Purpose: This study aimed to propose a methodological approach for reducing the radiation dose in pediatric conebeam computed tomography (CBCT), focusing exclusively on balancing image quality with dose optimization. Materials and Methods: The dose-area product (DAP) for exposure was reduced using copper-plate attenuation of an X-ray source. The thickness of copper (Cu) was increased from 0 to 2.2 mm, and 10 different DAP levels were used. The QUART DVT_AP phantom and pediatric radiologic dentiform were scanned under the respective DAP levels. The contrast-to-noise ratio (CNR), image homogeneity, and modulation transfer function (MTF) were analyzed using the QUART DVT_AP phantom. An expert evaluation (overall image grade, appropriateness of field of view, artifacts, noise, and resolution) was conducted using pediatric dentiform images. The critical DAP level was determined based on phantom and dentiform analysis results. Results: CNR and image homogeneity decreased as the DAP was reduced; however, there was an inflection point of image homogeneity at Cu 1.6 mm (DAP = 138.00 mGy·cm2 ), where the value started increasing. The MTF showed constant values as the DAP decreased. The expert evaluation of overall image grades showed “no diagnostic value” for dentiform images with Cu 1.9-2.2 mm (DAP = 78.00-103.33 mGy·cm2 ). The images with Cu 0-1.6 mm (DAP = 138.00-1697.67 mGy·cm2 ) had a “good,” “moderate,” or “poor but interpretable” grade. Conclusion Reducing DAP beyond a 1.6-mm Cu thickness degraded CBCT image quality. Image homogeneity and clinical image grades indicated crucial decision points for DAP reduction in pediatric CBCT scans.

Purpose: This study aimed to compare the therapeutic effects of corticosteroid irrigations and normal saline irrigations in the early inflammatory state of the salivary gland. Materials and Methods: Adult male Wistar rats were divided into experimental (n=6) and control (n=3) groups. Inflammation was induced in the experimental subjects on both sides of the submandibular gland with ligation. After 14 days, both sides of the glands were de-ligated and retroductal irrigation using saline (n=3) and a corticosteroid (n=3) was performed on the left sides only. The controls (n=3) were used to normalize the gland state for the effects of diet and aging. Magnetic resonance imaging was performed to confirm inflammation and post-irrigation gland recovery by measuring relative signal intensity (SI). The glands were excised for histological examination. Results: All experimental animals showed inflamed glands with increased SI and subsequent recovery of the gland with decreased SI to varying degrees. The SI of the controls showed no significant changes during the overall period. The mean SI change of the irrigated gland was higher than that of the non-irrigated side, without a significant difference. The corticosteroid-irrigated glands showed a greater change in SI than that of the saline-irrigated glands. Histology revealed that inflammation was not observed in most of the irrigated glands, while mild to moderate quantities inflammatory cells were found in non-irrigated glands. Conclusion Corticosteroid irrigation mitigated the early stages of salivary gland inflammation more effectively than normal saline.

Purpose: This study aimed to evaluate the performance of transfer learning in a deep convolutional neural network for classifying implant fixtures. Materials and Methods: Periapical radiographs of implant fixtures obtained using the Superline (Dentium Co. Ltd., Seoul, Korea), TS III (Osstem Implant Co. Ltd., Seoul, Korea), and Bone Level Implant (Institut Straumann AG, Basel, Switzerland) systems were selected from patients who underwent dental implant treatment. All 355 implant fixtures comprised the total dataset and were annotated with the name of the system. The total dataset was split into a training dataset and a test dataset at a ratio of 8 to 2, respectively. YOLOv3 (You Only Look Once version 3, available at https://pjreddie.com/darknet/yolo/), a deep convolutional neural network that has been pretrained with a large image dataset of objects, was used to train the model to classify fixtures in periapical images, in a process called transfer learning. This network was trained with the training dataset for 100, 200, and 300 epochs. Using the test dataset, the performance of the network was evaluated in terms of sensitivity, specificity, and accuracy. Results: When YOLOv3 was trained for 200 epochs, the sensitivity, specificity, accuracy, and confidence score were the highest for all systems, with overall results of 94.4%, 97.9%, 96.7%, and 0.75, respectively. The network showed the best performance in classifying Bone Level Implant fixtures, with 100.0% sensitivity, specificity, and accuracy. Conclusion Through transfer learning, high performance could be achieved with YOLOv3, even using a small amount of data.

Purpose: This study was to investigate the types of imaging modalities, analytical methods for age estimation, and the age of the subjects in research on age estimation using dental radiography through a scoping review, and to investigate the overall trends in age estimation studies. Materials and Methods: A scoping review was designed according to the Arksey and O’Malley guidelines and the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. Three electronic databases were used as search sources (Medline, Embase, and Cochrane Library). Studies were classified according to the three main components of the research question. “What are the imaging modalities, analytical methods, and target age in dental imaging-based age estimation studies?”Result: The final 198 studies were selected by two reviewers. The most common imaging modality used in studies was panoramic radiography (69.7%), and studies using cone-beam computed tomography have increased over time. Analytical methods for age estimation were 62.6% in studies based on tooth development and 26.3% in studies using pulp/tooth ratio. The subject age was 27.8% for children and 27.3% for adults. Studies conducted in all age groups comprised the smallest category (5.2%). Conclusion Panoramic radiography has been the most used types of imaging modalities for age estimation, and the most common analytical method was analysis of tooth development. Most studies targeted specific ages, and very few involved all age groups. Dental age estimation studies should be carried out with appropriate consideration of the imaging modality that is analyzed, the methods that are used, and the age that is targeted.

Purpose: In June 2016, the Model for End-Stage Liver Disease (MELD) score was employed in South Korea instead of the Child-Turcotte-Pugh (CTP) score. This study compared the outcomes of deceased donor liver transplantation (DDLT) before and after the MELD system application. Methods: This retrospective study reviewed 48 patients who underwent DDLT for end-stage liver disease at a single tertiary referral center between January 2014 and December 2018. The patients were categorized into the pre-MELD (22 patients) and post-MELD (26 patients) groups. The demographics, postoperative outcomes, and overall survival time were evaluated between the 2 groups. Results: The 2 groups had no differences in age, sex, ABO type, etiology for liver transplantation, CTP-score, operation time, cold ischemic time, and amount of red blood cell transfusion, although their MELD score differed significantly (postMELD group, 36.2 ± 4.9; pre-MELD group, 27.7 ± 11.8; P < 0.001). The post-MELD group has longer intensive care unit stay (11.2 ± 9.5 days vs. 5.7 ± 4.5 days, P = 0.018) and hospital stay than the pre-MELD group (36.8 ± 26 days vs. 22.8 ± 9.3 days, P = 0.016). The 1-year survival rate was lower in the post-MELD group (61.5% vs. 86.4%, P = 0.029). Conclusion After MELD allocation, patients with high MELD scores had increased DDLT and consequently required a longer recovery time, which could negatively affect survival. According to the experience of a small-volume center, these problems were related to both severe organ shortages in South Korea and MELD allocation.

PURPOSE: The aim of this study was to investigate the available alveolar bone height between the maxillary molars and the sinus floor according to their anatomical relationship using cone-beam computed tomographic (CBCT) images. METHODS: A total of 752 maxillary first (M1) and second molars (M2) on CBCT scans of 188 patients were selected. First, each maxillary molar was categorized as type 1, 2, 3, or 4 according to the relationship of the molar root with the maxillary sinus floor. The frequency distribution of each type was analyzed. Second, the shortest vertical distance (VD) of each molar was measured from the furcation midpoints of the roots to the lowest point of the sinus floor by 2 observers. Intraclass correlation coefficients and the t-test were calculated for the VD measurements. RESULTS: For M1, type 3 was the most frequent, followed by type 2. For M2, type 3 was the most common, followed by type 1. The VD measurements of type 1 were 9.51±3.68 mm and 8.07±2.73 mm for M1 and M2, and those of type 3 were 3.70±1.52 mm and 4.03±1.53 mm for M1 and M2, respectively. The VD measurements of M2 were significantly higher in female patients than in male patients. CONCLUSIONS Type 3 was the most frequent anatomical relationship in the maxillary molars, and showed the lowest alveolar bone height. This information will help clinicians to prevent complications related to the maxillary sinus during maxillary molar treatment and to predict the available bone height for immediate implant planning.

BACKGROUND: At most centers, general anesthesia (GA) has been preferred for endovascular treatment (EVT) of ruptured intracranial aneurysms (RIAs). In this study, we analyzed procedural results, clinical outcomes, and follow-up angiographic findings for patients undergoing EVT for RIA under local anesthesia (LA) with conscious sedation (CS). METHODS: We retrospectively evaluated 308 consecutive patients who underwent EVT for RIAs at a single institution between June 2009 and February 2017. EVT under LA with CS was considered for all patients with aneurysmal subarachnoid hemorrhage, regardless of Hunt and Hess (HH) scale score. RESULTS: EVT was performed for 320 aneurysms in 308 patients with subarachnoid hemorrhages. The mean patient age was 55.5±12.6 years. Moderate (III) and poor (IV, V) HH grades were observed in 75 (24.4%) and 77 patients (25%), respectively. Complete occlusion immediately after EVT was achieved for 270 (84.4%) of 320 aneurysms. Thromboembolic complications and intraprocedural ruptures occurred in 25 (7.8%) and 14 cases (4.3%), respectively. The morbidity rate at discharge (as defined by a modified Rankin scale score of 3 or greater) was 27.3% (84/308), while the mortality rate was 11.7% (36/308). Follow-up angiographic results were available for 210 (68.1%) of 308 patients. Recanalization was observed in 64 (29.3%) of 218 aneurysms in 210 patients. CONCLUSION: Based on our experience, EVT for RIAs under LA with CS was feasible, regardless of the clinical grade of the subarachnoid hemorrhage. Complication rates and follow-up angiographic results were also comparable to those observed when GA was used to perform the procedure.
Anesthesia, General ; Anesthesia, Local ; Aneurysm ; Conscious Sedation ; Endovascular Procedures ; Follow-Up Studies ; Humans ; Intracranial Aneurysm ; Mortality ; Retrospective Studies ; Rupture ; Subarachnoid Hemorrhage

PURPOSE: The purpose of this study was to assess the safety and early outcomes of the Pipeline device for large/giant or fusiform aneurysms. MATERIALS AND METHODS: The Pipeline was implanted in a total of 45 patients (mean age, 58 years; M:F=10:35) with 47 large/giant or fusiform aneurysms. We retrospectively evaluated the characteristics of the treated aneurysms, the periprocedural events, morbidity and mortality, and the early outcomes after Pipeline implantation. RESULTS: The aneurysms were located in the internal carotid artery (ICA) cavernous segment (n=25), ICA intradural segment (n=11), vertebrobasilar trunk (n=8), and middle cerebral artery (n=3). Procedure-related events occurred in 18 cases, consisting of incomplete expansion (n=8), shortening-migration (n=5), transient occlusion of a jailed branch (n=3), and in-stent thrombosis (n=2). Treatment-related morbidity occurred in two patients, but without mortality. Both patients had modified Rankin scale (mRS) scores of 2, but had an improved mRS score of 0 at 1-month follow-up. Of the 19 patients presenting with mass effect, 16 improved but three showed no changes in their presenting symptoms. All patients had excellent outcomes (mRS, 0 or 1) during the follow-up period (median, 6 months; range, 2-30 months). Vascular imaging follow-up (n=31, 65.9%; median, 3 months, range, 1-25 months) showed complete or near occlusion of the aneurysm in 24 patients (77.4%) and decreased sac size in seven patients (22.6%). CONCLUSION: In this initial multicenter study in Korea, the Pipeline seemed to be safe and effective for large/giant or fusiform aneurysms. However, a learning period may be required to alleviate device-related events.
Aneurysm* ; Carotid Artery, Internal ; Follow-Up Studies ; Humans ; Korea* ; Learning ; Middle Cerebral Artery ; Mortality ; Retrospective Studies ; Thrombosis

BACKGROUND: Inhaled corticosteroids (ICSs) are the most essential medication for asthma control. Many reports suggest that the usage of ICSs improves not only the control of asthma symptoms but also prevents exacerbation. We investigated whether increases in ICS prescriptions are associated with decreases in asthma exacerbation in the clinical practice setting. METHODS: We retrospectively analyzed the database of adult asthma patients who had visited a tertiary referral hospital, the Asan Medical Center between January 2000 and December 2009. The number of emergency department (ED) visits, admissions, intensive care unit (ICU) care, deaths, and ICS prescriptions were analyzed to evaluate the time trend of asthma exacerbation as a function of the ICS prescription rate during the ten years. RESULTS: The numbers of ED visits, admissions, and episodes of ICU care decreased during the ten years (p<0.001, p=0.033, p=0.001, respectively) while the number of ICS prescriptions increased (p<0.001). We found a correlation between the number of ICS prescriptions and the number of ED visits, admissions, or ICU care. For these outcomes, the correlation coefficients were r=-0.952, p<0.001; r=-0.673, p=0.033; r=-0.948, p<0.001, respectively. CONCLUSION: The number of ICS prescriptions increased during the past ten years while the number of asthma exacerbations decreased. Our results also showed a negative correlation between the ICS prescription rate and asthma exacerbation in the clinical practice setting. In other words, an increase in ICS prescription may be a major cause of a decrease in asthma exacerbations.
Adrenal Cortex Hormones ; Adult ; Asthma ; Disease Progression ; Emergencies ; Humans ; Intensive Care Units ; Nebulizers and Vaporizers ; Prescriptions ; Retrospective Studies ; Tertiary Care Centers

Epidermoid cysts presents as a nodular and fluctuant subcutaneous lesion beneath the skin and are most common in acne-prone areas of the head, neck and back. This cyst often arises after localized inflammation of the hair follicle and occasionally after the implantation of epithelium following trauma and surgery including a biopsy procedure. It is often associated with Gardner syndrome, particularly before puberty. The lesion is normally treated by a surgical excision or enucleation, and recurrence is uncommon. A 27 year old woman complained of a swelling of the left parotid gland when she visited our clinic. A cystic lesion was found in the left parotid gland from the high signal intensity on the MR images. Ultrasonography showed that the cystic lesion was heterogeneous echogenic. Six months earlier, botulinum toxin was injected in her left masseter muscles six months earlier and progressive swelling of the left parotid area was noticed four months after treatment. The lesion was surgically removed. It was encapsulated by a thin wall and filled mainly with keratin. The final diagnosis was an epidermoid cyst.
Biopsy ; Botulinum Toxins ; Epidermal Cyst ; Epithelium ; Female ; Gardner Syndrome ; Hair Follicle ; Head ; Humans ; Inflammation ; Keratins ; Masseter Muscle ; Neck ; Parotid Gland ; Puberty ; Recurrence ; Skin