Three-Dimensional Printing: Basic Principles and Applications in Medicine and Radiology

Kim, Guk Bae,Lee, Sangwook,Kim, Haekang,Yang, Dong Hyun,Kim, Young-Hak,Kyung, Yoon Soo,Kim, Choung-Soo,Choi, Se Hoon,Kim, Bum Joon,Ha, Hojin,Kwon, Sun U.,Kim, Namkug The Korean Society of Radiology 2016 KOREAN JOURNAL OF RADIOLOGY Vol.17 No.2

<P>The advent of three-dimensional printing (3DP) technology has enabled the creation of a tangible and complex 3D object that goes beyond a simple 3D-shaded visualization on a flat monitor. Since the early 2000s, 3DP machines have been used only in hard tissue applications. Recently developed multi-materials for 3DP have been used extensively for a variety of medical applications, such as personalized surgical planning and guidance, customized implants, biomedical research, and preclinical education. In this review article, we discuss the 3D reconstruction process, touching on medical imaging, and various 3DP systems applicable to medicine. In addition, the 3DP medical applications using multi-materials are introduced, as well as our recent results.</P>

Accuracy of one-step automated orthodontic diagnosis model using a convolutional neural network and lateral cephalogram images with different qualities obtained from nationwide multi-hospitals

Sunjin Yim,Sungchul Kim,Inhwan Kim,Jae-Woo Park,Jin-Hyoung Cho,Mihee Hong,Kyung-Hwa Kang,Minji Kim,Su-Jung Kim,Yoon-Ji Kim,Young Ho Kim,Sung-Hoon Lim,Sang Jin Sung,Namkug Kim,Seung-Hak Baek 대한치과교정학회 2022 대한치과교정학회지 Vol.52 No.1

Objective: The purpose of this study was to investigate the accuracy of one-step automated orthodontic diagnosis of skeletodental discrepancies using a convolutional neural network (CNN) and lateral cephalogram images with different qualities from nationwide multi-hospitals. Methods: Among 2,174 lateral cephalograms, 1,993 cephalograms from two hospitals were used for training and internal test sets and 181 cephalograms from eight other hospitals were used for an external test set. They were divided into three classification groups according to anteroposterior skeletal discrepancies (Class I, II, and III), vertical skeletal discrepancies (normodivergent, hypodivergent, and hyperdivergent patterns), and vertical dental discrepancies (normal overbite, deep bite, and open bite) as a gold standard. Pre-trained DenseNet-169 was used as a CNN classifier model. Diagnostic performance was evaluated by receiver operating characteristic (ROC) analysis, t-stochastic neighbor embedding (t-SNE), and gradientweighted class activation mapping (Grad-CAM). Results: In the ROC analysis, the mean area under the curve and the mean accuracy of all classifications were high with both internal and external test sets (all, > 0.89 and > 0.80). In the t-SNE analysis, our model succeeded in creating good separation between three classification groups. Grad-CAM figures showed differences in the location and size of the focus areas between three classification groups in each diagnosis. Conclusions: Since the accuracy of our model was validated with both internal and external test sets, it shows the possible usefulness of a one-step automated orthodontic diagnosis tool using a CNN model. However, it still needs technical improvement in terms of classifying vertical dental discrepancies.

Which combination of MR imaging modalities is best for predicting recurrent glioblastoma? Study of diagnostic accuracy and reproducibility.

Kim, Ho Sung,Goh, Myeong Ju,Kim, Namkug,Choi, Choong Gon,Kim, Sang Joon,Kim, Jeong Hoon Radiological Society of North America 2014 Radiology Vol.273 No.3

<P>To compare the added value of dynamic contrast material-enhanced ( CE contrast enhanced ) ( DCE dynamic CE ) magnetic resonance (MR) imaging with that of dynamic susceptibility CE contrast enhanced ( DSC dynamic susceptibility CE ) MR imaging with the combination of CE contrast enhanced T1-weighted imaging and diffusion-weighted ( DW diffusion weighted ) imaging for predicting recurrent glioblastoma.</P>

CT scanning-based phenotypes vary with <i>ADRB2</i> polymorphisms in chronic obstructive pulmonary disease

Kim, Woo Jin,Oh, Yeon-Mok,Sung, Joohon,Lee, Young Kyung,Seo, Joon Beom,Kim, NamKug,Kim, Tae-Hyung,Huh, Jin Won,Lee, Ji-Hyun,Kim, Eun-Kyung,Lee, Jin Hwa,Lee, Sang-Min,Lee, Sangyeub,Lim, Seong Yong,Shin Elsevier 2009 Respiratory medicine Vol.103 No.1

<P><B>Summary</B></P><P><B>Background</B></P><P>Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease that is characterized by varying degrees of involvement of airway and lung parenchyma. Although cigarette smoke is the major risk factor for COPD, the principal determining factors of involvement of the airway or lung parenchyma have not been clearly defined. Genetic variability in COPD patients might influence the varying degrees of involvement of airway and parenchyma. We therefore studied whether airway and parenchyma involvement might be associated with the <I>ADRB2</I> genotype, which has been reported to be associated with COPD susceptibility and the bronchodilator response.</P><P><B>Methods</B></P><P>One hundred and eleven COPD subjects, whose post-bronchodilator FEV<SUB>1</SUB>/FVC values were less than 0.7, and who had histories of smoking exceeding 10 pack-years, were prospectively recruited from pulmonology clinics of 11 hospitals in Seoul, Korea. The degrees of involvement of airway and parenchyma were evaluated by volumetric computed tomography (CT) scans. In-house software automatically calculated luminal areas, airway wall areas, percentages of wall areas in segmental bronchi, emphysema indices, and mean lung densities in the whole lung parenchyma. The <I>ADRB2</I> genotypes at codon 16 were determined for all patients.</P><P><B>Results</B></P><P>Gly16 was associated with lumen diameter, luminal area, and percentage of wall area in patients with COPD (<I>p</I>=0.02), whereas neither wall area nor wall thickness differed with <I>ADRB2</I> genotype. Neither emphysema index nor mean lung density was associated with <I>ADRB2</I> genotype.</P><P><B>Conclusion</B></P><P>Gly16 variant in <I>ADRB2</I> gene was associated with airway wall phenotypes measured using CT scanning in COPD patients.</P>

Development and Validation of a Model Using Radiomics Features from an Apparent Diffusion Coefficient Map to Diagnose Local Tumor Recurrence in Patients Treated for Head and Neck Squamous Cell Carcinoma

Kim Minjae,Lee Jeong Hyun,Joo Leehi,Jeong Boryeong,Kim Seonok,Ham Sungwon,Yun Jihye,Kim NamKug,Chung Sae Rom,Choi Young Jun,Baek Jung Hwan,Lee Ji Ye,Kim Ji-Hoon 대한영상의학회 2022 Korean Journal of Radiology Vol.23 No.11

Objective: To develop and validate a model using radiomics features from apparent diffusion coefficient (ADC) map to diagnose local tumor recurrence in head and neck squamous cell carcinoma (HNSCC). Materials and Methods: This retrospective study included 285 patients (mean age ± standard deviation, 62 ± 12 years; 220 male, 77.2%), including 215 for training (n = 161) and internal validation (n = 54) and 70 others for external validation, with newly developed contrast-enhancing lesions at the primary cancer site on the surveillance MRI following definitive treatment of HNSCC between January 2014 and October 2019. Of the 215 and 70 patients, 127 and 34, respectively, had local tumor recurrence. Radiomics models using radiomics scores were created separately for T2-weighted imaging (T2WI), contrast-enhanced T1-weighted imaging (CE-T1WI), and ADC maps using non-zero coefficients from the least absolute shrinkage and selection operator in the training set. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of each radiomics score and known clinical parameter (age, sex, and clinical stage) in the internal and external validation sets. Results: Five radiomics features from T2WI, six from CE-T1WI, and nine from ADC maps were selected and used to develop the respective radiomics models. The area under ROC curve (AUROC) of ADC radiomics score was 0.76 (95% confidence interval [CI], 0.62–0.89) and 0.77 (95% CI, 0.65–0.88) in the internal and external validation sets, respectively. These were significantly higher than the AUROC values of T2WI (0.53 [95% CI, 0.40–0.67], p = 0.006), CE-T1WI (0.53 [95% CI, 0.40– 0.67], p = 0.012), and clinical parameters (0.53 [95% CI, 0.39–0.67], p = 0.021) in the external validation set. Conclusion: The radiomics model using ADC maps exhibited higher diagnostic performance than those of the radiomics models using T2WI or CE-T1WI and clinical parameters in the diagnosis of local tumor recurrence in HNSCC following definitive treatment.

A multifunctional mesoporous nanocontainer with an iron oxide core and a cyclodextrin gatekeeper for an efficient theranostic platform

Lee, Jeonghun,Kim, Hyunjung,Kim, Seahee,Lee, Hyemi,Kim, Jin,Kim, Namkug,Park, Heon Joo,Choi, Eun Kyoung,Lee, Jin Seong,Kim, Chulhee The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.28

<P>We report on the dual function of a silica–iron oxide hybrid nanoparticle combined with a stimulus responsive gatekeeper on the surface. Multifunctional hybrid nanoparticles (Fe@Si–DOX–CD–PEG) composed of an Fe<SUB>3</SUB>O<SUB>4</SUB> core, a mesoporous silica shell, and GSH-responsive CD gatekeepers are an excellent platform for anticancer drug delivery and MR imaging. In particular, the CD gatekeepers on the surface of the hybrid nanoparticle play a key role in accommodating anticancer drug molecules in the pore of the silica shell without premature release until CD gatekeepers are cleaved by GSH. We confirmed, from an <I>in vitro</I> study with the A549 cell line, that DOX was released from the internalized carriers due to GSH-mediated cleavage of the CD gatekeeper. Consequently, apoptotic and clonogenic death occurred in the cells treated with Fe@Si–DOX–CD–PEG. The accumulation of Fe@Si–DOX–CD–PEG in the tumors was detected by <I>in vivo</I> MR imaging. The growth of the tumor <I>in vivo</I> was effectively suppressed by the intravenously injected Fe@Si–DOX–CD–PEG. In addition, the results of the <I>in vivo</I> MR imaging reflected the <I>in vivo</I> inhibition of the cancer growth by Fe@Si–DOX–CD–PEG.</P> <P>Graphic Abstract</P><P>Multimodal hybrid nanoparticles composed of a Fe<SUB>3</SUB>O<SUB>4</SUB> core, a mesoporous silica shell, and GSH-responsive CD gatekeepers are an excellent theranostic platform for MR imaging and anticancer drug delivery not only <I>in vitro</I> but also <I>in vivo</I>. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm32137h'> </P>

Post-Stenotic Recirculating Flow May Cause Hemodynamic Perforator Infarction

Bum Joon Kim,Hojin Ha,Hyung Kyu Huh,Guk Bae Kim,Jong S. Kim,Namkug Kim,Sang-Joon Lee,Dong-Wha Kang,Sun U. Kwon 대한뇌졸중학회 2016 Journal of stroke Vol.18 No.1

Background and Purpose The primary mechanism underlying paramedian pontine infarction (PPI) is atheroma obliterating the perforators. Here, we encountered a patient with PPI in the post-stenotic area of basilar artery (BA) without a plaque, shown by high-resolution magnetic resonance imaging (HR-MRI). We performed an experiment using a 3D-printed BA model and a particle image velocimetry (PIV) to explore the hemodynamic property of the post-stenotic area and the mechanism of PPI. Methods 3D-model of a BA stenosis was reconstructed with silicone compound using a 3D-printer based on the source image of HR-MRI. Working fluid seeded with fluorescence particles was used and the velocity of those particles was measured horizontally and vertically. Furthermore, microtubules were inserted into the posterior aspect of the model to measure the flow rates of perforators (pre-and post-stenotic areas). The flow rates were compared between the microtubules. Results A recirculating flow was observed from the post-stenotic area in both directions forming a spiral shape. The velocity of the flow in these regions of recirculation was about one-tenth that of the flow in other regions. The location of recirculating flow well corresponded with the area with low-signal intensity at the time-of-flight magnetic resonance angiography and the location of PPI. Finally, the flow rate through the microtubule inserted into the post-stenotic area was significantly decreased comparing to others (P<0.001). Conclusions Perforator infarction may be caused by a hemodynamic mechanism altered by stenosis that induces a recirculation flow. 3D-printed modeling and PIV are helpful understanding the hemodynamics of intracranial stenosis.

Accuracy of artificial intelligence-assisted landmark identification in serial lateral cephalograms of Class III patients who underwent orthodontic treatment and two-jaw orthognathic surgery

Mihee Hong,Inhwan Kim,Jin-Hyoung Cho,Kyung-Hwa Kang,Minji Kim,Su-Jung Kim,Yoon-Ji Kim,Sang-Jin Sung,Young Ho Kim,Sung-Hoon Lim,Namkug Kim,Seung-Hak Baek 대한치과교정학회 2022 대한치과교정학회지 Vol.52 No.4

Objective: To investigate the pattern of accuracy change in artificial intelligence-assisted landmark identification (LI) using a convolutional neural network (CNN) algorithm in serial lateral cephalograms (Lat-cephs) of Class III (C-III) patients who underwent twojaw orthognathic surgery. Methods: A total of 3,188 Lat-cephs of C-III patients were allocated into the training and validation sets (3,004 Lat-cephs of 751 patients) and test set (184 Lat-cephs of 46 patients; subdivided into the genioplasty and non-genioplasty groups, n = 23 per group) for LI. Each C-III patient in the test set had four Lat-cephs: initial (T0), pre-surgery (T1, presence of orthodontic brackets [OBs]), post-surgery (T2, presence of OBs and surgical plates and screws [S-PS]), and debonding (T3, presence of S-PS and fixed retainers [FR]). After mean errors of 20 landmarks between human gold standard and the CNN model were calculated, statistical analysis was performed. Results: The total mean error was 1.17 mm without significant difference among the four timepoints (T0, 1.20 mm; T1, 1.14 mm; T2, 1.18 mm; T3, 1.15 mm). In comparison of two time-points ([T0, T1] vs. [T2, T3]), ANS, A point, and B point showed an increase in error (p < 0.01, 0.05, 0.01, respectively), while Mx6D and Md6D showeda decrease in error (all p < 0.01). No difference in errors existed at B point, Pogonion, Menton, Md1C, and Md1R between the genioplasty and non-genioplasty groups. Conclusions: The CNN model can be used for LI in serial Lat-cephs despite the presence of OB, S-PS, FR, genioplasty, and bone remodeling.

Intravoxel incoherent motion diffusion-weighted MR imaging of the liver: effect of triggering methods on regional variability and measurement repeatability of quantitative parameters.

Lee, Yedaun,Lee, Seung Soo,Kim, Namkug,Kim, Eunki,Kim, Yeong Jae,Yun, Sung-Cheol,K?hn, Bernd,Kim, In Seong,Park, Seong Ho,Kim, So Yeon,Lee, Moon-Gyu Radiological Society of North America 2015 Radiology Vol.274 No.2

<P>To compare the influence of triggering methods for diffusion-weighted imaging (DWI) on apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) parameters in the liver, as well as regional variability and measurement repeatability.</P>

천장관절 나사 고정술을 위한 컴퓨터 지원 수술 장치의 개발

염진섭,최원식,김하용,김환정,강종원,김영호,김형민,서동현,이석,이제범,김남국,김철영 대한골절학회 2003 대한골절학회지 Vol.16 No.1

목 적 : 천장관철의 경피적 나사 고정술을 위한 컴퓨터 지원 수술 장치를 개발하여, 그 정확도를 측정하여 보고자 하였다. 대상 및 방법 : 광학 추적 장치(Polaris, Northern Digital, Canada)와 개인용 컴퓨터를 이용한 항법 장치를 개발하였다. 정확도 측정용 팬텀을 제작하여 복합 정합시의 정합 오차와 표적 지시 오차를 각각 30회씩 측정하였으며, 4개의 플라스틱 골반골 모델(Sawbone, USA)에 16개의 6.5 ㎜유관 나사를 삽입하여 정확히 삽입되었는지 여부를 호가인하였다. 결 과 : 정합 오차는 0.76±0.33㎜, 표적 지시 오차는 1.43±0.42㎜였다. 골반골 모델에 삽입한 16개의 나사는 모두 천장관절내에 삽입되었고, 피질골을 뚫고 나오거나 인접한 두 개의 나사나 와셔가 서로 충돌한 경우는 없었다. 결 론 : 개발된 컴퓨터 지원 수술 장치는 해외에서 개발된 장치와 유사한 정확도를 가지고 있었고, 골반골 모델을 이용한 모의 수술에서도 만족할 만한 결과를 얻었다. Purpose : The purpose of this study were to develop a computer-assisted surgery system for percutaneous screw fixation of the sacro-iliac joint and to evaluate its accuracy. Materials and Methods : We have developed a navigation system composed of an optical tracking device(Polaris, Northern Digital, Canada) and a personal computer. The registration error and target localization error at hybrid registration were measured using a phantom. The errors were measured 30 times for each. Sixteen 6.5㎜ cannulated screws were inserted into four plastic bone models (Sawbones, USA), and the accuracy was evaluated. Results : The registration error was 0.76±0.33 ㎜, and the target localization error was 1.43±0.42 ㎜. All of the 16 screws were inserted well across the sacro-iliac joint, and there was neither penetration of the cortical bones nor collision between screws or washers. Conclusion : The accuracy of the developed system was similar to existing ones, and its usefulness and helpfulness was proven with screw insertion into plastic bone models.