Orientation of the ultrasound probe to identify the taller-than-wide sign of thyroid malignancy: a registry-based study with the Thyroid Imaging Network of Korea

Purpose@#Although the taller-than-wide (TTW) sign has been regarded as one of the most specific ultrasound (US) features of thyroid malignancy, uncertainty still exists regarding the US probe’s orientation when evaluating it. This study investigated which US plane would be optimal to identify the TTW sign based on malignancy risk stratification using a registry-based imaging dataset. @*Methods@#A previous study by 17 academic radiologists retrospectively analyzed the US images of 5,601 thyroid nodules (≥1 cm, 1,089 malignant and 4,512 benign) collected in the webbased registry of Thyroid Imaging Network of Korea through the collaboration of 26 centers. The present study assessed the diagnostic performance of the TTW sign itself and fine needle aspiration (FNA) indications via a comparison of four international guidelines, depending on the orientation of the US probe (criterion 1, transverse plane; criterion 2, either transverse or longitudinal plane). @*Results@#Overall, the TTW sign was more frequent in malignant than in benign thyroid nodules (25.3% vs. 4.6%). However, the statistical differences between criteria 1 and 2 were negligible for sensitivity, specificity, and area under the curve (AUC) based on the size effect (all P0.05, respectively). @*Conclusion@#A longitudinal US probe orientation provided little additional diagnostic value over the transverse orientation in detecting the TTW sign of thyroid nodules.

Radiologic Follow-up of Ruptured Arachnoid Cysts With or Without Hemorrhage: Five Case Reports and a Review of the Literature

Arachnoid cysts are usually asymptomatic and discovered incidentally. However, cysts may occasionally rupture because of minor head trauma. We describe the radiologic follow-up of 5 patients with ruptured arachnoid cysts featuring spontaneous resolution, subdural hygroma formation, and cystic and subdural hemorrhage. From January 2004 through July 2020, 5 patients (1.3%) with ruptured arachnoid cysts were evaluated out of 388 patients with arachnoid cysts encountered at our institution at that time. The 5 patients were all male, and they ranged in age from 6–17 years (median, 12 years).The median duration of radiologic follow-up was 3.5 years (range, 2.3–10.1 years). All of the ruptured arachnoid cysts were overlying the temporal lobe with Galassi type II. The median cyst diameter was 4.9 cm (range, 4.4–8.9 cm). Four patients had a history of recent minor head trauma. There were no particular neurologic symptoms in their past medical history in all patients. In the follow-up, two patients’ cysts resolved spontaneously without hemorrhage. One patient’s cyst resolved post-burr-hole drainage for chronic subdural hemorrhage. Another patient, whose cyst led to a hemorrhage and chronic subdural hemorrhage, recovered following a craniotomy, hematoma removal, and cyst fenestration. Another patient, presenting with hygroma, cystic hemorrhage, and chronic subdural hemorrhage, was treated with burr-hole drainage. Three patients recovered postoperatively. Arachnoid cysts rarely rupture, and surgical intervention is required for some cases associated with hemorrhage. Postoperatively, all patients had good outcomes without complications in this series.

Malignancy risk of thyroid nodules with minimal cystic changes: a multicenter retrospective study

Purpose@#The aim of this multicenter study was to investigate the malignancy risk of minimally cystic thyroid nodules (MCTNs) using cyto-histopathologic diagnoses as the reference standard. @*Methods@#From June 2015 to September 2015, 5,601 thyroid nodules (≥1 cm) from 4,989 consecutive patients who underwent thyroid ultrasonography (US) at 26 institutions were retrospectively analyzed. Each thyroid nodule was categorized according to its cystic proportion: purely solid, minimally cystic (≤10%), and partially cystic (>10%). The malignancy risk of MCTNs was compared with those of purely solid nodules and partially cystic thyroid nodules (PCTNs). The malignancy risk of MCTNs was assessed according to echogenicity and the presence of suspicious US features. @*Results@#The prevalence of MCTNs was 22.5%. The overall malignancy risk of MCTNs was 8.8%, which was significantly lower than that of purely solid nodules (29.5%) (P0.05). MCTNs were associated with a higher risk of malignancy in hypoechoic nodules than in isohyperechoic nodules and in nodules with suspicious US features than in those without suspicious US features (all P<0.001). @*Conclusion@#The malignancy risk of MCTNs was significantly lower than that of purely solid nodules. MCTNs could be categorized as PCTNs rather than as solid nodules to increase the accuracy of the risk stratification system for thyroid nodules.

Application of Machine Learning and Deep Learning in Imaging of Ischemic Stroke

Timely analysis of imaging data is critical for diagnosis and decision-making for proper treatment strategy in the cases of ischemic stroke. Various efforts have been made to develop computer-assisted systems to improve the accuracy of stroke diagnosis and acute stroke triage. The widespread emergence of artificial intelligence technology has been integrated into the field of medicine. Artificial intelligence can play an important role in providing care to patients with stroke. In the past few decades, numerous studies have explored the use of machine learning and deep learning algorithms for application in the management of stroke. In this review, we will start with a brief introduction to machine learning and deep learning and provide clinical applications of machine learning and deep learning in various aspects of stroke management, including rapid diagnosis and improved triage, identifying large vessel occlusion, predicting time from stroke onset, automated ASPECTS (Alberta Stroke Program Early CT Score) measurement, lesion segmentation, and predicting treatment outcome. This work is focused on providing the current application of artificial intelligence techniques in the imaging of ischemic stroke, including MRI and CT.

2021 Korean Thyroid Imaging Reporting and Data System and Imaging-Based Management of Thyroid Nodules: Korean Society of Thyroid Radiology Consensus Statement and Recommendations

Incidental thyroid nodules are commonly detected on ultrasonography (US). This has contributed to the rapidly rising incidence of low-risk papillary thyroid carcinoma over the last 20 years. The appropriate diagnosis and management of these patients is based on the risk factors related to the patients as well as the thyroid nodules. The Korean Society of Thyroid Radiology (KSThR) published consensus recommendations for US-based management of thyroid nodules in 2011 and revised them in 2016. These guidelines have been used as the standard guidelines in Korea. However, recent advances in the diagnosis and management of thyroid nodules have necessitated the revision of the original recommendations. The task force of the KSThR has revised the Korean Thyroid Imaging Reporting and Data System and recommendations for US lexicon, biopsy criteria, US criteria of extrathyroidal extension, optimal thyroid computed tomography protocol, and US follow-up of thyroid nodules before and after biopsy. The biopsy criteria were revised to reduce unnecessary biopsies for benign nodules while maintaining an appropriate sensitivity for the detection of malignant tumors in small (1–2 cm) thyroid nodules. The goal of these recommendations is to provide the optimal scientific evidence and expert opinion consensus regarding US-based diagnosis and management of thyroid nodules.

The Tumor Control According to Radiation Dose of Gamma Knife Radiosurgery for Small and Medium-Sized Brain Metastases from Non-Small Cell Lung Cancer

Objective@#: The effectiveness of gamma knife radiosurgery (GKR) in the treatment of brain metastases is well established. The aim of this study was to evaluate the efficacy and safety of maximizing the radiation dose in GKR and the factors influencing tumor control in cases of small and medium-sized brain metastases from non-small cell lung cancer (NSCLC). @*Methods@#: We analyzed 230 metastatic brain tumors less than 5 mL in volume in 146 patients with NSCLC who underwent GKR. The patients had no previous radiation therapy for brain metastases. The pathologies of the tumors were adenocarcinoma (n=207), squamous cell carcinoma (n=18), and others (n=5). The radiation doses were classified as 18, 20, 22, and 24 Gy, and based on the tumor volume, the tumors were categorized as follows : small-sized (less than 1 mL) and medium-sized (1–3 and 3–5 mL). The progression-free survival (PFS) of the individual 230 tumors and 146 brain metastases was evaluated after GKR depending on the pathology, Eastern Cooperative Oncology Group (ECOG) performance score (PS), tumor volume, radiation dose, and anti-cancer regimens. The radiotoxicity after GKR was also evaluated. @*Results@#: After GKR, the restricted mean PFS of individual 230 tumors at 24 months was 15.6 months (14.0–17.1). In small-sized tumors, as the dose of radiation increased, the tumor control rates tended to increase (p=0.072). In medium-sized tumors, there was no statistically difference in PFS with an increase of radiation dose (p=0.783). On univariate analyses, a statistically significant increase in PFS was associated with adenocarcinomas (p=0.001), tumors with ECOG PS 0 (p=0.005), small-sized tumors (p=0.003), radiation dose of 24 Gy (p=0.014), synchronous lesions (p=0.002), and targeted therapy (p=0.004). On multivariate analyses, an improved PFS was seen with targeted therapy (hazard ratio, 0.356; 95% confidence interval, 0.150–0.842; p=0.019). After GKR, the restricted mean PFS of brain at 24 months was 9.8 months (8.5–11.1) in 146 patients, and the pattern of recurrence was mostly distant within the brain (66.4%). The small and medium-sized tumors treated with GKR showed radiotoxicitiy in five out of 230 tumors (2.2%), which were controlled with medical treatment. @*Conclusion@#: The small-sized tumors were effectively controlled without symptomatic radiation necrosis as the radiation dose was increased up to 24 Gy. The medium-sized tumors showed potential for symptomatic radiation necrosis without signifcant tumor control rate, when greater than 18 Gy. GKR combined targeted therapy improved the tumor control of GKR-treated tumors.

Pictorial Review of Mediastinal Masses with an Emphasis on Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) has become a crucial tool for evaluating mediastinal masses considering that several lesions that appear indeterminate on computed tomography and radiography can be differentiated on MRI. Using a three-compartment model to localize the mass and employing a basic knowledge of MRI, radiologists can easily diagnose mediastinal masses. Here, we review the use of MRI in evaluating mediastinal masses and present the images of various mediastinal masses categorized using the International Thymic Malignancy Interest Group’s three-compartment classification system. These masses include thymic hyperplasia, thymic cyst, pericardial cyst, thymoma, mediastinal hemangioma, lymphoma, mature teratoma, bronchogenic cyst, esophageal duplication cyst, mediastinal thyroid carcinoma originating from ectopic thyroid tissue, mediastinal liposarcoma, mediastinal pancreatic pseudocyst, neurogenic tumor, meningocele, and plasmacytoma.

Predictors of Catastrophic Outcome after Endovascular Thrombectomy in Elderly Patients with Acute Anterior Circulation Stroke

Predictors of a Favorable Outcome after Emergent Carotid Artery Stenting in Acute Anterior Circulation Stroke Patients

Purpose@#This study aimed to identify independent predictors of favorable outcomes associated with emergent carotid artery stenting (CAS) in patients with acute anterior circulation stroke. @*Materials and Methods@#This study included 93 patients with acute stroke who underwent emergent CAS to treat stenoocclusive lesions in the cervical internal carotid artery (ICA) within 6 hours of the onset of the associated symptoms. Data were compared between patients with and without favorable outcomes. The independent predictors of a favorable outcome were determined via logistic regression analysis (modified Rankin Scale 0–2 at 90 days). @*Results@#Intracranial tandem occlusion was noted in 81.7% of patients (76/93) among which (76/93), 55 of whom underwent intracranial recanalization therapy. Intracranial reperfusion was successful in 74.2% (69/93) and favorable outcomes were noted in 51.6% of patients (48/93). The mortality rate was 6.5% (6/93). In logistic regression analysis, diffusion-weighted imaging-Alberta Stroke Program Early CT Score [odds ratio (OR), 1.487; 95% confidence interval (CI), 1.018–2.173, p = 0.04], successful reperfusion (OR, 5.199; 95% CI, 1.566–17.265, p = 0.007), and parenchymal hemorrhage (OR, 0.042; 95% CI, 0.003–0.522, p = 0.014) were independently associated with a favorable outcome. @*Conclusion@#Baseline infarct size, reperfusion status, and parenchymal hemorrhage were independent predictors of favorable outcomes after emergent CAS to treat stenoocclusive lesions in the cervical ICA in patients with acute anterior circulation stroke.

Case Reports of Tectal Plate Gliomas Showing Indolent Course

From 2004 to 2020, we studied three pediatric patients (age: 9-13 years, all male) and one adult patient (age: 29 years, female) with tectal plate glioma with obstructing hydrocephalus on MRI. One patient had neurofibromatosis type 1. All patients complained about headaches and vomiting, and one patient had diplopia. Endoscopic third ventriculostomy (ETV) was underwent in all patients and a biopsy was obtained from two patients. Pathologic diagnoses were a pilocytic astrocytoma and a lowgrade glioma. After ETV with or without biopsy, neurological symptoms were improved in all patients.Three patients did the clinical and radiological follow-up without adjuvant treatment. One patient underwent gamma knife radiosurgery. In two pediatric patients and the adult patient, there was no clinical and radiological progression after 6.2, 6.9, and 8.0 years, respectively. One pediatric patient whose lesion had focal enhancement had radiologic progression without any neurologic symptoms after 5.1 years. Without adjuvant treatment for this lesion, there was no clinical deterioration neither further radiological progression for 6.2 years after radiological aggravation. Tectal plate gliomas showed indolent clinical courses, even after radiologic tumor progression. After the treatment of obstructing hydrocephalus, clinical and radiologic follow-up can be recommended for indolent tectal plate gliomas.

Primary Intraparenchymal Central Nervous System Solitary Fibrous Tumor/Hemangiopericytoma Presenting with Intracerebral Hemorrhage: A Case Report

A 53-year old man who had a left hemiparesis from head injury of traffic accident 20 years ago visited an emergency room with suddenly developed semi-comatose mental status. Brain CT showed 8.6-cm sized solid and cystic mass on right temporal lobe that was associated with hemorrhage. Solid lesion showed a strong enhancement after an administration of contrast media. Because of severe mass effect, emergency operation was performed. The mass was an intraparenchymal lesion with yellowish cystic fluid and the firm reddish-brown solid lesion was hemorrhagic. The lesion was totally resected. Pathologically, anaplastic solitary fibrous tumor/hemangiopericytoma was diagnosed with 70/10 high power fields. Postoperative radiotherapy of 50 Gy was done. Postoperative 2 months later, the patient was recovered to alert mental state. We report this unusual case of non-dural based intraparenchymal solitary fibrous tumor/hemangiopericytoma with high mitotic index and acute massive hemorrhage. Rapid tumor growth of hypervascular tumor might have a chance of bleeding.

Neural Mechanism of Second Language Processing in Korean-English Bilingual Children

PURPOSE@#To evaluate the neural mechanism of second language processing in Korean-English bilingual children using functional MRI (fMRI).@*MATERIALS AND METHODS@#The study was conducted on 20 Korean elementary school children who were learning English as a foreign language. fMRI was performed during short-passage comprehension tasks in Korean and English languages. We analyzed which brain areas were activated according to the language, English proficiency, and task difficulty.@*RESULTS@#Higher activities were observed in the dorsolateral prefrontal cortex, supplementary motor area, precentral gyrus, left basal ganglia, and left temporoparietal and occipital lobes during English comprehension than during Korean comprehension. The low English proficiency group showed higher activities than the high English proficiency group in the frontotemporal cortex, including the prefrontal cortex. Higher activities were observed in the right inferior frontal gyrus and right temporoparietal lobe during the English comprehension task of intermediate difficulty compared to that of low difficulty. However, the brain activities significantly decreased while performing a high-difficulty English task.@*CONCLUSION@#Brain activities significantly increased during English comprehension in the lower English proficiency group while performing an intermediate-difficulty task. However, brain activation decreased when the task difficulty exceeded the moderate comprehension level. These results suggest that a proper level of education is important to learn a second language.

Predictive Factors for Good Outcome and Mortality After Stent-Retriever Thrombectomy in Patients With Acute Anterior Circulation Stroke / 대한뇌졸중학회지

BACKGROUND AND PURPOSE: Predictive factors associated with stent-retriever thrombectomy for patients with acute anterior circulation stroke remain to be elucidated. This study aimed to investigate clinical and procedural factors predictive of good outcome and mortality after stent-retriever thrombectomy in a large cohort of patients with acute anterior circulation stroke. METHODS: We analyzed clinical and procedural data in 335 patients with acute anterior circulation stroke treated with stent-retriever thrombectomy. A good outcome was defined as a modified Rankin Scale score of 0 to 2 at 3 months. The associations between clinical, imaging, and procedural factors and good outcome and mortality, respectively, were evaluated using logistic regression analysis. RESULTS: Using multivariate analysis, age (odds ratio [OR], 0.965; 95% confidence interval [CI], 0.944-0.986; P=0.001), successful revascularization (OR, 4.658; 95% CI, 2.240-9.689; P<0.001), parenchymal hemorrhage (OR, 0.150; 95% CI, 0.049-0.460; P=0.001), and baseline NIHSS score (OR, 0.908; 95% CI, 0.855-0.965; P=0.002) were independent predictors of good outcome. Independent predictors of mortality were age (OR, 1.043; 95% CI, 1.002-1.086; P=0.041), successful revascularization (OR, 0.171; 95% CI, 0.079-0.370; P<0.001), parenchymal hemorrhage (OR, 2.961; 95% CI, 1.059-8.276; P=0.038), and a history of previous stroke/TIA (OR, 3.124; 95% CI, 1.340-7.281; P=0.008). CONCLUSIONS: Age, revascularization status, and parenchymal hemorrhage are independent predictors of both good outcome and mortality after stent retriever thrombectomy for acute anterior circulation stroke. In addition, NIHSS score on admission is independently associated with good outcome, whereas a history of previous stroke is independently associated with mortality.

A Mild Form of COG5 Defect Showing Early-Childhood-Onset Friedreich's-Ataxia-Like Phenotypes with Isolated Cerebellar Atrophy

Progressive cerebellar ataxias are rare diseases during childhood, especially under 6 years of age. In a single family, three affected siblings exhibited Friedreich's-ataxia-like phenotypes before 2 years of age. They had progressive cerebellar atrophy, intellectual disability, and scoliosis. Although their phenotypes were similar to those observed in patients with autosomal recessive cerebellar ataxias, other phenotypes (e.g., seizure, movement disorders, ophthalmologic disturbance, cardiomyopathy, and cutaneous disorders) were not noted in this family. Whole-exome sequencing of the family members revealed one potential heterozygous mutation (c.1209delG, NM_181733.2; p.Met403IlefsX3, NP_859422.2) of the gene encoding conserved oligomeric Golgi complex subunit 5 (COG5). The heterozygous deletion at the fifth base in exon 12 of COG5 caused a frameshift and premature stop. Western blotting of COG5 proteins in the skin tissues from an affected proband showed a significantly decreased level of full length COG5 and smaller, aberrant COG5 proteins. We reported a milder form of COG5 defect showing Friedreich's-ataxia-like phenotypes without hypotonia, microcephaly, and short stature that were observed in most patients with COG5 defect.

Ependymomas: Prognostic Factors and Outcome Analysis in a Retrospective Series of 33 Patients

BACKGROUND: The purpose of this study was to evaluate the prognostic factors and outcomes in patients with ependymoma to management plans. METHODS: Between 1997 and 2013, 33 patients with 25 ependymomas (WHO grade II) and eight anaplastic ependymomas (WHO grade III) were pathologically diagnosed. Six were pediatric patients (mean age, 6.15 years; range, 1.3–11 years), while 27 were adults (mean age, 47.5 years; range, 19–70 years). Of those, there were 12 adult patients with totally resected ependymomas without anaplastic pathology and adjuvant treatment. Prognostic factors were assessed in ependymoma patients. Prognostic factors were studied using Kaplan-Meier estimates in subgroups. RESULTS: For six pediatric patients, the progression-free survival (PFS) was 43.7±13.5 months, and the overall survival (OS) was 58.1±13.7 months. For 27 adult patients, the PFS was 125.6±14.3 months, and the OS was 151.2±12.5 months. Age demonstrated a statistically significant effect on PFS (p=0.03) and OS (p=0.03). In adult ependymomas, the extent of tumor removal significantly affected PFS (p=0.03) and trended towards an effect on OS (p=0.06). Out of 12 patients with totally resected ependymomas without anaplastic pathology and adjuvant treatment, one patient showed tumor recurrence during follow-up (mean, 93.5 months; range, 27.9–162.7 months). CONCLUSION: Adult patients with ependymomas were found to have better survival rates compared to pediatric patients. We suggest that totally resected adult ependymomas without anaplastic pathology could be observed without any adjuvant treatment, regardless of the tumor location.

Primary Central Nervous System Vasculitis Mimicking a Cortical Brain Tumor: A Case Report

We report a case of primary central nervous system vasculitis (PCNSV) mimicking a cortical brain tumor. A 25-year-old woman presented with a 2-week history of headache and transient right hemiparesis. Brain magnetic resonance imaging (MRI) revealed a cortical-involving lesion on the left frontal lobe. The 6-cm sized lesion showed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. The lesion had continual linear enhancement on the subcortical white matter and leptomeninges. There was no evidence of hemorrhage on susceptibility-weighted images and no diffusion restriction on diffusion-weighted images. The regional cerebral blood volume was decreased on the MR perfusion images, and spectroscopy showed increased lactate and lipid peaks. The symptoms were aggravated by fever and seizures. Biopsy was performed to rule out tumorous or inflammatory lesions. Pathologically, lymphocytes were infiltrated on the vessels, and the arachnoid membrane was thickened with inflammatory cells. The patient did not have any underlying diseases, including immune disorders. After high-dose steroid administration, her symptoms improved. Two months later, brain MRI showed a reduction in the infiltration of the T2 hyperintensity lesion with subtle subcortical enhancement. We present a case of PCNSV involving the left frontal lobe, showing vasogenic edema, mass effect, and subcortical linear contrast enhancement without hemorrhage or infarction.

Subependymal Giant Cell Astrocytoma Presenting with Tumoral Bleeding: A Case Report

We report a rare case of subependymal giant cell astrocytoma (SEGA) associated with tumoral bleeding in a pediatric patient without tuberous sclerosis complex (TSC). A 10-year-old girl presented with a 2-week history of an increasingly aggravating headache. Brain magnetic resonance imaging revealed an approximately 3.6-cm, well-defined, heterogeneously enhancing mass with multistage hemorrhages on the right-sided foramen of Monro. The tumor was completely resected using a transcallosal approach. Intraoperatively, the mass presented as a gray-colored firm tumor associated with acute and subacute hemorrhages. The origin of the mass was identified as the ventricular septum adjacent to the foramen of Monro. A pathological analysis revealed pleomorphic multinucleated eosinophilic tumor cells with abundant cytoplasm. These cells showed positive staining for the glial fibrillary acidic protein and S100 protein. A diagnosis of SEGA was established. The patient recovered without any neurological symptoms. There was no evidence of TSC. The radiological follow-up showed no recurrence for 2 years. This was a case of SEGA with intratumoral hemorrhage, for which a favorable outcome was achieved, without any neurological deficit after tumoral resection.

Successful Cross-circulation Stent-Retriever Embolectomy Through Posterior Communicating Artery for Acute MCA Occlusion by Using Trevo XP ProVue / 신경중재치료의학

Acute ischemic stroke due to embolic occlusion of the middle cerebral artery (MCA) in patients with chronic ipsilateral internal carotid artery (ICA) occlusion is quite rare. Several previous reports demonstrated that intra-arterial (IA) thrombolytic therapy or aspiration thrombectomy using the cross-circulation technique via an alternative collateral pathway is feasible in acute stroke patients with an unfavorable direct route to the occluded sites. However, stent-retriever embolectomy via the cross-circulation approach has not been reported in the literature. The present paper reports the first case of successful stent-retriever embolectomy for acute MCA occlusion via the patent posterior communicating artery (PComA) by using Trevo XP ProVue stent-retriever in a patient with acute MCA stroke and chronic occlusion at the origin site of the ipsilateral ICA.

Chordoid Glioma with Intraventricular Dissemination: A Case Report with Perfusion MR Imaging Features

Chordoid glioma is a rare low grade tumor typically located in the third ventricle. Although a chordoid glioma can arise from ventricle with tumor cells having features of ependymal differentiation, intraventricular dissemination has not been reported. Here we report a case of a patient with third ventricular chordoid glioma and intraventricular dissemination in the lateral and fourth ventricles. We described the perfusion MR imaging features of our case different from a previous report.

Chlorfenapyr-Induced Toxic Leukoencephalopathy with Radiologic Reversibility: A Case Report and Literature Review

Chlorfenapyr is a widely used, moderately hazardous pesticide. Previous reports have indicated that chlorfenapyr intoxication can be fatal in humans. We reported the first non-fatal case of chlorfenapyr-induced toxic leukoencephalopathy in a 44-year-old female with resolution of extensive and abnormal signal intensities in white matter tracts throughout the brain, brain stem, and spinal cord on serial magnetic resonance imaging.