Eunhye Yoo

Korea University, Seoul, Seoul, South Korea

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Publications (13)32.02 Total impact

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    ABSTRACT: Early and accurate diagnosis of small metastatic brain tumors may affect outcomes and treatment strategies. For this reason, 3-dimensional (3D) thin-section imaging is preferred. However, with conventional contrast-enhanced (CE) 3D imaging, such as magnetization-prepared rapid gradient echo (MP-RAGE), many visually enhanced vessels may mimic small metastatic tumors, hindering tumor detection. CE black-blood single-slab 3D turbo-spin echo imaging (BB-ssTSE) was recently developed, which uses variable refocusing flip angles and flow-sensitizing gradient schemes, to enhance metastatic brain tumors while selectively suppressing blood vessels. The purpose of this work was to investigate the efficiency of the proposed CE BB-ssTSE in detecting small metastatic brain tumors as compared with conventional MP-RAGE. Numerical comparisons of MP-RAGE and BB-ssTSE were performed by simulation studies to investigate the signal/contrast behaviors of flowing blood and stationary CE tumors. For in vivo studies, we enrolled 35 patients (18 women; mean age, 58.1 years) with breast or lung cancer who underwent brain magnetic resonance imaging. After administering a double dose of contrast medium, whole-brain 2-dimensional T1-weighted imaging followed by high-resolution isotropic 3D BB-ssTSE and MP-RAGE was performed at 3.0 T. Two reviewers independently evaluated the presence of metastatic brain tumors using: (1) MP-RAGE; (2) BB-ssTSE; and (3) MP-RAGE + BB-ssTSE sequentially in 3 review sessions, 2 weeks apart. The lesions were classified by size into 2 groups: large (≥5 mm) and small (<5 mm). Both reviewers marked all tumors detected at each session. Another reviewer combined the results of the 2 reviewers and compared the detection rates of metastatic brain tumors between BB-ssTSE and MP-RAGE by using follow-up imaging. Intraclass correlation coefficients between the 2 reviewers were measured. Numerical simulations showed that the proposed BB-ssTSE effectively attenuated the signal intensity of flowing blood over the entire echo train, resulting in CE tumor-to-white matter contrast comparable with conventional MP-RAGE. The combined evaluation of MP-RAGE + BB-ssTSE showed 242 tumors in 28 patients. Of these, 153 lesions were <5 mm. MP-RAGE found 111 small metastatic brain tumors, BB-ssTSE found 150, and MP-RAGE + BB-ssTSE found 153. Significantly, more small tumors were detected by BB-ssTSE than MP-RAGE (P = 0.001, Wilcoxon signed-rank test). All large tumors were detected similarly by both MP-RAGE and BB-ssTSE. By combined results for MP-RAGE + BB-ssTSE, sensitivities for detection of small metastatic tumors were 72.5% for MP-RAGE and 98.0% for BB-ssTSE (P < 0.0001, McNemar test). Intraclass correlation coefficients between the 2 reviewers were 0.826 for MP-RAGE and 0.954 for BB-ssTSE. Compared with conventional MP-RAGE, the proposed CE BB-ssTSE imaging, which enhances tumors while selectively suppressing blood vessels, leads to significantly better detection of small metastatic brain tumors <5 mm.
    Investigative radiology 11/2011; 47(2):136-41. DOI:10.1097/RLI.0b013e3182319704 · 4.45 Impact Factor
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    ABSTRACT: Self-expandable stents are an effective tool for coil embolization of wide-neck intracranial aneurysms. The purpose of this study was to assess the feasibility and results of bailout stent positioning during rescue situations after deployment of > or =1 coil. Among 318 aneurysms treated by coil embolization in 267 patients, 16 patients who were treated by bailout stent deployment were retrospectively reviewed. Bailout procedures were performed to relieve potential parent artery compromise caused by the protruded coil loops or to prevent migration of the unstable coil basket. The size/location of the aneurysm, technical feasibility, successful stabilization rate, and procedure-related complications were evaluated. The locations of the aneurysms were the internal carotid artery (n = 12) and basilar artery (n = 4). The mean aneurysm size was 8.3 mm (range, 3.5-19.4 mm) with hemorrhagic presentation in 3 patients. Relief/prevention of parent artery compromise was achieved by molding the encroached loops back into the sac (n = 11), scaffolding the aneurysmal neck in cases with an unstable coil basket (n = 4), and sidetacking the migrated loop to the parent vessel wall (n = 1). The procedure was technically successful in 87.5% (n = 14). Satisfactory molding or stabilization of the coil was seen in 75% (n = 12). Unsatisfactory molding of the protruded small coil loop was noted in 2 cases of small aneurysms. Acute in-stent thrombosis was successfully managed by thrombolysis (n = 1). Bailout self-expandable stent deployment may be a feasible and effective method for relief/prevention of parent artery compromise or coil migration caused by prolapsed or unstable coil loops during embolization of aneurysms.
    American Journal of Neuroradiology 02/2009; 30(5):1028-34. DOI:10.3174/ajnr.A1482 · 3.68 Impact Factor
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    ABSTRACT: To investigate whether thin-section axial double inversion-recovery (DIR) brain magnetic resonance (MR) imaging at 3.0 T can help distinguish the primary motor cortex (PMC), or Brodmann area 4, from other selected cortical regions, including the primary sensory cortex (PSC), or Brodmann areas 1-3, on the basis of the presence of a "triple-layer" appearance. This prospective study was approved by the institutional review board; informed consent was obtained from patients. This study included 191 patients (94 female, age range, 5-80 years; 97 male, age range, 5-76 years) with normal findings at 3.0-T MR imaging. The presence or absence of a triple-layer appearance within selected cortical regions on DIR images was graded independently by two neuroradiologists as definitely present (grade 2), probably present (grade 1), or definitely absent (grade 0). Ten additional patients with tumors underwent DIR imaging and intraoperative cortical mapping for further validation of the PMC. A myelin-stained brain specimen image in a patient not imaged with DIR was correlated with a representative set of DIR images. A triple-layer appearance was found in the PMC bilaterally in 184 of 191 patients; grade 0 was assigned in only seven patients, who were all younger than 10 years. Grades were significantly lower in patients younger than 10 years than in others (P < .0001) but were not significantly different between older age groups (P > .0018). Interobserver agreement was excellent (weighted kappa = 0.843). The PMC determined on DIR images was confirmed with cortical mapping in all 10 patients with tumors. Triple-layer appearance was not present in the other cortical regions examined, including the PSC (P < .01). The triple-layer appearance on DIR images corresponded to the myelin band within the PMC present on the myelin-stained specimen image. A triple-layer appearance was found in the PMC at thin-section 3.0-T DIR imaging but not in other examined brain regions and therefore might be useful as an adjunct sign for identification of motor regions.
    Radiology 12/2008; 250(2):515-22. DOI:10.1148/radiol.2502080266 · 6.21 Impact Factor
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    ABSTRACT: Although the hyperattenuated middle cerebral artery sign is known to be related to acute infarction, the volume of clot associated with it is not known. We investigated whether the presence or absence of hyperattenuated artery sign (HAS) on noncontrast CT (NCCT) can predict the thrombus volume. We enrolled 90 consecutive patients with acute infarction who underwent both 5- and 1.25-mm NCCT and CT angiography (CTA). HAS was determined on 5-mm NCCT retrospectively. According to the location of thrombi, the patients were classified into ICA (ICA terminus/ICA and others), M1 (M1/both M1 and M2), and M2 (M2) groups. Thrombus volumes were measured by 1.25-mm NCCT and were compared between patients with and without HAS. Occlusion of major arteries was seen on CTA in 78 patients. HAS was found in 46 patients (59.0%). The mean thrombus volume was significantly larger in patients with HAS than in those without except for the M2 group (ICA group: [n = 14], 188.7 +/- 122.5 mm(3) versus 39.4 +/- 12.1 mm(3) [P = .022]; M1 group: [n = 42], 128.1 +/- 119.2 versus 56.8 +/- 32.5 [P = .005]; M2 group: [n = 22], 34.7 +/- 32.2 versus 20.0 +/- 20.0 [P = .18]). Thrombus volumes determined by receiver operating characteristic curve analysis were 52.36 mm(3) in the ICA group (sensitivity, 90.9%; specificity, 100%) and 53.96 mm(3) in the M1 group (sensitivity, 88.0%; specificity, 58.8%). Thrombus volumes were significantly larger in patients with HAS than in those without in ICA and M1 occlusions. The detection of HAS may provide an idea concerning rapid and dichotomized estimation of thrombus volume, which may be helpful for treatment decisions in potential candidates for thrombolysis.
    American Journal of Neuroradiology 03/2008; 29(2):359-62. DOI:10.3174/ajnr.A0800 · 3.68 Impact Factor
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    ABSTRACT: PURPOSE Double inversion-recovery (DIR) imaging suppresses the signals from both white matter and cerebrospinal fluid, selectively depicting cortex with bright signal intensity. The primary motor cortex (PMC) contains prominent myelin in its layers 3 and 5 (more in layer 3), which may be seen as triple-layer appearance on thin-section DIR (outer hyperintense, middle hypointense, and inner mildly hyperintense layers). The purpose of this study was to investigate whether the PMC can be differentiated from other cortices by thin-section DIR. METHOD AND MATERIALS We enrolled 90 patients (female, 41; age, 5-80 years; mean, 35.9 years) without neurological abnormalities who underwent 2-mm DIR at 3.0 T. The presence or absence of the triple-layer appearance within the cortices at the level of the centrum semiovale was graded independently by two neuroradiologists as definitely present (grade 2), probably present (grade 1), or definitely absent (grade 0). Differences in grades between the two sexes and among age groups were analyzed by Mann-Whitney test and Kruskal-Wallis one-way ANOVA test, respectively. According to the previously defined criteria, the central sulcus was found by another neuroradiologist who was not involved in evaluation of the PMC. RESULTS The triple-layer appearance of grade 1 and 2 was found only in the PMC on both sides in 75 (83.3%) and 10 (11.1%) of 90 patients, respectively. Grade 0 was determined in 4 patients younger than 10 years of age. Grades were significantly lower in patients younger than 10 years of age than those in the others (p .0001), but not different among age groups older than 10 years (p > .05). Interobserver agreement was excellent (weighted κ = .915). No significant difference was present in grades between age-matched female and male patients (p > .05). CONCLUSION The PMC can be differentiated from other cortices by showing triple-layer appearance on thin-section DIR over 10 years of age. CLINICAL RELEVANCE/APPLICATION The triple-layer appearance on thin-section DIR is a new marker of the primary motor cortex, and may be useful for presurgical identification of this crucial cortex.
    Radiological Society of North America 2007 Scientific Assembly and Annual Meeting; 11/2007
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    ABSTRACT: PURPOSE/AIM 1. To understand the gyral and sulcal anatomy for localization of the central sulcus and perirolandic cortex. 2. To present various imaging methods and techniques for localization of the central sulcus and perirolandic cortex. CONTENT ORGANIZATION 1. Gyral and sulcal patterns for localization of the central sulcus a. Basic surface anatomy of the brain b. Useful landmarks 2. Imaging methods a. Techniques based on anatomic landmarks and relationships on imaging b. Cortical thickness of the perirolandic cortex c. MR signal intensity of the perirolandic cortex d. Functional MRI e. Magnetic encephalography SUMMARY 1. Accurate localization of the lesions near the central sulcus is essential for preoperative diagnosis and surgical planning. 2. Understanding of anatomical landmarks and relationships improve the accuracy in localization of the central sulcus and perirolandic cortex. 3. Various imaging methods and techniques can be used for the localization of the central sulcus and perirolandic cortex.
    Radiological Society of North America 2007 Scientific Assembly and Annual Meeting; 11/2007
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    ABSTRACT: Previous studies have shown that maturation of the white matter in terms of its relative signal intensity changes on MRI is almost complete at 2-3 years of age. We hypothesized that quantitative analysis may show maturation of the white matter during childhood and adolescence. In the present study we performed multi-echo T2 relaxometry in 33 healthy subjects (girls, 15; boys, 18) aged 3-15 years. T2 relaxation times of the genu and splenium were measured. In healthy subjects, the T2 relaxation times were significantly correlated with age in both girls (r=0.611, p=.016) and boys (r=0.721, p=.001) in the splenium, but not in the genu (p>.05). To further confirm genu-to-splenium signal intensity ratio changes, a total of 389 brain MRIs were retrospectively selected from the patients who had normal results (189 girls/women, 200 boys/men; age range, 3-20 years). The genu-to-splenium signal intensity ratio was obtained from the T2-weighted images. In patients with normal MRI, the genu-to-splenium signal intensity ratio was significantly decreased with age (p<.001) by 16 years. The T2 relaxation times gradually increase in the splenium during childhood and adolescence, suggestive of maturation.
    International Journal of Developmental Neuroscience 11/2007; 25(6):409-14. DOI:10.1016/j.ijdevneu.2007.05.005 · 2.92 Impact Factor
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    ABSTRACT: The peritoneum is the largest serous membrane in the body and the one with the most complex structure. The omentum is a double-layered extension of the peritoneum that connects the stomach to adjacent organs. The peritoneal reflections form the greater and lesser omenta, and the natural flow of peritoneal fluid determines the route of spread of intraperitoneal fluid and consequently of disease processes within the abdominal cavity. The omenta serve both as boundaries for disease processes and as conduits for disease spread. The omenta are frequently involved by infectious, inflammatory, neoplastic, vascular, and traumatic processes. Computed tomography (CT) is a primary diagnostic method for evaluation of omental diseases, most of which may manifest with nonspecific clinical features. Multidetector CT with multiplanar reformation allows accurate examination of the complex anatomy of the peritoneal cavity, knowledge of which is the key to understanding the pathologic processes affecting the greater and lesser omenta.
    Radiographics 05/2007; 27(3):707-20. DOI:10.1148/rg.273065085 · 2.73 Impact Factor
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    ABSTRACT: Mesenteric cystic lymphangioma is an uncommon lesion that may be difficult to diagnose radiologically. In our case, a septate cystic mass showed fluid attenuation on a computed tomography scan. We were able to define the fat content within the cystic tumor by magnetic resonance (MR) imaging. The presence of fat within an intra-abdominal cystic mass is suggestive of a dermoid cyst, cystic lymphangioma, or lymphocele. The pathologic diagnosis revealed a cystic lymphangioma, which originated from the mesentery. Although the MR imaging features of dermoid cysts and lymphangiomas are well known, the demonstration of fat content by chemical shift and fat saturation MRI has not yet been reported for a cystic lymphangioma.
    Journal of Magnetic Resonance Imaging 01/2006; 23(1):77-80. DOI:10.1002/jmri.20474 · 2.79 Impact Factor
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    ABSTRACT: LEARNING OBJECTIVES 1. to understand the anatomy of the greater omentum and the lesser omentum 2. to illustrate the omental anatomy as a route or as a barrier of disease spreads 3. to demonstrate the roles of multi-detector row CT for evaluation of the omental pathology ABSTRACT The peritoneum is the largest and most complexly arranged serous membrane in the body. The peritoneal reflections form the greater and the lesser omenta and the natural flow of peritoneal fluid determine the route of spread of intraperitoneal fluid and, consequently, disease processes within the abdominal cavity. The omenta also serve as boundaries for disease processes and conduits for disease spread. The omentum is frequently involved by infectious, inflammatory, neoplastic and traumatic processes, and infarction. Multi-detector CT with multiplanar reformations allows the accurate examination of the complex anatomy of the peritoneal cavity, which is the key to understanding the pathological processes affecting it. This article reviews the normal omental anatomy and its disease processes.
    Radiological Society of North America 2005 Scientific Assembly and Annual Meeting; 11/2005
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    ABSTRACT: Physiologic (18)F-FDG uptake in the stomach can often cause false-positive results and lowers the usefulness of (18)F-FDG PET in evaluating the remnant stomach. We assessed the role of gastric distension to see whether it is beneficial for the differentiation of recurrent tumors from physiologic (18)F-FDG uptake in the remnant stomach. Thirty patients (22 men and 8 women; age range, 27-80 y; mean age, 58.3 y) with a history of subtotal gastrectomy for gastric cancer underwent (18)F-FDG PET for various clinical indications. After whole-body imaging, the patients were asked to drink water, and then spot imaging of the stomach was performed. (18)F-FDG uptake in the remnant stomach was considered positive for malignancy if it was persistently increased, whether focal or diffuse, after water ingestion. We used 2 standardized uptake value (SUV) criteria to differentiate benign from malignant uptake. First, a lesion was considered benign if its SUV was less than 2 on whole-body imaging. Second, for a lesion with an SUV of 2 or above, it was classified as benign if SUV decreased by more than 10% after water ingestion. Visual analysis of whole-body images produced 9 true-negative, 4 false-positive, 16 true-positive, and 1 false-negative results. Use of additional spot images produced 12 true-negative, 1 false-positive, 15 true-positive, and 2 false-negative results. When an SUV cutoff of 2 was applied for malignancy before water ingestion, all 17 patients with local recurrence were correctly identified, but 11 of the 13 patients without local recurrence were falsely considered to have a recurrent tumor in the remnant stomach. To reduce the false-positive results, we used the second SUV criterion after water ingestion. Use of that criterion produced 4 false-negative results although it correctly identified the 11 false-positive results as true negative. Gastric distension by having patients drink a glass of water seems to be a simple, cost-effective way of improving the diagnostic accuracy of (18)F-FDG PET in patients with suspected recurrence in the remnant stomach. Visual analysis with special attention to the configuration of (18)F-FDG activity after water ingestion seems to be more useful than the change in SUV in evaluating the remnant stomach.
    Journal of Nuclear Medicine 07/2005; 46(6):953-7. · 5.56 Impact Factor
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    ABSTRACT: PURPOSE/AIM 1) To review the mechanism of sulcal hyperintensity on FLAIR imaging (SH). 2) To review the various conditions and disorders causing SH. 3) To discuss the imaging findings for differential diagnosis in patient with SH. CONTENT ORGANIZATION 1) The mechanism of SH. 2) Various conditions and disorders causing SH. a. Subarachnoid hemorrhage b. Meningitis c. Leptomeningeal metastasis d. Acute ischemic stroke e. Chronic stenosis or occlusion f. Moyamoya disease g. Dural sinus thrombosis h. Dural arteriovenous fistula i. Sulci adjacent to the large mass j. Contrast media k. Oxygen inhalation during MRI acquisition l. Susceptibility artifact 3) Review of imaging findings focused on differential diagnosis. SUMMARY 1. Sulcal hyperintensity on FLAIR can be found in various conditions and disorders. 2. A thorough knowledge of these conditions and disorders may be helpful for diagnosis and proper management.
    Radiological Society of North America 2007 Scientific Assembly and Annual Meeting;
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    ABSTRACT: BACKGROUND AND PURPOSE: Although the hyperattenuated middle cerebral artery sign is known to be related to acute infarction, the volume of clot associated with it is not known. We investigated whether the presence or absence of hyperattenuated artery sign (HAS) on noncontrast CT (NCCT) can predict the thrombus volume. MATERIALS AND METHODS: We enrolled 90 consecutive patients with acute infarction who underwent both 5- and 1.25-mm NCCT and CT angiography (CTA). HAS was determined on 5-mm NCCT retrospectively. According to the location of thrombi, the patients were classified into ICA (ICA terminus/ICA and others), M1 (M1/both M1 and M2), and M2 (M2) groups. Thrombus volumes were measured by 1.25-mm NCCT and were compared between patients with and without HAS. RESULTS: Occlusion of major arteries was seen on CTA in 78 patients. HAS was found in 46 patients (59.0%). The mean thrombus volume was significantly larger in patients with HAS than in those without except for the M2 group (ICA group: (n 14), 188.7 122.5 mm3 versus 39.4 12.1 mm3 (P.022); M1 group: (n 42), 128.1 119.2 versus 56.8 32.5 (P.005); M2 group: (n 22), 34.7 32.2 versus 20.0 20.0 (P.18)). Thrombus volumes determined by receiver operating characteristic curve analysis were 52.36 mm3 in the ICA group (sensitivity, 90.9%; specificity, 100%) and 53.96 mm3 in the M1 group (sensitivity, 88.0%; specificity, 58.8%). CONCLUSION: Thrombus volumes were significantly larger in patients with HAS than in those without in ICA and M1 occlusions. The detection of HAS may provide an idea concerning rapid and dichoto- mized estimation of thrombus volume, which may be helpful for treatment decisions in potential candidates for thrombolysis. surement of its volume in patients with acute ischemic stroke became feasible by using thin-section NCCT.9,10 Therefore, we hypothesized that the relationship between the thrombus volume and the presence of HAS on conventional 5-mm CT could be determined with measurement of thrombus volume by using thin-section NCCT, and also the best threshold of thrombusvolumeforpredictingthepresenceofHAScouldbe determined. The purpose of this study was to investigate whether the presence or absence of HAS can be used in the prediction of thrombus volume.

Publication Stats

122 Citations
32.02 Total Impact Points

Institutions

  • 2011
    • Korea University
      • Department of Brain and Cognitive Engineering
      Seoul, Seoul, South Korea
  • 2007–2008
    • Yonsei University
      • Institute of Gastroenterology
      Sŏul, Seoul, South Korea
    • Yonsei University Hospital
      • Department of Internal Medicine
      Sŏul, Seoul, South Korea