Publications by authors named "Yon Kwon Ihn"

Purpose: To compare the sensitivities of T2-weighted image (T2WI) and susceptibility-weighted imaging (SWI) in detecting cerebral arteriovenous fistula (AVF), cerebral arteriovenous malformation (AVM), and carotid-cavernous sinus fistula (CCF), and to qualitatively evaluate single-echo SWI (s-SWI) and multi-echo SWI (m-SWI) in characterizing vascular lesions.

Materials And Methods: From January 2016 to December 2021, cerebral angiography-proven lesions were recruited. The sensitivities of T2WI and SWI in detecting vascular lesions were compared using McNemar's test.

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Objectives: (1) To find strategies to improve diagnostic performance of ultrasound-guided biopsy of intermediate and high suspicion thyroid nodules with macrocalcifications. (2) To find malignancy rates of nodules with macrocalcification.

Materials And Methods: From 2018 to 2022, fine-needle aspiration biopsy (FNAB) and core needle biopsy (CNB) were retrospectively evaluated.

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Spinal epidural arteriovenous fistulas (SEDAVFs) are rare spinal vascular malformations that are difficult to diagnose and treat. SEDAVFs can be asymptomatic; however, symptoms can arise from the compression of adjacent nerve roots by dilated vein and perimedullary venous reflux, caused by shunting into the epidural venous plexus. A 31-year-old male presented to our institution with a 2-year history of progressively worsening low-back pain, radiating thigh pain, and sensory changes in his lower extremities.

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Article Synopsis
  • This study aimed to assess how effective susceptibility-weighted imaging (SWI) is in detecting intracranial vertebral artery dissection (VAD) and unruptured intracranial aneurysms (UIAs).
  • A total of 110 patients were evaluated using SWI, with 55 confirmed cases of either VAD (38.2%) or UIA (61.8%), focusing on specific image features that indicate these conditions.
  • The findings showed that SWI had high sensitivity and specificity for detecting VAD and UIAs over 7 mm, highlighting significant agreements among observers on the results.
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Purpose: To assess patient radiation doses during diagnostic and therapeutic neurointerventional procedures from multiple centers and propose dose reference level (RL).

Materials And Methods: Consecutive neurointerventional procedures, performed in 22 hospitals from December 2020 to June 2021, were retrospectively studied. We collected data from a sample of 429 diagnostic and 731 therapeutic procedures.

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Purpose: This study was aimed to compare thyroid fine needle aspiration biopsy (FNAB) techniques (conventional vs. whirling) in terms of cell harvesting ability ex vivo, the unsatisfactory rate and complication rate in vivo, and multi-operator performance in a phantom study.

Methods: In the ex vivo study, cell counts per background at ×100 magnification were compared between both techniques.

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Background: It remains controversial whether carotid artery stenting (CAS) is needed in cases of tandem cervical internal carotid artery occlusion (cICAO) and intracranial large vessel occlusion (LVO).

Objective: To investigate the efficacy and safety of CAS in combination with endovascular thrombectomy (CAS-EVT) in cICAO-LVO patients and to compare its outcomes with those of EVT without CAS (EVT-alone).

Methods: We identified all patients who underwent EVT for tandem cICAO-LVO from the prospectively maintained registries of 17 stroke centers.

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Backgroud: The need for rescue treatment (RT) may differ depending on first-line modality (stent retriever (SR) or contact aspiration (CA)) in endovascular thrombectomy (EVT). We aimed to investigate whether the type of first-line modality in EVT was associated with the need for RT.

Methods: We identified all patients who underwent EVT for anterior circulation large-vessel occlusion from prospectively maintained registries of 17 stroke centers.

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Background and Purpose- Stent retriever (SR) thrombectomy has become the mainstay of treatment of acute intracranial large artery occlusion. However, it is still not much known about the optimal limit of SR attempts for favorable outcome. We evaluated whether a specific number of SR passes for futile recanalization can be determined.

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Bow hunter syndrome (BHS) is a rare vascular phenomenon of vertebrobasilar insufficiency caused by dynamic stenosis of the vertebral artery (VA) by osteophytes, fibrous bands, or disk herniation with neck rotation. We present a rare case of a patient with bilaterally patent VAs on neutral imaging and bilateral dynamic compression of VA with left head rotation. Provocation tests are critical toward understanding dynamic pathophysiology of BHS because normal neutral vascular imaging does not preclude diagnosis of BHS.

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Background And Purpose: Effective rescue treatment has not yet been suggested in patients with mechanical thrombectomy (MT) failure. This study aimed to test whether rescue stenting (RS) improved clinical outcomes in MT-failed patients.

Methods: This is a retrospective analysis of the cohorts of the 16 comprehensive stroke centers between September 2010 and December 2015.

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Objective: To characterise the time window in which endovascular thrombectomy (EVT) is associated with good outcome, and to test the differential relationship between functional outcome and onset-to-reperfusion time (ORT), depending on collateral status.

Methods: This was a retrospective analysis of clinical and imaging data of 554 consecutive patients, who had recanalisation success by EVT for anterior circulation large artery occlusion, from the prospectively maintained registries of 16 comprehensive stroke centres between September 2010 and December 2015. The patients were dichotomised into good and poor collateral groups, based on CT angiography.

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Endovascular coiling for intracranial aneurysms has become an accepted treatment with good clinical results and provides adequate protection against rebleeding and rupture of aneurysms. However, despite the experience, preparation, or skill of the physician, complications during endovascular treatment still occur. The main complications of endovascular coiling are: procedural aneurysmal perforations by the microcatheter, micro-guidewire, or coil, and thromboembolic events.

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Purpose: To assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms across multi-centers and propose a diagnostic reference level (DRL).

Materials And Methods: We studied a sample of 490 diagnostic and 371 therapeutic procedures for intracranial aneurysms, which were performed at 23 hospitals in Korea in 2015. Parameters including dose-area product (DAP), cumulative air kerma (CAK), fluoroscopic time and total angiographic image frames were obtained and analyzed.

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Hemangiomas of the sinonasal tract are rare, and because these lesions lack the typical signs or symptoms, they can be confused with other malignant conditions. We report a case of cavernous hemangioma of the maxillary sinus in a 68-year-old man that was completely resected by endoscopic sinus surgery. Although computed tomography (CT) and magnetic resonance imaging (MRI) showed several enhancing areas within the tumor, the substantial bone erosion and remodeling made it difficult to differentiate this cavernous hemangioma from other expansile maxillary sinus lesions.

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Objective: To assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms in a large sample size from a single center.

Materials And Methods: We studied a sample of 439 diagnostic and 149 therapeutic procedures for intracranial aneurysms in 480 patients (331 females, 149 males; median age, 57 years; range, 21-88 years), which were performed in 2012 with a biplane unit. Parameters including fluoroscopic time, dose-area product (DAP), and total angiographic image frames were obtained and analyzed.

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Objectives: Coil embolization of wide-necked and fusiform aneurysms is challenging and is frequently associated with recanalization despite assistance of any additional device. The purpose of this study was to evaluate the feasibility and mid-term outcomes of complex aneurysms after multiple overlapping stent-assisted coiling (OSAC).

Methods: We retrospectively evaluated 26 wide-necked and fusiform atherosclerotic or dissecting aneurysms that were treated with multiple OSAC.

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Background: Controversy remains about the optimal treatment for blood blister--like aneurysms (BBAs).

Objective: To evaluate clinical and angiographic outcomes after reconstructive treatment for BBA with stent and coil.

Methods: Thirty-four patients (6 men, 28 women; mean age, 47.

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Purpose: The aim of this study was to evaluate the feasibility and safety of the transfacial venous embolization of cavernous or paracavernous dural arteriovenous fistula (DAVF) in which approach via inferior petrosal sinus (IPS) was not feasible.

Materials And Methods: We identified the cases of transfacial venous embolization of cavernous sinus (CS) or adjacent dural sinuses from the neurointerventional database of three hospitals. The causes and clinical and angiographic outcomes of transfacial venous embolization were retrospectively evaluated.

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Objective: A small branch-incorporated aneurysm is an aneurysm with a small branch incorporated into the sac or the neck. It is one of the most difficult aneurysms to treat with coil embolization. The aim of this study was to evaluate the safety and effectiveness of the coil-protected embolization technique for small-branch incorporated aneurysm.

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The authors present a case of isolated dural arteriovenous fistula (DAVF) in the transverse sinus, which developed six years after microvascular decompression caused by hemifacial spasm via suboccipital craniectomy. The lesion was successfully treated by transarterial embolization using Onyx. We reviewed the related radiologic and therapeutic features of DAVF involving an isolated sinus and described the feasibility of the use of Onyx.

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Objectives: The purpose of this study is to compare the various magnetic resonance imaging (MRI) sequences when they are used to visualize and evaluate cerebral venous thrombosis.

Methods: Eleven patients with cerebral venous thrombosis were retrospectively analyzed using computed tomography, MRI, magnetic resonance angiography (MRA), and conventional angiography. The MR sequence included T1-weighted spin echo (SE) imaging, obtained before and after administration of contrast medium, T2-weighted turbo spin echo (TSE), fluid-attenuated inversion recovery (FLAIR), T2*-weighted conventional gradient-echo (GRE), as well as three-dimensional (3D) venous time-of-flight MRA and conventional angiography.

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We report a patient with a ruptured vertebral artery (VA) dissecting aneurysm that was treated by internal trapping of the aneurysm and parent artery using detachable coils with subsequent antegrade recanalization of occluded vertebral artery during the follow-up period. A 38-year-old man was admitted with a ruptured right VA dissecting aneurysm just distal to origin of right posterior inferior cerebellar artery. The dissected segment of the VA was occluded by coil embolization.

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Objective: The purpose of this study was to test a first hypothesis that fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values continue to change in late childhood and adolescence and a second hypothesis that less mature white matter (WM) regions have a higher rate of change than WM regions that are relatively more mature.

Subjects And Methods: Eighty-seven healthy children (50 girls, 37 boys; mean age, 11.2 ± 3.

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Background And Purpose: The incidence and risk factors for recurrence after endovascular treatment of intracranial vertebrobasilar dissecting aneurysms (VBDAs) have not been studied. We aimed to evaluate the incidence and risk factors for recurrence after endovascular treatment of VBDAs.

Methods: A total of 111 patients (mean age, 45±10 years) underwent endovascular treatment for 119 VBDAs (ruptured/unruptured=73:46).

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