Bone Age Assessment Using Artificial Intelligence in Korean Pediatric Population: A Comparison of Deep-Learning Models Trained With Healthy Chronological and Greulich-Pyle Ages as Labels

Objective@#To develop a deep-learning-based bone age prediction model optimized for Korean children and adolescents and evaluate its feasibility by comparing it with a Greulich-Pyle-based deep-learning model. @*Materials and Methods@#A convolutional neural network was trained to predict age according to the bone development shown on a hand radiograph (bone age) using 21036 hand radiographs of Korean children and adolescents without known bone development-affecting diseases/conditions obtained between 1998 and 2019 (median age [interquartile range {IQR}], 9 [7–12] years; male:female, 11794:9242) and their chronological ages as labels (Korean model). We constructed 2 separate external datasets consisting of Korean children and adolescents with healthy bone development (Institution 1: n = 343;median age [IQR], 10 [4–15] years; male: female, 183:160; Institution 2: n = 321; median age [IQR], 9 [5–14] years; male:female, 164:157) to test the model performance. The mean absolute error (MAE), root mean square error (RMSE), and proportions of bone age predictions within 6, 12, 18, and 24 months of the reference age (chronological age) were compared between the Korean model and a commercial model (VUNO Med-BoneAge version 1.1; VUNO) trained with Greulich-Pyle-based age as the label (GP-based model). @*Results@#Compared with the GP-based model, the Korean model showed a lower RMSE (11.2 vs. 13.8 months; P = 0.004) and MAE (8.2 vs. 10.5 months; P = 0.002), a higher proportion of bone age predictions within 18 months of chronological age (88.3% vs. 82.2%; P = 0.031) for Institution 1, and a lower MAE (9.5 vs. 11.0 months; P = 0.022) and higher proportion of bone age predictions within 6 months (44.5% vs. 36.4%; P = 0.044) for Institution 2. @*Conclusion@#The Korean model trained using the chronological ages of Korean children and adolescents without known bone development-affecting diseases/conditions as labels performed better in bone age assessment than the GP-based model in the Korean pediatric population. Further validation is required to confirm its accuracy.

Clinical Significance and Characteristics of Newly Detected Lesions on Breast MRI During Neoadjuvant Chemotherapy

Purpose@#This study aimed to evaluate clinical significance and imaging findings of newly detected lesions on breast MRI while monitoring patients’ response to neoadjuvant chemotherapy (NAC). @*Materials and Methods@#We identified 291 patients with newly diagnosed breast cancer who underwent breast MRI to assess their response to NAC between January 2017 and August 2021. We evaluated 26 new lesions in 24 women (mean age, 49.8 years; range, 35–63 years) who were included in this study. Two radiologists assessed imaging findings of new lesions according to Breast Imaging Reporting and Data System (BI-RADS) lexicon 5th edition and evaluated follow-up MRI during NAC. Outcomes of new lesions were determined based on pathologic examination or imaging follow-up after surgery. @*Results@#All 26 new lesions were found on the first follow-up imaging. They disappeared or decreased in size on the second follow-up imaging. Lesion types included mass (n = 22, 84.6%) and non-mass enhancement (n = 4, 15.4%). The majority of the mass types showed oval to round shapes (22/22, 100%), circumscribed margins (21/22, 95.5%), and rim enhancement (18/22, 81.8%). Seven (26.9%) new lesions were ipsilateral to the index cancer, 7 (26.9%) were contralateral, and 12 (46.2%) were bilateral. None of these new lesions were malignant. @*Conclusion@#New lesions were detected in 4.7% of breast MRI during NAC. Most new lesions tended to

Re-Assessment of Applicability of Greulich and Pyle-Based Bone Age to Korean Children Using Manual and Deep Learning-Based Automated Method

Purpose@#To evaluate the applicability of Greulich-Pyle (GP) standards to bone age (BA) assessment in healthy Korean children using manual and deep learning-based methods. @*Materials and Methods@#We collected 485 hand radiographs of healthy children aged 2–17 years (262 boys) between 2008 and 2017. Based on GP method, BA was assessed manually by two radiologists and automatically by two deep learning-based BA assessment (DLBAA), which estimated GP-assigned (original model) and optimal (modified model) BAs. Estimated BA was compared to chronological age (CA) using intraclass correlation (ICC), Bland-Altman analysis, linear regression, mean absolute error, and root mean square error. The proportion of children showing a difference >12 months between the estimated BA and CA was calculated. @*Results@#CA and all estimated BA showed excellent agreement (ICC ≥0.978, p12 months in 44.3%, 44.5%, 39.2%, and 36.1% for radiologist 1, radiologist 2, original, and modified DLBAA models, respectively. @*Conclusion@#Contemporary healthy Korean children showed different rates of skeletal development than GP standard-BA, and systemic bias should be considered when determining children’s skeletal maturation.

Comparison of a Deep Learning-Based Reconstruction Algorithm with Filtered Back Projection and Iterative Reconstruction Algorithms for Pediatric Abdominopelvic CT

Objective@#To compare a deep learning-based reconstruction (DLR) algorithm for pediatric abdominopelvic computed tomography (CT) with filtered back projection (FBP) and iterative reconstruction (IR) algorithms. @*Materials and Methods@#Post-contrast abdominopelvic CT scans obtained from 120 pediatric patients (mean age ± standard deviation, 8.7 ± 5.2 years; 60 males) between May 2020 and October 2020 were evaluated in this retrospective study. Images were reconstructed using FBP, a hybrid IR algorithm (ASiR-V) with blending factors of 50% and 100% (AV50 and AV100, respectively), and a DLR algorithm (TrueFidelity) with three strength levels (low, medium, and high). Noise power spectrum (NPS) and edge rise distance (ERD) were used to evaluate noise characteristics and spatial resolution, respectively. Image noise, edge definition, overall image quality, lesion detectability and conspicuity, and artifacts were qualitatively scored by two pediatric radiologists, and the scores of the two reviewers were averaged. A repeated-measures analysis of variance followed by the Bonferroni post-hoc test was used to compare NPS and ERD among the six reconstruction methods. The Friedman rank sum test followed by the Nemenyi-Wilcoxon-Wilcox all-pairs test was used to compare the results of the qualitative visual analysis among the six reconstruction methods. @*Results@#The NPS noise magnitude of AV100 was significantly lower than that of the DLR, whereas the NPS peak of AV100 was significantly higher than that of the high- and medium-strength DLR (p < 0.001). The NPS average spatial frequencies were higher for DLR than for ASiR-V (p < 0.001). ERD was shorter with DLR than with ASiR-V and FBP (p < 0.001). Qualitative visual analysis revealed better overall image quality with high-strength DLR than with ASiR-V (p < 0.001). @*Conclusion@#For pediatric abdominopelvic CT, the DLR algorithm may provide improved noise characteristics and better spatial resolution than the hybrid IR algorithm.

A Case Report of Postinfectious Bronchiolitis Obliterans After Coronavirus Disease 2019 in a 10-YearOld Child

Coronavirus disease 2019 (COVID-19) is usually less severe in children and adolescents than in adults. However, it can cause severe respiratory illness in a small proportion of children with risk factors. Here, we report a rare case of a 10-year-old boy with postinfectious bronchiolitis obliterans that developed after pneumonia caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). This patient was previously healthy apart from a high body mass index (BMI, 30.13; 99.6th percentile for the age bracket), history of preterm birth (35 weeks), and low birth weight (1,850 g). He had persistent exertional dyspnea after recovering from SARS-CoV-2-related pneumonia. Spirometry revealed obstructive lung disease with the following results: predicted forced vital capacity (FVC% pred ), 71%; forced expiratory volume in 1 second (FEV 1 % pred ), 63%; FEV 1 /FVC, 0.81; and forced expiratory flow 25-75 % pred , 55%. Chest computed tomography showed multifocal areas of parenchymal hyperlucency and mosaic attenuation in both lungs. This case suggests that careful observation of children with obesity and low birth weight is necessary after recovery from SARS-CoV-2-related pneumonia.

Diagnosis of Nonmigrating Metallic Foreign Bodies in the Abdomen Using Ultrasound: An Alternative Approach Using a Traditional Method / 대한소아소화기영양학회지

Ingestion of foreign bodies (FBs) is a common phenomenon among young children. Plain radiography is the first step diagnostic modality to detect the radio-opaque FBs. And computed tomography has been recommended by several guidelines as useful modalities for diagnosing ingested FBs. However, there is a risk of radiation exposure, making it burdensome to use in asymptomatic patients. Ultrasound (US) is not a commonly used technique for diagnosing ingested foreign bodies. However, US can provide real-time imaging with good resolutions without radiation exposure in pediatric patients. Herein, we report two pediatric cases of metallic foreign body ingestion that were successfully diagnosed using US for localizing foreign bodies. This study indicates that US may be used as an alternative method for detecting the localization of metallic foreign bodies in the gastrointestinal tract without exposure of radiation, particularly in pediatric patients.

Korean Clinical Practice Guidelines for Adverse Reactions to Intravenous Iodinate and MRI-Gadolinium Contrast Agents: Revised Clinical Consensus and Recommendations (3rd Edition, 2022)

The Korean Society of Radiology and Medical Guidelines Committee amended the existing 2016 guidelines to publish the “Korean Clinical Practice Guidelines for Adverse Reactions to Iodide Contrast for Injection and Gadolinium Contrast for MRI: The Revised Clinical Consensus and Recommendations (2022 Third Edition).” Expert members recommended and approved by the Korean Society of Radiology, the Korean Academy of Asthma, Allergy and Clinical Immunology, and the Korean Nephrology Society participated together. According to the expert consensus or systematic literature review, the description of the autoinjector and connection line for the infection control while using contrast medium, the acute adverse reaction, and renal toxicity to iodized contrast medium were modified and added. We would like to introduce the revised contents.

The Behavioral Effects of Combination Therapy of Memantine and Acetylcholinesterase Inhibitors Compared with Acetylcholinesterase Inhibitors Alone in Patients with Moderate Alzheimer’s Dementia: A Double-Blind Randomized Placebo-Controlled Trial

Objective@#This study aimed to investigate treatment effects of combination therapy of memantine and acetylcholinesterase inhibitors (AchEIs) compared with AchEIs alone on behavioral and psychological symptoms of dementia (BPSD) in patients with moderate Alzheimer’s dementia (AD). @*Methods@#This was a 12-week, double-blind, randomized, placebo-controlled trial. A total of 148 patients with moderate AD participated in this study. Mini-Mental State Examination, Neuropsychiatric Inventory (NPI), Clinician’s Interview-Based Impression of Change plus caregiver input, Gottfries–Bråne–Steen Scale, and Zarit Burden Interview were used as assessment scales. @*Results@#There were no significant differences in age, sex, or education between AChEIs alone and combination groups. The combination group showed significantly more improvement of NPI-disinhibition score (0.76±2.15) than the AChEIs alone group (-0.14±1.71) after 12 weeks. @*Conclusion@#Our findings suggest that the combination therapy of memantine and AchEIs might be a beneficial option for reducing disinhibition symptoms of patients with moderate AD compared with AchEIs alone. We believe that clinicians need to consider additional memantine treatment when patients with moderate AD complain disinhibition symptom. A larger clinical trial is needed to further determine the efficacy and advantages of such combination therapy of memantine and AchEIs for treating BPSD of patients with moderate AD.

Diagnostic Performance of Blood Culture Bottles for Abscess Culture in Patient with Abdominal Soft Tissue Abscess

Culture tests are very important in choosing the appropriate antibiotics for bacterial infections. In some cases, bacteria that could not be identified in standard culture bottles could be detected using blood culture bottles. A previously healthy 13-year-old boy visited our emergency room. He experienced pain, redness, and hardness of periumbilical skin and a fever for five days. There was no history of abdominal surgery and penetrating trauma.Computed tomography showed abscess with cellulitis at the periumbilical soft tissue with no congenital anomaly. Ultrasonography-guided aspiration was performed, and about 8.5 mL of the purulent abscess was aspirated. The abscess was cultured using blood culture bottle. The pus grew Actinomyces radingae and Clostridium ramosum. When performing the pus culture, using blood culture bottles can be more effective and rapid than the standard culture method for the detection of bacterial pathogens.

Establishment of Local Diagnostic Reference Levels of Pediatric Abdominopelvic and Chest CT Examinations Based on the Body Weight and Size in Korea

Objective@#The purposes of this study were to analyze the radiation doses for pediatric abdominopelvic and chest CT examinations from university hospitals in Korea and to establish the local diagnostic reference levels (DRLs) based on the body weight and size. @*Materials and Methods@#At seven university hospitals in Korea, 2494 CT examinations of patients aged 15 years or younger (1625 abdominopelvic and 869 chest CT examinations) between January and December 2017 were analyzed in this study. CT scans were transferred to commercial automated dose management software for the analysis after being de-identified. DRLs were calculated after grouping the patients according to the body weight and effective diameter. DRLs were set at the 75th percentile of the distribution of each institution’s typical values. @*Results@#For body weights of 5, 15, 30, 50, and 80 kg, DRLs (volume CT dose index [CTDIvol]) were 1.4, 2.2, 2.7, 4.0, and 4.7 mGy, respectively, for abdominopelvic CT and 1.2, 1.5, 2.3, 3.7, and 5.8 mGy, respectively, for chest CT. For effective diameters of 24 cm, DRLs (size-specific dose estimates [SSDE]) were 4.1, 5.0, 5.7, 7.1, and 7.2 mGy, respectively, for abdominopelvic CT and 2.8, 4.6, 4.3, 5.3, and 7.5 mGy, respectively, for chest CT.SSDE was greater than CTDIvol in all age groups. Overall, the local DRL was lower than DRLs in previously conducted dose surveys and other countries. @*Conclusion@#Our study set local DRLs in pediatric abdominopelvic and chest CT examinations for the body weight and size.Further research involving more facilities and CT examinations is required to develop national DRLs and update the current DRLs.

Diagnostic Performance of a New Convolutional Neural Network Algorithm for Detecting Developmental Dysplasia of the Hip on Anteroposterior Radiographs

Objective@#To evaluate the diagnostic performance of a deep learning algorithm for the automated detection of developmental dysplasia of the hip (DDH) on anteroposterior (AP) radiographs. @*Materials and Methods@#Of 2601 hip AP radiographs, 5076 cropped unilateral hip joint images were used to construct a dataset that was further divided into training (80%), validation (10%), or test sets (10%). Three radiologists were asked to label the hip images as normal or DDH. To investigate the diagnostic performance of the deep learning algorithm, we calculated the receiver operating characteristics (ROC), precision-recall curve (PRC) plots, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) and compared them with the performance of radiologists with different levels of experience. @*Results@#The area under the ROC plot generated by the deep learning algorithm and radiologists was 0.988 and 0.988–0.919, respectively. The area under the PRC plot generated by the deep learning algorithm and radiologists was 0.973 and 0.618– 0.958, respectively. The sensitivity, specificity, PPV, and NPV of the proposed deep learning algorithm were 98.0, 98.1, 84.5, and 99.8%, respectively. There was no significant difference in the diagnosis of DDH by the algorithm and the radiologist with experience in pediatric radiology (p = 0.180). However, the proposed model showed higher sensitivity, specificity, and PPV, compared to the radiologist without experience in pediatric radiology (p < 0.001). @*Conclusion@#The proposed deep learning algorithm provided an accurate diagnosis of DDH on hip radiographs, which was comparable to the diagnosis by an experienced radiologist.

The Behavioral Effects of Combination Therapy of Memantine and Acetylcholinesterase Inhibitors Compared with Acetylcholinesterase Inhibitors Alone in Patients with Moderate Alzheimer’s Dementia: A Double-Blind Randomized Placebo-Controlled Trial

Objective@#This study aimed to investigate treatment effects of combination therapy of memantine and acetylcholinesterase inhibitors (AchEIs) compared with AchEIs alone on behavioral and psychological symptoms of dementia (BPSD) in patients with moderate Alzheimer’s dementia (AD). @*Methods@#This was a 12-week, double-blind, randomized, placebo-controlled trial. A total of 148 patients with moderate AD participated in this study. Mini-Mental State Examination, Neuropsychiatric Inventory (NPI), Clinician’s Interview-Based Impression of Change plus caregiver input, Gottfries–Bråne–Steen Scale, and Zarit Burden Interview were used as assessment scales. @*Results@#There were no significant differences in age, sex, or education between AChEIs alone and combination groups. The combination group showed significantly more improvement of NPI-disinhibition score (0.76±2.15) than the AChEIs alone group (-0.14±1.71) after 12 weeks. @*Conclusion@#Our findings suggest that the combination therapy of memantine and AchEIs might be a beneficial option for reducing disinhibition symptoms of patients with moderate AD compared with AchEIs alone. We believe that clinicians need to consider additional memantine treatment when patients with moderate AD complain disinhibition symptom. A larger clinical trial is needed to further determine the efficacy and advantages of such combination therapy of memantine and AchEIs for treating BPSD of patients with moderate AD.

Diagnostic Performance of Blood Culture Bottles for Abscess Culture in Patient with Abdominal Soft Tissue Abscess

Culture tests are very important in choosing the appropriate antibiotics for bacterial infections. In some cases, bacteria that could not be identified in standard culture bottles could be detected using blood culture bottles. A previously healthy 13-year-old boy visited our emergency room. He experienced pain, redness, and hardness of periumbilical skin and a fever for five days. There was no history of abdominal surgery and penetrating trauma.Computed tomography showed abscess with cellulitis at the periumbilical soft tissue with no congenital anomaly. Ultrasonography-guided aspiration was performed, and about 8.5 mL of the purulent abscess was aspirated. The abscess was cultured using blood culture bottle. The pus grew Actinomyces radingae and Clostridium ramosum. When performing the pus culture, using blood culture bottles can be more effective and rapid than the standard culture method for the detection of bacterial pathogens.

Establishment of Local Diagnostic Reference Levels of Pediatric Abdominopelvic and Chest CT Examinations Based on the Body Weight and Size in Korea

Objective@#The purposes of this study were to analyze the radiation doses for pediatric abdominopelvic and chest CT examinations from university hospitals in Korea and to establish the local diagnostic reference levels (DRLs) based on the body weight and size. @*Materials and Methods@#At seven university hospitals in Korea, 2494 CT examinations of patients aged 15 years or younger (1625 abdominopelvic and 869 chest CT examinations) between January and December 2017 were analyzed in this study. CT scans were transferred to commercial automated dose management software for the analysis after being de-identified. DRLs were calculated after grouping the patients according to the body weight and effective diameter. DRLs were set at the 75th percentile of the distribution of each institution’s typical values. @*Results@#For body weights of 5, 15, 30, 50, and 80 kg, DRLs (volume CT dose index [CTDIvol]) were 1.4, 2.2, 2.7, 4.0, and 4.7 mGy, respectively, for abdominopelvic CT and 1.2, 1.5, 2.3, 3.7, and 5.8 mGy, respectively, for chest CT. For effective diameters of 24 cm, DRLs (size-specific dose estimates [SSDE]) were 4.1, 5.0, 5.7, 7.1, and 7.2 mGy, respectively, for abdominopelvic CT and 2.8, 4.6, 4.3, 5.3, and 7.5 mGy, respectively, for chest CT.SSDE was greater than CTDIvol in all age groups. Overall, the local DRL was lower than DRLs in previously conducted dose surveys and other countries. @*Conclusion@#Our study set local DRLs in pediatric abdominopelvic and chest CT examinations for the body weight and size.Further research involving more facilities and CT examinations is required to develop national DRLs and update the current DRLs.

Diagnostic Performance of a New Convolutional Neural Network Algorithm for Detecting Developmental Dysplasia of the Hip on Anteroposterior Radiographs

Objective@#To evaluate the diagnostic performance of a deep learning algorithm for the automated detection of developmental dysplasia of the hip (DDH) on anteroposterior (AP) radiographs. @*Materials and Methods@#Of 2601 hip AP radiographs, 5076 cropped unilateral hip joint images were used to construct a dataset that was further divided into training (80%), validation (10%), or test sets (10%). Three radiologists were asked to label the hip images as normal or DDH. To investigate the diagnostic performance of the deep learning algorithm, we calculated the receiver operating characteristics (ROC), precision-recall curve (PRC) plots, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) and compared them with the performance of radiologists with different levels of experience. @*Results@#The area under the ROC plot generated by the deep learning algorithm and radiologists was 0.988 and 0.988–0.919, respectively. The area under the PRC plot generated by the deep learning algorithm and radiologists was 0.973 and 0.618– 0.958, respectively. The sensitivity, specificity, PPV, and NPV of the proposed deep learning algorithm were 98.0, 98.1, 84.5, and 99.8%, respectively. There was no significant difference in the diagnosis of DDH by the algorithm and the radiologist with experience in pediatric radiology (p = 0.180). However, the proposed model showed higher sensitivity, specificity, and PPV, compared to the radiologist without experience in pediatric radiology (p < 0.001). @*Conclusion@#The proposed deep learning algorithm provided an accurate diagnosis of DDH on hip radiographs, which was comparable to the diagnosis by an experienced radiologist.

Clinical and Imaging Findings of Neonatal Seizures Presenting as Diffuse Cerebral White Matter Abnormality on Diffusion-Weighted Imaging without any Structural or Metabolic Etiology

Purpose@#Some patients with neonatal seizures show diffuse, symmetric diffusion-restricted lesions in the cerebral white matter. The aim of this study was to describe clinical and imaging findings of patients with neonatal seizures who had diffuse, symmetric diffusion-restricted lesions without any structural or metabolic etiology. @*Materials and Methods@#A total of 56 neonates aged less than 1 week underwent brain magnetic resonance imaging (MRI) for evaluation of seizures from November 2008 to February 2017. After excluding 43 patients, 13 patients showed diffuse white matter abnormality on diffusion-weighted imaging. Initial and follow-up clinical and MRI findings were analyzed retro-spectively. @*Results@#All 13 patients were born at full term. Among the ten patients who underwent a stool test for viruses, six were positive for rotavirus and one for astrovirus. MRI revealed diffuse, symmetric diffusion-restricted lesions distributed along the cerebral white matter, thalami, and midbrain variably. @*Conclusion@#Diffuse, symmetric diffusion-restricted lesions involving the cerebral white matter can be seen in patients with neonatal seizures without any structural or metabolic etiology. Rotavirus is commonly but not exclusively detected in these patients. Nevertheless, viral infection-associated encephalopathy should be considered for patients with characteristic clinical and MRI findings.

Radiological Manifestations of Childhood Fractures

Musculoskeletal injury is the most common cause of children visiting the department of emergency medicine. Since the bone is still developing, pediatric patients have characteristic radiological manifestations, including plastic deformation, greenstick fractures, and buckle (or torus) fractures. Furthermore, growth arrest can occur in those with physeal fractures. Various mechanisms are responsible for pediatric musculoskeletal injury since children have different ranges of activities, depending on their age, such as birth injury and fall and traffic accidents. Some fractures have characteristic locations and radiological manifestations. In this review, we will discuss various radiological manifestations of fractures involving both upper and lower limbs in pediatric patients.

Meteorological Factors Associated with the Number of Emergency Room Patients with Wrist-Cutting Behavior / 정신신체의학

Objectives@#：Although the seasonality of suicide is a well-known phenomenon, little is reported about the seasonality of non-suicidal self-injury. The purpose of this study was to identify the seasonality of wristcutting behavior and to examine its relationship with meteorological factors. @*Methods@#：To identify the presence of seasonality, we investigated whether there was a difference in the average number of visits per month to an emergency room (ER) of an urban hospital for 226 patients with wrist-cutting behavior enrolled between December 2014 and May 2019. To ascertain significant meteorological factors, we used the multiple Poisson regression using generalized additive model with time, monthly temperature, monthly sunshine hour, and atmospheric pressure in the prior month as explanatory variables. @*Results@#：In males, the average number of monthly visits to the ER for wrist cutting behavior differed by month and was the highest in September (male : p=0.048, female : p=0.21, total : p=0.28). As a result of multiple regression analysis, the average number of patients admitted to the ER for wrist cutting behavior was related to the interaction between atmospheric pressure in the prior month and temperature in males (p=0.010), and showed a positive correlation with sunlight in females [p=0.044 , β=4.70×10-3 , 95% CI=(1.19×10-4 , 9.27×10-3 )]. @*Conclusions@#：Wrist cutting behavior shows seasonality in male, which is associated with changes in meteorological variables.

Meteorological Factors Associated with the Number of Emergency Room Patients with Wrist-Cutting Behavior / 정신신체의학

Objectives@#：Although the seasonality of suicide is a well-known phenomenon, little is reported about the seasonality of non-suicidal self-injury. The purpose of this study was to identify the seasonality of wristcutting behavior and to examine its relationship with meteorological factors. @*Methods@#：To identify the presence of seasonality, we investigated whether there was a difference in the average number of visits per month to an emergency room (ER) of an urban hospital for 226 patients with wrist-cutting behavior enrolled between December 2014 and May 2019. To ascertain significant meteorological factors, we used the multiple Poisson regression using generalized additive model with time, monthly temperature, monthly sunshine hour, and atmospheric pressure in the prior month as explanatory variables. @*Results@#：In males, the average number of monthly visits to the ER for wrist cutting behavior differed by month and was the highest in September (male : p=0.048, female : p=0.21, total : p=0.28). As a result of multiple regression analysis, the average number of patients admitted to the ER for wrist cutting behavior was related to the interaction between atmospheric pressure in the prior month and temperature in males (p=0.010), and showed a positive correlation with sunlight in females [p=0.044 , β=4.70×10-3 , 95% CI=(1.19×10-4 , 9.27×10-3 )]. @*Conclusions@#：Wrist cutting behavior shows seasonality in male, which is associated with changes in meteorological variables.

Acoustic radiation force impulse imaging of biopsy-proven Kikuchi disease: initial experiences for evaluating feasibility in pediatric patients

PURPOSE: This study evaluated the feasibility of acoustic radiation force impulse (ARFI) elastography and characterized the sonographic features of lymph nodes (LNs) with Kikuchi disease in pediatric patients. METHODS: Seventy-six cervical LN biopsies were performed for the diagnosis of cervical lymphadenopathy. ARFI imaging was performed, and the characteristic ultrasound features of the biopsied LNs and the contralateral LNs were analyzed. We also reviewed clinical and conventional ultrasonographic findings. RESULTS: On histology, 56 patients were diagnosed with Kikuchi disease. These LNs were large and elongated, with increased perinodal echogenicity and capsular thickening. In 38 of them, ARFI elastography was performed, and the median shear wave velocity (SWV) of the biopsied LNs with Kikuchi disease (2.19 m/sec; range, 1.45 to 4.57 m/sec) was higher than of the contralateral LNs (1.72 m/sec; range, 0.95 to 2.65 m/sec; P < 0.001). In patients with reactive hyperplasia, the mean SWV of the biopsied LNs (2.00 m/sec; range, 1.49 to 2.26 m/sec) was higher than that of the contralateral LNs (1.55 m/sec; range, 1.21 to 2.32 m/sec; P=0.031). CONCLUSION: The SWV of LNs with Kikuchi disease was significantly higher than that of the contralateral LNs. Morphologically, LNs with Kikuchi disease showed an enlarged, elongated, and oval shape, increased perinodal echogenicity, and capsular thickening. In addition to the conventional ultrasonographic findings, the application of ARFI is feasible even in pediatric patients for the evaluation of cervical lymphadenopathy.