Youngjun Kim

Imagoworks Inc.

BACKGROUND: There is considerable debate on the recovery of rotator cuff muscle atrophy after rotator cuff repair. PURPOSE: To evaluate the serial changes in supraspinatus muscle volume after rotator cuff repair by using semiautomatic segmentation software and to determine the relationship with functional outcomes. STUDY DESIGN: Case series; Level...

Deformable surface mesh registration is a useful technique for various medical applications, such as intra-operative treatment guidance and intra- or inter-patient study. In this paper, we propose an automatic deformable mesh registration technique. The proposed method iteratively deforms a source mesh to a target mesh without manual feature extrac...

Background: The convergence of three-dimensional (3D) simulation, tissue engineering, and 3D printing technology is creating a paradigm shift in plastic surgery. In augmentation rhinoplasty, determining the ideal material and design method has been a critical issue for many years. Thus, these technologies are expected to make important contribution...

Background and objectives: With significant increase in the number of people suffering from shoulder problems, the automatic image segmentation of the supraspinatus (one of the shoulder muscles) has become necessary for efficient and deliberate diagnosis and surgery. In this study, we developed an automatic segmentation method to extract the three...

Recently, virtual reality (VR) and augmented reality (AR) have received increasing attention, with the development of VR/AR devices such as head-mounted displays, haptic devices, and AR glasses. Medicine is considered to be one of the most effective applications of VR/AR. In this article, we describe a systematic literature review conducted to inve...

Purpose Although the Dejour classification is the primary classification system for evaluating trochlear dysplasia, concerns have been raised about its reliability owing to its qualitative criteria and challenges associated with obtaining accurate radiographs. This study aimed to quantify trochlear dysplasia using three‐dimensional (3D) computed to...

This study compared the marginal and internal fit of zirconia crowns fabricated using conventional and high-speed induction sintering. A typodont mandibular right first molar was prepared and 60 zirconia crowns were fabricated: 30 crowns using conventional sintering and 30 crowns using high-speed sintering. We presented a new evaluation methodology...

With the increase of the adult orthodontic population, there is a need for an accurate and evidence-based prediction of the posttreatment face in 3 dimensions (3D). The objectives of this study are 1) to develop a 3D postorthodontic face prediction method based on a deep learning network using the patient-specific factors and orthodontic treatment...

Objectives To evaluate whether the accuracy and duration of registration for cone beam computed tomography (CBCT) and intraoral scans differ according to the method of registration and ratio of dental restorations to natural teeth. Materials and methods CBCT data and intraoral scans of eligible patients were grouped as follows according to the rat...

Sophisticated segmentation of the craniomaxillofacial bones (the mandible and maxilla) in computed tomography (CT) is essential for diagnosis and treatment planning for craniomaxillofacial surgeries. Conventional manual segmentation is time-consuming and challenging due to intrinsic properties of craniomaxillofacial bones and head CT such as the va...

Background Small-incision lenticule extraction (SMILE) is a surgical procedure for the refractive correction of myopia and astigmatism, which has been reported as safe and effective. However, over- and under-correction still occur after SMILE. The necessity of nomograms is emphasized to achieve optimal refractive results. Ophthalmologists diagnose...

Geometrical and topological inconsistencies, such as self-intersections and non-manifold elements, are common in triangular meshes, causing various problems across all stages of geometry processing. In this paper, we propose a method to resolve these inconsistencies using a graph-based approach. We first convert geometrical inconsistencies into top...

In recent years, artificial intelligence (AI) technologies have greatly advanced and become a reality in many areas of our daily lives. In the health care field, numerous efforts are being made to implement the AI technology for practical medical treatments. With the rapid developments in machine learning algorithms and improvements in hardware per...

Rotator cuff tear (RCT) is one of the most common shoulder injuries. When diagnosing RCT, skilled orthopedists visually interpret magnetic resonance imaging (MRI) scan data. For automated and accurate diagnosis of RCT, we propose a full 3D convolutional neural network (CNN) based method using deep learning. This 3D CNN automatically diagnoses the p...

Background: Small-incision lenticule extraction (SMILE) is a surgical procedure for the refractive correction of myopia and astigmatism, which has been reported as safe and effective. However, over- and under-correction still occur after SMILE. The necessity of nomograms is emphasized to achieve optimal refractive results. Ophthalmologists diagnose...

Background: Small-incision lenticule extraction (SMILE) is a surgical procedure for the refractive correction of myopia and astigmatism, which has been reported as safe and effective. However, over- and under-correction still occur after SMILE. The necessity of nomograms is emphasized to achieve optimal refractive results. Ophthalmologists diagnose...

Background and Objective An accurate lateral cephalometric analysis is vital in orthodontic diagnosis. Identification of anatomic landmarks on lateral cephalograms is tedious, and errors may occur depending on the doctor's experience. Several attempts have been made to reduce this time-consuming process by automating the process through machine lea...

Surgical plates used for reconstructive surgery require a repetitive manual bending process to fit the plate to the defect during reconstruction. However, this process may not produce a plate that fits well, and repetitive bending may significantly increase the risk of plate fracture due to the accumulation of residual stress. In this study, the in...

Surgical plates, which are used in various bone reconstruction surgeries, must be accurately bent intraoperatively or preoperatively. Manual bending is a time- and labor-consuming process, which sometimes results in residual stress to the plate after repeated operations. To overcome these problems, we propose a motorized bending apparatus for surgi...

In this paper, we propose a surgical planning system to automate the preoperative planning for mandibular reconstruction with a fibula free flap. We designed surgical guides with user-friendly interfaces based on the surgical plans. In this system, the osteotomy planes of the fibula and the position of each fibular segment are calculated automatica...

In this study, we developed a new 3-dimensional (3D) preoperative planning software and investigated its effectiveness by measuring orbital volume change. Fifty-six patients who underwent unilateral orbital wall reconstruction between December 2015 and February 2018 in our institute were recruited. We developed an orbit-specific automatic 3D modeli...

Purpose: Three-dimensional orbital wall modeling is a time-consuming process because of the presence of pseudoforamina. We developed an automated three-dimensional modeling software to characterize the orbital wall, and evaluated it using data from fracture patients. Methods: We first characterized the air and face regions using multiphase segme...

Background: The correction of orbital deformities is an ongoing challenge in maxillofacial surgery. Computer-assisted navigation can improve surgical outcomes. However, conventional registration methods for navigation are not appropriate for orbital reconstructive surgery. This study proposes an accurate, noninvasive, patient-specific navigation m...

Background and purpose — We aimed to evaluate the ability of artificial intelligence (a deep learning algorithm) to detect and classify proximal humerus fractures using plain anteroposterior shoulder radiographs. Patients and methods — 1,891 images (1 image per person) of normal shoulders (n = 515) and 4 proximal humerus fracture types (greater tub...

Background: A decreased flap volume can be an obstacle to proper phonation and swallowing. In this study we verified the proportion of volume decrease using 3D reconstructed images and identified the contributors to flap volume loss. Methods: We retrospectively analyzed all patients who underwent radical excision of tongue cancer and reconstruct...

X-ray imaging is the conventional method for diagnosing the orthopedic condition of a patient. Computerized Tomography(CT) scanning is another diagnostic method that provides patient’s 3D anatomical information. However, both methods have limitations when diagnosing the whole leg; X-ray imaging does not provide 3D information, and normal CT scannin...

Purpose: The purpose of this study was to evaluate the anatomical similarity of three-dimensional (3D) morphometric parameters between right and left knees. Materials and methods: Ten fresh-frozen paired cadaveric knees were tested. Following dissection, footprint areas of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL...

Boolean operations are classic procedures in computer-aided design, and allow the creation of complex objects by combining simple objects. Although Boolean operations are trivial in implicit surface representations, they are problematic in polygonal meshes. Methods that directly use meshes to compute Boolean operations consistently consider the int...

Image-based surgical techniques can support minimally invasive keyhole neurosurgery through the segmentation of computed tomography or magnetic resonance imaging, optimal surgical planning, and surgical guidance. Keyhole neurosurgery requires automatic surgical planning and accuracy guidance for a target of the non-invasive or minimally invasive tr...

Purpose: Boolean operations in computer-aided design or computer graphics are a set of operations (e.g. intersection, union, subtraction) between two objects (e.g. a patient model and an implant model) that are important in performing accurate and reproducible virtual surgical planning. This requires accurate and robust techniques that can handle...

Study design: Study for feasibility of commercially available action cameras in recording video of spine. Objective: Recent innovation of the wearable action camera with high definition video recording enables surgeons to use camera in the operation at ease without high costs. The purpose of this study is to compare the feasibility, safety, effi...

Background: Recently, surgical navigation systems have been widely used to improve the results of various orthopaedic surgeries. However, surgical navigation has not been successful in anterior cruciate ligament reconstruction, owing to its inaccuracy and inconvenience. This study investigated the registration of preoperative and intraoperative da...

Positioning a surgical robot for optimal operation in a crowded operating room is a challenging task. In the robotic-assisted surgical procedures, the surgical robot’s end-effector must reach the patient’s anatomical targets because repositioning of the patient or surgical robot requires additional time and labor. This paper proposes an optimizatio...

The limited workspace and potential for collision between the robot arm and surrounding environment are challenges in robotassisted surgery. In robot-assisted surgical procedures, the surgical robot’s end-effector must reach the patient’s anatomical targets without collision with the patient or surrounding instrument. This paper proposes a novel en...

IntroductionSimultaneous bilateral total knee arthroplasty (TKA) has been associated with a high risk of morbidity and mortality. The orthopedic surgeon must, therefore, decide whether bilateral simultaneous TKA is a safe operation to perform and endeavor to decrease the risk of serious complications or even death. Methods This retrospective review...

PurposeTo evaluate the clinical advantages of a navigation system developed with an emphasis on attaining an appropriate femoral tunnel length and posterior wall margin with no posterior wall blowout, as well as having accurate tunnel positioning, in anatomical anterior cruciate ligament reconstruction (ACLR). Methods Ten freshly frozen human knees...

In mandibular reconstructive surgery, straight surgical plates are predominantly used for osteotomy. In this process, a straight plate is bent to fit to the shape of the patient's defect. This potentially compromises the stability of the plate because of changes in mechanical properties resulting from plastic deformation; however, the effect of pla...

Compared to conventional mandibular reconstruction surgery, a recent approach of virtual planning can reduce surgical time providing reliable surgical outcomes. We present our virtual surgical planning software using automatic segmentation and user-friendly techniques. Evaluation experiments compared with a commercial software prove that the propos...

Background: To develop a preoperative planning and navigation system for anatomic anterior cruciate ligament (ACL) reconstruction and to evaluate the accuracy and the efficacy of anatomical ACL reconstruction using only navigation guidance. Methods: A three-dimensional (3D) preoperative planning and navigation system was developed from open sour...

In this paper, we propose a virtual surgical planning system specialized to mandible reconstruction surgery. Mandible reconstruction surgery is one of the most difficult surgeries, even for experienced surgeons. Compared to the traditional surgical procedures, virtual surgical planning can reduce the operation time in operating room while expecting...

Recently, computed tomography (CT) has been used for non-destructive inspection. The rapid development of CT scanning hardware and software, CT became one of the major inspection solutions for non-destructive inspection. Because non-destructive inspection does not damage the product, it is beneficial in time and money in product quality testing. Mo...

Background: The aim of this prospective randomized study was to compare the efficacy of 3 injection methods, intra-articular injection, subacromial injection, and hydrodilatation (HD), in the treatment of primary frozen shoulder. Methods: Patients with primary frozen shoulder were randomized to undergo intra-articular injection (n = 29), subacro...

In this study, the effect of the geometrical configuration of retroreflective markers on the maximum tracking uncertainty of target points during a medical navigation is analyzed. Methods that help users select and set up an optimal configuration for minimizing the navigation uncertainty are proposed. The methods are evaluated by simulating surgica...

In this paper, we propose calibration methods that can be applied to the markerless surgical robotic system for Intracerebral Hematoma (ICH) Surgery. This surgical robotic system does not require additional process of patient imaging but only uses CT images that are initially taken for a diagnosis purpose. Furthermore, the system applies markerless...

Conventional intracerebral hemorrhage (ICH) surgery uses a stereotactic frame to access an intracerebral hematoma. Using a stereotactic frame for ICH surgery requires a long preparation time. In order to resolve this problem, we propose a markerless surgical robotic system. This system uses weighted iterative closest point technology for surface re...

This paper presents a new active contour segmentation model using a level set function that can correctly capture both the strong and the weak boundaries of a target enclosed by bright and dark regions at the same time. We introduce an enhanced image obtained from prior information about the intensity of the target. The enhanced image emphasizes th...

Virtual simulation of laparoscopic surgery is get-ting attention for training novice surgeons and medical res-idents for practice. Virtual surgical simulation has many advantages because it can provide users with a safe envi-ronment without animal or patient subjects. Although sev-eral solutions are available in the market, there are no reported st...

Purpose: 3D optical surface imaging has been applied to patient positioning in radiation therapy (RT). The optical patient positioning system is advantageous over conventional method using cone-beam computed tomography (CBCT) in that it is radiation free, frameless, and is capable of real-time monitoring. While the conventional radiographic method...

Advances in computer vision technology and virtual reality technology have been achieved through improvements in camera performance and computability. Cost-effective simulation systems for laparoscopic surgery are proposed by combining such technologies. In this study, we propose a novel 3D instrument tracking technique using a single camera to obt...

In this paper, we present a new active contours model to segment human leg bones in computed tomography images that is based on a variable-weighted combination of local and global intensity. This model can split an object surrounded by both weak and strong boundaries, and also distinguish very adjacent objects with those boundaries. The ability of...

Purpose: Focal radiosurgery is a common treatment modality for trigeminal neuralgia (TN), a neuropathic facial pain condition. Assessment of treatment effectiveness is primarily clinical, given the paucity of investigational tools to assess trigeminal nerve changes. The efficiency of radiosurgery is related to its highly precise targeting. We asses...

Purpose: Optical surface imaging has been applied to radiation therapy patient setup. This study aims to investigate the accuracy of the surface registration of the optical surface imaging compared with that of the conventional method of volumetric registration for patient setup in head and neck radiation therapy. Methods: Clinical datasets of plan...

The inferior alveolar nerve canal is an important nerve canal in the jaw bone, and any damage to this canal can cause pain or fatal complications. Since such damage can be caused by a wrong surgical procedure or surgery plan, accurate surgery planning is necessary. Cone-beam computed tomography (CBCT) is a three-dimensional medical imaging method t...

Anterior cruciate ligament (ACL) injury is one of the most common ligament injuries and the risk of that is being increased. Arthroscopic technique is commonly used for ACL reconstruction surgery. The arthroscopic surgery for ACL reconstruction contains arthroscopic examination, tunnel formation, and graft passage and fixation. It is important to m...

Laparoscopic surgery has many advantages, but it is difficult for a surgeon to achieve the necessary surgical skills. Recently, virtual training simulations have been gaining interest because they can provide a safe and efficient learning environment for medical students and novice surgeons. In this paper, we present a hybrid modeling method for si...

Template-guided intraoral surgery is attracting interest due to its accuracy and convenience. Usually, fiducial markers are used for registration of the different model coordinates for patients or plaster and fabrication coordinates in template-guided dental surgery. The accuracy of markers is important because it is directly related to the accurac...

Conventional Conventional Conventional Conventional Conventional Conventional Conventional Conventional Conventional intracerebral ntracerebral ntracerebral ntracerebral ntracerebral ntracerebral ntracerebral hematoma ematoma ematoma ematoma ematoma ematoma (ICH) removal s(ICH) removal s(ICH) removal s(ICH) removal s (ICH) removal s(ICH) removal s(...

We present a novel method of volume removal for deformable mesh data. The proposed method has the advantages of both volumetric mesh removal technique and hexahedral mesh deformation. Barycentric mapping combines the volumetric mesh for carving and the hexahedral mesh for deformation. The proposed algorithm for carving the deformable mesh is applie...

It is required to use a stereotactic frame on a patient's crainial surface to access an intracerebral hematoma in conventional ICH (Intracerebral Hemorrhage) removal surgery. Since ICH using a stereotactic frame is an invasive procedure and also takes a long time, we attempt to develop a robotic ICH removal procedure with a markerless registration...

Calibration of an X-ray imaging system involves estimation of the 3D geometrical configuration of the system components. Here, we propose a calibration method for stereo X-ray imaging systems, which capture two X-ray images at two orthogonal positions. The calibration parameters include the relation between image coordinates and world coordinates,...

With a number of advantages over traditional laparotomy, laparoscopic surgery is a successful minimally invasive surgical procedure. However, laparoscopy demands high surgical skill. For efficient and safe training, virtual surgery simulation systems have been developed recently. In this paper, we describe the development of a laparoscopic surgery...

In spite of the several advantages of the laparoscopic surgery simulation system, its high cost prohibits many medical institutions from using it. To address this issue, this paper proposes a system that utilizes an off-the-shelf product, the Falcon™ (Novint Technologies Inc., USA) device, for controlling the movement of surgical instruments and th...

Most laparoscopic surgery simulation systems are expensive and complex. To overcome these problems, this study presents a novel three-dimensional tracking method for laparoscopic surgical instruments that uses only a single camera and fiducial markers. The proposed method does not require any mechanical parts to measure the three-dimensional positi...

Radiographic evaluation of patients after total knee arthroplasty is an important tool for assessing the correct position of the implants and the axis of limb alignment because this will determine long-term durability of the implants. Recently, 2D-3D medical image registration methods are developed for 3D postoperative analysis of total knee arthro...

We propose a robust mesh-to-mesh collision detection algorithm using a ray tracing method. The algorithm checks all vertices of a geometrical object based on the proposed criteria, and then the colliding vertices are detected. In order to realize a real-time calculation, acceleration by spatial subdivision is performed. Since the proposed ray-trace...