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Leonard Sunwoo

Seoul National University · Medicine

About the Lab

Professor Leonard Sunwoo's research lab specializes in medical image analysis and artificial intelligence, with a focus on advancing deep learning and compressed sensing techniques for magnetic resonance imaging (MRI) reconstruction and diagnosis. The lab explores data-driven approaches such as low-rank Hankel matrix completion and unpaired deep learning to enable accurate k-space interpolation with reduced scan time, particularly in accelerated MRI. Additionally, the lab investigates the application of convolutional neural networks in detecting diseases like brain metastasis, sinusitis, and vascular changes from retinal fundus images, emphasizing diagnostic accuracy and clinical relevance.

accelerated MRIdeep learningk-space reconstructionmedical image analysisdiagnostic AI

Research Overview

Papers
115
Total Citations
1,904
Papers (5y)
65
Primary Field
Medicine

Research Output Trend

Figures are computed from collected data and may differ slightly.

Publications per year (5y)
65total
2022
2023
2024
2025
2026
Citations per year (5y)
336total
20222023202420252026

Selected Papers

15
1
Article|336 citations·2019
k -Space Deep Learning for Accelerated MRI
Yoseob Han, Leonard Sunwoo, Jong Chul Ye
SJR Q1IEEE Transactions on Medical Imaging

The annihilating filter-based low-rank Hankel matrix approach (ALOHA) is one of the state-of-the-art compressed sensing approaches that directly interpolates the missing k -space data using low-rank Hankel matrix completion. The success of ALOHA is due to the concise signal representation in the k -space domain, thanks to the duality between structured low-rankness in the k -space domain and the image domain sparsity. Inspired by the recent mathematical discovery that links convolutional neural

Computational MechanicsEngineering
2
Review|119 citations·2020
Brain metastasis detection using machine learning: a systematic review and meta-analysis
Se Jin Cho, Leonard Sunwoo, Sung Hyun Baik, Yun Jung Bae, Byung Se Choi, Jae Hyoung Kim
SJR Q1Neuro-OncologyOA

BACKGROUND: Accurate detection of brain metastasis (BM) is important for cancer patients. We aimed to systematically review the performance and quality of machine-learning-based BM detection on MRI in the relevant literature. METHODS: A systematic literature search was performed for relevant studies reported before April 27, 2020. We assessed the quality of the studies using modified tailored questionnaires of the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) criteria and the Ch

Pulmonary and Respiratory MedicineMedicine
3
Article|108 citations·2018
Deep Learning in Diagnosis of Maxillary Sinusitis Using Conventional Radiography
Youngjune Kim, Kyong Joon Lee, Leonard Sunwoo, Dongjun Choi, Chang-Mo Nam, Jungheum Cho, Jihyun Kim, Yun Jung Bae, Roh‐Eul Yoo, Byung Se Choi, Cheolkyu Jung, Jae Hyoung Kim
SJR Q1Investigative Radiology

OBJECTIVES: The aim of this study was to compare the diagnostic performance of a deep learning algorithm with that of radiologists in diagnosing maxillary sinusitis on Waters' view radiographs. MATERIALS AND METHODS: Among 80,475 Waters' view radiographs, examined between May 2003 and February 2017, 9000 randomly selected cases were classified as normal or maxillary sinusitis based on radiographic findings and divided into training (n = 8000) and validation (n = 1000) sets to develop a deep lear

OtorhinolaryngologyMedicine
4
Article|84 citations·2020
Unpaired Deep Learning for Accelerated MRI Using Optimal Transport Driven CycleGAN
Gyutaek Oh, Byeongsu Sim, Hyungjin Chung, Leonard Sunwoo, Jong Chul Ye
SJR Q1IEEE Transactions on Computational Imaging

Recently, deep learning approaches for accelerated MRI have been extensively studied thanks to their high performance reconstruction in spite of significantly reduced run-time complexity. These neural networks are usually trained in a supervised manner, so matched pairs of subsampled, and fully sampled k-space data are required. Unfortunately, it is often difficult to acquire matched fully sampled k-space data, since the acquisition of fully sampled k-space data requires long scan time, and ofte

Radiology, Nuclear Medicine and ImagingMedicine
5
Article|79 citations·2020
Effects of Hypertension, Diabetes, and Smoking on Age and Sex Prediction from Retinal Fundus Images
Yong Dae Kim, Kyoung Jin Noh, Seong Jun Byun, Soochahn Lee, Tackeun Kim, Leonard Sunwoo, Kyong Joon Lee, Si‐Hyuck Kang, Kyu Hyung Park, Sang Jun Park
SJR Q1Scientific ReportsOA

Abstract Retinal fundus images are used to detect organ damage from vascular diseases (e.g. diabetes mellitus and hypertension) and screen ocular diseases. We aimed to assess convolutional neural network (CNN) models that predict age and sex from retinal fundus images in normal participants and in participants with underlying systemic vascular-altered status. In addition, we also tried to investigate clues regarding differences between normal ageing and vascular pathologic changes using the CNN

Radiology, Nuclear Medicine and ImagingMedicine
6
Article|65 citations·2016
Differentiation of Glioblastoma from Brain Metastasis: Qualitative and Quantitative Analysis Using Arterial Spin Labeling MR Imaging
Leonard Sunwoo, Tae Jin Yun, Sung‐Hye You, Roh‐Eul Yoo, Koung Mi Kang, Seung Hong Choi, Ji‐hoon Kim, Chul‐Ho Sohn, Sun‐Won Park, Cheolkyu Jung, Chul‐Kee Park
SJR Q1PLoS ONEOA

ASL perfusion MR imaging can aid in the differentiation of GBM from brain metastasis.

GeneticsMedicine
7
Article|60 citations·2019
Fully Automatic Segmentation of Acute Ischemic Lesions on Diffusion-Weighted Imaging Using Convolutional Neural Networks: Comparison with Conventional Algorithms
Ilsang Woo, A-Reum Lee, Seung Chai Jung, Hyunna Lee, Namkug Kim, Se Jin Cho, Donghyun Kim, Jung Bin Lee, Leonard Sunwoo, Dong‐Wha Kang
SJR Q1Korean Journal of RadiologyOA

The CNN algorithm for automatic segmentation of acute ischemic lesions on DWI achieved Dice indices greater than or equal to 0.85 and showed superior performance to conventional algorithms.

EpidemiologyMedicine
8
Article|56 citations·2017
Computer-aided detection of brain metastasis on 3D MR imaging: Observer performance study
Leonard Sunwoo, Young Jae Kim, Seung Hong Choi, Kwang Gi Kim, Ji Hee Kang, Yeonah Kang, Yun‐Jung Bae, Roh‐Eul Yoo, Jihang Kim, Kyong Joon Lee, Seung-Hyun Lee, Byung Se Choi
SJR Q1PLoS ONEOA

CAD as a second reader helps radiologists improve their diagnostic performance in the detection of BM on MR imaging, particularly for less-experienced reviewers.

Pulmonary and Respiratory MedicineMedicine
9
Article|51 citations·2012
Correlation of apparent diffusion coefficient values measured by diffusion MRI and MGMT promoter methylation semiquantitatively analyzed with MS‐MLPA in patients with glioblastoma multiforme
Leonard Sunwoo, Seung Hong Choi, Chul‐Kee Park, Jin Wook Kim, Kyung Sik Yi, Woong Jae Lee, Tae Jin Yoon, Sang Woo Song, Ja‐Eun Kim, Ji Young Kim, Tae Min Kim, Se‐Hoon Lee
SJR Q1Journal of Magnetic Resonance ImagingOA

PURPOSE: To retrospectively determine whether the apparent diffusion coefficient (ADC) values correlate with O(6)-methylguanine DNA methyltransferase (MGMT) promoter methylation semiquantitatively analyzed by methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) in patients with glioblastoma. MATERIALS AND METHODS: The study was approved by the Institutional Review Board and was Health Insurance Portability and Accountability Act (HIPAA) compliant. Newly diagnosed patie

GeneticsMedicine
10
Article|51 citations·2018
Machine learning for detecting moyamoya disease in plain skull radiography using a convolutional neural network
Tackeun Kim, Jaehyuk Heo, Dong‐Kyu Jang, Leonard Sunwoo, Joonghee Kim, Kyong Joon Lee, Si‐Hyuck Kang, Sang Jun Park, O-Ki Kwon, Chang Wan Oh
SJR Q1EBioMedicineOA

DL can distinguish MMD cases within specific ages from controls in plain skull radiograph images with considerable accuracy and AUROC. The viscerocranium may play a role in MMD-related skull features. FUND: This work was supported by grant no. 18-2018-029 from the Seoul National University Bundang Hospital Research Fund.

RheumatologyMedicine
11
Article|43 citations·2021
Deep Learning for Diagnosis of Paranasal Sinusitis Using Multi-View Radiographs
Yejin Jeon, Kyeorye Lee, Leonard Sunwoo, Dongjun Choi, Dong Yul Oh, Kyong Joon Lee, Youngjune Kim, Jeong‐Whun Kim, Se Jin Cho, Sung Hyun Baik, Roh‐Eul Yoo, Yun Jung Bae
SJR Q2DiagnosticsOA

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 (n = 1403, sinusitis% = 34.3%) and the test set (n = 132, sinusitis% = 29.5%) by temporal separation. The algorithm can simultaneously detect and classify each paranasal sinus us

OtorhinolaryngologyMedicine
12
Article|27 citations·2021
Deep Learning-Based Computer-Aided Detection System for Automated Treatment Response Assessment of Brain Metastases on 3D MRI
Jungheum Cho, Young Jae Kim, Leonard Sunwoo, Gi Pyo Lee, Toan Nguyen, Se Jin Cho, Sung Hyun Baik, Yun Jung Bae, Byung Se Choi, Cheolkyu Jung, Chul‐Ho Sohn, Jungho Han
SJR Q2Frontiers in OncologyOA

BACKGROUND: Although accurate treatment response assessment for brain metastases (BMs) is crucial, it is highly labor intensive. This retrospective study aimed to develop a computer-aided detection (CAD) system for automated BM detection and treatment response evaluation using deep learning. METHODS: We included 214 consecutive MRI examinations of 147 patients with BM obtained between January 2015 and August 2016. These were divided into the training (174 MR images from 127 patients) and test da

Pulmonary and Respiratory MedicineMedicine
13
Review|27 citations·2021
Classification of true progression after radiotherapy of brain metastasis on MRI using artificial intelligence: a systematic review and meta-analysis
Hae Young Kim, Se Jin Cho, Leonard Sunwoo, Sung Hyun Baik, Yun Jung Bae, Byung Se Choi, Cheolkyu Jung, Jae Hyoung Kim
SJR Q1Neuro-Oncology AdvancesOA

BACKGROUND: Classification of true progression from nonprogression (eg, radiation-necrosis) after stereotactic radiotherapy/radiosurgery of brain metastasis is known to be a challenging diagnostic task on conventional magnetic resonance imaging (MRI). The scope and status of research using artificial intelligence (AI) on classifying true progression are yet unknown. METHODS: We performed a systematic literature search of MEDLINE and EMBASE databases to identify studies that investigated the perf

Pulmonary and Respiratory MedicineMedicine
14
Article|25 citations·2015
Evaluation of the degree of arteriovenous shunting in intracranial arteriovenous malformations using pseudo-continuous arterial spin labeling magnetic resonance imaging
Leonard Sunwoo, Chul‐Ho Sohn, Jong Young Lee, Kyung Sik Yi, Tae Jin Yun, Seung Hong Choi, Young Dae Cho, Ji‐hoon Kim, Sun‐Won Park, Moon Hee Han, Sun Ha Paek, Yong Hwy Kim
SJR Q1Neuroradiology
NeurologyMedicine
15
Article|16 citations·2018
Metal Artifact Reduction for Orthopedic Implants: Brain CT Angiography in Patients with Intracranial Metallic Implants
Leonard Sunwoo, Sun‐Won Park, Jung Hyo Rhim, Yeonah Kang, Young Seob Chung, Young‐Je Son, Soo Chin Kim
SJR Q2Journal of Korean Medical ScienceOA

In conclusion, the use of the O-MAR in patients with metallic implants significantly reduces image noise. However, the degree of the streak artifacts and surrounding vessel depiction were not significantly improved on O-MAR images.

Biomedical EngineeringEngineering

Research Areas

EpidemiologyRadiology, Nuclear Medicine and ImagingPulmonary and Respiratory MedicineNeurologyOtorhinolaryngologyBiomedical Engineering

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