• Investigative Magnetic Resonance Imaging
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• v.22 no.3
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• pp.150-157
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• 2018

Purpose: To assess associations between morphological characteristics of intracranial arteries in time-of-flight MR angiography (TOF-MRA) and atherosclerotic risk factors. Materials and Methods: From January 2014 to October 2015, a total of 129 patients (65 men and 64 women) without intracranial arterial stenosis > 50% were included in this study. All MRIs were performed using a 3T machine with 3D TOF-MRA sequences. We evaluated irregularity, tortuosity, and dilatation of intracranial arteries in maximal intensity projection (MIP) of TOF-MRA. Subjects' risk factors for atherosclerosis including history of hypertension and diabetes were collected by reviewing their medical records. Associations between morphological characteristics and each known atherosclerosis risk factor were examined using univariate regression analysis. Multivariate regression models were built to determine combined association between those risk factors and morphologic changes of intracranial arteries. Results: In multivariate analysis, hypertension (coefficient [95% CI]: 0.162 [0.036, 0.289], P = 0.012) and absence of diabetes (coefficient [95% CI]: -0.159 [-0.296, -0.023], P = 0.022) were associated with large diameter of intracranial arteries. Males (coefficient [95% CI]: 0.11 [-0.006, 0.23], P = 0.062) and higher age (coefficient [95% CI]: 0.003 [-0.001, 0.008], P = 0.138) had marginal association with increased diameter. Tortuosity was associated with old age (OR: 1.04 [1.02, 1.07], P < 0.001). Irregular contour of intracranial arteries was significantly associated with old age (OR: 1.05 [1.02, 1.09], P = 0.004), presence of diabetes (OR: 2.88 [1.36, 6.15], P = 0.0058), and previous ischemic stroke (OR: 3.91 [1.41, 11.16], P = 0.0092). Conclusion: Morphological characteristics (irregularity, tortuosity, dilatation) of intracranial arteries seen in TOF-MRA might be associated with atherosclerotic risk factors in subjects with no or mild stenosis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.14
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• pp.97-109
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• 1973

1. The relatively lower prehardening temperature was more effective on increase of the hardiness of the intermediately hardy varieties than the higher one but either the extremely hardy or nonhardy varieties did not respond to the temperature as much as the intermediate types. 2. Five degree Centigrade was generally more favorable than $2^{\circ}C$ on hardening of the plants, especially when frozen at higher temperature for shorter duration. 3. It appears that photoperiod during prehardening and hardening did not play so important role as temperature on the hardiness. 4. The higher the soil moisture content, the higher the frost injury occurred. 5. Application of nitrogen increased markedly the hardiness and % DM of the plants. Percentage of dry matter of young seedlings might be used as an easy and rough criterion for evaluating hardiness since there was a highly significant regression of varietal frost injury on the %DM. 6. Four days appeared to be enough for hardening of plants although the plants increased gradually the hardiness as duration of hardening extended. Dehardening of the plants at relativity higher temperature took place rapidly within one to four days. 7. Under this controlled environment, freezing at about $-8^{\circ}C$ for 24 hours seemed the best for the purpose of evaluating the hardiness to low temperature. 8. It is believed that assessment of frost injury should be done at least one week after freezing. Some varieties showed strong ability to recover from the damage as recovery period was extended. 9. As a whole, Cd 80 and 83 were the most hardy and followed by Cappelle and Maris Otter. Four. winter oats varieties and Jufy I belonged to the intermediate type while the other three spring varieties were nonhardy at all. Peniarth was comparable with Maris Otter in hardiness. S 147 appeared the least hardy among the winter oats varieties. 10. It is evident that water-soluble carbohydrate content is associated with the hardiness to some extent but not primary factor involved in hardiness.

• Journal of Korean Medicine Rehabilitation
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• v.28 no.4
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• pp.33-41
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• 2018

Objectives The purpose of this study is to analyze the effects of Korean Medicine treatment on lumbar disc herniation (LDH) and predictive factors associated with disc resorption by magnetic resonance imaging (MRI). Methods A retrospective study was carried out in 79 lumbar disc herniation patients who had visited Haeundae Jaseng Hospital of Korean Medicine. Patients' diagnosis was based on MRI. MRI was performed on two or more occasions and patients were received Korean Medicine treatment within the period. The volume of each herniated disc was measured three-dimensionally and patient characteristics, interval between MRIs, herniated disc level, disc herniation type, disc migration, intactness of posterior longitudinal ligament (PLL), initial volume of herniated disc, modic change, disc resorption rate were statistically analyzed. Results The mean volumes of herniated discs before Korean Medicine treatment and after Korean Medicine treatment were $1,547.81{\pm}598.15mm^3$ and $947.06{\pm}335.28mm^3$, respectively. The mean resorption rate was $35.7{\pm}16.3%$. Disc extent, intactness of PLL and initial volume of herniated discs were significantly correlated with resorption rate (p=0.003, p=0.001 and p=0.024, respectively). Conclusions Korean Medicine treatment is an effective conservative treatment for lumbar disc herniation. Factors such as disc migration, intactness of PLL, initial volume of herniated disc have a significant association with disc resorption rate.

• Clinics in Shoulder and Elbow
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• v.20 no.3
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• pp.133-137
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• 2017

Background: To determine the natural progression of conservatively treated rotator cuff tears, we evaluated changes in radiologic and clinical parameters in patients whose recalcitrant tears were neglected after conservative treatment. Methods: A total of 73 patients with recalcitrant rotator cuff tears in spite of conservative treatment were included in this study. We measured changes in tear size and in the extent of fatty infiltration of the rotator cuff by comparing the initial and final follow-up magnetic resonance imagings (MRIs). To determine factors influencing the change in tear size, we collected the medical history of patients taken at the time of initial admission. Results: The average follow-up period was 20.1 months, and the average increase in tear size across this period was 6.2 mm. In terms of steroid injection, we found that the increases in tear size of the steroid injection group (p=0.049) and of the sub-group that had received more than three steroid injections (p=0.010) were significantly greater than that of the non-steroid injection group. Conclusions: We found that the increase in cuff tear size was on average 6.2 mm across the follow-up period, indicating that neglecting cuff tears may cause them to progress into more severe tears. We also observed that a history of steroid injection might be a possible risk factor for a worse prognosis of cuff tears. Therefore, we suggest that patients with rotator cuff tears and a history of steroid injection are recommended aggressive modes of treatment such as surgery.

• Journal of Korean Neurosurgical Society
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• v.62 no.4
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• pp.414-421
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• 2019

Objective : To evaluate 3-dimensional magnetic resonance imaging (MRI) of Kambin's safe zone to calculate maximum cannula diameter permissible for safe percutaneous endoscopic lumbar discectomy. Methods : Fifty 3D MRIs of 19 males and 31 females (mean, 47 years) were analysed. Oblique, axial and sagittal views were used for image analysis. Three authors calculated the inscribed circle (cannula diameter) individually, within the neural (original) and bony Kambin's triangle in oblique views, disc heights on sagittal views and root to facet distances at upper and lower end plate levels on axial views and their averages were taken. Results : The mean root to facet distances at upper end plate level measured on axial sections increased from $3.42{\pm}3.01mm$ at L12 level to $4.57{\pm}2.49mm$ at L5S1 level. The mean root to facet distances at lower end plate level measured on axial sections also increased from $6.07{\pm}1.13mm$ at L12 level to $12.9{\pm}2.83mm$ at L5S1 level. Mean maximum cannula diameter permissible through the neural Kambin's triangle increased from $5.67{\pm}1.38mm$ at L12 level to $9.7{\pm}3.82mm$ at L5S1 level. The mean maximum cannula diameter permissible through the bony Kambin's triangle also increased from $4.03{\pm}1.08mm$ at L12 level to $6.11{\pm}1mm$ at L5S1 level. Only 2% of the 427 bony Kambin's triangles could accommodate a cannula diameter of 8mm. The base of the bony Kambin's triangle taken in oblique view (3D MRI) was significantly higher than the root to facet distance at lower end plate level taken in axial view. Conclusion : The largest mean diameter of endoscopic cannula passable through "bony" Kambin's triangle was distinctively smaller than the largest mean diameter of endoscopic cannula passable through "neural" Kambin's triangle at all levels. Although proximity of exiting root to the facet joint is always taken into consideration before PELD procedure, our 3D MRI based anatomical study is the first to provide actual maximum cannula dimensions permissible in this region.

• Investigative Magnetic Resonance Imaging
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• v.25 no.1
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• pp.35-42
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• 2021

Purpose: To evaluate and analyze the adequacy of breast magnetic resonance imaging (MRI)s taken before publication of the 2018 recommendation in South Korea. Materials and Methods: We enrolled 87 cases of breast MRIs, from January 2010 to November 2013, taken at external hospitals in the study. Breast MRI protocol elements are divided into three categories based on the recommendation by the Breast Imaging Study Group of the Korean Society of Magnetic Resonance: (1) Essential elements for breast MRI protocol; (2) Element to consider when evaluating imaging quality; and (3) Optional element for breast MRI protocol. Also, we divided enrolled cases into three groups based on their conducting locations -- (1) Primary hospitals, (2) Secondary hospitals, and (3) Tertiary hospitals-and analyzed them for the adequacy of imaging protocols based on the 2018 recommendation. We used a Chi-square test and Fisher's exact test to identify differences between categorical variables. Results: Over 98% of the criteria for 'essential elements for breast MRI protocol' were satisfied when compared with the 2018 Recommendation. Over 96% of the criteria for 'elements to consider when evaluating imaging quality' were also satisfied, except for the slice thickness (83.9%). Optional elements for breast MRI protocol were satisfied with various percentages. There were no statistically significant differences between groups of tertiary, secondary, and primary hospitals; however, 3 tesla of MRI (P = 0.04), subtraction image protocol (P = 0.032), and DWI protocol (P = 0.03) were used more frequently in the tertiary hospitals than in the others. Conclusion: We found that the categories of 'essential elements' and 'elements to consider when evaluating imaging quality' were satisfied at 98% and 96%, respectively, when compared with the 2018 Recommendation by the Breast Imaging Study Group of the Korean Society of Magnetic Resonance.

• Korean Journal of Radiology
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• v.22 no.10
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• pp.1628-1639
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• 2021

Objective: Based on the Liver Imaging Reporting and Data System version 2018 (LI-RADS, v2018), this study aimed to analyze LR-5 diagnostic performance for hepatocellular carcinoma (HCC) when threshold growth as a major feature is replaced by a more HCC-specific ancillary feature, as well as the frequency of threshold growth in HCC and non-HCC malignancies and its association with tumor size. Materials and Methods: This retrospective study included treatment-naive patients who underwent gadoxetate disodium-enhanced MRIs for focal hepatic lesions and surgery between January 2009 and December 2016. The frequency of major and ancillary features was evaluated for HCC and non-HCC malignancies, and the LR-category was assessed. Ancillary features that were significantly more prevalent in HCC were then used to either replace threshold growth or were added as additional major features, and the diagnostic performance of the readjusted LR category was compared to the LI-RADS v2018. Results: A total of 1013 observations were analyzed. Unlike arterial phase hyperenhancement, washout, or enhancing capsule which were more prevalent in HCCs than in non-HCC malignancies (521/616 vs. 18/58, 489/616 vs. 19/58, and 181/616 vs. 5/58, respectively; p < 0.001), threshold growth was more prevalent in non-HCC malignancies than in HCCs (11/23 vs. 17/119; p < 0.001). The mean size of non-HCC malignancies showing threshold growth was significantly smaller than that of non-HCC malignancies without threshold growth (22.2 mm vs. 42.9 mm, p = 0.040). Similar results were found for HCCs; however, the difference was not significant (26.8 mm vs. 33.1 mm, p = 0.184). Additionally, Fat-in-nodule was more frequent in HCCs than in non-HCC malignancies (99/616 vs. 2/58, p = 0.010). When threshold growth and fat-in-nodule were considered as ancillary and major features, respectively, LR-5 sensitivity (73.2% vs. 73.9%, p = 0.289) and specificity (98.2% vs. 98.5%, p > 0.999) were comparable to the LI-RADS v2018. Conclusion: Threshold growth is not a significant diagnostic indicator of HCC and is more common in non-HCC malignancies. The diagnostic performance of LR-5 was comparable when threshold growth was recategorized as an ancillary feature and replaced by a more HCC-specific ancillary feature.

• Korean Journal of Radiology
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• v.21 no.12
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• pp.1334-1344
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• 2020

Objective: Compressed sensing (CS) has gained wide interest since it accelerates MRI acquisition. We aimed to compare the 3D post-contrast T1-weighted volumetric isotropic turbo spin echo acquisition (VISTA) with CS (VISTA-CS) and without CS (VISTA-nonCS) in intracranial vessel wall MRIs (VW-MRI). Materials and Methods: From April 2017 to July 2018, 72 patients who underwent VW-MRI, including both VISTA-CS and VISTA-nonCS, were retrospectively enrolled. Wall and lumen volumes, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured from normal and lesion sites. Two neuroradiologists independently evaluated overall image quality and degree of normal and lesion wall delineation with a four-point scale (scores ≥ 3 defined as acceptable). Results: Scan coverage was increased in VISTA-CS to cover both anterior and posterior circulations with a slightly shorter scan time compared to VISTA-nonCS (approximately 7 minutes vs. 8 minutes). Wall and lumen volumes were not significantly different with VISTA-CS or VISTA-nonCS (interclass correlation coefficient = 0.964-0.997). SNR was or trended towards significantly higher values in VISTA-CS than in VISTA-nonCS. At normal sites, CNR was not significantly different between two sequences (p = 0.907), whereas VISTA-CS provided lower CNR in lesion sites compared with VISTA-nonCS (p = 0.003). Subjective wall delineation was superior with VISTA-nonCS than with VISTA-CS (p = 0.019), although overall image quality did not differ (p = 0.297). The proportions of images with acceptable quality were not significantly different between VISTA-CS (83.3-97.8%) and VISTA-nonCS (75-100%). Conclusion: CS may be useful for intracranial VW-MRI as it allows for larger scan coverage with slightly shorter scan time without compromising image quality.

• Investigative Magnetic Resonance Imaging
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• v.3 no.2
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• pp.154-158
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• 1999

Purpose : The purpose of this study was to find the optimum TE value for enhancing $T_2^{*}$ weighting effect and minimizing the SNR degradation and to compare the BOLD effects according to the changes of TE in 1.5T and 3.0T MRI systems. Materials and Methods : Healthy normal volunteers (eight males and two females with 24-38 years old) participated in this study. Each volunteer was asked to perform a simple finger-tapping task (sequential opposition of thumb to each of the other four fingers) with right hand with a mean frequency of about 2Hz. The stimulus was initially off for 3 images and was then alternatively switched on and off for 2 cycles of 6 images. Images were acquired on the 1.5T and 3.0T MRI with the FLASH (fast low angle shot) pulse sequence (TR : 100ms, FA : $20^{\circ}$, FOV : 230mm) that was used with 26, 36, 46, 56, 66, 76ms of TE times in 1.5T and 16, 26, 36, 46, 56, 66ms of TE in 3.0T MRI system. After the completion of scan, MR images were transferred into a PC and processed with a home-made analysis program based on the correlation coefficient method with the threshold value of 0.45. To search for the optimum TE value in fMRI, the difference between the activation and the rest by the susceptibility change for each TE was used in 1.5T and 3.0T respectively. In addition, the functional $T_2^{*}$ map was calculated to quantify susceptibility change. Results : The calculated optimum TE for fMRI was $61.89{\pm}2.68$ at 1.5T and $47.64{\pm}13.34$ at 3.0T. The maximum percentage of signal intensity change due to the susceptibility effect inactivation region was 3.36% at TE 66ms in 1.5T 10.05% at TE 46ms in 3.0T, respectively. The signal intensity change of 3.0T was about 3 times bigger than of 1.5T. The calculated optimum TE value was consistent with TE values which were obtained from the maximum signal change for each TE. Conclusion : In this study, the 3.0T MRI was clearly more sensitive, about three times bigger than the 1.5T in detecting the susceptibility due to the deoxyhemoglobin level change in the functional MR imaging. So the 3.0T fMRI I ore useful than 1.5T.

• Investigative Magnetic Resonance Imaging
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• v.8 no.1
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• pp.17-23
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• 2004

Purpose : To evaluate changes in total cerebral blood flow (tCBF) with aging, parenchymal volume changes and vascular abnormalities, using 2 dimensional (D) phase-contrast magnetic resonance imaging (PC MRI). Materials and Methods : Routine brain MRI including T2 weighted image, time-of-flight (TOF) MR Angiography (MRA) and 2D PC MRI were performed in 73 individuals, including 12 volunteers. Normal subjects (12 volunteers, and 21 individuals with normal MRI and normal MRA) were classified into groups according to age (18-29, 30-49 and 50-66 years). For the group with abnormalities in brain MRIs, cerebral parenchymal volume changes were scored according to the T2 weighted images, and atherosclerotic changes were scored according to the MRA findings. Abnormal groups were classified into 4 groups: (i) mild reduction in volume, (ii) marked reduction in volume by parenchymal volume and atherosclerotic changes, and (iii) increased volume and (iv) Moya-moya disease. Volumetric flow was measured at the internal carotid artery (ICA) and vertebral artery bilaterally using the velocity-flow diagrams from PC MRI, and combined 4 vessel flows and tCBF were compared among all the groups. Results : The age-specific distribution of tCBFs in normal subjects were as follows: $12.0{\pm}2.1ml/sec$ in 18-29 years group, $11.8{\pm}1.9ml/sec$ in 30-49 years group, $10.9{\pm}2.2ml/sec$ in 50-66 years group. The distribution of tCBFs in the different subsets of the abnormal population were as follows: $9.5{\pm}2.5ml/sec$ in the group with mild reduction in volume, $7.6{\pm}2.0ml/sec$ in the group with marked reduction in volume, and $7.3{\pm}1.2ml/sec$ and $7.0{\pm}1.1ml/sec$ in the increased parenchymal volume and Moya-moya disease groups respectively. Conclusion : Total cerebral blood flow decreases with increasing age with a concomitant reduction in parenchymal volumes and increasing atherosclerotic changes. It is also reduced in the presence of increased parenchymal volume and Moya-moya disease.2D PC MRI can be used as a tool to evaluate tCBF with aging and in the presence of various conditions that can affect parenchymal volume and cerebral vasculature.