• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.5
• /
• pp.42-47
• /
• 1998

Bridcage RF coil is one of the most widely used RF coils in MRI. In order to use birdcage RF coils in open MRI systems, an open tructured birdcage RF coil has been investigated. By opening the ring structure of an original birdcage RF coil and driving the coil at two opening ends, the original birdcage RF coil can be modified to an open structured coil. In order to improve magnetic field uniformity of the open birdcage RF coil, driving voltage phases at the two opening ends can be controlled to be in-phase or out-of-phase each other. Operating frequency of the open birdcage RF coil has been theoretically derived, and the theoretical derivation has been verified by experiments.

• The Journal of the Korea Contents Association
• /
• v.11 no.6
• /
• pp.289-301
• /
• 2011

This study is a research based on the non-equivalent control group pretest-posttest design whose purpose is to examine the effects of music therapy on the anxiety of patients who take the magnetic resonance imaging(MRI) test and their feeling of discomfort during the test. "The first hypothesis that the experimental group who receive music therapy will be lower in score for anxiety during the MRI test than the control group who do not was supported because after the therapy, the experimental group was found significantly decreased in that score in comparison to the control group. "The second hypothesis that the experimental group who receive music therapy will be fewer in vital signs after the MRI test than the control group who do not" was rejected in terms of both systolic and diastolic blood pressure. But the same hypothesis was partially supported because the two groups showed a significant difference in pulse rate after the test. "The third hypothesis that the experimental group who receive music therapy will be less in the feeling of subjective discomfort during the MRI test than the control group who do not" was verified to find that the two groups were significantly different from each other in the feeling. Specifically, there was a significant difference between the two groups in only one sub-area of that feeling, that is, tension. These findings suggest that music therapy could be an alternative method which can effectively reduce the state anxiety of patients during the magnetic resonace imaging(MRI) test.

• The KIPS Transactions:PartB
• /
• v.15B no.6
• /
• pp.507-516
• /
• 2008

Cardiac disease is the leading cause of death in the world. Quantification of cardiac function is performed by manually calculating blood volume and ejection fraction in routine clinical practice, but it requires high computational costs. In this study, an automatic left ventricle (LV) segmentation algorithm using short-axis cine cardiac MRI is presented. We compensate coil sensitivity of magnitude images depending on coil location, classify edge information after extracting edges, and segment LV by applying region-growing segmentation. We design a weighting function for intensity signal and calculate a blood volume of LV considering partial voxel effects. Using cardiac cine SSFP of 38 subjects with Cornell University IRB approval, we compared our algorithm to manual contour tracing and MASS software. Without partial volume effects, we achieved segmentation accuracy of $3.3mL{\pm}5.8$ (standard deviation) and $3.2mL{\pm}4.3$ in diastolic and systolic phases, respectively. With partial volume effects, the accuracy was $19.1mL{\pm}8.8$ and $10.3mL{\pm}6.1$ in diastolic and systolic phases, respectively. Also in ejection fraction, the accuracy was $-1.3%{\pm}2.6$ and $-2.1%{\pm}2.4$ without and with partial volume effects, respectively. Results support that the proposed algorithm is exact and useful for clinical practice.

• Investigative Magnetic Resonance Imaging
• /
• v.15 no.1
• /
• pp.67-71
• /
• 2011

Purpose : To compare T2 relaxation times (T2) in the cingulate cortex, amygdaloid body, hippocampal body, and insular cortex between 1.5T and 3.0T MR imagers. Materials and Methods : Twelve healthy volunteers underwent FLAIR and CPMG imaging perpendicular to the hippocampal body at both 3.0T and 1.5T. T2 was measured in the cingulate cortex, amygdaloid body, hippocampal body, and insular cortex. The T2 relaxation time ratios of the cingulate cortex, insular cortex, and amygdaloid body to the hippocampal body were compared between 1.5T and 3.0T. Results : The mean T2 of the cingulate cortex, amygdaloid body, hippocampal body, and insular cortex at 1.5T were $109.5{\pm}3.1$, $117.0{\pm}7.1$, $114.7{\pm}2.4$, and $111.3{\pm}2.4$, respectively; $99.7{\pm}3.8$, $100.7{\pm}4.3$, $97.9{\pm}3.4$, and $96.2{\pm}2.0$, respectively, at 3.0T. Percentage changes of T2 in the cingulate cortex, insular cortex, amygdaloid body, and hippocampal body at 3.0T with respect to those at 1.5T were -8.9%, -13.5%, -14.6%, and -13.5%, respectively. The mean T2 ratios of the cingulate gyrus, insular cortex, and amygdaloid body to the hippocampal body at 1.5T and 3.0T were 0.96 and 1.02 (p = 0.003); 1.02 and 1.03 (p>0.05); 0.97 and 0.98 (p>0.05), respectively. Conclusion : T2 decrease in the cingulate cortex was less than the amygdaloid body, insular cortex, and hippocampal body at 3.0T. The mean T2 ratio of the cingulate gyrus to the hippocampal body was significantly different between 1.5T and 3.0T.

• Journal of the Korean Society of Radiology
• /
• v.11 no.5
• /
• pp.343-351
• /
• 2017

T1, T2 relaxation time and relaxation rates were measured and analyzed according to the change of RF coil channel number of MAGiC sequence. T1, T2, R1 and R2 maps were obtained by using MAGiC sequence with phantom (1.0, 0.6, 0.2, 0 mM) on the RF coil with channel number of 1, 8, 16 and 32 respectively. T1, T2, R1, R2 values and relaxation rates were measured for each channel number and concentration, and Relaxivity was calculated according to each concentration. T1, T2, R1, and R2 values were measured in each coil. There was no significant difference between T1 and R1 values (p> 0.05). However, T2 and R2 values were significantly different (p <0.05). In the post-analysis results, T2 value was significantly different from that measured on 1, 8, 16, and 32 channel coils (p <0.05) and There was no difference between 8, 16, and 32 channel coils (p> 0.05). The R2 value was significantly different from that measured on the 8, 16, and 32 channel coils in the 1 channel coil, and the results on the 8 channel coils and the 16 channel coils showed a significant difference (P <0.05). In conclusion, T1 and R1 values were not significantly different according to the number of channels in the coil, but T2 and R2 values were significantly different. Therefore, when quantitative measurement of T2 and R2 values using the MAGiC sequence, the same number of coils should be used for reproducibility.

• Investigative Magnetic Resonance Imaging
• /
• v.2 no.1
• /
• pp.14-30
• /
• 1998

Manganese is an essential element in the body. It is mainly deposited in the liver and to a lesser degree in the basal ganglia of the brain and eliminated through the bile duct. Rapid turnover of managanese in the body makes it difficult to evaluate the manganese exposure in workers, esecially in those with irregular or intermittent exposure, like welders. Therefore, conventional biomarkers, including blood and urine manganese can provide only a limited information about the long-tern or cumulative exposure to manganese. Introduction of magnetic resonance imaging (MRI) made a progress in the assessment of manganese exposure in the medical conditions related to manganese accumulation, e. g. hepatic failure and long-term total parenteral nutrition. Manganese shortens spin-lattice(T1) relaxation time on MRI due to its paramagnetic property, resulting in high signal intensity (HSI) on T1-weighted image(T1W1) of MRI. Manganese deposition in the brain, therefore, can be visualizedas an HSI in the globus pallidus, the substantia nigra, the putamen and the pituitary. clinical and epidemiologic studies regarding the MRI findings in the cases of occupational and non-occupational manganese exposure were reviewed. relationships between HSI on T1W1 of MRI and age, gender, occupational manganese exposure, and neurological dysfunction were analysed. Relationships betwen biological exposure indices and HSI on MRE werealso reviewed. Literatures were reviewed to establish the relationships between HSI, Manganese deposition in the brain, pathologic findings, and neurological dysfunction. HSI on T1W1 of MRI reflects regional manganese deposition in the brain. This relationship enables an estimation of regional manganese deposition in the brain by analysing MR signal intensity. Manganese deposition in the brain can induce a neuronal loss in the basal ganglia but functional abnormality is supposed to be related to the cumulative exposure of manganese in the brain, use of brain MRI for the assessment of exposure in a group of workers seems to be hardly rationalized, while ti can be a useful adjunct for the evaluation of manganese exposure int he cases with suspected manganese-related health problems.

• Investigative Magnetic Resonance Imaging
• /
• v.8 no.2
• /
• pp.79-85
• /
• 2004

Purpose : To evaluate the usefulness and reproducibility of $^1H$ MRS in different 1.5 T MR machines with different coils to compare the SNR, scan time and the spectral patterns in different brain regions in normal volunteers. Materials and Methods : Localized $^1H$ MR spectroscopy ($^1H$ MRS) was performed in a total of 10 normal volunteers (age; 20-45 years) with spectral parameters adjusted by the autoprescan routine (PROBE package). In all volunteers, MRS was performed in a three times using conventional MRS (Signa Horizon) with 1 channel coil and upgraded MRS (Echospeed plus with EXCITE) with both 1 channel and 8 channel coil. Using these three different machines and coils, SNRs of the spectra in both phantom and volunteers and (pre)scan time of MRS were compared. Two regions of the human brain (basal ganglia and deep white matter) were examined and relative metabolite ratios (NAA/Cr, Cho/Cr, and mI/Cr ratios) were measured in all volunteers. For all spectra, a STEAM localization sequence with three-pulse CHESS $H_2O$ suppression was used, with the following acquisition parameters: TR=3.0/2.0 sec, TE=30 msec, TM=13.7 msec, SW=2500 Hz, SI=2048 pts, AVG : 64/128, and NEX=2/8 (Signa/Echospeed). Results : The SNR was about over $30\%$ higher in Echospeed machine and time for prescan and scan was almost same in different machines and coils. Reliable spectra were obtained on both MRS systems and there were no significant differences in spectral patterns and relative metabolite ratios in two brain regions (p>0.05). Conclusion : Both conventional and new MRI systems are highly reliable and reproducible for $^1H$ MR spectroscopic examinations in human brains and there are no significant differences in applications for $^1H$ MRS between two different MRI systems.

• The KIPS Transactions:PartB
• /
• v.18B no.2
• /
• pp.57-66
• /
• 2011

To prevent cardiac diseases, quantifying cardiac function is important in routine clinical practice by analyzing blood volume and ejection fraction. These works have been manually performed and hence it requires computational costs and varies depending on the operator. In this paper, an automatic left ventricle segmentation algorithm is presented to segment left ventricle on cardiac magnetic resonance images. After coil sensitivity of MRI images is compensated, a K-mean clustering scheme is applied to segment blood area. A graph searching scheme is employed to correct the segmentation error from coil distortions and noises. Using cardiac MRI images from 38 subjects, the presented algorithm is performed to calculate blood volume and ejection fraction and compared with those of manual contouring by experts and GE MASS software. Based on the results, the presented algorithm achieves the average accuracy of 6.2mL${\pm}$5.6, 2.9mL${\pm}$3.0 and 2.1%${\pm}$1.5 in diastolic phase, systolic phase and ejection fraction, respectively. Moreover, the presented algorithm minimizes user intervention rates which was critical to automatize algorithms in previous researches.

• Investigative Magnetic Resonance Imaging
• /
• v.17 no.2
• /
• pp.123-132
• /
• 2013

Purpose : We report the results of the various parameters of diffusion tensor imaging (DTI) and CSF flow study of the cervical spinal cord using magnetic resonance (MR) imaging techniques. Materials and Methods: Intramedullary FA and MD were measured in the gray matter and posterior cord of the white matter and both lateral cords of the white matter at the C2-3, C4-5, C5-6 spinal levels. For the CSF flow study, velocity encoding was obtained at the C2-3, C4-5, C5-6 spinal levels. Results: There was a significant difference of the FA and MD between the white matter and gray matter (p < 0.05). The FA of the gray matter was significantly different according to the cervical spinal cord levels (p < 0.05). Otherwise, the FA and MD parameters were not significantly different (p > 0.05). The mean peak systolic velocity and mean peak diastolic velocity were $5.18{\pm}2.00cm/sec$ and $-7.32{\pm}3.18cm/sec$, respectively from C2 to C6 spinal cords. There was no significant difference in these velocities among the cervical spinal cord (p > 0.05). Conclusion: This basic information about DTI and CSF dynamics of the cervical spinal cord may be useful for assessing cervical spinal cord abnormalities using MR imaging.

• The Journal of Korean Orthopaedic Ultrasound Society
• /
• v.4 no.2
• /
• pp.101-110
• /
• 2011

To describe the background, mechanism, clinical results and complications of prolotheapy based on the literature review. Prolotherapy is a minimally invasive injection-based treatment of chronic musculoskeletal pain, including ligament and joint laxity. The mechanism of this injection-based technique is to initiate a local inflammatory response with resultant tissue healing. The used proliferants are classified by bio-mechanism to act in three different ways as osmotic, irritants, and chemotatics. The most commonly used proliferant is hyperosmolar (10~25%) dextrose to act by osmotic rupture of cells. High resolution ultrasound imaging of musculoskeletal structure provide a more accurate diagnosis. Also ultrasound-guided intervention provides a more high efficacy and low rate of complications. The most common complication is local pain at the injected site, that is self-limited and good responsive to anti-inflammatory agents. Other complications are rare. It is reported that prolotherapy appears safe when performed by an experienced clinician. Prolotherapy has grown in popularity and has received significant recent attention. However there are limited evidence-based data supporting the indication and efficacy of prolotherapy in the treatment of chronic musculoskeletal pain or soft tissue injuries. Future studies are necessary to determine whether prolotherapy can play an independent and definitive role in a treatment for chronic musculoskeletal pain.