• Title/Summary/Keyword: Radiology science department

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Reference line-pair values of panoramic radiographs using an arch-form phantom stand to assess clinical image quality

  • Choi, Da-Hye;Choi, Bo-Ram;Choi, Jin-Woo;Huh, Kyung-Hoe;Yi, Won-Jin;Heo, Min-Suk;Choi, Soon-Chul;Lee, Sam-Sun
    • Imaging Science in Dentistry
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    • v.43 no.1
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    • pp.7-15
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    • 2013
  • Purpose: This study was performed to suggest reference line-pair values of panoramic images with clinically desirable qualities using an arch-form phantom stand. Materials and Methods: The line-pair test phantom was chosen. A real skull model was selected for setting the arch-form model of the phantom stand. The phantom stand had slits in four regions (incisor, premolar, molar, TMJ). Four raw images of the test phantom in each region and one raw image of the real skull were converted into 50 test phantom images and 50 skull phantom images with various line-pair values. 50 post-processed real skull phantom images were divided into 4 groups and were randomly submitted to 14 evaluators. Image quality was graded on a 4 point scale (1. good, 2. normal, 3. poor but interpretable, and 4. not interpretable). The reference line pair was determined as the first line-pair value scored less than 2 points. Result: The mean scores tended to decrease as the line-pair values increased. The reference line-pair values were 3.19 LP/mm in the incisor, 2.32 LP/mm in the premolar and TMJ, and 1.88 LP/mm in the molar region. Conclusion: Image quality evaluation methods and criteria should be able to assess various regions considering the characteristics of panoramic systems. This study suggested overall and regional reference line-pair values and established a set of standard values for them.

Multilocular Cystic Renal Neoplasm of Low Malignant Potential: A Case Report and Literature Review (낮은악성가능성을 가진 다방성낭성신장생성물: 증례 보고와 문헌 고찰)

  • Jihyun Lee;Dong Won Kim;Joo Yeon Song;Seong Kuk Yoon
    • Journal of the Korean Society of Radiology
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    • v.83 no.1
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    • pp.173-177
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    • 2022
  • Multilocular cystic renal neoplasm of low malignant potential (MCRNLMP) is a rare subtype of renal cell carcinoma that has a favorable outcome. Most cases of MCRNLMP usually present as distinct multilocular cystic lesions; however, they may appear as small complicated cysts with hemorrhagic components. Herein, we present a case of MCRNLMP and provide a review of the literature.

Imaging Patterns of Bacillus Calmette-Guérin-Related Granulomatous Prostatitis Based on Multiparametric MRI

  • Seungsoo Lee;Young Taik Oh;Hye Min Kim;Dae Chul Jung;Hyesuk Hong
    • Korean Journal of Radiology
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    • v.23 no.1
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    • pp.60-67
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    • 2022
  • Objective: To categorize multiparametric MRI features of Bacillus Calmette-Guérin (BCG)-related granulomatous prostatitis (GP) and discover potential manifestations for its differential diagnosis from prostate cancer. Materials and Methods: The cases of BCG-related GP in 24 male (mean age ± standard deviation, 66.0 ± 9.4 years; range, 50-88 years) pathologically confirmed between January 2011 and April 2019 were retrospectively reviewed. All patients underwent intravesical BCG therapy followed by a MRI scan. Additional follow-up MRI scans, including diffusion-weighted imaging (DWI), were performed in 19 patients. The BCG-related GP cases were categorized into three: A, B, or C. The lesions with diffusion restriction and homogeneous enhancement were classified as type A. The lesions with diffusion restriction and a poorly enhancing component were classified as type B. A low signal intensity on high b-value DWI (b = 1000 s/mm2) was considered characteristic of type C. Two radiologists independently interpreted the MRI scans before making a consensus about the types. Results: The median lesion size was 22 mm with the interquartile range (IQR) of 18-26 mm as measured using the initial MRI scans. The lesion types were A, B, and C in 7, 15, and 2 patients, respectively. Cohen's kappa value for the inter-reader agreement for the interpretation of the lesion types was 0.837. On the last follow-up MRI scans of 19 patients, the size decreased (median, 5.8 mm; IQR, 3.4-8.5 mm), and the type changed from A or B to C in 11 patients. The lesions resolved in four patients. In five patients who underwent prostatectomy, caseous necrosis on histopathology matched with the non-enhancing components of type B lesions and the entire type C lesions. Conclusion: BCG-related GP demonstrated three imaging patterns on multiparametric MRI. Contrast-enhanced T1-weighted imaging and DWI may play a role in its differential diagnosis from prostate cancer.

Reliability of Skeletal Muscle Area Measurement on CT with Different Parameters: A Phantom Study

  • Dong Wook Kim;Jiyeon Ha;Yousun Ko;Kyung Won Kim;Taeyong Park;Jeongjin Lee;Myung-Won You;Kwon-Ha Yoon;Ji Yong Park;Young Jin Kee;Hong-Kyu Kim
    • Korean Journal of Radiology
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    • v.22 no.4
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    • pp.624-633
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    • 2021
  • Objective: To evaluate the reliability of CT measurements of muscle quantity and quality using variable CT parameters. Materials and Methods: A phantom, simulating the L2-4 vertebral levels, was used for this study. CT images were repeatedly acquired with modulation of tube voltage, tube current, slice thickness, and the image reconstruction algorithm. Reference standard muscle compartments were obtained from the reference maps of the phantom. Cross-sectional area based on the Hounsfield unit (HU) thresholds of muscle and its components, and the mean density of the reference standard muscle compartment, were used to measure the muscle quantity and quality using different CT protocols. Signal-to-noise ratios (SNRs) were calculated in the images acquired with different settings. Results: The skeletal muscle area (threshold, -29 to 150 HU) was constant, regardless of the protocol, occupying at least 91.7% of the reference standard muscle compartment. Conversely, normal attenuation muscle area (30-150 HU) was not constant in the different protocols, varying between 59.7% and 81.7% of the reference standard muscle compartment. The mean density was lower than the target density stated by the manufacturer (45 HU) in all cases (range, 39.0-44.9 HU). The SNR decreased with low tube voltage, low tube current, and in sections with thin slices, whereas it increased when the iterative reconstruction algorithm was used. Conclusion: Measurement of muscle quantity using HU threshold was reliable, regardless of the CT protocol used. Conversely, the measurement of muscle quality using the mean density and narrow HU thresholds were inconsistent and inaccurate across different CT protocols. Therefore, further studies are warranted in future to determine the optimal CT protocols for reliable measurements of muscle quality.

Comparison of Clinical and Radiologic Findings Between Perforated and Non-Perforated Choledochal Cysts in Children

  • Yu Jin Kim;Soo-Hyun Kim;So-Young Yoo;Ji Hye Kim;Soo-Min Jung;Sanghoon Lee;Jeong-Meen Seo;Sung-Hoon Moon;Tae Yeon Jeon
    • Korean Journal of Radiology
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    • v.23 no.2
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    • pp.271-279
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    • 2022
  • Objective: To compare the clinical and radiologic findings between perforated and non-perforated choledochal cysts in children. Materials and Methods: Fourteen patients (mean age ± standard deviation, 1.7 ± 1.2 years) with perforated choledochal cysts (perforated group) and 204 patients (3.6 ± 3.8 years) with non-perforated choledochal cysts (non-perforated group) were included between 2000 and 2019. All patients underwent choledochal cyst excision after ultrasound, CT, or MR cholangiopancreatography. Relevant data including demographics, clinical symptoms, laboratory findings, imaging findings, and outcomes were analyzed. Statistical differences were compared using the Mann-Whitney U test and Fisher's exact test. Results: Choledochal cyst perforation occurred only in children under the age of 4 years. Acute symptoms, including fever (p < 0.001), were more common in the perforated group than in the non-perforated group. High levels of white blood cells (p = 0.004), C-reactive protein (p < 0.001), and serum amylase (p = 0.002), and low levels of albumin (p < 0.001) were significantly associated with the perforated group. All 14 patients with perforated choledochal cysts had ascites, whereas only 16% (33/204) of patients in the non-perforated group had ascites (p < 0.001). In the subgroup of patients who had ascites, a large amount of ascites (p = 0.001), increase in the amount of ascites in a short time (p < 0.001), complex ascites (p < 0.001), and perihepatic pseudocysts (p < 0.001) were more common in the perforated group than in the non-perforated group. Conclusion: Children with perforated choledochal cysts have characteristic clinical and radiologic findings compared to those with non-perforated choledochal cysts. In young children with choledochal cysts, perforation should be differentiated in cases with acute symptoms, laboratory abnormalities, and characteristic ascites findings.

Education of Oral and Maxillofacial Radiology in South Korea (우리 나라 구강악안면방사선학 교육 현황)

  • Choi, Soon-Chul
    • Imaging Science in Dentistry
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    • v.39 no.1
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    • pp.1-5
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    • 2009
  • Although x-ray had been used in Dental Clinic and taught as Roentgenology as a part of other lectures, the independent lecture was established at Seoul National University in 1953. The first independent Department was separated from the Department of Oral Surgery at Seoul National University in 1963. Nowadays, there are 6 national and 5 private dental schools in South Korea. Each dental school has a Department of Oral and Maxillofacial Radiology, which fulfills its role in student education and clinical service. What is specially noteworthy is that 8 of the 11 dental schools have changed or will change from the 2+4 year system to 4+4 year system (postgraduate course). The curriculum has also been or is being amended according to this change. Although the contents of courses for Oral and Maxillofacial Radiology are not much different among dental schools, the methods and structure of education are various. We have to do a systematic and comprehensive analysis of the present educational methods and structure of Oral and Maxillofacial Radiology and need to seek the new and more suitable ones based on competency.

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An overview of deep learning in the field of dentistry

  • Hwang, Jae-Joon;Jung, Yun-Hoa;Cho, Bong-Hae;Heo, Min-Suk
    • Imaging Science in Dentistry
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    • v.49 no.1
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    • pp.1-7
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    • 2019
  • Purpose: Artificial intelligence (AI), represented by deep learning, can be used for real-life problems and is applied across all sectors of society including medical and dental field. The purpose of this study is to review articles about deep learning that were applied to the field of oral and maxillofacial radiology. Materials and Methods: A systematic review was performed using Pubmed, Scopus, and IEEE explore databases to identify articles using deep learning in English literature. The variables from 25 articles included network architecture, number of training data, evaluation result, pros and cons, study object and imaging modality. Results: Convolutional Neural network (CNN) was used as a main network component. The number of published paper and training datasets tended to increase, dealing with various field of dentistry. Conclusion: Dental public datasets need to be constructed and data standardization is necessary for clinical application of deep learning in dental field.

Review of Statistical Methods for Evaluating the Performance of Survival or Other Time-to-Event Prediction Models (from Conventional to Deep Learning Approaches)

  • Seo Young Park;Ji Eun Park;Hyungjin Kim;Seong Ho Park
    • Korean Journal of Radiology
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    • v.22 no.10
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    • pp.1697-1707
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    • 2021
  • The recent introduction of various high-dimensional modeling methods, such as radiomics and deep learning, has created a much greater diversity in modeling approaches for survival prediction (or, more generally, time-to-event prediction). The newness of the recent modeling approaches and unfamiliarity with the model outputs may confuse some researchers and practitioners about the evaluation of the performance of such models. Methodological literacy to critically appraise the performance evaluation of the models and, ideally, the ability to conduct such an evaluation would be needed for those who want to develop models or apply them in practice. This article intends to provide intuitive, conceptual, and practical explanations of the statistical methods for evaluating the performance of survival prediction models with minimal usage of mathematical descriptions. It covers from conventional to deep learning methods, and emphasis has been placed on recent modeling approaches. This review article includes straightforward explanations of C indices (Harrell's C index, etc.), time-dependent receiver operating characteristic curve analysis, calibration plot, other methods for evaluating the calibration performance, and Brier score.

Automated Measurement of Native T1 and Extracellular Volume Fraction in Cardiac Magnetic Resonance Imaging Using a Commercially Available Deep Learning Algorithm

  • Suyon Chang;Kyunghwa Han;Suji Lee;Young Joong Yang;Pan Ki Kim;Byoung Wook Choi;Young Joo Suh
    • Korean Journal of Radiology
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    • v.23 no.12
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    • pp.1251-1259
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    • 2022
  • Objective: T1 mapping provides valuable information regarding cardiomyopathies. Manual drawing is time consuming and prone to subjective errors. Therefore, this study aimed to test a DL algorithm for the automated measurement of native T1 and extracellular volume (ECV) fractions in cardiac magnetic resonance (CMR) imaging with a temporally separated dataset. Materials and Methods: CMR images obtained for 95 participants (mean age ± standard deviation, 54.5 ± 15.2 years), including 36 left ventricular hypertrophy (12 hypertrophic cardiomyopathy, 12 Fabry disease, and 12 amyloidosis), 32 dilated cardiomyopathy, and 27 healthy volunteers, were included. A commercial deep learning (DL) algorithm based on 2D U-net (Myomics-T1 software, version 1.0.0) was used for the automated analysis of T1 maps. Four radiologists, as study readers, performed manual analysis. The reference standard was the consensus result of the manual analysis by two additional expert readers. The segmentation performance of the DL algorithm and the correlation and agreement between the automated measurement and the reference standard were assessed. Interobserver agreement among the four radiologists was analyzed. Results: DL successfully segmented the myocardium in 99.3% of slices in the native T1 map and 89.8% of slices in the post-T1 map with Dice similarity coefficients of 0.86 ± 0.05 and 0.74 ± 0.17, respectively. Native T1 and ECV showed strong correlation and agreement between DL and the reference: for T1, r = 0.967 (95% confidence interval [CI], 0.951-0.978) and bias of 9.5 msec (95% limits of agreement [LOA], -23.6-42.6 msec); for ECV, r = 0.987 (95% CI, 0.980-0.991) and bias of 0.7% (95% LOA, -2.8%-4.2%) on per-subject basis. Agreements between DL and each of the four radiologists were excellent (intraclass correlation coefficient [ICC] of 0.98-0.99 for both native T1 and ECV), comparable to the pairwise agreement between the radiologists (ICC of 0.97-1.00 and 0.99-1.00 for native T1 and ECV, respectively). Conclusion: The DL algorithm allowed automated T1 and ECV measurements comparable to those of radiologists.

Formation of ghost images due to metal objects on the surface of the patient's face: A pictorial essay

  • Ramos, Barbara Couto;da Silva Izar, Bruna Raquel;Pereira, Jessica Lourdes Costa;Souza, Priscilla Sena;Valerio, Claudia Scigliano;Tuji, Fabricio Mesquita;Manzi, Flavio Ricardo
    • Imaging Science in Dentistry
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    • v.46 no.1
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    • pp.63-68
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    • 2016
  • Panoramic radiographs are a relatively simple technique that is commonly used in all dental specialties. In panoramic radiographs, in addition to the formation of real images of metal objects, ghost images may also form, and these ghost images can hinder an accurate diagnosis and interfere with the accuracy of radiology reports. Dentists must understand the formation of these images in order to avoid making incorrect radiographic diagnoses. Therefore, the present study sought to present a study of the formation of panoramic radiograph ghost images caused by metal objects in the head and neck region of a dry skull, as well as to report a clinical case in order to warn dentists about ghost images and to raise awareness thereof. An understanding of the principles of the formation of ghost images in panoramic radiographs helps prevent incorrect diagnoses.