• Journal of Biomedical Engineering Research
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• v.19 no.1
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• pp.91-100
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• 1998

In magnetic resonance imaging, the fast spin echo imaging technique is a widely used clinical imaging method. since its scanning time is much shorter than the conventional spin echo imaging and it gives the almost same image quality. However, the fast spin echo technique has two times longer imaging time for the dual echo acquisition which can obtain a spin density image and a T-give the same qulity images at the single echo imaging time. T he proposed technique reduces the imaging time by overlapping most of were obtained at the 0.3T permanent MRI system are presented.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.294-298
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• 1997

In the magnetic resonance imaging, the fast spin echo imaging technique is a widely used clinical imaging method, since its scanning time is much shorter than the conventional spin echo imaging and it gives the almost same image quality. However, the fast spin echo technique has two times longer imaging time or the dual echo acquisition which can obtain a spin density image and a $T_2$-weighted image simultaneously. To overcome such a drawback, this paper proposes a new fast dual echo imaging technique which can give the same quality images at the single echo imaging time. The proposed technique reduces the imaging time by overlapping most of echo train data for each image reconstruction. In order to verify its validity and usability the human head experimental results which were obtained at the 0.3T permanent MRI system are presented.

• Korean Journal of Digital Imaging in Medicine
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• v.15 no.2
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• pp.55-61
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• 2013

The purpose of this study is to evaluate image blurring according to variation of the ETL and propose the clinically appropriate ETL range. SIEMENS MAGNETOM Skyra 3.0T and 20 channel head coil were used for the study. MRI phantom was kept the lines horizontally to three direction(X,Y,Z) of the coil and T1, T2 weighted images that used the fast spin echo technique acquired. The ETL with increase of 10 was applied from 10 to 80. In addition, the ETL with increase of 1 was applied in the interval statistically significant differences occurred. And T1, T2 weighted images that used the conventional spin echo technique acquired to compare image blurring of the images that used the fast spin echo technique. The slope of lattice in the images was measured using Image J 1.47v program to evaluate image blurring. And image blurring was determined by the degree of the slope. The statistical significance of both techniques was evaluated by the Kruskal-Wallis test of the SPSS 17.0v. And the correlation of the ETL and image blurring was evaluated quantitatively by regression analysis. The slope of the T1, T2 weighted images that used fast spin echo technique decreased as contrasted with conventional spin echo technique. In the result of the Kruskal-Wallis test, the T1, T2 weighted images that used fast spin echo technique made a significant difference with conventional spin echo technique. Particularly, in the Tomhane' T2 test, the T1, T2 weighted images made a significant difference from ETL 22 and 31 respectively. In the result of the regression analysis, the R-squared of the T1, T2 weighted images are 0.762 and 0.793. It is difficult to apply the long ETL in the T1 weighted image caused by the short TR and multi-slices study. Therefore, clinical impact according to variation of the ETL is very slight in the T1 weighted images. But the application of the proper ETL is demanded in T2 weighted images using the fast spin echo technique in order to prevent image blurring.

• Journal of Magnetics
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• v.17 no.2
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• pp.138-144
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• 2012

3-dimensional magnetic resonance cholangiopancreatography (MRCP) images reconstructed using the maximum intensity projection technique were analyzed qualitatively in patients diagnosed with pancreatobiliary diseases to determine their diagnostic utility. Single shot fast spin echo (SSFSE), fast spin echo (FSE) and 3-dimensional reconstructive images were acquired from 20 patients diagnosed histologically with pancreatobiliary diseases using a 3.0T MR scanner. According to qualitative analysis, the fast spin echo images and 3-dimensional reconstructed images of the hepatic duct, gall bladder and common bile duct had a higher signal to noise ratio (SNR) than the single shot fast spin echo images. Fast spin echo images and 3-dimensional reconstructed images did not show any differences. The contrast to noise ratio of the hepatic duct, gallbladder and common bile duct on the fast spin echo images and 3-dimensional reconstructed images was higher than that of the single shot fast spin echo images. The fast spin echo images and 3-dimensional reconstructed images showed similar quality.

• Journal of the Korean Magnetics Society
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• v.26 no.3
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• pp.105-114
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• 2016

In this study, For assessment of triangular fibrocartilage complex (TFCC) injury, we acquired images by fat suppressed 3D fast spoiled gradient recalled T1 and fat suppressed Isotropic 3D fast spin echo T1 techniques. For quantitative evaluation, measured signal to noise ratio and contrast to noise ratio and verified statistical significance between two imaging techniques by Mann-Whitney U verification. And for qualitative evaluation, marked 4-grade scoring (0: non diagnostic, 1: poor, 2: adequate, 3: good) on shape of TFCC, artifacts by partial volumes, description of the lesions by two radiologist, verified coincidence between 2 observer using Kappa-value verification. We used 3.0 Tesla MR equipment and 8-channel RF coil for imaging acquisition. As quantitative evaluation results, signal to noise ratio and contrast to noise ratio value of Isotropic 3D fast spin echo T1 technique is higher in every image sections, also between two imaging techniques by Mann-Whitney U verification was statistically significant (p < 0.05). As qualitative results, observer 1, 2 marked a higher grade on Isotropic 3D FSE T1 technique, coincidence verification of evaluation results between two observers by Kappa-value verification was statistically significant (p < 0.05). As a result, during MRI examination on TFCC injury, fat suppressed Isotropic 3D fast spin echo T1 technique is considered offering more useful information about abnormal lesion of TFCC.

• Proceedings of the KSMRM Conference
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• 2006.11a
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• pp.51-51
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• 2006

• Investigative Magnetic Resonance Imaging
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• v.25 no.1
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• pp.1-9
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• 2021

The aim of this study was to provide a new assessment of rotator cuff muscle activity. Eight male subjects (24.7 ± 3.2 years old,171.2 ± 9.8 cm tall, and weighing 63.8 ± 11.9 kg) performed the study exercises. The subjects performed 10 sets of the exercise while fixing the elbow at 90 degrees flexure and lying supine on a bed. One exercise set consisted of the subject performing external shoulder rotation 50 times using training equipment. Two imaging protocols were employed: (a) true fast imaging with steady precession (TrueFISP) at an acquisition time of 12 seconds and (b) multi-shot spin-echo echo-planar imaging (MSSE-EPI) at an acquisition time of 30 seconds for one echo. The main method of assessing rotator cuff muscle activity was functional T2 mapping using ultrafast imaging (fast-acquired muscle functional MRI [fast-mfMRI]). Fast-mfMRI enabled real-time imaging for the identification and evaluation of the degree of muscle activity induced by the exercise. Regions of interest were set at several places in the musculus subscapularis (sub), musculus supraspinatus (sup), musculus teres minor (ter), and deltoid muscle (del). We used the MR signal of the images and transverse relaxation time (T2) for comparison. Most of the TrueFISP signal was not changed by exercise and there was no significant difference from the resting values. Only the T2 in the musculus teres minor was increased after one set and the change were seen on the T2 images. Additionally, except for those after one and two sets, the changes in T2 were significant compared to those at rest (P < 0.01). We also demonstrated identify and visualize the extent to which muscles involved in muscle activity by exercise. In addition, we showed that muscle activity in a region such as a shoulder, which is susceptible to B0 inhomogeneity, could be easily detected using this technique.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4313-4319
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• 2013

The purpose of our study is to shorten the scanning time and minimize the inconveniences of the patients in acquisition of the black blood images using the signal void effect in the fast spin echo technique while keeping the diagnostic value of the test. Thirty-two consecutive patients who underwent black blood MR imaging were examed with additional double inversion recovery (DIR) sequence and the conventional fast spin echo (FSE) sequence. Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) of the internal carotid arteries' lumen were compared in T1 and T2 weighted images to determine whether there are differences between the two techniques for depiction of the signal void effect inside the vessel wall. The FSE images showed lower SNR values than the DIR images in both of the T1 and T2 weighted images (11.49% and 13.66% respectively). While the CNR values were higher in the FSE images than in the DIR images in both of the T1 and T2 weighted images (8.69% and 7.55% respectively).There was no significant difference between the two techniques for either of the SNR or CNR (p>0.05, p>0.05 respectively). The DIR and the FSE images demonstrated almost identical imaging patterns. Therefore, it is anticipated that the use of FSE technique in acquisition of the black blood imaging could reduce the inconveniences of the patients during the scanning and minimize exam time while keeping the diagnostic value of the test.

• Investigative Magnetic Resonance Imaging
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• v.10 no.2
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• pp.108-116
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• 2006

Purpose : High-resolution spiral-scan imaging is performed at 3 Tesla MRI system. Since the gradient waveforms for the spiral-scan imaging have lower slopes than those for the Echo Planar Imaging (EPI), they can be implemented with the gradient systems having lower slew rates. The spiral-scan imaging also involves less eddy currents due to the smooth gradient waveforms. The spiral-scan imaging method does not suffer from high specific absorption rate (SAR), which is one of the main obstacles in high field imaging for rf echo-based fast imaging methods such as fast spin echo techniques. Thus, the spiral-scan imaging has a great potential for the high-speed imaging in high magnetic fields. In this paper, we presented various high-resolution images obtained by the spiral-scan methods at 3T MRI system for various applications. Materials and Methods : High-resolution spiral-scan imaging technique is implemented at 3T whole body MRI system. An efficient and fast higher-order shimming technique is developed to reduce the inhomogeneity, and the single-shot and interleaved spiral-scan imaging methods are developed. Spin-echo and gradient-echo based spiral-scan imaging methods are implemented, and image contrast and signal-tonoise ratio are controlled by the echo time, repetition time, and the rf flip angles. Results : Spiral-scan images having various resolutions are obtained at 3T MRI system. Since the absolute magnitude of the inhomogeneity is increasing in higher magnetic fields, higher order shimming to reduce the inhomogeneity becomes more important. A fast shimming technique in which axial, sagittal, and coronal sectional inhomogeneity maps are obtained in one scan is developed, and the shimming method based on the analysis of spherical harmonics of the inhomogeneity map is applied. For phantom and invivo head imaging, image matrix size of about $100{\times}100$ is obtained by a single-shot spiral-scan imaging, and a matrix size of $256{\times}256$ is obtained by the interleaved spiral-scan imaging with the number of interleaves of from 6 to 12. Conclusion : High field imaging becomes increasingly important due to the improved signal-to-noise ratio, larger spectral separation, and the higher BOLD-based contrast. The increasing SAR is, however, a limiting factor in high field imaging. Since the spiral-scan imaging has a very low SAR, and lower hardware requirements for the implementation of the technique compared to EPI, it is suitable for a rapid imaging in high fields. In this paper, the spiral-scan imaging with various resolutions from $100{\times}100$ to $256{\times}256$ by controlling the number of interleaves are developed for the high-speed imaging in high magnetic fields.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2809-2811
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• 1999

In this paper, we develope an algorithm to calculate field inhomogeneity in MR imaging using a dual fast spin echo pulse sequence. Because phase modulation time can be easily modified with this pulse sequence, high resolution image can be obtained and acquisition time can be reduced compared to gradient echo technique. In the case of phase wrapping in field map, phase corrected using image processing technique. We assume the field pattern to be second order polynomial and apply Pseudo-Inverse equation to calculate second order polynomial coefficients. These coefficients can be used for the shimming of the magnetic field.