Publications by authors named "Inseon Ryoo"

35 Publications

Usefulness of 3D High-resolution Vessel Wall MRI in Diffuse Nonaneurysmal SAH Patients.

Clin Neuroradiol 2021 May 11. Epub 2021 May 11.

Siemens Healthineers Ltd., Seoul, Korea (Republic of).

Purpose: In 15-20% of patients with nontraumatic diffuse subarachnoid hemorrhage (SAH), the initial conventional angiography does not reveal a causative vascular abnormality, such as intracranial aneurysm. In this study, we evaluated clinical utility of 3D high-resolution vessel wall magnetic resonance imaging (HR-VWI) in patients with diffuse nonaneurysmal SAH.

Methods: A total of 17 patients with diffuse nonaneurysmal SAH were included in this retrospective study. We characterized demographics and HR-VWI findings and reviewed the clinical management and outcomes.

Results: Of the patients 14 (14/17; 82.4%,) showed abnormal findings on HR-VWI, including 5 with intracranial dissections (29.4%), 3 with blood blister-like aneurysm (17.6%), 1 with ruptured fusiform aneurysm (5.9%), and 5 with focal nodular wall enhancement without unclassified pathology (29.4%). Of these patients were treated with endovascular management. Most patients (16/17) had a favorable modified Rankin scale scores of 0-2 on discharge.

Conclusion: The 3D HR-VWI revealed various hidden pathologies, such as intracranial arterial dissection, blood blister-like aneurysm, and fusiform aneurysm in patients with diffuse nonaneurysmal SAH. In addition, 3D HR-VWI had an impact on the management of SAH. The 3D HR-VWI can be a complementary diagnostic method for patients with diffuse nonaneurysmal SAH in a research or clinical setting.
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http://dx.doi.org/10.1007/s00062-021-01018-0DOI Listing
May 2021

Performance of deep learning to detect mastoiditis using multiple conventional radiographs of mastoid.

PLoS One 2020 11;15(11):e0241796. Epub 2020 Nov 11.

Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.

Objectives: This study aimed to compare the diagnostic performance of deep learning algorithm trained by single view (anterior-posterior (AP) or lateral view) with that trained by multiple views (both views together) in diagnosis of mastoiditis on mastoid series and compare the diagnostic performance between the algorithm and radiologists.

Methods: Total 9,988 mastoid series (AP and lateral views) were classified as normal or abnormal (mastoiditis) based on radiographic findings. Among them 792 image sets with temporal bone CT were classified as the gold standard test set and remaining sets were randomly divided into training (n = 8,276) and validation (n = 920) sets by 9:1 for developing a deep learning algorithm. Temporal (n = 294) and geographic (n = 308) external test sets were also collected. Diagnostic performance of deep learning algorithm trained by single view was compared with that trained by multiple views. Diagnostic performance of the algorithm and two radiologists was assessed. Inter-observer agreement between the algorithm and radiologists and between two radiologists was calculated.

Results: Area under the receiver operating characteristic curves of algorithm using multiple views (0.971, 0.978, and 0.965 for gold standard, temporal, and geographic external test sets, respectively) showed higher values than those using single view (0.964/0.953, 0.952/0.961, and 0.961/0.942 for AP view/lateral view of gold standard, temporal external, and geographic external test sets, respectively) in all test sets. The algorithm showed statistically significant higher specificity compared with radiologists (p = 0.018 and 0.012). There was substantial agreement between the algorithm and two radiologists and between two radiologists (κ = 0.79, 0.8, and 0.76).

Conclusion: The deep learning algorithm trained by multiple views showed better performance than that trained by single view. The diagnostic performance of the algorithm for detecting mastoiditis on mastoid series was similar to or higher than that of radiologists.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0241796PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7657495PMC
January 2021

Diagnostic Accuracy and Confidence of [18F] FDG PET/MRI in comparison with PET or MRI alone in Head and Neck Cancer.

Sci Rep 2020 06 11;10(1):9490. Epub 2020 Jun 11.

Department of Radiology, Seoul National University Hospital, 101, Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.

The usefulness of PET/MRI in head and neck malignancy has not been fully elucidated. The purpose of our study was to evaluate the diagnostic accuracy and confidence of PET/MRI in comparison with PET or MRI alone. This study included 73 consecutive patients who underwent [18F] FDG PET/MRI in head and neck under the suspicion of malignancy. A neuroradiologist and a nuclear medicine specialist reviewed MRI and PET images, respectively and independently, followed by a consensus review of PET/MRI one month later. For 134 lesions, accuracy and confidence were compared among PET, MRI, and PET/MRI. For lesion base, PET/MRI had a sensitivity of 85.7%, a specificity of 89.1%, a PPV of 89.6%, a negative predictive value of 85.1%, and an accuracy of 87.3%. AUCs of PET/MRI per lesion (0.926) and per patient (0.934) for diagnosing malignancy were higher than PET (0.847 and 0.747, respectively) or MRI (0.836 and 0.798, respectively) alone (P < 0.05). More than 80% of the cases (111/134) showed diagnostic concordance between PET and MRI. PPV of PET/MRI was higher in malignant concordant cases (93.2%, 55/59) than in discordant cases (62.5%, 5/8) (p = 0.040). Confident scoring rate in malignant concordant cases was higher on PET/MRI (96.6%, 57/59) than on MRI (76.3%, 45/59) (p = 0.003). In conclusion, compared with PET or MRI alone, PET/MRI presents better diagnostic performance in accuracy and confidence for diagnosis of malignancy. PET/MRI is useful in patients with head and neck cancer.
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http://dx.doi.org/10.1038/s41598-020-66506-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7289810PMC
June 2020

Rathke Cleft Cysts with Apoplexy-Like Symptoms: Clinicoradiologic Comparisons with Pituitary Adenomas with Apoplexy.

World Neurosurg 2020 10 23;142:e1-e9. Epub 2020 Mar 23.

Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Guro, Seoul, South Korea.

Background: Rathke cleft cyst (RCC) can cause acute symptoms mimicking pituitary adenoma (PA) apoplexy. We evaluated the clinicoradiologic features for distinguishing RCC from PA apoplexy.

Methods: We retrospectively evaluated 22 patients with RCC and 24 patients with PA with apoplexy-like symptoms who underwent surgery via a transsphenoidal approach between November 1999 and December 2016. We compared the clinical data and magnetic resonance (MR) images between the 2 groups.

Results: The RCC group was younger and had smaller tumors compared with the PA group (P = 0.02 and 0.001, respectively). The incidences of visual deficits and cranial nerve palsy were lower in the RCCs than in the PAs (P ≤ 0.02 for all). MR images showed more frequent intracystic nodules in the RCCs (P < 0.001), whereas nodular enhancement and lateral deviation of the pituitary stalk were more commonly seen in the PAs (P ≤ 0.003 for both). However, the presence of endocrine dysfunction or decreased consciousness, and the recurrence ratio, were not significantly different between the groups (P ≥ 0.48 for all). In the multivariable logistic regression analysis, patients without nodular enhancement had a 15.84-fold greater risk of RCC than did those with nodular enhancement (P = 0.031). The probability of RCC decreased 0.59-fold with each 1-cm increase in tumor volume.

Conclusions: RCC with apoplexy-like symptoms has different clinicoradiologic features compared with PA apoplexy. Patients with RCC present with milder ocular symptoms and smaller tumor volumes compared with those with PA apoplexy. The absence of nodular enhancement on MR images could suggest RCC.
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http://dx.doi.org/10.1016/j.wneu.2020.03.086DOI Listing
October 2020

MR Findings of Fungus Ball: Significance of High Signal Intensity on T1-Weighted Images.

J Korean Med Sci 2020 Jan 20;35(3):e22. Epub 2020 Jan 20.

Department of Radiology, Seoul National University Hospital Healthcare System Gangnam Center, Seoul National University College of Medicine, Seoul, Korea.

Background: Central dark-signal intensity with high-signal, hypertrophic mucosal wall of paranasal sinuses on T2-weighted images (T2WI) is a characteristic magnetic resonance imaging (MRI) feature of sinonasal fungus ball. However, this finding is usually interpreted as non-fungal chronic sinusitis with central normal sinus air. In addition, T1-weighted images (T1WI) and T2WI are basic sequences of all magnetic resonance (MR) examinations. Therefore, we evaluated the usefulness of T1WI for detecting fungus balls comparing with computed tomography (CT) findings and T2-weighted MRI findings.

Methods: This retrospective study was approved by the Institutional Review Board of Korea University Guro Hospital. Two reviewers assessed preoperative CT and MR images of 55 patients with pathologically confirmed fungus balls. Reviewers evaluated the presence and patterns of calcifications on CT. Overall signals and the presence and extent of certain signals of fungus balls on MRI were also assessed. The relationship between calcifications and MRI signals was also evaluated.

Results: Of the patients, 89.1% had calcifications on CT. All had dark signal portions with high signal, hypertrophic mucosal walls on T2WI. Most (92.7%) patients showed iso- to hyper-intense overall signals on T1WI and 89.1% had T1-weighted high signal portions on MRI. The presence, patterns, and location of calcifications had no significant correlation with T1-weighted high-signal intensity portion.

Conclusion: Fungus ball can be suggested by the presence of the hyper-signal intensity portions in the fungal mass on T1WI in conjunction with dark-signal lesions surrounded by high-signal, hypertrophic mucosal walls in paranasal sinuses on T2WI.
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http://dx.doi.org/10.3346/jkms.2020.35.e22DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6970076PMC
January 2020

Differentiating cervical metastatic lymphadenopathy and lymphoma by shear wave elastography.

Sci Rep 2019 08 27;9(1):12396. Epub 2019 Aug 27.

Department of Radiology, Korea University Guro Hospital, Seoul, 08308, Korea.

Shear wave elastography (SWE) is a recent technological advance of ultrasonography (US) to assess tissue stiffness. The purpose of this study is to assess tissue stiffness of malignant cervical lymph nodes (LN) with SWE, to reveal diagnostic performance of SWE in differentiating metastatic LN from lymphoma, and to assess inter-observer agreement of SWE. We assessed 62 malignant LN (24 lymphomas and 38 metastatic LN) and their median speed was 6.34 m/s and median elasticity was 69.7 kPa. Add of SWE with conventional US improved diagnostic accuracy of differentiating metastasis from lymphoma (16.13, 8.07 and 11.3% for three radiologists). Kendall's Coefficient of Concordance of three readers for analyzing SWE patterns was 0.86. SWE can be a useful tool to discriminate metastatic cervical LN from lymphoma with improvement of diagnostic accuracy when using with conventional US.
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http://dx.doi.org/10.1038/s41598-019-48705-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6712052PMC
August 2019

Early Prediction of Periventricular Leukomalacia Using Quantitative Texture Analysis of Serial Cranial Ultrasound Scans in Very Preterm Infants.

Ultrasound Med Biol 2019 10 19;45(10):2658-2665. Epub 2019 Jul 19.

Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.

We compared texture parameters of serial cranial ultrasound (cUS) images of periventricular leukomalacia (PVL) and normal periventricular echogenicity (PVE) in very preterm infants and evaluated the early predictive values of texture analysis (TA) for PVL. Ten individuals with PVL and 10 control individuals with PVE assessed with an initial cUS within 1 wk of birth and follow-up cUS at 2-3 and 4-6 wk of life were included. TA was performed on the region of interest of PVE at the parieto-occipital area on serial cUS. Opposite changes in variance were obtained between the first two cUS sessions in both groups (p = 0.017 in PVL and p = 0.005 in PVE). The variance-to-mean ratio (VMR) between the second and first cUS sessions differed (p = 0.016) and reliably stratified the groups (area under the receiver operating characteristic curve: 0.820, 95% confidence interval: 0.587-1.000, sensitivity: 100%, specificity: 60%). TA of serial cUS helps to predict PVL within 3 wk of life.
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http://dx.doi.org/10.1016/j.ultrasmedbio.2019.06.413DOI Listing
October 2019

MRI Findings of Spontaneous Intracranial Hypotension: Usefulness of Straight Sinus Distention.

AJR Am J Roentgenol 2019 Feb 26:1-7. Epub 2019 Feb 26.

3 Department of Radiology, SMG-SNU Boramae Medical Center, Seoul National University College of Medicine, Seoul, Korea.

Objective: Spontaneous intracranial hypotension (SIH) shows various characteristic MRI findings. We evaluated the usefulness of straight sinus distention compared with transverse sinus distention and also evaluated other MRI findings of SIH.

Materials And Methods: Forty-three consecutive patients (28 female and 15 male patients) treated for SIH and 43 age- and sex-matched control subjects at two institutions from 2012 through 2014 were included in this study. Two reviewers determined whether the transverse sinus distention sign and straight sinus distention sign were present on MRI. Diagnostic performance values and interobserver agreement were calculated. Reviewers also assessed MRI examinations in consensus for the presence of the following findings: pachymeningeal enhancement, subdural effusion or hematoma, enlargement of the pituitary gland, and downward displacement of the brainstem and tonsils.

Results: The sensitivity, specificity, and diagnostic accuracy of the transverse sinus distention sign for SIH were 76.7%, 83.7%, and 80.2%, whereas those of the straight sinus distention sign were 79.1%, 95.4%, and 87.2%, respectively. The specificity of the straight sinus distention sign for SIH was significantly higher (p = 0.025) than that of the transverse sinus distention sign. In addition, the straight sinus distention sign showed substantial agreement (κ = 0.79), whereas the transverse sinus distention sign showed moderate agreement (κ = 0.60). The diagnostic accuracy of the presence of either transverse or straight sinus distention (83.7%) was significantly higher than that of pachymeningeal enhancement (80.2%, p = 0.032).

Conclusion: The straight sinus distention sign could be helpful for the diagnosis of SIH because it has sensitivity comparable to other imaging findings and higher specificity and higher level of interobserver agreement than other imaging findings.
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http://dx.doi.org/10.2214/AJR.18.20369DOI Listing
February 2019

Dual-energy CT iodine quantification for characterizing focal thyroid lesions.

Head Neck 2019 04 18;41(4):1024-1031. Epub 2018 Dec 18.

Department of Biostatistics, Korea University College of Medicine, Seoul, Republic of Korea.

Background: To determine the usefulness of dual-energy CT (DECT) iodine quantification to classify the focal thyroid lesions.

Methods: We retrospectively enrolled a total of 76 cytopathologically confirmed focal thyroid lesions (mean size: 1.9 cm). After drawing a region of interest on the DECT-derived iodine maps, the obtained iodine concentration values of thyroid nodules (IC_N) and normalized IC_N were compared between 3 groups: papillary thyroid carcinoma (PTC), benign nodule, and cyst.

Results: From all lesions, 46, 17, and 13 were assigned to the PTC, benign nodule, and cyst groups. IC_N was the highest in the benign nodule, lower in the PTC, and the lowest in the cyst (median [interquartile range]: 4.3 [3.13-5.48], 3.15 [2.29-4.01], 0.60 [0.33-0.88], all P < .001). Similarly, the normalized IC_N values were all statistically different from each other (P < .05).The multi-class area under the curves using the optimal cutoff values were 0.931 for IC_N and 0.918, 0.920 for normalized IC, respectively.

Conclusion: DECT iodine quantification could be helpful to classify the focal thyroid lesions.
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http://dx.doi.org/10.1002/hed.25524DOI Listing
April 2019

Hyperintense Thyroid Incidentaloma on Time of Flight Magnetic Resonance Angiography.

Front Endocrinol (Lausanne) 2018 23;9:417. Epub 2018 Jul 23.

Department of Radiology, Seoul National University Hospital Healthcare System Gangnam Center, Seoul National University College of Medicine, Seoul, South Korea.

The purpose of this study was to evaluate the clinical significance of thyroid incidentaloma with hypersignal intensity on the time of flight magnetic resonance (TOF-MR) angiography and correlation with ultrasound (US). We retrospectively reviewed 3,505 non-contrast TOF-MR angiography performed at our institution between September 2014 and May 2017. Two radiologists correlated the thyroid incidentalomas detected on TOF-MR angiography with US features that were obtained within a three-month interval between MR and US examinations in consensus. The prevalence of hyperintense thyroid nodules incidentally detected by TOF-MR angiography was 1.2% (43/3,505 patients). Among these, 35 people (77.8%) underwent US examinations, and a total of 45 hyperintense thyroid nodules were detected by US studies. Of these 45 nodules, more than 70% were categorized as benign on US exams. Fine needle aspiration was performed on nine nodules according to indications recommended by the Korean Society of Thyroid Radiology. All except one high-suspicion thyroid nodule were confirmed as benign (Bethesda 2) on cytologic examination. The high-suspicion nodule on US showed a nondiagnostic result (Bethesda 1). However, this nodule collapsed after aspiration of thick colloid. Our study demonstrated that the most hyperintense thyroid nodules detected on TOF-MR angiography were benign. Therefore, if a hyperintense incidentaloma is found on TOF-MR angiography, the thyroid nodule is more likely to be benign. We believe that these findings could offer additional information for further clinical management.
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http://dx.doi.org/10.3389/fendo.2018.00417DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6064725PMC
July 2018

Postoperative Neck Ultrasonography Surveillance After Thyroidectomy in Patients With Medullary Thyroid Carcinoma: A Multicenter Study.

Front Endocrinol (Lausanne) 2018 15;9:102. Epub 2018 Mar 15.

Department of Radiology, Gyeongsang National University School of Medicine, Gyeongsang National University Changwon Hospital, Changwon, South Korea.

Background: For detecting tumor recurrence of medullary thyroid carcinoma (MTC) in the neck, an appropriate frequency and interval of postoperative ultrasonography (US) surveillance remains unclear. This study aimed to assess an appropriate interval and frequency of postoperative neck US surveillance for detecting tumor recurrence in patients who had undergone thyroid surgery due to MTC.

Methods: A total of 86 patients who had undergone thyroid surgery for the treatment of MTC and had at least one postoperative US follow-up examination at any of nine affiliated hospitals were included. Postoperative follow-up US, clinical, and histopathological results of patients were reviewed. The tumor recurrence/persistence rate of MTC was investigated, and the interval and session number of postoperative follow-up US and clinicopathologic factors were compared between tumor recurrence/persistence and non-recurrence groups.

Results: Of the 86 patients, 22 (25.6%) showed tumor recurrence/persistence. Of the 22 patients with tumor recurrence/persistence, 11 (50%) showed structural recurrence/persistence in the neck on follow-up US. In these 11 patients, the mean interval and session number of postoperative follow-up US between initial surgery and the first US detection of recurrence/persistence was 41.3 ± 39.3 months (range, 6-128 months) and 2.6 ± 2.3 (range, 1-8), respectively. On follow-up US, 6 (54.5%, 6/11) were diagnosed with tumor recurrence/persistence within 3 years of the initial surgery. Tumor recurrence/persistence was significantly correlated with TNM stage ( < 0.001) and multiplicity/bilaterality ( = 0.013).

Conclusion: For detecting MTC recurrence/persistence, postoperative US surveillance at 1-year intervals may be sufficient within the first 3 years after thyroid surgery, but depending on the presence of relevant risk factors, annual or biannual US surveillance may be recommendable for 4-10 years after thyroid surgery.
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http://dx.doi.org/10.3389/fendo.2018.00102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5862825PMC
March 2018

Comparison of clinicoradiological findings between patients with recovering diplopia and those with residual diplopia after surgery for pure orbital blowout fracture.

J Craniomaxillofac Surg 2018 Mar 15;46(3):375-380. Epub 2017 Dec 15.

Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, South Korea.

Purpose: Diplopia is a common symptom of blowout fracture (BOF), and can persist after proper surgical management. We compared clinicoradiological findings between patients with recovering diplopia and those with residual diplopia after surgery for orbital BOF.

Materials And Methods: We retrospectively evaluated the CT images of 170 patients with orbital BOF and preoperative diplopia. We reviewed the following factors: sex, age, mechanism of injury, presence of diplopia before surgery, presence of enophthalmos before surgery, presence of an ocular motility abnormality before surgery, time interval between the trauma and surgery, fracture type, fracture size, volume of herniated orbital soft tissue, ratio of the volume of herniated orbital soft tissue to fracture size, number of points of contact between the extraocular muscle (EOM) and bony edge, EOM swelling, EOM swelling ratio, EOM displacement, EOM circling, EOM tenting, and EOM entrapment. The associations between the presence of diplopia 6 months after surgical repair and various clinicoradiological findings were analyzed using Wilcoxon rank-sum tests, Student's t-tests, Fisher's exact tests for univariable analysis, and logistic regression analysis for multivariable analysis. A Kaplan-Meier curve and log-rank test were used to identify the recovery status from diplopia.

Results: The following findings were significantly different between patients with recovering diplopia and those with residual diplopia on univariable analysis (p < 0.05 for each): patient age, EOM entrapment, EOM circling, and EOM tenting. Multivariable analyses showed that patients who were older or those who had EOM circling or tenting on CT images had a greater probability of residual diplopia after surgery [p-values: 0.006, 0.013, and <0.001, respectively; odds ratio (95% confidence interval): 1.035 (1.010-1.061), 14.809 (1.775-123.556), and 4.851 (2.069-11.375), respectively]. The recovery rate for diplopia was significantly different between patients with EOM tenting and those without (p = 0.02). Additionally, young patients (0-12 years) showed a shorter recovery time from diplopia compared with older patients (>24 years) (p < 0.05).

Conclusion: Patients with residual diplopia after surgical management have different clinicoradiological findings compared with patients with recovering diplopia. Patients who are older, or those who have circling or tenting of the EOM on CT scans, are more likely to have residual diplopia.
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http://dx.doi.org/10.1016/j.jcms.2017.12.006DOI Listing
March 2018

Vascular Pattern Analysis on Microvascular Sonography for Differentiation of Pleomorphic Adenomas and Warthin Tumors of Salivary Glands.

J Ultrasound Med 2018 Mar 8;37(3):613-620. Epub 2017 Sep 8.

Department of Radiology, Seoul National University Hospital, Healthcare System Gangnam Center, Seoul, Korea.

Objectives: Pleomorphic adenomas and Warthin tumors are the most common salivary gland tumors. It is important to differentiate between them because at least a partial parotidectomy is necessary for pleomorphic adenomas, whereas enucleation is sufficient for Warthin tumors. This study aimed to evaluate the usefulness of vascular pattern analysis using microvascular sonography to differentiate between the tumors.

Methods: Sixty-two patients with pathologically proven pleomorphic adenomas (n = 38) and Warthin tumors (n = 24) were included. For all tumors, grayscale, power Doppler, and microvascular sonographic examinations were performed. Differences in vascular patterns (vascular distribution and internal vascularity) on power Doppler and microvascular sonography as well as grayscale sonographic features (size, shape, border, echogenicity, heterogeneity, and cystic change) between pleomorphic adenomas and Warthin tumors were evaluated. A comparison of diagnostic performances of grayscale sonography with power Doppler sonography and grayscale sonography with microvascular sonography was performed. The level of interobserver agreement between 2 reviewers in diagnosing tumors was evaluated.

Results: No grayscale sonographic features showed a significant difference between the tumors. Vascular distributions and internal vascularity on power Doppler sonography (P = .01 and .002) and microvascular sonography (both P < .001) were all significantly different. The diagnostic accuracy of grayscale sonography with microvascular sonography (79.0%) was higher than that of grayscale sonography with power Doppler sonography (72.6%). This difference was significant according to the McNemar test (P = .004). Interobserver agreement was excellent in diagnosing tumors on both grayscale sonography with power Doppler sonography (κ = 0.83) and grayscale sonography with microvascular sonography (κ = 0.94).

Conclusions: Vascular pattern analysis using microvascular sonography with other sonographic features is helpful for differentiating between pleomorphic adenomas and Warthin tumors.
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http://dx.doi.org/10.1002/jum.14368DOI Listing
March 2018

Clinical features of recently diagnosed papillary thyroid carcinoma in elderly patients aged 65 and older based on 10 years of sonographic experience at a single institution in Korea.

Ultrasonography 2017 Oct 13;36(4):355-362. Epub 2017 Apr 13.

Department of Radiology, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.

Purpose: The aim of this study was to assess the characteristics of papillary thyroid carcinoma (PTC) in patients aged 65 and older in order to predict postoperative recurrence based on the results of ultrasonographic surveillance.

Methods: Among 1,494 patients (200 male and 1,294 female; mean age, 46.6±11.3 years) who underwent surgery for thyroid cancer at our institution between 2006 and 2015, we retrospectively enrolled 150 PTC patients (29 male and 121 female; mean age, 69.4±4.2 years). To identify the risk factors for recurrence, we analyzed age, gender, multiplicity, size, number, extrathyroidal extension (ETE) of the tumor, lymph node metastasis (LNM), type of surgery, and the dose of radioactive ablation using a Cox regression model to identify hazard ratios (HRs).

Results: Among the 115 asymptomatic patients with PTCs detected by screening ultrasonography (n=86), other cross-sectional imaging modalities (computed tomography or positron emission tomography-computed tomography, n=13), or incidentally through a surgical specimen (n=16), 78 patients were confirmed to have papillary thyroid microcarcinomas (PTMCs). The other 35 patients presented with palpable neck masses (n=25), vocal cord palsy (n=9) or blood-tinged sputum (n=1). During the follow-up period (mean, 43.6 months), 17 patients (12.5%) experienced recurrence in the neck. None of the patients died due to PTC-related recurrence or distant metastasis during the follow-up period. Cox regression analysis demonstrated that tumor size (HR, 2.12; P<0.001) and LNM (central LNM: HR, 9.08; P=0.004; lateral LNM: HR, 14.71; P=0.002; both central and lateral LNM: HR, 58.41; P<0.001) significantly increased the recurrence rate. ETE, LNM, and recurrence were significantly less frequent in PTMCs than in non-PTMC (all P<0.001).

Conclusion: PTCs of small size and absent LNM showed significantly better prognoses in patients 65 years and older.
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http://dx.doi.org/10.14366/usg.17010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5621799PMC
October 2017

Analysis of postoperative ultrasonography surveillance after total thyroidectomy in patients with papillary thyroid carcinoma: a multicenter study.

Acta Radiol 2018 Feb 26;59(2):196-203. Epub 2017 Mar 26.

7 Department of Radiology, Thyroid Center, Daerim St. Mary's Hospital, Seoul, Republic of Korea.

Background In papillary thyroid carcinoma (PTC) patients, postoperative ultrasonography (US) surveillance is recommended at intervals of six or 12 months even though evidence is weak. Purpose To determine the optimal interval of postoperative US surveillance in patients after total thyroidectomy for the treatment of PTC using multicenter data. Material and Methods A total of 1400 patients from seven tertiary hospitals who underwent total thyroidectomy for treatment of PTC were included. Based on a retrospective review of clinical and pathologic results, multiple factors were analyzed according to recurrence/persistence or no recurrence/persistence. In recurrence/persistence group, the interval and number of follow-up US sessions in the initial detection of recurrence/persistence were investigated. Results Of the 1400 patients, 115 (8.2%) showed tumor recurrence/persistence on follow-up US. Of 115 recurrence/persistence cases, 89 (77.4%) were initially detected on US: nodal recurrence/persistence (n = 92), non-nodal recurrence/persistence (n = 22), and both (n = 1). Among the clinical and pathologic factors, only tumor size and N stage were significant predictors for recurrence/persistence. In the recurrence/persistence group, the mean interval and number of follow-up US sessions in the initial detection of recurrence/persistence was 22.3 ± 16.8 months and 2.2 ± 1.9, respectively. Approximately two-thirds of recurrence/persistence cases (76/115, 66.1%) were detected in follow-up US within two years after total thyroidectomy. Conclusion In PTC patients after total thyroidectomy, the optimal interval of the first US follow-up may be one to two years after thyroid surgery, and the appropriate number of postoperative US surveillance sessions within the first five years may be only one or two.
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http://dx.doi.org/10.1177/0284185117700448DOI Listing
February 2018

A semi-automated volumetric software for segmentation and perfusion parameter quantification of brain tumors using 320-row multidetector computed tomography: a validation study.

Neuroradiology 2017 May 24;59(5):461-469. Epub 2017 Mar 24.

Department of Radiology, Korea University Guro Hospital, 148 Gurodong-ro, Guro-gu, Seoul, South Korea.

Purpose: We developed a semi-automated volumetric software, NPerfusion, to segment brain tumors and quantify perfusion parameters on whole-brain CT perfusion (WBCTP) images. The purpose of this study was to assess the feasibility of the software and to validate its performance compared with manual segmentation.

Methods: Twenty-nine patients with pathologically proven brain tumors who underwent preoperative WBCTP between August 2012 and February 2015 were included. Three perfusion parameters, arterial flow (AF), equivalent blood volume (EBV), and Patlak flow (PF, which is a measure of permeability of capillaries), of brain tumors were generated by a commercial software and then quantified volumetrically by NPerfusion, which also semi-automatically segmented tumor boundaries. The quantification was validated by comparison with that of manual segmentation in terms of the concordance correlation coefficient and Bland-Altman analysis.

Results: With NPerfusion, we successfully performed segmentation and quantified whole volumetric perfusion parameters of all 29 brain tumors that showed consistent perfusion trends with previous studies. The validation of the perfusion parameter quantification exhibited almost perfect agreement with manual segmentation, with Lin concordance correlation coefficients (ρ ) for AF, EBV, and PF of 0.9988, 0.9994, and 0.9976, respectively. On Bland-Altman analysis, most differences between this software and manual segmentation on the commercial software were within the limit of agreement.

Conclusions: NPerfusion successfully performs segmentation of brain tumors and calculates perfusion parameters of brain tumors. We validated this semi-automated segmentation software by comparing it with manual segmentation. NPerfusion can be used to calculate volumetric perfusion parameters of brain tumors from WBCTP.
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http://dx.doi.org/10.1007/s00234-017-1790-6DOI Listing
May 2017

Postoperative ultrasonography surveillance in patients with follicular thyroid carcinoma: a multicenter study.

Radiol Med 2017 Jul 14;122(7):530-537. Epub 2017 Mar 14.

Department of Radiology, Thyroid Center, Daerim St. Mary's Hospital, Seoul, 07442, South Korea.

Objective: This study aimed to evaluate the locoregional recurrence rate of follicular thyroid carcinoma (FTC) and to assess the appropriate frequency of postoperative ultrasonography (US) surveillance for detecting tumor recurrence.

Methods: The review boards of the seven participating institutions approved this study. From 2000 to 2011, 186 patients underwent at postoperative US at least once; US was performed by experienced radiologists at each institution. Based on the US and histopathological results, locoregional tumor recurrence was assessed.

Results: The T stages of the 186 patients were T1a (8.1%), T1b (21.5%), T2 (39.8%), T3 (30.6%), T4a (0%), and T4b (0%). The N stages were unknown (24.2%), N0 (71.5%), N1a (3.2%), and N1b (1.1%), and the M stages unknown (29.6%), M0 (66.1%), and M1 (4.3%). Tumors recurred in only 6 (3.2%) patients during the follow-up period over 5 years. Among them, no patients showed the initial suspicion of recurrences on routine follow-up US. The session number and interval of postoperative US differed significantly between patients with recurrence and those without recurrence. The mean interval of postoperative follow-up US at the first detection time of tumor recurrence was 37.5 ± 18.5 months (range 9-62 months). Significantly more FTCs were at an advanced N and M stage in the recurrence group than in the non-recurrence group (p < 0.05).

Conclusions: Routine postoperative US surveillance may be unnecessary for detecting tumor recurrence after thyroid surgery in FTC patients.
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http://dx.doi.org/10.1007/s11547-017-0753-7DOI Listing
July 2017

Metabolomic analysis of percutaneous fine-needle aspiration specimens of thyroid nodules: Potential application for the preoperative diagnosis of thyroid cancer.

Sci Rep 2016 07 21;6:30075. Epub 2016 Jul 21.

Department of Radiology, Seoul National University Hospital, College of Medicine, Seoul, Korea.

Thyroid nodules are a very common problem. Since malignant thyroid nodules should be treated surgically, preoperative diagnosis of thyroid cancer is very crucial. Cytopathologic analysis of percutaneous fine-needle aspiration (FNA) specimens is the current gold standard for diagnosing thyroid nodules. However, this method has led to high rates of inconclusive results. Metabolomics has emerged as a useful tool in medical fields and shown great potential in diagnosing various cancers. Here, we evaluated the potential of nuclear magnetic resonance (NMR) analysis of percutaneous FNA specimens for preoperative diagnosis of thyroid cancer. We analyzed metabolome of FNA samples of papillary thyroid carcinoma (n = 35) and benign follicular nodule (n = 69) using a proton NMR spectrometer. The metabolomic profiles showed a considerable discrimination between benign and malignant nodules. Receiver operating characteristic (ROC) curve analysis indicated that seven metabolites could serve as discriminators (area under ROC curve value, 0.64-0.85). These findings demonstrated that NMR analysis of percutaneous FNA specimens of thyroid nodules can be potentially useful in the accurate and rapid preoperative diagnosis of thyroid cancer.
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http://dx.doi.org/10.1038/srep30075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4954945PMC
July 2016

Usefulness of Microvascular Ultrasonography in Differentiating Metastatic Lymphadenopathy from Tuberculous Lymphadenitis.

Ultrasound Med Biol 2016 09 25;42(9):2189-95. Epub 2016 Jun 25.

Department of Radiology, Korea University Guro Hospital, College of Medicine, Seoul, Korea.

This study was undertaken to evaluate the usefulness of vascular pattern analysis on microvascular ultrasonography in distinguishing metastatic lymphadenopathy from tuberculous lymphadenitis, compared with conventional power Doppler ultrasonography, and to evaluate inter-observer agreement for microvascular ultrasonography. Thirty-four patients with metastatic lymphadenopathy and 27 patients with tuberculous lymphadenitis were included. The level of inter-observer agreement was excellent or good for all aspects of vascular pattern analysis on both ultrasonographic examinations. Vascular distribution, internal vascularity and internal vascular features of lymph nodes on microvascular ultrasonography differed significantly different (p ≤ 0.002) between metastatic lymphadenopathy and tuberculous lymphadenitis. A central vascular pattern with displacement was prevalent in metastasis, and an avascular pattern was more frequent in tuberculosis. Internal vascularity of metastasis was higher than that of tuberculosis. Vascular patterns on power Doppler ultrasonography did not differ significantly. Vascular pattern analysis using microvascular ultrasonography can be helpful in differentiating metastatic lymphadenopathy from tuberculous lymphadenitis with good inter-observer agreement.
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http://dx.doi.org/10.1016/j.ultrasmedbio.2016.05.012DOI Listing
September 2016

Feasibility Study of a Contrast-Enhanced Multi-Detector CT (64 Channels) Protocol for Papillary Thyroid Carcinoma: The Influence of Different Scan Delays on Tumor Conspicuity.

Thyroid 2016 05 5;26(5):726-33. Epub 2016 Apr 5.

4 Department of Biostatistics, Korea University College of Medicine , Seoul, Republic of Korea.

Background: Recently, a number of studies have advocated the diagnostic benefit of contrast-enhanced computed tomography (CECT) in the current ultrasound (US)-based preoperative evaluation of thyroid cancer. However, no study has been conducted to optimize a CECT protocol focusing on tumor conspicuity using a multi-detector CT scanner. This study aimed at determining the optimal scan delay for increased CT attenuation differences between thyroid cancer and parenchymal background using a biphasic CECT examination.

Methods: This study retrospectively enrolled 84 patients (M:F = 7:77; Mage = 44.8 ± 10.9 years) with 87 papillary thyroid carcinomas (Msize = 14.1 mm) who consecutively underwent US and CECT examination prior to surgery. In each patient, CT scanning was taken twice-once with a 40-second delay and once with a 70-second delay-using a 64-channel multi-detector scanner. After obtaining the mean attenuation value (MAV) of the thyroid cancer and the ipsilateral parenchyma by drawing regions of interest on the CECT images based on their cytopathologic results and US findings, the parenchyma-cancer differences (PCD) between the early and delayed scans were simply compared using a paired t-test. Then, the mean differences in the MAVs of the thyroid cancer and ipsilateral parenchyma (hereafter abbreviated as Group) between the early and delayed scans (abbreviated as Time) were compared after adjusting for the other factors that significantly affected MAVs, such as concentration of iodinated contrast medium (abbreviated as CCM) and size of thyroid cancer (abbreviated as Size) using a repeated-measures general linear model.

Results: Because the ipsilateral parenchyma exhibited significantly higher attenuation on the early scan and further decline on the delayed scan compared with thyroid cancer (p < 0.001), the PCD for thyroid cancer was significantly better with a 40-second scan delay than a 70-second delay (58.8 ± 36.6 Hounsfield units [HU] vs. 40.4 ± 25.6 HU; p < 0.001). Similar results were obtained from the repeated-measures general linear model that considered the effects of CCM, Size, Group, and Time, and the interaction of Group and Time.

Conclusion: Based on this CECT study that adjusted for the effects of CCM and size on MAV, early scans (e.g., 40-second scan delay) are helpful for improving the tumor conspicuity of thyroid cancer on CECT images.
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http://dx.doi.org/10.1089/thy.2015.0415DOI Listing
May 2016

Off-site evaluation of three-dimensional ultrasound for the diagnosis of thyroid nodules: comparison with two-dimensional ultrasound.

Eur Radiol 2016 Oct 22;26(10):3353-60. Epub 2016 Jan 22.

Department of Radiology, Seoul National University College of Medicine, Seoul National University Hospital, 28 Yongon-Dong, Chongno-Gu, Seoul, Korea, 110-744.

Objectives: We compared the diagnostic performance of off-site evaluation between prospectively obtained 3D and 2D ultrasound for thyroid nodules.

Methods: 3D and 2D ultrasonographies were preoperatively obtained from 85 consecutive patients (mean age, 51 years; age range, 28-83 years) who were referred for a total thyroidectomy. Three radiologists independently evaluated 3D and 2D images of 91 pathologically confirmed thyroid nodules (30 benign and 61 malignant nodules) for nodule characterization. Diagnostic performance, interobserver agreement and time for scanning were compared between 3D and 2D.

Results: 3D had significantly higher sensitivities than 2D for predicting malignancy (78.7 % vs. 61.2 %, P < 0.01) and extrathyroidal extension (66.7 % vs. 46.4 %, P = 0.03) in malignancy. In terms of specificities, there were no statistically significant differences between 2D and 3D for predicting malignancy (78.4 % vs. 74.8 %, P = 1.00) and extrathyroidal extension (63.6 % vs. 57.6 %, P = 0.46). With respect to interobserver agreement, 3D showed moderate agreement (κ = 0.53) for predicting extrathyroidal extension in malignancy compared with 2D ultrasound, which showed fair agreement (κ = 0.37). 3D saved time (30 ± 56.52 s) for scanning compared with 2D.

Conclusion: For off-site evaluation, 3D US is more useful for diagnosis of thyroid nodules than 2D US.

Key Points: • 3D had higher sensitivity than 2D for predicting malignancy and extrathyroidal extension. • 3D showed better agreement for predicting extrathyroidal extension in malignancy than 2D. • 3D thyroid ultrasound saved time for scanning compared with 2D. • For off-site evaluation of thyroid nodules, 3D is more useful than 2D.
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http://dx.doi.org/10.1007/s00330-015-4193-2DOI Listing
October 2016

Comparison of Ultrasonographic Findings of Biopsy-Proven Tuberculous Lymphadenitis and Kikuchi Disease.

Korean J Radiol 2015 Jul-Aug;16(4):767-75. Epub 2015 Jul 1.

Department of Radiology, Guro Hospital, Korea University College of Medicine, Seoul 152-703, Korea.

Objective: Although tuberculous lymphadenitis and Kikuchi disease are common causes of cervical lymphadenopathy in Asians and exhibit similar clinical manifestations, their treatment strategies are totally different. The purpose of this study was to identify ultrasonographic features that distinguish these two diseases.

Materials And Methods: This study was approved by the Institutional Review Board. The study included 77 patients with tuberculous lymphadenitis and 135 patients with Kikuchi disease. The sex and age distributions of the patients were analyzed. The size and shape of lymph nodes (LNs), presence of conglomeration, increased perinodal echogenicity, echogenic hilum, posterior neck involvement, internal calcification, patterns of internal necrosis, laterality of involved LNs, and hilar vascular patterns on ultrasonography were compared between the two groups. Multiple logistic regression analysis was conducted to identify independent findings to discriminate tuberculous lymphadenitis from Kikuchi disease. Finally, diagnostic accuracies were calculated using the independent findings.

Results: The presence of an echogenic hilum, internal calcification, patterns of internal necrosis, and LN hilar vascular structures on power Doppler ultrasonography were independent findings that discriminated tuberculous lymphadenitis from Kikuchi disease. The diagnostic accuracy of each of these four factors was 84.9% (181/212), 76.9% (163/212), 84% (178/212), and 89.2% (189/212), respectively. A combination of internal calcification and hilar vascular structures showed the best accuracy of 89.6% (190/212) (sensitivity, 86.7% [117/135]; specificity, 94.8% [73/77]) for diagnosing Kikuchi disease.

Conclusion: The presence of an echogenic hilum, internal calcification, pattern of internal necrosis, and LN hilar vascular structures are useful ultrasonographic findings to differentiate tuberculous lymphadenitis from Kikuchi disease.
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http://dx.doi.org/10.3348/kjr.2015.16.4.767DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4499540PMC
February 2016

Squamous Cell Carcinoma of the Head and Neck: Comparison of Diffusion-weighted MRI at b-values of 1,000 and 2,000 s/mm(2) to Predict Response to Induction Chemotherapy.

Magn Reson Med Sci 2015 23;14(4):337-45. Epub 2015 Jun 23.

Department of Radiology, Korea University Guro Hospital.

Purpose: Recent publications have reported contradictory results of pretreatment diffusion-weighted magnetic resonance imaging (DWI) for the prediction of chemoradiotherapeutic response in primary squamous cell carcinomas of the head and neck (HNSCC). Therefore, we evaluated the diagnostic performance of DWI obtained with both standard (b = 0 and 1,000 s/mm²) and high (b = 0 and 2,000 s/mm²) b-values for predicting response to induction chemotherapy in HNSCCs.

Methods: For 25 patients with primary HNSCC who underwent DWI with both standard and high b-values prior to treatment, we calculated corresponding apparent diffusion coefficient (ADC) maps. Regions of interest containing the tumor were drawn on every section of ADC maps and summated to make volume-based data of the entire tumor. Histogram parameters (mean ADC, kurtosis, and skewness) were correlated with treatment response using unpaired Student t test. Univariate and multivariate analysis of the ADC parameters, patient age, sex, whole tumor volume, and T stage were also performed to predict tumor response to induction chemotherapy.

Results: Response to induction chemotherapy was good in 13 of the 25 patients and poor in 12. The mean ADC values of good responders at standard b-value (ADC1000), 1.23 ± 0.34 (× 10⁻³ mm²/s), and high b-value (ADC2000), 0.62 ± 0.14 (× 10⁻³ mm²/s), were lower than those of poor responders (ADC1000, 1.32 ± 0.28 [× 10⁻³ mm²/s]; ADC2000, 0.76 ± 0.15 [× 10⁻³ mm²/s]), but significant difference was achieved only at the ADC2000 map (P = 0.02). In addition, mean tumor volume prior to treatment of good responders was smaller than that of poor responders. However, at multiple logistic regression analysis, only the mean ADC2000 value remained as a significant predictor of response to induction chemotherapy.

Conclusion: DWI with high b-values (b = 0 and 2,000 s/mm²) as an assessment of ADC values may help predict tumor response to neoadjuvant chemotherapy for primary HNSCCs.
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http://dx.doi.org/10.2463/mrms.2015-0003DOI Listing
September 2016

Usefulness of core needle biopsy for thyroid nodules with macrocalcifications: comparison with fine-needle aspiration.

Thyroid 2015 Jun 5;25(6):657-64. Epub 2015 May 5.

1Department of Radiology, Seoul National University Hospital, Seoul, Korea.

Background: This study was performed to determine the benefits of core needle biopsy (CNB), as compared with fine-needle aspiration (FNA), for the diagnosis of thyroid nodules with macrocalcifications.

Materials And Methods: The institutional review board approved this retrospective study, and informed consent was waived. From February 2010 to March 2012, the study included 147 thyroid nodules with macrocalcification of 145 consecutive patients who underwent simultaneous FNA and CNB for each nodule. Diagnostic accuracy and inconclusive diagnoses, including nondiagnostic reading and atypia of undetermined significance or follicular lesion of undetermined significance reading were compared among FNA, CNB, and a combination of FNA and CNB (FNA/CNB) using McNemar's test; the benefits of CNB were calculated.

Results: Compared to FNA, CNB and FNA/CNB showed fewer inconclusive diagnoses (FNA vs. CNB: 62/147 [42.2%] vs. 14/147 [9.5%], p<0.001; FNA vs.

Fna/cnb: 62/147 [42.2%] vs. 14/147 [9.5%], p<0.001), resulting in the avoidance of repeat FNA or diagnostic surgery in 48 of 62 patients (77.4%, respectively in CNB and FNA/CNB) who would have undergone these procedures if only FNA was performed. Compared to FNA, FNA/CNB showed higher sensitivity and accuracy (sensitivity: 23/32 [71.9%] vs. 31/32 [96.9%], p=0.008; accuracy: 77/86 [89.5%] vs. 85/86 [98.8%], p=0.008), resulting in avoidance of delayed surgery in eight of nine patients (88.9%) with thyroid cancer in whom the surgery would have been missed if FNA only had been performed.

Conclusion: In the workup of thyroid nodules with macrocalcification, compared with FNA alone, FNA/CNB decreases inconclusive diagnoses and increases sensitivity, thereby reducing repeated FNA procedures, diagnostic surgeries, and delayed therapeutic surgeries.
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http://dx.doi.org/10.1089/thy.2014.0596DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4490626PMC
June 2015

Prognosis prediction of measurable enhancing lesion after completion of standard concomitant chemoradiotherapy and adjuvant temozolomide in glioblastoma patients: application of dynamic susceptibility contrast perfusion and diffusion-weighted imaging.

PLoS One 2014 24;9(11):e113587. Epub 2014 Nov 24.

Department of Radiation Oncology, Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.

Purpose: To assess the prognosis predictability of a measurable enhancing lesion using histogram parameters produced by the normalized cerebral blood volume (nCBV) and normalized apparent diffusion coefficient (nADC) after completion of standard concomitant chemoradiotherapy (CCRT) and adjuvant temozolomide (TMZ) medication in glioblastoma multiforme (GBM) patients.

Materials And Methods: This study was approved by the institutional review board (IRB), and the requirement for informed consent was waived. A total of 59 patients with newly diagnosed GBM who received standard CCRT with TMZ and adjuvant TMZ for six cycles underwent perfusion-weighted and diffusion-weighted imaging. Twenty-seven patients had a measurable enhancing lesion and 32 patients lacked a measurable enhancing lesion based on the Response Assessment in Neuro-Oncology (RANO) criteria in the follow-up MRI, which was performed within 3 months after adjuvant TMZ therapy was completed. We measured the nCBV and nADC histogram parameters based on the measurable enhancing lesion. The progression free survival (PFS) was analyzed by the Kaplan-Meier method with the use of the log-rank test.

Results: The median PFS of patients lacking measurable enhancing lesion was longer than for those with measurable enhancing lesions (17.6 vs 3.3 months, P<.0001). There was a significant, positive correlation between the 99th percentile nCBV value of a measurable enhancing lesion and the PFS (P= .044, R(2)= .152). In addition, the median PFS was longer in patients with a 99th percentile nCBV value ≧ 4.5 than it was in those with a value <4.5 (4.4 vs 3.1 months, P = .036).

Conclusion: We found that the nCBV value can be used for the prognosis prediction of a measurable enhancing lesion after the completion of standard treatment for GBM, wherein a high 99th percentile nCBV value (≧ 4.5) suggests a better PFS for GBM patients.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0113587PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4242641PMC
January 2016

Evaluation of the microenvironmental heterogeneity in high-grade gliomas with IDH1/2 gene mutation using histogram analysis of diffusion-weighted imaging and dynamic-susceptibility contrast perfusion imaging.

J Neurooncol 2015 Jan 10;121(1):141-50. Epub 2014 Sep 10.

Department of Radiology, Seoul National University College of Medicine, 28, Yongon-dong, Chongno-gu, Seoul, 110-744, Korea.

The purpose of our study was to explore the difference between isocitrate dehydrogenase (IDH)-1/2 gene mutation-positive and -negative high-grade gliomas (HGGs) using histogram analysis of apparent diffusion coefficient (ADC) and normalized cerebral blood volume (nCBV) maps. We enrolled 52 patients with histopathologically confirmed HGGs with IDH1/2 (P) (n = 16) or IDH1/2 (N) (n = 36). Histogram parameters of ADC and nCBV maps were correlated with gene mutations by using the unpaired student's t test and multivariable stepwise logistic regression analysis. The mean ADC value was higher in the IDH1 (P) group than IDH1 (N) (1,282.8 vs. 1,159.6 mm(2)/s, P = .0113). In terms of the cumulative ADC histograms, the 10th and 50th percentile values were also higher in the IDH1 (P) than IDH1 (N) (P = .0104 and .0183, respectively). We observed a higher 90th percentile value (3.121 vs. 2.397, P = .0208) and a steeper slope between the 10th (C10) and 90th (C90) of cumulative nCBV histograms (0.03386 vs. 0.02425/%, P = .0067) in the IDH1 (N) group. Multivariate analysis showed that the mean ADC mean value (P = .0048), the C90 value (P = .0113), and the slope between C10 and C90 (P = .0049) were the significant variables in the differentiation of IDH1 (P) from IDH1 (N). In conclusion, histogram analysis of ADC and nCBV maps based on entire tumor volume can be a useful tool for distinguishing IDH1 (P) and IDH1 (N), and it predicts that IDH (P) tumors have a more heterogeneous microenvironment than IDH (N) ones.
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http://dx.doi.org/10.1007/s11060-014-1614-zDOI Listing
January 2015

Contrast-enhanced FLAIR (fluid-attenuated inversion recovery) for evaluating mild traumatic brain injury.

PLoS One 2014 16;9(7):e102229. Epub 2014 Jul 16.

Department of Radiology, Seoul National University College of Medicine, Seoul, Korea; Department of Radiology, Seoul National University Hospital, Seoul, Korea.

Purpose: To evaluate whether adding a contrast-enhanced fluid-attenuated inversion recovery (FLAIR) sequence to routine magnetic resonance imaging (MRI) can detect additional abnormalities in the brains of symptomatic patients with mild traumatic brain injury.

Materials And Methods: Fifty-four patients with persistent symptoms following mild closed head injury were included in our retrospective study (M ∶ F =  32 ∶ 22, mean age: 59.8 ± 16.4, age range: 26-84 years). All MRI examinations were obtained within 14 days after head trauma (mean: 3.2 ± 4.1 days, range: 0.2-14 days). Two neuroradiologists recorded (1) the presence of traumatic brain lesions on MR images with and without contrast-enhanced FLAIR images and (2) the pattern and location of meningeal enhancement depicted on contrast-enhanced FLAIR images. The number of additional traumatic brain lesions diagnosed with contrast-enhanced FLAIR was recorded. Correlations between meningeal enhancement and clinical findings were also evaluated.

Results: Traumatic brain lesions were detected on routine image sequences in 25 patients. Three additional cases of brain abnormality were detected with the contrast-enhanced FLAIR images. Meningeal enhancement was identified on contrast-enhanced FLAIR images in 9 cases while the other routine image sequences showed no findings of traumatic brain injury. Overall, the additional contrast-enhanced FLAIR images revealed more extensive abnormalities than routine imaging in 37 cases (p<0.001). In multivariate logistic regression analysis, subdural hematoma and posttraumatic loss of consciousness showed a significant association with meningeal enhancement on contrast-enhanced FLAIR images, with odds ratios 13.068 (95% confidence interval 2.037 to 83.852), and 15.487 (95% confidence interval 2.545 to 94.228), respectively.

Conclusion: Meningeal enhancement on contrast-enhanced FLAIR images can help detect traumatic brain lesions as well as additional abnormalities not identified on routine unenhanced MRI. Therefore contrast-enhanced FLAIR MR imaging is recommended when a contrast MR study is indicated in a patient with a symptomatic prior closed mild head injury.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0102229PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4100883PMC
March 2015

The role of core needle biopsy in the preoperative diagnosis of follicular neoplasm of the thyroid.

APMIS 2014 Oct 28;122(10):993-1000. Epub 2014 Mar 28.

Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.

Follicular neoplasm/suspicious for follicular neoplasm (FN/SFN) can often be challenging to diagnose using core needle biopsy (CNB) specimens. We have developed the histologic criteria for the CNB diagnosis of FN and validated the usefulness of CNB. We retrospectively reviewed 184 CNBs and 224 FNACs diagnosed with FN/SFN. CNBs were histologically classified into four subgroups, based on the histologic features of follicular proliferation, fibrous capsulation, and surrounding parenchyma. Among 184 CNBs, 103 (55.9%) had previous FNAC results of non-diagnostic or indeterminate. Overall malignancy rates in FNAC (48%) and CNB (46%) were nearly identical (p > 0.05), and the neoplasm rate was higher in CNB (88%) than FNAC (74%) (p = 0.007). There was no significant difference in the malignancy rates among the four histologic subgroups. Among the 40 nodules with simultaneous CNB and FNAC, only nine had the FNAC diagnosis of FN/SFN, and others were non-diagnostic, benign, or atypia of undetermined significance. Overall, CNB improved specimen adequacy and achieved better sensitivity of the FN/SFN diagnosis in thyroid nodules that were inconclusive by FNAC. In the preoperative diagnosis of FN/SFN, CNB has no advantage over FNAC in predicting the likelihood of malignancy, but helps to reduce the need for repeat biopsy.
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http://dx.doi.org/10.1111/apm.12244DOI Listing
October 2014

Cerebral blood volume calculated by dynamic susceptibility contrast-enhanced perfusion MR imaging: preliminary correlation study with glioblastoma genetic profiles.

PLoS One 2013 19;8(8):e71704. Epub 2013 Aug 19.

Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.

Purpose: To evaluate the usefulness of dynamic susceptibility contrast (DSC) enhanced perfusion MR imaging in predicting major genetic alterations in glioblastomas.

Materials And Methods: Twenty-five patients (M:F = 13∶12, mean age: 52.1±15.2 years) with pathologically proven glioblastoma who underwent DSC MR imaging before surgery were included. On DSC MR imaging, the normalized relative tumor blood volume (nTBV) of the enhancing solid portion of each tumor was calculated by using dedicated software (Nordic TumorEX, NordicNeuroLab, Bergen, Norway) that enabled semi-automatic segmentation for each tumor. Five major glioblastoma genetic alterations (epidermal growth factor receptor (EGFR), phosphatase and tensin homologue (PTEN), Ki-67, O6-methylguanine-DNA methyltransferase (MGMT) and p53) were confirmed by immunohistochemistry and analyzed for correlation with the nTBV of each tumor. Statistical analysis was performed using the unpaired Student t test, ROC (receiver operating characteristic) curve analysis and Pearson correlation analysis.

Results: The nTBVs of the MGMT methylation-negative group (mean 9.5±7.5) were significantly higher than those of the MGMT methylation-positive group (mean 5.4±1.8) (p = .046). In the analysis of EGFR expression-positive group, the nTBVs of the subgroup with loss of PTEN gene expression (mean: 10.3±8.1) were also significantly higher than those of the subgroup without loss of PTEN gene expression (mean: 5.6±2.3) (p = .046). Ki-67 labeling index indicated significant positive correlation with the nTBV of the tumor (p = .01).

Conclusion: We found that glioblastomas with aggressive genetic alterations tended to have a high nTBV in the present study. Thus, we believe that DSC-enhanced perfusion MR imaging could be helpful in predicting genetic alterations that are crucial in predicting the prognosis of and selecting tailored treatment for glioblastoma patients.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0071704PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3747204PMC
April 2014

Cerebral blood volume analysis in glioblastomas using dynamic susceptibility contrast-enhanced perfusion MRI: a comparison of manual and semiautomatic segmentation methods.

PLoS One 2013 8;8(8):e69323. Epub 2013 Aug 8.

Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.

Purpose: To compare the reproducibilities of manual and semiautomatic segmentation method for the measurement of normalized cerebral blood volume (nCBV) using dynamic susceptibility contrast-enhanced (DSC) perfusion MR imaging in glioblastomas.

Materials And Methods: Twenty-two patients (11 male, 11 female; 27 tumors) with histologically confirmed glioblastoma (WHO grade IV) were examined with conventional MR imaging and DSC imaging at 3T before surgery or biopsy. Then nCBV (means and standard deviations) in each mass was measured using two DSC MR perfusion analysis methods including manual and semiautomatic segmentation method, in which contrast-enhanced (CE)-T1WI and T2WI were used as structural imaging. Intraobserver and interobserver reproducibility were assessed according to each perfusion analysis method or each structural imaging. Interclass correlation coefficient (ICC), Bland-Altman plot, and coefficient of variation (CV) were used to evaluate reproducibility.

Results: Intraobserver reproducibilities on CE-T1WI and T2WI were ICC of 0.74-0.89 and CV of 20.39-36.83% in manual segmentation method, and ICC of 0.95-0.99 and CV of 8.53-16.19% in semiautomatic segmentation method, repectively. Interobserver reproducibilites on CE-T1WI and T2WI were ICC of 0.86-0.94 and CV of 19.67-35.15% in manual segmentation method, and ICC of 0.74-1.0 and CV of 5.48-49.38% in semiautomatic segmentation method, respectively. Bland-Altman plots showed a good correlation with ICC or CV in each method. The semiautomatic segmentation method showed higher intraobserver and interobserver reproducibilities at CE-T1WI-based study than other methods.

Conclusion: The best reproducibility was found using the semiautomatic segmentation method based on CE-T1WI for structural imaging in the measurement of the nCBV of glioblastomas.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0069323PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3738566PMC
April 2014
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