^5$, $5{\times}10^5\;cells/m{\ell}$ and for control $5{\times}10^5\cells/m{\ell}$. MRI technique using T2, $T^2$ and SWI. Photothrombotic infarction was located 2.5mm from bregma right, posterior. Cell injected through the tail vein of rat for 8 rats. MRI performed pre injection and post injection of 1, 3, 7 and 14days and sacrifice for pathology. MRI analysed on quantitatively. In vitro result, SWI was highest CNR as compared with $T2^*WI$, T2WI and $2.5{\times}10^5\;cells/m{\ell}$ cell concentration. In vivo result among the T2WI, $T2^WI$, SWI, T2WI is highest CNR between normal and infarction. CNR in normal-SPIO and infarction-SPIO is high score in SWI. Therefore, T2WI is good distinguish between normal and infarction, SWI are well detect SPIO-labelled hMSC from normal and infarction. Nowaday, SWI are mostly used on hemorrhage, calcification etc. in clinically, but for the future, stem cell therapy is commonly application at all disease which is good observing tool for SPIO-labelled stem cells.