Publications by authors named "Dongkyu Oh"

This study investigates the hydrogen embrittlement behavior of API X70 linepipe steel. The microstructure was primarily composed of a dislocation-rich bainitic microstructure and polygonal ferrite. Slow strain-rate tests (SSRTs) were performed under both ex situ and in situ electrochemical hydrogen charging conditions to examine the difference between hydrogen diffusion and trapping behaviors.

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Introduction: Technetium thyroid uptake (TcTU) measured by single-photon emission CT/CT (SPECT/CT) is an important diagnostic tool for the differential diagnosis of Graves' disease and destructive thyroiditis. Artificial intelligence (AI) may reduce CT-induced radiation exposure by substituting the role of CT in attenuation correction (AC) and thyroid segmentation, thus realising CT-free SPECT. This study aims to compare the diagnostic accuracy for the differential diagnosis of thyrotoxicosis between CT-free SPECT and SPECT/CT.

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Background: Accurate attenuation correction (AC) is vital in nuclear medicine, particularly for quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) imaging. This study aimed to establish a CT-free quantification technology in kidney SPECT imaging using deep learning to generate synthetic attenuation maps (μ-maps) from SPECT data, thereby reducing radiation exposure and eliminating the need for CT scans.

Results: A dataset of 1000 Tc-99m DTPA SPECT/CT scans was analyzed for training (n = 800), validation (n = 100), and testing (n = 100) using a modified 3D U-Net for deep learning.

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Objective: We aimed to investigate the recovery of gait function, muscle strength, and the achievement of an independent gait after lung transplantation (LT) in patients with and without pretransplant extracorporeal membrane oxygenation (ECMO) support.

Methods: We retrospectively reviewed the medical records of 33 inpatients who underwent bilateral LT and received physical therapy. We assessed the Functional Ambulatory Category (FAC) and Manual Muscle Test (MMT) scores at baseline, 1 month, and 3 months of rehabilitation and the time it took to achieve a FAC score of 3 within 3 months of LT surgery in ECMO and non-ECMO patients.

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Purpose: Quantitative thyroid single-photon emission computed tomography/computed tomography (SPECT/CT) requires computed tomography (CT)-based attenuation correction and manual thyroid segmentation on CT for %thyroid uptake measurements. Here, we aimed to develop a deep-learning-based CT-free quantitative thyroid SPECT that can generate an attenuation map (μ-map) and automatically segment the thyroid.

Methods: Quantitative thyroid SPECT/CT data (n = 650) were retrospectively analyzed.

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Purpose: To determine whether arterioportal shunting to the contralateral lobe attenuates liver function and hypertrophy of the nontargeted liver after radioembolization in patients with hepatocellular carcinoma (HCC).

Materials And Methods: The current retrospective study included 46 patients who received radioembolization for HCC contained within the right lobe between 2012 and 2020. The patients were divided into the following groups on the basis of the presence and extent of arterioportal shunting: patients with retrograde arterioportal shunting to the left lobe (contralateral group) and patients with arterioportal shunt limited to the right lobe or no arterioportal shunt (control group).

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Purpose:  Ga-DOTA-TOC uptake in the pancreas uncinate process is often found due to physiologic expression of somatostatin receptors (SSTR). We investigated the association of physiologic  Ga-DOTA-TOC uptake in the pancreas uncinate process with blood glucose level.

Methods:  Ga-DOTA-TOC PET scans acquired from 44 patients (male:female = 20:24, age = 50.

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Background: The current diagnostic criteria for temporomandibular disorders (TMD) do not require imaging for the diagnosis of degenerative joint disease (DJD) of the temporomandibular joint (TMJ) condyle, and there is a lack of data investigating the effectiveness of imaging modalities in predicting long-term TMJ DJD prognosis.

Objectives: To verify the association between initial bone scintigraphy results and long-term DJD bone changes occurring in the TMJ condyle on cone beam computed tomography (CBCT).

Methods: Initial bone scintigraphy, panoramic radiography and CBCT results were analysed in relation to long-term (12 months) TMJ DJD bone change on CBCTs in 55 TMD patients (110 joints).

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Quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) using Tc-99m pertechnetate aids in evaluating salivary gland function. However, gland segmentation and quantitation of gland uptake is challenging. We develop a salivary gland SPECT/CT with automated segmentation using a deep convolutional neural network (CNN).

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Introduction: Patients presenting with tears of the triangular fibrocartilage complex (TFCC) can have ulnar positive variance, for which the clinical relevance to concomitant ulnar impaction syndrome (UIS) may be unclear. We hypothesized that maximum standardized uptake value (SUVmax), a semiquantitative single-photon-emission computed tomography/computed tomography (SPECT/CT) value, would distinguish between the traumatic TFCC tear and degenerative TFCC tear associated with the UIS. This study aimed to compare SUVmax between patients with TFCC tear only and patients with TFCC tear and UIS.

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Introduction: This case is shared to reiterate and confirm the principles of ensuring the safety of the surgical team caring for COVID-19-confirmed patients, thus, preventing the spread of infection within the hospital.

Case Presentation: A 54-year-old male, COVID-19-confirmed patient complaining of abdominal pain since two days prior was transferred to our hospital. Perforated appendicitis with a periappendiceal abscess was diagnosed by computed tomography.

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Purpose: Amyloid PET which has been widely used for noninvasive assessment of cortical amyloid burden is visually interpreted in the clinical setting. As a fast and easy-to-use visual interpretation support system, we analyze whether the deep learning-based end-to-end estimation of amyloid burden improves inter-reader agreement as well as the confidence of the visual reading.

Methods: A total of 121 clinical routines [F]Florbetaben PET images were collected for the randomized blind-reader study.

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Purpose: Although quantification of amyloid positron emission tomography (PET) is important for evaluating patients with cognitive impairment, its routine clinical use is hampered by complicated preprocessing steps and required MRI. Here, we suggested a one-step quantification based on deep learning using native-space amyloid PET images of different radiotracers acquired from multiple centers.

Methods: Amyloid PET data of the Alzheimer Disease Neuroimaging Initiative (ADNI) were used for this study.

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As the need for the organ donation increases, strategies to increase kidney transplantation (KT) through expanded living donation have become essential. These include kidney paired donation (KPD) programs and desensitization in incompatible transplantations. KPD enables kidney transplant candidates with incompatible living donors to join a registry with other incompatible pairs in order to find potentially compatible living donor.

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Extragonadal teratoma originating from the retroperitoneum represents less than 5% of all teratomas and accounts for less than 10% of all pediatric retroperitoneal neoplasms. To date, there has been no report of teratoma managed with LT. This study reports an infant aged 3 months with retroperitoneal immature teratoma involving the hepatic hilum, refractory to chemotherapy and treated with LT.

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Patients with large spontaneous splenorenal shunts (SRSs) prove challenging during liver transplantation (LT), regardless of organizing portal vein (PV) thrombosis. Here, we detail the clinical outcomes of 26 patients who underwent direct ligation of large SRSs during LT. Direct ligation of large SRS was applied in poor portal flow during LT.

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Background: Despite increases in the performance of pure laparoscopic living donor hepatectomy, variations in the bile duct or portal vein have been regarded as relative contraindications to this technique [1-3]. This report describes a donor with separate right posterior and right anterior hepatic ducts and portal veins who underwent pure laparoscopic living donor right hemihepatectomy, integrated with 3D laparoscopy and indocyanine green (ICG) near-infrared fluorescence cholangiography [1, 4, 5].

Methods: A 50-year-old man offered to donate part of his liver to his older brother, who required a transplant for hepatitis B-associated liver cirrhosis and hepatocellular carcinoma.

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Objectives: The purpose of this study is to identify the safety and feasibility of laparoscopic caudate lobectomy.

Background: Caudate lobectomy has been considered as technically difficult because of the deep location of the caudate lobe and its proximity to great vessels. Due to the technical difficulty, laparoscopic caudate lobectomy was not feasible in patients with malignancy in the caudate lobe.

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