Publications by authors named "Roh Eul Yoo"

81 Publications

Prediction of Prognosis in Glioblastoma Using Radiomics Features of Dynamic Contrast-Enhanced MRI.

Korean J Radiol 2021 Sep 14;22(9):1514-1524. Epub 2021 Jul 14.

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

Objective: To develop a radiomics risk score based on dynamic contrast-enhanced (DCE) MRI for prognosis prediction in patients with glioblastoma.

Materials And Methods: One hundred and fifty patients (92 male [61.3%]; mean age ± standard deviation, 60.5 ± 13.5 years) with glioblastoma who underwent preoperative MRI were enrolled in the study. Six hundred and forty-two radiomic features were extracted from volume transfer constant (K), fractional volume of vascular plasma space (V), and fractional volume of extravascular extracellular space (V) maps of DCE MRI, wherein the regions of interest were based on both T1-weighted contrast-enhancing areas and non-enhancing T2 hyperintense areas. Using feature selection algorithms, salient radiomic features were selected from the 642 features. Next, a radiomics risk score was developed using a weighted combination of the selected features in the discovery set (n = 105); the risk score was validated in the validation set (n = 45) by investigating the difference in prognosis between the "radiomics risk score" groups. Finally, multivariable Cox regression analysis for progression-free survival was performed using the radiomics risk score and clinical variables as covariates.

Results: 16 radiomic features obtained from non-enhancing T2 hyperintense areas were selected among the 642 features identified. The radiomics risk score was used to stratify high- and low-risk groups in both the discovery and validation sets (both < 0.001 by the log-rank test). The radiomics risk score and presence of isocitrate dehydrogenase (IDH) mutation showed independent associations with progression-free survival in opposite directions (hazard ratio, 3.56; = 0.004 and hazard ratio, 0.34; = 0.022, respectively).

Conclusion: We developed and validated the "radiomics risk score" from the features of DCE MRI based on non-enhancing T2 hyperintense areas for risk stratification of patients with glioblastoma. It was associated with progression-free survival independently of IDH mutation status.
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http://dx.doi.org/10.3348/kjr.2020.1433DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8390822PMC
September 2021

Contrast-enhanced MRI T1 Mapping for Quantitative Evaluation of Putative Dynamic Glymphatic Activity in the Human Brain in Sleep-Wake States.

Radiology 2021 Sep 22;300(3):661-668. Epub 2021 Jun 22.

From the Departments of Radiology (S.L., R.E.Y., S.H.C., J.Y.L., I.H., K.M.K., T.J.Y., J.H.K., C.H.S.) and Clinical Pharmacology and Therapeutics (K.Y.H.), Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehangno, Jongno-gu, Seoul 03080, Republic of Korea; Center for Nanoparticle Research, Institute for Basic Science, Seoul, Republic of Korea (S.H.C.); School of Chemical and Biological Engineering (S.H.C.) and Department of Electrical and Computer Engineering (S.J., J.L.), Seoul National University, Seoul, Republic of Korea; and Department of Biomedical Engineering, Hankuk University of Foreign Studies, Yongin-si, Republic of Korea (S.H.O.).

Background Evaluation of the glymphatic system with intrathecal contrast material injection has limited clinical use. Purpose To investigate the feasibility of using serial intravenous contrast-enhanced T1 mapping in the quantitative evaluation of putative dynamic glymphatic activity in various brain regions and to demonstrate the effect of sleep on glymphatic activity in humans. Materials and Methods In this prospective study from May 2019 to February 2020, 25 healthy participants (mean age, 25 years ± 2 [standard deviation]; 15 men) underwent two cycles of MRI (day and night cycles). For each cycle, T1 maps were acquired at baseline and 0.5, 1, 1.5, 2, and 12 hours after intravenous contrast material injection. For the night cycle, participants had a normal night of sleep between 2 and 12 hours. The time () to reach the minimum T1 value (T1), the absolute difference between baseline T1 and T1 (peak ΔT1), and the slope between two measurements at 2 and 12 hours (slope) were determined from T1 value-time curves in cerebral gray matter (GM), cerebral white matter (WM), cerebellar GM, cerebellar WM, and putamen. Mixed-model analysis of variance (ANOVA), Friedman test, and repeated-measures ANOVA were used to assess the effect of sleep on slope and to compare and peak ΔT1 among different regions. Results The slope increased from the day to night cycles in cerebral GM, cerebellar GM, and putamen (geometric mean ratio [night/day] = 1.4 [95% CI: 1.2, 1.7], 1.3 [95% CI: 1.1, 1.4], and 2.4 [95% CI: 1.6, 3.6], respectively; = .001, < .001, and < .001, respectively). Median values were 0.5 hour in cerebral and cerebellar GM and putamen for both cycles. Cerebellar GM had the highest mean peak ΔT1, followed by cerebral GM and putamen in both day (159 msec ± 6, 99 msec ± 4, and 62 msec ± 5, respectively) and night (152 msec ± 6, 104 msec ± 6, and 58 msec ± 4, respectively) cycles. Conclusion Clearance of a gadolinium-based contrast agent was greater after sleep compared with daytime wakefulness. These results suggest that sleep was associated with greater glymphatic clearance compared with wakefulness. © RSNA, 2021 . See also the editorial by Anzai and Minoshima in this issue.
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http://dx.doi.org/10.1148/radiol.2021203784DOI Listing
September 2021

Diagnostic Performance of the Modified Korean Thyroid Imaging Reporting and Data System for Thyroid Malignancy: A Multicenter Validation Study.

Korean J Radiol 2021 Sep 1;22(9):1579-1586. Epub 2021 Jun 1.

Department of Radiology and Research Institute of Radiology, Asian Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Objective: To evaluate the diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System (K-TIRADS), and compare it with the 2016 version of K-TIRADS using the Thyroid Imaging Network of Korea.

Materials And Methods: Between June and September 2015, 5708 thyroid nodules (≥ 1.0 cm) from 5081 consecutive patients who had undergone thyroid ultrasonography at 26 institutions were retrospectively evaluated. We used a biopsy size threshold of 2 cm for K-TIRADS 3 and 1 cm for K-TIRADS 4 (modified K-TIRADS 1) or 1.5 cm for K-TIRADS 4 (modified K-TIRADS 3). The modified K-TIRADS 2 subcategorized the K-TIRADS 4 into 4A and 4B, and the cutoff sizes for the biopsies were defined as 1 cm for K-TIRADS 4B and 1.5 cm for K-TIRADS 4A. The diagnostic performance and the rate of unnecessary biopsies of the modified K-TIRADS for detecting malignancy were compared with those of the 2016 K-TIRAD, which were stratified by nodule size (with a threshold of 2 cm).

Results: A total of 1111 malignant nodules and 4597 benign nodules were included. The sensitivity, specificity, and unnecessary biopsy rate of the benign nodules were 94.9%, 24.4%, and 60.9% for the 2016 K-TIRADS; 91.0%, 39.7%, and 48.6% for the modified K-TIRADS 1; 84.9%, 45.9%, and 43.5% for the modified K-TIRADS 2; and 76.1%, 50.2%, and 40.1% for the modified K-TIRADS 3. For small nodules (1-2 cm), the diagnostic sensitivity of the modified K-TIRADS decreased by 5.2-25.6% and the rate of unnecessary biopsies reduced by 19.2-32.8% compared with those of the 2016 K-TIRADS ( < 0.001). For large nodules (> 2 cm), the modified K-TIRADSs maintained a very high sensitivity for detecting malignancy (98%).

Conclusion: The modified K-TIRADSs significantly reduced the rate of unnecessary biopsies for small (1-2 cm) nodules while maintaining a very high sensitivity for malignancy for large (> 2 cm) nodules.
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http://dx.doi.org/10.3348/kjr.2021.0230DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8390813PMC
September 2021

Renal Safety of Repeated Intravascular Administrations of Iodinated or Gadolinium-Based Contrast Media within a Short Interval.

Korean J Radiol 2021 Sep 1;22(9):1547-1554. Epub 2021 Jun 1.

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

Objective: We aimed to investigate whether repeated intravascular administration of iodinated contrast media (ICM) or gadolinium-based contrast agents (GBCAs) within a short interval was associated with an increased risk of post-contrast acute kidney injury (PC-AKI).

Materials And Methods: This retrospective study included 300 patients (mean age ± standard deviation, 68.5 ± 8.1 years; 131 male and 169 female) who had undergone at least one ICM-enhanced perfusion brain CT scan, had their baseline and follow-up serum creatinine levels available, and had not undergone additional contrast-enhanced examinations 72 hours before and after a time window of interest were included. The study population was divided into three groups: single-dose group and groups of patients who had received multiple contrast administrations in the time window of interest with the minimum contrast repeat interval either within 4 hours (0-4-hour group) or between 4 to 48 hours (4-48-hour group). Multivariable logistic regression analysis was conducted to evaluate the association between AKI and repeated ICM administrations. A similar supplementary analysis was performed including both ICM and GBCA.

Results: When ICM was only considered ignoring GBCA, among 300 patients, 207 patients received a single dose of ICM, 58 had repeated doses within 4 hours (0-4-hour group), and 35 patients had repeated doses between 4 to 48 hours (4-48-hour group). Most patients (> 95%) had a baseline estimated glomerular filtration rate (eGFR) of ≥ 30 mL/min/1.73 m². AKI occurred in 7.2%, 13.8%, and 8.6% of patients in the single-dose, 0-4-hour, and 4-48-hour groups, respectively. In the 0-4-hour and 4-48-hour groups, additional exposure to ICM was not associated with AKI after adjusting for comorbidities and nephrotoxic drugs (all values > 0.05).

Conclusion: Repeated intravascular administrations of ICM within a short interval did not increase the risk of AKI in our study patients suspected of acute stroke with a baseline eGFR of ≥ 30 mL/min/1.73 m².
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http://dx.doi.org/10.3348/kjr.2020.1153DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8390825PMC
September 2021

Prediction of brain age from routine T2-weighted spin-echo brain magnetic resonance images with a deep convolutional neural network.

Neurobiol Aging 2021 09 28;105:78-85. Epub 2021 Apr 28.

Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea. Electronic address:

Our study investigated the feasibility and clinical relevance of brain age prediction using axial T2-weighted images (T2-WIs) with a deep convolutional neural network (CNN) algorithm. The CNN model was trained by 1,530 scans in our institution. The performance was evaluated by the mean absolute error (MAE) between the predicted brain age and the chronological age based on an internal test set (n=270) and an external test set (n=560). The ensemble CNN model showed an MAE of 4.22 years in the internal test set and 9.96 years in the external test set. Participants with grade 2-3 white matter hyperintensity (WMH) showed a higher corrected predicted age difference (PAD) than grade 0 WMH (posthoc p<0.001). Participants diagnosed with diabetes mellitus also had a higher corrected PAD than those without diabetes (adjusted p=0.048), although it showed no significant differences according to the diagnosis of hypertension or dyslipidemia. We suggest that routine clinical T2-WIs are feasible to predict brain age, and it might be clinically relevant according to the WMH grade and the presence of diabetes mellitus.
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http://dx.doi.org/10.1016/j.neurobiolaging.2021.04.015DOI Listing
September 2021

Differentiation between glioblastoma and primary CNS lymphoma: application of DCE-MRI parameters based on arterial input function obtained from DSC-MRI.

Eur Radiol 2021 May 18. Epub 2021 May 18.

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

Objective: This study aimed to evaluate whether arterial input functions (AIFs) obtained from dynamic susceptibility contrast (DSC)-MRI (AIF) improve the reliability and diagnostic accuracy of dynamic contrast-enhanced (DCE)-derived pharmacokinetic (PK) parameters for differentiating glioblastoma from primary CNS lymphoma (PCNSL) compared with AIFs derived from DCE-MRI (AIF).

Methods: This retrospective study included 172 patients with glioblastoma (n = 147) and PCNSL (n = 25). All patients had undergone preoperative DSC- and DCE-MRI. The volume transfer constant (K), volume of the vascular plasma space (v), and volume of the extravascular extracellular space (v) were acquired using AIF and AIF. The relative cerebral blood volume (rCBV) was obtained from DSC-MRI. Intraclass correlation coefficients (ICC) and ROC curves were used to assess the reliability and diagnostic accuracy of individual parameters.

Results: The mean K, v, and v values revealed better ICCs with AIF than with AIF (K, 0.911 vs 0.355; v, 0.766 vs 0.503; v, 0.758 vs 0.657, respectively). For differentiating all glioblastomas from PCNSL, the mean rCBV (AUC = 0.856) was more accurate than the AIF-driven mean K, which had the largest AUC (0.711) among the DCE-derived parameters (p = 0.02). However, for glioblastomas with low rCBV (≤ 75th percentile of PCNSL; n = 30), the AIF-driven mean K and v were more accurate than rCBV (AUC: K, 0.807 vs rCBV, 0.515, p = 0.004; v, 0.715 vs rCBV, p = 0.045).

Conclusion: DCE-derived PK parameters using the AIF showed improved reliability and diagnostic accuracy for differentiating glioblastoma with low rCBV from PCNSL.

Key Points: • An accurate differential diagnosis of glioblastoma and PCNSL is crucial because of different therapeutic strategies. • In contrast to the rCBV from DSC-MRI, another perfusion imaging technique, the DCE parameters for the differential diagnosis have been limited because of the low reliability of AIFs from DCE-MRI. • When we analyzed DCE-MRI data using AIFs from DSC-MRI (AIF), AIF-driven DCE parameters showed improved reliability and better diagnostic accuracy than rCBV for differentiating glioblastoma with low rCBV from PCNSL.
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http://dx.doi.org/10.1007/s00330-021-08044-zDOI Listing
May 2021

Prognostic Prediction Based on Dynamic Contrast-Enhanced MRI and Dynamic Susceptibility Contrast-Enhanced MRI Parameters from Non-Enhancing, T2-High-Signal-Intensity Lesions in Patients with Glioblastoma.

Korean J Radiol 2021 08 4;22(8):1369-1378. Epub 2021 May 4.

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

Objective: Few attempts have been made to investigate the prognostic value of dynamic contrast-enhanced (DCE) MRI or dynamic susceptibility contrast (DSC) MRI of non-enhancing, T2-high-signal-intensity (T2-HSI) lesions of glioblastoma multiforme (GBM) in newly diagnosed patients. This study aimed to investigate the prognostic values of DCE MRI and DSC MRI parameters from non-enhancing, T2-HSI lesions of GBM.

Materials And Methods: A total of 76 patients with GBM who underwent preoperative DCE MRI and DSC MRI and standard treatment were retrospectively included. Six months after surgery, the patients were categorized into early progression (n = 15) and non-early progression (n = 61) groups. We extracted and analyzed the permeability and perfusion parameters of both modalities for the non-enhancing, T2-HSI lesions of the tumors. The optimal percentiles of the respective parameters obtained from cumulative histograms were determined using receiver operating characteristic (ROC) curve and univariable Cox regression analyses. The results were compared using multivariable Cox proportional hazards regression analysis of progression-free survival.

Results: The 95th percentile value (PV) of Ktrans, mean Ktrans, and median Ve were significant predictors of early progression as identified by the ROC curve analysis (area under the ROC curve [AUC] = 0.704, = 0.005; AUC = 0.684, = 0.021; and AUC = 0.670, = 0.0325, respectively). Univariable Cox regression analysis of the above three parametric values showed that the 95th PV of Ktrans and the mean Ktrans were significant predictors of early progression (hazard ratio [HR] = 1.06, = 0.009; HR = 1.25, = 0.017, respectively). Multivariable Cox regression analysis, which also incorporated clinical parameters, revealed that the 95th PV of Ktrans was the sole significant independent predictor of early progression (HR = 1.062, < 0.009).

Conclusion: The 95th PV of Ktrans from the non-enhancing, T2-HSI lesions of GBM is a potential prognostic marker for disease progression.
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http://dx.doi.org/10.3348/kjr.2020.1272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8316772PMC
August 2021

Application of T1 Map Information Based on Synthetic MRI for Dynamic Contrast-Enhanced Imaging: A Comparison Study with the Fixed Baseline T1 Value Method.

Korean J Radiol 2021 08 4;22(8):1352-1368. Epub 2021 May 4.

Department of Radiology, Human Medical Imaging & Intervention Center, Seoul, Korea.

Objective: For an accurate dynamic contrast-enhanced (DCE) MRI analysis, exact baseline T1 mapping is critical. The purpose of this study was to compare the pharmacokinetic parameters of DCE MRI using synthetic MRI with those using fixed baseline T1 values.

Materials And Methods: This retrospective study included 102 patients who underwent both DCE and synthetic brain MRI. Two methods were set for the baseline T1: one using the fixed value and the other using the T1 map from synthetic MRI. The volume transfer constant (K), volume of the vascular plasma space (v), and the volume of the extravascular extracellular space (v) were compared between the two methods. The interclass correlation coefficients and the Bland-Altman method were used to assess the reliability.

Results: In normal-appearing frontal white matter (WM), the mean values of K, v, and v were significantly higher in the fixed value method than in the T1 map method. In the normal-appearing occipital WM, the mean values of v and v were significantly higher in the fixed value method. In the putamen and head of the caudate nucleus, the mean values of K, v, and v were significantly lower in the fixed value method. In addition, the T1 map method showed comparable interobserver agreements with the fixed baseline T1 value method.

Conclusion: The T1 map method using synthetic MRI may be useful for reflecting individual differences and reliable measurements in clinical applications of DCE MRI.
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http://dx.doi.org/10.3348/kjr.2020.1201DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8316777PMC
August 2021

Radiomics-based neural network predicts recurrence patterns in glioblastoma using dynamic susceptibility contrast-enhanced MRI.

Sci Rep 2021 May 11;11(1):9974. Epub 2021 May 11.

Seoul National University College of Medicine, Seoul, Republic of Korea.

Glioblastoma remains the most devastating brain tumor despite optimal treatment, because of the high rate of recurrence. Distant recurrence has distinct genomic alterations compared to local recurrence, which requires different treatment planning both in clinical practice and trials. To date, perfusion-weighted MRI has revealed that perfusional characteristics of tumor are associated with prognosis. However, not much research has focused on recurrence patterns in glioblastoma: namely, local and distant recurrence. Here, we propose two different neural network models to predict the recurrence patterns in glioblastoma that utilizes high-dimensional radiomic profiles based on perfusion MRI: area under the curve (AUC) (95% confidence interval), 0.969 (0.903-1.000) for local recurrence; 0.864 (0.726-0.976) for distant recurrence for each patient in the validation set. This creates an opportunity to provide personalized medicine in contrast to studies investigating only group differences. Moreover, interpretable deep learning identified that salient radiomic features for each recurrence pattern are related to perfusional intratumoral heterogeneity. We also demonstrated that the combined salient radiomic features, or "radiomic risk score", increased risk of recurrence/progression (hazard ratio, 1.61; p = 0.03) in multivariate Cox regression on progression-free survival.
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http://dx.doi.org/10.1038/s41598-021-89218-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8113258PMC
May 2021

The Fate of Partially Thrombosed Intracranial Aneurysms Treated with Endovascular Intervention.

J Korean Neurosurg Soc 2021 May 26;64(3):427-436. Epub 2021 Feb 26.

Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea.

Objective: The fate of partially thrombosed intracranial aneurysms (PTIAs) is not well known after endovascular treatment. The authors aimed to analyze the treatment outcomes of PTIAs.

Methods: We retrospectively reviewed the medical records of 27 PTIAs treated with endovascular intervention between January 1999 and March 2018. Twenty-one aneurysms were treated with intraluminal embolization (ILE), and six were treated with parent artery occlusion (PAO) with or without bypass surgery. Radiological results, clinical outcomes and risk factors for major recurrence were assessed.

Results: The initial clinical status was similar in both groups; however, the last status was better in the ILE group than in the PAO group (p=0.049). Neurological deterioration resulted from mass effect in one case and rupture in one after ILE, and mass effect in two and perforator infarction in one after PAO. Twenty cases (94.2%) in the ILE group initially achieved complete occlusion or residual neck status. However, 13 cases (61.9%) showed major recurrence, the major causes of which included coil migration or compaction. Seven cases (33.3%) ultimately achieved residual sac status after repeat treatment. In the PAO group, all initially showed complete occlusion or a residual neck, and just one case ultimately had a residual sac. Two cases showed major recurrence, the cause of which was incomplete PAO. Aneurysm wall calcification was the only significantly protective factor against major recurrence (odds ratio, 36.12; 95% confidence interval, 1.85 to 705.18; p=0.018).

Conclusion: Complete PAO of PTIAs is the best option if treatment-related complications can be minimized. Simple fluoroscopy is a useful imaging modality because of the recurrence pattern.
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http://dx.doi.org/10.3340/jkns.2020.0195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8128530PMC
May 2021

Deep Learning for Diagnosis of Paranasal Sinusitis Using Multi-View Radiographs.

Diagnostics (Basel) 2021 Feb 5;11(2). Epub 2021 Feb 5.

Department of Radiology, Seoul National University Bundang Hospital, Seongnam 13620, Korea.

Accurate image interpretation of Waters' and Caldwell view radiographs used for sinusitis screening is challenging. Therefore, we developed a deep learning algorithm for diagnosing frontal, ethmoid, and maxillary sinusitis on both Waters' and Caldwell views. The datasets were selected for the training and validation set ( = 1403, sinusitis% = 34.3%) and the test set ( = 132, sinusitis% = 29.5%) by temporal separation. The algorithm can simultaneously detect and classify each paranasal sinus using both Waters' and Caldwell views without manual cropping. Single- and multi-view models were compared. Our proposed algorithm satisfactorily diagnosed frontal, ethmoid, and maxillary sinusitis on both Waters' and Caldwell views (area under the curve (AUC), 0.71 (95% confidence interval, 0.62-0.80), 0.78 (0.72-0.85), and 0.88 (0.84-0.92), respectively). The one-sided DeLong's test was used to compare the AUCs, and the Obuchowski-Rockette model was used to pool the AUCs of the radiologists. The algorithm yielded a higher AUC than radiologists for ethmoid and maxillary sinusitis ( = 0.012 and 0.013, respectively). The multi-view model also exhibited a higher AUC than the single Waters' view model for maxillary sinusitis ( = 0.038). Therefore, our algorithm showed diagnostic performances comparable to radiologists and enhanced the value of radiography as a first-line imaging modality in assessing multiple sinusitis.
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http://dx.doi.org/10.3390/diagnostics11020250DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7914751PMC
February 2021

Diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System for thyroid malignancy according to nodule size: a comparison with five society guidelines.

Ultrasonography 2021 Oct 9;40(4):474-485. Epub 2020 Dec 9.

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

Purpose: The aim of this study was to evaluate the diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System (K-TIRADS) compared with five society risk stratification systems (RSSs) according to nodule size.

Methods: In total, 3,826 consecutive thyroid nodules (≥1 cm) with final diagnoses in 3,088 patients were classified according to five RSSs. The K-TIRADS was modified by raising the biopsy size threshold for low-suspicion nodules and subcategorizing intermediate-suspicion nodules. We assessed the performance of the RSSs as triage tests and their diagnostic accuracy according to nodule size (with a threshold of 2 cm).

Results: Of all nodules, 3,277 (85.7%) were benign and 549 (14.3%) were malignant. In small thyroid nodules (≤2 cm), the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) had the highest reduction rate of unnecessary biopsies (76.3%) and the lowest sensitivity (76.1%). The modified K-TIRADS had the second highest reduction rate of unnecessary biopsies (67.6%) and sensitivity (86.6%). The modified K-TIRADS and ACR TI-RADS had the highest diagnostic odds ratios (P=0.165) and the highest areas under the curve (P=0.315). In large nodules (>2 cm), the sensitivity of the ACR TI-RADS for malignancy was significantly lower (88.8%) than the sensitivities of the modified K-TIRADS and other RSSs, which were very high (98.7%-99.3%) (P<0.001).

Conclusion: The modified K-TIRADS allows a large proportion of unnecessary biopsies to be avoided, while maintaining high sensitivity and diagnostic accuracy for small malignant tumors and very high sensitivity for large malignant tumors.
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http://dx.doi.org/10.14366/usg.20148DOI Listing
October 2021

Revascularization Evaluation in Adult-Onset Moyamoya Disease after Bypass Surgery: Superselective Arterial Spin Labeling Perfusion MRI Compared with Digital Subtraction Angiography.

Radiology 2020 12 22;297(3):630-637. Epub 2020 Sep 22.

From the Departments of Radiology (I.H., R.E.Y., K.M.K., D.H.Y., T.J.Y., S.H.C., J..K., C.H.S.) and Neurosurgery (W.S.C., J.E.K.), Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea; and Department of Radiology, Seoul National University College of Medicine, Seoul, Korea (S.H.C., J..K., C.H.S.).

Background A superselective (SS) arterial spin labeling (ASL) MRI technique can be used to monitor the revascularization area as a supplementary or alternative modality to digital subtraction angiography (DSA), with the advantage of being noninvasive. Purpose To evaluate whether SS-ASL perfusion MRI could be used to visualize the revascularization area after combined direct and indirect bypass surgery in adults with moyamoya disease compared with DSA. Materials and Methods Patients diagnosed with moyamoya disease who underwent DSA and SS-ASL 6 months after surgery between June 2017 and November 2019 in a single institution were retrospectively evaluated. Subjective grading of the revascularization area and collateral grading in 10 Alberta Stroke Program Early CT Score (ASPECTS) locations were performed. The change in perfusion status in a subgroup that underwent both preoperative and postoperative SS-ASL studies was evaluated. Intermodality agreement was analyzed by using weighted κ statistics. Results Thirty-seven hemispheres from 33 patients (mean age, 39 years ± 12 [standard deviation]; 20 women) were evaluated. The intermodality agreement of the revascularization area grading was substantial (weighted κ = 0.70; 95% confidence interval [CI]: 0.37, 1.00). The overall intermodality agreement of the postoperative collateral grading in the 10 ASPECTS locations for all vessels was substantial (weighted κ = 0.77; 95% CI: 0.74, 0.80). For the presence of postoperative collateral supplied by the ipsilateral external carotid artery in 10 ASPECTS locations (a total of 370 locations) using DSA as a reference test, the SS-ASL showed a sensitivity of 92% (183 of 199 locations; 95% CI: 87%, 95%) and a specificity of 83% (142 of 171 locations; 95% CI: 77%, 88%). The overall intermodality agreement of the changes in perfusion status was moderate (weighted κ = 0.59; 95% CI: 0.54, 0.65). Conclusion Superselective arterial spin labeling imaging precisely depicted the revascularization territory in patients with moyamoya disease who underwent bypass surgery, and it showed the changes in the vascular supplying territories before and after bypass surgery. © RSNA, 2020 See also the editorial by Hendrikse in this issue.
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http://dx.doi.org/10.1148/radiol.2020201448DOI Listing
December 2020

Comparison of Genetic Profiles and Prognosis of High-Grade Gliomas Using Quantitative and Qualitative MRI Features: A Focus on G3 Gliomas.

Korean J Radiol 2021 02 10;22(2):233-242. Epub 2020 Sep 10.

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

Objective: To evaluate the association of MRI features with the major genomic profiles and prognosis of World Health Organization grade III (G3) gliomas compared with those of glioblastomas (GBMs).

Materials And Methods: We enrolled 76 G3 glioma and 155 GBM patients with pathologically confirmed disease who had pretreatment brain MRI and major genetic information of tumors. Qualitative and quantitative imaging features, including volumetrics and histogram parameters, such as normalized cerebral blood volume (nCBV), cerebral blood flow (nCBF), and apparent diffusion coefficient (nADC) were evaluated. The G3 gliomas were divided into three groups for the analysis: with this isocitrate dehydrogenase ()-mutation, mutation and a -codeleted (IDHmut1p/19qdel), mutation, -nondeleted (IDHmut1p/19qnondel), and wildtype (IDHwt). A prediction model for the genetic profiles of G3 gliomas was developed and validated on a separate cohort. Both the quantitative and qualitative imaging parameters and progression-free survival (PFS) of G3 gliomas were compared and survival analysis was performed. Moreover, the imaging parameters and PFS between IDHwt G3 gliomas and GBMs were compared.

Results: IDHmut G3 gliomas showed a larger volume ( = 0.017), lower nCBF ( = 0.048), and higher nADC ( = 0.007) than IDHwt. Between the IDHmut tumors, IDHmut1p/19qdel G3 gliomas had higher nCBV ( = 0.024) and lower nADC ( = 0.002) than IDHmut1p/19qnondel G3 gliomas. Moreover, IDHmut1p/19qdel tumors had the best prognosis and IDHwt tumors had the worst prognosis among G3 gliomas ( < 0.001). PFS was significantly associated with the 95th percentile values of nCBV and nCBF in G3 gliomas. There was no significant difference in neither PFS nor imaging features between IDHwt G3 gliomas and IDHwt GBMs.

Conclusion: We found significant differences in MRI features, including volumetrics, CBV, and ADC, in G3 gliomas, according to mutation and codeletion status, which can be utilized for the prediction of genomic profiles and the prognosis of G3 glioma patients. The MRI signatures and prognosis of IDHwt G3 gliomas tend to follow those of IDHwt GBMs.
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http://dx.doi.org/10.3348/kjr.2020.0011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817637PMC
February 2021

Reduced Brainstem Volume After Mild Traumatic Brain Injury.

Am J Phys Med Rehabil 2021 05;100(5):473-482

From the Department of Rehabilitation Medicine (EK, HGS, HHL, SHL, SJY, M-GK, B-MO), Biomedical Research Institute (EK), Department of Radiology (SHC, R-EY), and Department of Neurosurgery (W-SC), Seoul National University Hospital, Seoul, Korea; Department of Rehabilitation Medicine, Konkuk University School of Medicine and Konkuk University Medical Center, Seoul, Korea (HHL); Department of Rehabilitation Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea (SHL); Department of Radiology (SHC, R-EY), Department of Rehabilitation Medicine (B-MO), and Neuroscience Research Institute (B-MO), Seoul National University College of Medicine, Seoul, Korea; Institute on Aging, Seoul National University, Seoul, Korea (B-MO); and National Traffic Injury Rehabilitation Hospital, Yangpyeong, Korea (B-MO).

Objective: The aims of this study were to investigate changes in regional brain volume after concussion (mild traumatic brain injury) and to examine the relationship between change in brain volume and cognitive deficits.

Design: Twenty-eight patients with mild traumatic brain injury and 27 age-matched controls were included in this study. Magnetic resonance imaging (3 T) data were obtained from the participants. Structural brain volume changes were examined using tensor-based morphometry, which identifies regional structural differences in the whole brain, including cerebrospinal fluid, gray matter, and white matter. Volume contraction and expansion were compared between groups using a two-sample t test. The association between time post-injury or neurocognitive function and volumetric changes was examined using regression analysis.

Results: Individuals with mild traumatic brain injury exhibited volume reduction in the brainstem, including the pontine reticular formation. Regional cerebral volume changes were not associated with time post-injury but were significantly associated with neurocognitive function, especially with executive card sorting test, forward digit span test, and performance on verbal learning test. The greater regional cerebral volume was associated with better cognitive performance after mild traumatic brain injury.

Conclusion: Decreased brainstem volume may indicate its vulnerability to traumatic injury, and cerebral volume in specific regions was positively associated with patients' cognitive function after injury.
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http://dx.doi.org/10.1097/PHM.0000000000001580DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8032213PMC
May 2021

CT and MR imaging findings of ocular adnexal mucosa-associated lymphoid tissue lymphoma associated with IgG4-related disease: multi-institutional case series.

Int J Ophthalmol 2020 18;13(8):1231-1237. Epub 2020 Aug 18.

Department of Radiology, Inje University Haeundae Paik Hospital, Busan 47392, Republic of Korea.

Aim: To report CT and MR imaging findings of ocular adnexal mucosa-associated lymphoid tissue lymphoma associated with IgG4-related disease (IgG4-MALT lymphoma), a rare but clinically important complication of ocular adnexal IgG4-related disease.

Methods: We retrospectively reviewed all cases of histologically confirmed ocular adnexal IgG4-related disease at three tertiary and one secondary referral centers, between February 2003 and December 2016. Seven cases of histopathologically diagnosed IgG4-MALT lymphoma were identified. CT and MR images were analyzed by consensus of two experienced head and neck radiologists.

Results: Lacrimal glands were the main site of involvement in all seven patients. The lesions typically showed well-demarcated margins, iso- to hyperattenuation on precontrast CT, T2 hypo- to isointensity, T1 isointensity, and homogenous internal architecture with homogenous enhancement pattern. Lesions were mostly hyperdense and isointense to normal extraocular muscles on postcontrast CT and MR images, respectively.

Conclusion: Unlike in typical ocular adnexal IgG4-related disease, T2 isointensity and hyperattenuation on precontrast CT images were noted in some IgG4-MALT lymphoma cases. Although the findings may be nonspecific, the possibility of accompanying MALT lymphoma may need to be considered, when ocular adnexal lesions in patients clinically suspected of having IgG4-related disease are refractory to glucocorticoids and show T2 isointensity and hyperattenuation on precontrast CT for the optimal management of the patients. However, this is a case series of a very rare complication of ocular adnexal IgG4-related disease, and thus caution is warranted to generalize the conclusion.
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http://dx.doi.org/10.18240/ijo.2020.08.08DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7387900PMC
August 2020

Prediction of Amyloid Positivity in Mild Cognitive Impairment Using Fully Automated Brain Segmentation Software.

Neuropsychiatr Dis Treat 2020 22;16:1745-1754. Epub 2020 Jul 22.

Department of Neuropsychiatry, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.

Objective: To assess the predictive ability of regional volume information provided by fully automated brain segmentation software for cerebral amyloid positivity in mild cognitive impairment (MCI).

Methods: This study included 130 subjects with amnestic MCI who participated in the Korean brain aging study of early diagnosis and prediction of Alzheimer's disease, an ongoing prospective cohort. All participants underwent comprehensive clinical assessment as well as C-labeled Pittsburgh compound PET/MRI scans. The predictive ability of volumetric results provided by automated brain segmentation software was evaluated using binary logistic regression and receiver operating characteristic curve analysis.

Results: Subjects were divided into two groups: one with Aβ deposition (58 subjects) and one without Aβ deposition (72 subjects). Among the varied volumetric information provided, the hippocampal volume percentage of intracranial volume (%HC/ICV), normative percentiles of hippocampal volume (HC), and gray matter volume were associated with amyloid-β (Aβ) positivity (all < 0.01). Multivariate analyses revealed that both %HC/ICV and HC were independent significant predictors of Aβ positivity (all < 0.001). In addition, prediction scores derived from %HC/ICV with age and HC showed moderate accuracy in predicting Aβ positivity in MCI subjects (the areas under the curve: 0.739 and 0.723, respectively).

Conclusion: Relative hippocampal volume measures provided by automated brain segmentation software can be useful for screening cerebral Aβ positivity in clinical practice for patients with amnestic MCI. The information may also help clinicians interpret structural MRI to predict outcomes and determine early intervention for delaying the progression to Alzheimer's disease dementia.
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http://dx.doi.org/10.2147/NDT.S252293DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7383107PMC
July 2020

Blood-Brain Barrier Disruption in Mild Traumatic Brain Injury Patients with Post-Concussion Syndrome: Evaluation with Region-Based Quantification of Dynamic Contrast-Enhanced MR Imaging Parameters Using Automatic Whole-Brain Segmentation.

Korean J Radiol 2021 01 11;22(1):118-130. Epub 2020 Aug 11.

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

Objective: This study aimed to investigate the blood-brain barrier (BBB) disruption in mild traumatic brain injury (mTBI) patients with post-concussion syndrome (PCS) using dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging and automatic whole brain segmentation.

Materials And Methods: Forty-two consecutive mTBI patients with PCS who had undergone post-traumatic MR imaging, including DCE MR imaging, between October 2016 and April 2018, and 29 controls with DCE MR imaging were included in this retrospective study. After performing three-dimensional T1-based brain segmentation with FreeSurfer software (Laboratory for Computational Neuroimaging), the mean K and v from DCE MR imaging (derived using the Patlak model and extended Tofts and Kermode model) were analyzed in the bilateral cerebral/cerebellar cortex, bilateral cerebral/cerebellar white matter (WM), and brainstem. K values of the mTBI patients and controls were calculated using both models to identify the model that better reflected the increased permeability owing to mTBI (tendency toward higher K values in mTBI patients than in controls). The Mann-Whitney U test and Spearman rank correlation test were performed to compare the mean K and v between the two groups and correlate K and v with neuropsychological tests for mTBI patients.

Results: Increased permeability owing to mTBI was observed in the Patlak model but not in the extended Tofts and Kermode model. In the Patlak model, the mean K in the bilateral cerebral cortex was significantly higher in mTBI patients than in controls ( = 0.042). The mean v values in the bilateral cerebellar WM and brainstem were significantly lower in mTBI patients than in controls ( = 0.009 and = 0.011, respectively). The mean K of the bilateral cerebral cortex was significantly higher in patients with atypical performance in the auditory continuous performance test (commission errors) than in average or good performers ( = 0.041).

Conclusion: BBB disruption, as reflected by the increased K and decreased v values from the Patlak model, was observed throughout the bilateral cerebral cortex, bilateral cerebellar WM, and brainstem in mTBI patients with PCS.
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http://dx.doi.org/10.3348/kjr.2020.0016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7772380PMC
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

Prognostic Value of Dynamic Contrast-Enhanced MRI-Derived Pharmacokinetic Variables in Glioblastoma Patients: Analysis of Contrast-Enhancing Lesions and Non-Enhancing T2 High-Signal Intensity Lesions.

Korean J Radiol 2020 06;21(6):707-716

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

Objective: To evaluate pharmacokinetic variables from contrast-enhancing lesions (CELs) and non-enhancing T2 high signal intensity lesions (NE-T2HSILs) on dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging for predicting progression-free survival (PFS) in glioblastoma (GBM) patients.

Materials And Methods: Sixty-four GBM patients who had undergone preoperative DCE MR imaging and received standard treatment were retrospectively included. We analyzed the pharmacokinetic variables of the volume transfer constant (Ktrans) and volume fraction of extravascular extracellular space within the CEL and NE-T2HSIL of the entire tumor. Univariate and multivariate Cox regression analyses were performed using preoperative clinical characteristics, pharmacokinetic variables of DCE MR imaging, and postoperative molecular biomarkers to predict PFS.

Results: The increased mean Ktrans of the CEL, increased 95th percentile Ktrans of the CELs, and absence of methylated O⁶-methylguanine-DNA methyltransferase promoter were relevant adverse variables for PFS in the univariate analysis ( = 0.041, = 0.032, and = 0.083, respectively). The Kaplan-Meier survival curves demonstrated that PFS was significantly shorter in patients with a mean Ktrans of the CEL > 0.068 and 95th percentile Ktrans of the CEL>0.223 (log-rank = 0.038 and = 0.041, respectively). However, only mean Ktrans of the CEL was significantly associated with PFS ( = 0.024; hazard ratio, 553.08; 95% confidence interval, 2.27-134756.74) in the multivariate Cox proportional hazard analysis. None of the pharmacokinetic variables from NE-T2HSILs were significantly related to PFS.

Conclusion: Among the pharmacokinetic variables extracted from CELs and NE-T2HSILs on preoperative DCE MR imaging, the mean Ktrans of CELs exhibits potential as a useful imaging predictor of PFS in GBM patients.
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http://dx.doi.org/10.3348/kjr.2019.0629DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7231611PMC
June 2020

Added Value of Computed Tomography to Ultrasonography for Assessing LN Metastasis in Preoperative Patients with Thyroid Cancer: Node-By-Node Correlation.

Cancers (Basel) 2020 May 8;12(5). Epub 2020 May 8.

Department of Radiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul 03080, Korea.

Diagnostic accuracy of US in the evaluation of lymph node (LN) metastasis for thyroid cancer patients is limited. We investigated the value of CT added to US for characterizing LNs in preoperative thyroid cancer patients by node-by-node correlation. A total of 225 primary thyroid cancer patients who underwent LN biopsy were included. Based on node-by-node correlation, 274 LNs were classified into probably benign, indeterminate, and suspicious categories on US, CT, and combined US/CT. Malignancy risks were calculated for each category and were compared between US/CT concordant and discordant cases. On US, CT, and combined US/CT, malignancy risks were 1.7%, 8.7%, and 0% in the probably benign category, 22.4%, 5.9%, and 8.0% in the indeterminate category, and 77.2%, 82.0%, and 75.6% in the suspicious category, respectively. Malignancy risk of the concordant suspicious category was higher than that of the discordant suspicious category (84.7% vs. 43.2%, < 0.001). The addition of CT helped correctly detect additional metastasis in 16.4% of the US indeterminate LNs and in 1.7% of the US probably benign LNs. CT may complement US for LN characterization in thyroid cancer patients by suggesting the diagnostic confidence level for the suspicious category and helping correctly detect metastasis in US indeterminate LNs.
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http://dx.doi.org/10.3390/cancers12051190DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281101PMC
May 2020

Ultrasonographic Indeterminate Lymph Nodes in Preoperative Thyroid Cancer Patients: Malignancy Risk and Ultrasonographic Findings Predictive of Malignancy.

Korean J Radiol 2020 05;21(5):598-604

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

Objective: Proper management of lymph nodes (LNs) with ultrasonographic (US) indeterminate features in thyroid cancer patients remains elusive. We aimed to evaluate the malignancy risk and US findings predictive of malignancy for US indeterminate LNs in preoperative thyroid cancer patients through node-by-node correlation.

Materials And Methods: A total of 348 LNs in 284 thyroid cancer patients, who underwent fine-needle aspiration or core-needle biopsy between December 2006 and June 2015, were included. We determined the malignancy risks for US probably benign, indeterminate, and suspicious categories. For US indeterminate LNs, which had neither echogenic hilum nor hilar vascularity in the absence of any suspicious finding, US findings were compared between benign and metastatic LNs using Mann-Whitney U test and Fisher's exact test.

Results: US imaging diagnoses were probably benign in 20.7% (n = 72) cases, indeterminate in 23.6% (n = 82), and suspicious in 55.7% (n = 194). Malignancy risk of US indeterminate LNs (19.5% [16/82]) differed from those of the US probably benign (2.8% [2/72]) ( = 0.002) and US suspicious LNs (78.4% [152/194]) ( < 0.001). Among US indeterminate LNs, there were no significant differences in short, long, and long-to-short diameter (L/S) ratios between benign and metastatic LNs (3.9 vs. 3.8 mm, = 0.619; 7.3 vs. 7.3 mm, = 0.590; 1.9 vs. 1.9, = 0.652).

Conclusion: US indeterminate LNs were frequently encountered during preoperative evaluation and had intermediate malignancy risk. Given the lack of discriminative power of size criteria and L/S ratio, clinical factors such as surgical strategy and node size should be considered for proper triage of US indeterminate LNs in thyroid cancer.
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http://dx.doi.org/10.3348/kjr.2019.0755DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7183832PMC
May 2020

Radiomics prognostication model in glioblastoma using diffusion- and perfusion-weighted MRI.

Sci Rep 2020 03 6;10(1):4250. Epub 2020 Mar 6.

Deparment of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, 05505, Korea.

We aimed to develop and validate a multiparametric MR radiomics model using conventional, diffusion-, and perfusion-weighted MR imaging for better prognostication in patients with newly diagnosed glioblastoma. A total of 216 patients with newly diagnosed glioblastoma were enrolled from two tertiary medical centers and divided into training (n = 158) and external validation sets (n = 58). Radiomic features were extracted from contrast-enhanced T1-weighted imaging, fluid-attenuated inversion recovery, diffusion-weighted imaging, and dynamic susceptibility contrast imaging. After radiomic feature selection using LASSO regression, an individualized radiomic score was calculated. A multiparametric MR prognostic model was built using the radiomic score and clinical predictors. The results showed that the multiparametric MR prognostic model (radiomics score + clinical predictors) exhibited good discrimination (C-index, 0.74) and performed better than a conventional MR radiomics model (C-index, 0.65, P < 0.0001) or clinical predictors (C-index, 0.66; P < 0.0001). The multiparametric MR prognostic model also showed robustness in external validation (C-index, 0.70). Our results indicate that the incorporation of diffusion- and perfusion-weighted MR imaging into an MR radiomics model to improve prognostication in glioblastoma patients improved its performance over that achievable using clinical predictors alone.
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http://dx.doi.org/10.1038/s41598-020-61178-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7060336PMC
March 2020

Distribution and malignancy risk of six categories of the pathology reporting system for thyroid core-needle biopsy in 1,216 consecutive thyroid nodules.

Ultrasonography 2020 Apr 16;39(2):159-165. Epub 2020 Jan 16.

Department of Radiology, Human Medical Imaging and Intervention Center, Seoul, Korea.

Purpose: The purpose of this study was to present the distribution of lesions among the six categories of the pathology reporting system for thyroid core-needle biopsy (CNB), along with the range of malignancy risk of each category based on different diagnostic criteria for benignity in a clinical cohort.

Methods: For 1,216 consecutive nodules (≥1 cm) of 1,125 patients who underwent CNB at two hospitals, the diagnostic results based on the six categories of thyroid CNB were analyzed. Patients were divided into three groups according to prior fine-needle aspiration (FNA) status: second-line CNB for nodules where prior FNA yielded nondiagnostic or unsatisfactory results (n=57), second-line CNB for nodules with prior FNA results of atypia/follicular lesion of undetermined significance (AUS/FLUS) (n=303), and first-line CNB (n=856).

Results: The proportion of nodules in each CNB category and the range of the malignancy rate for each category was as follows, in order from category I to VI: 1.8%, 23.1%-75.0%; 57.9%, 0.7%-16.7%; 16.0%, 13.2%-46.7%; 8.8%, 53.8%-56.8%; 2.0%, 100%; and 13.5%, 100%. First-line CNB was associated with a higher rate of conclusive diagnoses (category II, IV, or VI) (725 of 856, 84.7%) than second-line CNB with prior nondiagnostic or AUS/FLUS FNA results (241 of 360, 66.9%; P<0.001).

Conclusion: The overall distribution of nodules across the six categories of thyroid CNB and the ranges of malignancy risk for those categories were presented in a clinical cohort. First-line CNB tended to produce a higher rate of conclusive results than second-line CNB with prior inconclusive FNA results.
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http://dx.doi.org/10.14366/usg.19056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7065982PMC
April 2020

Regional Arterial Spin Labeling Perfusion Defect Is Associated With Early Ischemic Recurrence in Patients With a Transient Ischemic Attack.

Stroke 2020 01 13;51(1):186-192. Epub 2019 Nov 13.

Department of Radiology (R.-E.Y., C.-H.S.), Seoul National University Hospital, Korea.

Background and Purpose- With the lack of confirmatory examinations, the distinction of a transient ischemic attack (TIA) from various TIA-mimicking diseases is difficult, particularly in diffusion-weighted imaging (DWI)-negative TIAs. In this study, we aimed to evaluate the relationship between arterial spin labeling (ASL) perfusion defects and early ischemic recurrence (FU-DWI [+]) in patients with DWI-negative TIAs. Methods- We assessed consecutive patients with a DWI-negative TIA within 24 hours of symptom onset, who underwent both ASL images and follow-up magnetic resonance imaging during the acute period. As markers of the ASL images, we evaluated the ASL perfusion defects in each hemisphere. Arterial transit artifact (ATA) and intraarterial high-intensity signal (IAS) were also rated as markers of collateral status and blood stagnation due to large vessel occlusion, respectively. Results- Among the 136 patients with a DWI-negative TIA, 33 patients had FU-DWI (+) lesions in 36 hemispheres. In the multivariable analysis, ASL defects remained an independent predictor of FU-DWI (+) (adjusted odds ratio, 13.94 [95% CI, 5.77-33.70], <0.001). In the evaluation of the interactive relationship between ASL defects and ATA/IAS, the (ASL [+] ATA [-]) group showed the highest frequencies of FU-DWI (+) events (55.6%) with the highest adjusted odds ratio values (adjusted odds ratio, 14.86 [95% CI, 5.63-39.24], <0.001), indicating a negative synergistic effect between the ASL defects and ATA. Meanwhile, the (ASL [+] IAS [+]) group showed higher frequencies of FU-DWI (+) and higher adjusted odds ratio values than those of the (ASL [+] IAS [-]) and (ASL [-] IAS [-]) groups, indicating a positive synergistic effect. Conclusions- We demonstrated that ASL perfusion defects were associated with ipsilateral FU-DWI (+) in patients with a DWI-negative TIA. Furthermore, this association was enhanced with IASs and attenuated with ATAs.
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http://dx.doi.org/10.1161/STROKEAHA.119.026556DOI Listing
January 2020

Arterial spin labeling perfusion-weighted imaging aids in prediction of molecular biomarkers and survival in glioblastomas.

Eur Radiol 2020 Feb 29;30(2):1202-1211. Epub 2019 Aug 29.

Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea.

Objectives: Prediction of progression-free survival (PFS) and overall survival (OS) and early identification of molecular biomarkers with prognostic information are clinically important in glioblastoma (GBM) patients. We aimed to explore the utility of arterial spin labeling perfusion-weighted imaging (ASL-PWI) in the prediction of molecular biomarkers and survival in GBM patients.

Methods: We retrospectively analyzed 149 consecutive GBM patients, who had undergone maximal surgical resection or biopsy followed by concurrent chemoradiotherapy and adjuvant chemotherapy using temozolomide between November 2010 and June 2016. On preoperative ASL-PWI, cerebral blood flow (CBF) within contrast-enhancing (CE) and nonenhancing (NE) portions were evaluated both qualitatively (perfusion pattern and perfusion pattern) and quantitatively (nCBF and nCBF). ASL-PWI findings were correlated with molecular biomarkers, including isocitrate dehydrogenase (IDH) and O6-methylguanine-DNA methyltransferase (MGMT) methylation statuses, and survival, using the Mann-Whitney U-test, Spearman rank correlation, Kaplan-Meier analysis, and receiver operating characteristics analysis.

Results: nCBF was significantly higher in the IDH wild-type group than in the IDH mutant group (p = .013) and in the MGMT unmethylated group than in the methylated group (p = .047). Areas under the receiver operating characteristic curve were 0.678 for IDH mutation (p = .022) and 0.601 for MGMT promoter methylation (p = .043). Hyperperfusion was associated with the shortest median PFS for both perfusion pattern (7.6 months) and perfusion pattern (4.0 months). The perfusion pattern remained an independent predictor for PFS and OS even after adjusting for clinical and molecular predictors, unlike perfusion pattern.

Conclusions: ASL-PWI can aid to predict survival and molecular biomarkers including IDH mutation and MGMT promoter methylation statuses in GBM patients.

Key Points: • ASL-PWI can aid to predict survival in GBM patients. • ASL-PWI can aid to predict IDH and MGMT promoter methylation statuses in GBM.
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http://dx.doi.org/10.1007/s00330-019-06379-2DOI Listing
February 2020

Altered Vascular Permeability in Migraine-associated Brain Regions: Evaluation with Dynamic Contrast-enhanced MRI.

Radiology 2019 09 2;292(3):713-720. Epub 2019 Jul 2.

From the Departments of Radiology (Y.S.K., S.H.C., R.E.Y., K.M.K., T.J.Y.), Neurology (M.K., S.T.L., J.M., Y.W.S.), and Neurosurgery (J.M.), Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea; Department of Radiology (Y.S.K., S.H.C., R.E.Y., K.M.K., T.J.Y.), Neuroscience Research Institute (M.K.), and Protein Metabolism Research Center (M.K.), Seoul National University College of Medicine, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea (S.H.C.); and Department of Radiology, Korea University Anam Hospital, Seoul, Republic of Korea (S.H.Y.).

Background Recent studies showed the possible association between inflammation-induced blood-brain barrier (BBB) structural changes followed by greater permeability of the BBB and chronic pain. Thus, measurement of BBB breakdown would be a valuable aid in the diagnosis in migraine. Dynamic contrast material-enhanced (DCE) MRI can determine perfusion and permeability properties related to the BBB. Purpose To evaluate the relationship between permeability of the BBB in migraine-associated brain regions by using DCE MRI. Materials and Methods In this prospective study, from September 2016 to December 2017, 56 study participants underwent DCE MRI after gadobutrol administration and were classified into migraine ( = 35) and healthy control ( = 21) groups. Automatic volumetric segmentation was performed on the pre-contrast-enhanced T1-weighted images by using FreeSurfer, and migraine-associated brain region masks were extracted by using the software NordicICE. The corresponding maps for pharmacokinetic parameters (the volume transfer constant) and (the fractional plasma volume) were coregistered with the region-of-interest masks, and their mean values of corresponding total volume of interest were calculated. For comparison analyses, the Mann-Whitney tests were used. Receiver operating characteristic curve analysis and Spearman rank correlation tests were used to identify correlations between clinical characteristics and the aforementioned perfusion parameters. Results Mean age was younger in the migraine group (mean ± standard deviation, 57 years ± 12) than in the healthy control group (mean, 71 years ± 8) ( < .001). In the migraine group, the mean value of in the left amygdala (median, 0.27 mL/100 g) was lower than that in the healthy control group (median, 0.39 mL/100 g) ( = .04). The mean value of in the left amygdala was correlated with the intensity of headache attack in participants with migraine (correlation coefficient, -0.34; = .04). Conclusion Lower fractional plasma volume in the left amygdala was observed in participants with migraine than in healthy participants. © RSNA, 2019 See also the editorial by Carroll and Ginat in this issue.
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http://dx.doi.org/10.1148/radiol.2019182566DOI Listing
September 2019

Onodi cell mucocele causing isolated trochlear nerve palsy: A case report.

Medicine (Baltimore) 2019 May;98(21):e15475

Department of Otorhinolaryngology-Head and Neck Surgery, National Medical Center, Seoul.

Rationale: Acquired vertical diplopia is commonly observed in trochlear nerve palsy, often resulting from blunt head trauma or vascular problems. It is rarely caused by tumorous conditions or space occupying lesion. We report the first case of Onodi cell mucocele causing isolated trochlear nerve palsy.

Patient Concerns: A 62-year-old male noticed a double vision which worsened when looking down. On ophthalmologic examinations, the patient showed no abnormalities in visual acuity, intraocular pressure, and no swelling in optic disc. In ocular motility test, he was notable for 10° left hypertropia in primary position, 6° in right head tilt position, 14° in left head tilt position and this was aggravated in right and down gaze. Ostiomeatal complex CT depicted an expansile soft tissue density completely filling the left Onodi cell.

Diagnoses: He was diagnosed with a trochlear nerve palsy caused by an isolated mucocele in the left Onodi cell.

Interventions: Three days after presentation, he underwent endoscopic sinus surgery for marsupialization of the mucocele in the left Onodi cell.

Outcomes: The mucocele was completely removed through the endoscopic endonasal approach. Within 4 months after surgery, his 4th nerve palsy had gradually and completely improved.

Lessons: Onodi cell mucoceles that cause trochlear nerve palsy are extremely rare. Timely surgical decompression is essential to achieve optimal recovery of the neural function. Combined trochlear nerve palsy should be evaluated when Onodi cell mucocele involves the orbital apex from above.
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http://dx.doi.org/10.1097/MD.0000000000015475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6571400PMC
May 2019

Diagnostic value of computed tomography combined with ultrasonography in detecting cervical recurrence in patients with thyroid cancer.

Head Neck 2019 05 14;41(5):1206-1212. Epub 2018 Dec 14.

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

Background: To determine the diagnostic role of CT added to ultrasound for the diagnosis of recurrent differentiated thyroid cancer (DTC) and to evaluate potential benefits for patients.

Methods: A total of 193 patients with recurrent DTC were retrospectively included. The diagnostic performances of ultrasound and combination of ultrasound and CT (ultrasound/CT) in detecting recurrence were compared. Benefits of CT were assessed based on the presence of any recurrence detected only with additional CT.

Results: In detecting cervical recurrence, ultrasound/CT showed higher sensitivity (P = .001) and lower specificity (P < .001) than ultrasound alone, overall resulting in higher area under the curve (P < .001). Seventy-nine patients (40.9%) benefited from additional CT in detecting recurrence.

Conclusion: For reoperation of cervical recurrence in patients with DTC, addition of CT to ultrasound offers better surgical planning by enhancing detection of recurrent cancers that were overlooked with ultrasound alone.
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http://dx.doi.org/10.1002/hed.25538DOI Listing
May 2019

Persistent/Recurrent Differentiated Thyroid Cancer: Clinical and Radiological Characteristics of Persistent Disease and Clinical Recurrence Based on Computed Tomography Analysis.

Thyroid 2018 11 16;28(11):1490-1499. Epub 2018 Oct 16.

7 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea.

Background: The natural course of persistent/recurrent differentiated thyroid cancer (DTC) has not been fully elucidated. The purpose of this study was to assess the relative incidence and clinico-radiological characteristics of persistent disease and clinical recurrence based on computed tomography (CT) analysis in patients with persistent/recurrent DTC.

Methods: From January 2005 to December 2016, this retrospective study included 107 patients (M:F = 28:79; M = 53.5 years) with surgically proven cervical locoregional recurrence of DTC. Two neck CT examinations (median interval 1.92 years; range 0.17-7.58 years) before the last thyroid cancer surgery within the study period were reevaluated. Based on the presence of the lesion on the first CT and its progression on the second CT, the locoregional recurrence was classified into the following categories: stable persistence (decrease, no change, or increase by <2 mm in short dimension on the second CT), progressive persistence (increase by ≥2 mm), and clinical recurrence (newly appeared on the second CT). Clinical and radiological characteristics of the three groups were compared using univariate and multivariate logistic regression analyses.

Results: The relative incidences of stable persistence, progressive persistence, and clinical recurrence were 56.1% (60/107), 15.0% (16/107), and 29.0% (31/107), respectively. Multivariate analysis between the clinical recurrence (29.0%) and persistence (71.0%) groups revealed various independent factors for prediction of clinical recurrence. These included longer interval between the two CT examinations (median 2.67 vs. 1.79 years; p = 0.021), a smaller number of thyroid surgeries (1.16 ± 0.45 vs. 1.55 ± 0.81; p = 0.002), and a history of neck dissection at the location of the largest locoregional recurrence (70.0% vs. 31.4%; p < 0.001). There was no significant independent factor for differentiation between the stable persistence (78.9%; 60/76) and progressive persistence (21.1%; 16/76) groups. The results may have been influenced by selection bias because this study included only surgically proven cases.

Conclusions: With regard to cervical locoregional recurrence of DTC, active surveillance may be favored because more than a half of the cases are structurally persistent and stable. However, meticulous evaluation is necessary to detect progressive persistence and clinical recurrence, considering various clinical factors.
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http://dx.doi.org/10.1089/thy.2018.0151DOI Listing
November 2018
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