Faculty Bibliography

BACKGROUND AND PURPOSE/OBJECTIVE:Mild traumatic brain injury (MTBI) is a common public health concern with potential long-term consequences, yet its underlying pathophysiology remains poorly understood. Clinical heterogeneity of individuals having diverse extent and array of symptoms has impeded the identification of reliable imaging biomarkers. Traditional group-level analyses may obscure biologically meaningful subtypes. This study uses latent class analysis (LCA) to classify MTBI subjects into symptom-defined subgroups and examines corresponding WM microstructural alterations using advanced diffusion MRI. MATERIALS AND METHODS/METHODS:Sixty-one MTBI patients within one month of injury completed the Rivermead Post-Concussion Symptoms Questionnaire (RPQ). LCA was used to identify symptom-based subgroups. Of these, 54 MTBI patients underwent multi-shell diffusion MRI and were compared with 31 controls. WM changes were assessed across subgroups using ROI-based diffusion analyses. RESULTS:LCA identified three distinct MTBI subgroups: those with minimal to no symptoms (31.5%), the cognitively symptomatic (38.9%), and the more globally symptomatic (29.6%). The three groups were associated with different patterns of diffusion MRI differences compared with controls. The cognitively symptomatic subgroup showed predominantly central WM differences, the globally symptomatic subgroup exhibited more peripheral differences with right-hemisphere predominance and sparing the corpus callosum, marked by reduced fractional anisotropy and kurtosis and elevated diffusivities, the less symptomatic subgroup demonstrated focal differences in the callosal genu, with increased fractional anisotropy and kurtosis and decreased diffusivity measures. CONCLUSIONS:MTBI comprises biologically distinct phenotypes with subgroup-specific WM signatures on diffusion MRI. Even individuals with minimal to no symptoms show WM differences compared with controls, underscoring the limitations of symptom reporting alone. Integrating symptom-based classification with advanced diffusion MRI may improve diagnostic precision to help risk stratification and provide insight into mechanisms of injury. ABBREVIATIONS/BACKGROUND:LCA = latent class analysis; MTBI = mild traumatic brain injury; RPQ = Rivermead post-concussion symptoms questionnaire.

IMPORTANCE/UNASSIGNED:Patients with sporadic breast cancer have comparable prognoses after undergoing either breast-conserving treatment (BCT) or mastectomy. However, there are limited and inconsistent data on the assessment of oncologic outcomes between BCT and mastectomy in patients with pathogenic variants in BRCA1 or BRCA2. OBJECTIVE/UNASSIGNED:To investigate the outcomes of BCT on recurrence and survival in patients with breast cancer with BRCA1 or BRCA2 pathogenic variants. DESIGN, SETTING, AND PARTICIPANTS/UNASSIGNED:This retrospective multicenter cohort study analyzed patients from 13 institutions in South Korea with primary breast cancer with BRCA1 or BRCA2 pathogenic variants who underwent either BCT or mastectomy from January 2008 through December 2015. The median (IQR) follow-up period was 8.3 (6.4-9.6) years. Data were analyzed from September 2023 to August 2024. EXPOSURE/UNASSIGNED:BRCA1 or BRCA2 pathogenic variant and BCT. MAIN OUTCOMES AND MEASURES/UNASSIGNED:Primary outcomes were logoregional recurrence-free survival, distant recurrence-free survival, and overall survival. Propensity score matching (PSM) using the greedy nearest neighbor method was performed to match covariates to minimize potential selection bias. RESULTS/UNASSIGNED:A total of 575 female patients with BRCA1 or BRCA2 pathogenic variants were identified, all of whom were South Korean with a mean (SD) age of 42.0 (9.7) years. Among them, 367 patients (66.2%) received BCT and 186 (33.8%) were treated with mastectomy. BCT was not a factor associated with oncologic outcomes, including locoregional recurrence, compared with mastectomy. After adjusting for clinicopathologic characteristics through 1:1 PSM, there were still no statistically significant differences in oncologic outcomes between the BCT group and the mastectomy group. Multivariate analysis showed that the type of breast surgery was not significantly associated with oncologic outcomes. In subgroup analysis among matched patients based on BRCA1 or BRCA2 status, tumor size, lymph node metastasis, histologic grade, and subtype, BCT was also not a factor associated with risk for recurrence. CONCLUSIONS AND RELEVANCE/UNASSIGNED:The findings from this cohort study of patients with BRCA1 or BRCA2 pathogenic variants suggested that there were no significant differences in oncologic outcomes between patients who underwent BCT and those who underwent mastectomy. Therefore, breast conservation with close surveillance can be considered a viable treatment option for BRCA1 or BRCA2 pathogenic variant carriers. Further studies incorporating prospectively collected data are warranted to validate our findings.

BACKGROUND AND PURPOSE/OBJECTIVE:Accurate localization of the ventral intermediate nucleus (VIM) within the dentatorubrothalamic tract (DRTT) is critical for effective neurosurgical treatment of essential tremor (ET). This study evaluated the feasibility and anatomical specificity of quantitative susceptibility mapping (QSM) for direct VIM/DRTT visualization, comparing it with conventional diffusion tractography-based reconstructions. MATERIALS AND METHODS/METHODS:Twenty-seven participants (10 healthy controls, 17 ET patients) were enrolled across two institutions and imaged on 3T MRI systems. QSM-defined VIM/DRTT regions were manually segmented based on characteristic hypointense susceptibility contrast. Whole-brain diffusion tractography was performed to reconstruct the DRTT, pyramidal tract (PT), and medial lemniscus (ML) tracts. Spatial overlap between QSM-and tractography-defined VIM/DRTT regions was calculated, as well as overlap with neighboring PT and ML tracts to assess specificity. RESULTS:Two participants were excluded due to insufficient VIM/DRTT streamlines in tractography reconstruction. In healthy controls, QSM-and tractography-defined VIM/DRTT showed high spatial correspondence (left: 87.6 ± 5.1%; right: 85.3 ± 6.5%). ET patients exhibited slightly lower overlap (mean range: 71.5 - 85.1%). Overlap with neighboring PT and ML tracts was minimal (<3.3%), confirming high anatomical specificity of QSM-derived VIM/DRTT regions. CONCLUSIONS:QSM enables direct visualization of the VIM/DRTT with high spatial agreement to conventional tractography-based approaches while demonstrating minimal overlap with adjacent tracts. These findings support QSM as a complementary or standalone imaging modality for improved, patient-specific neurosurgical targeting in ET. ABBREVIATIONS/BACKGROUND:DBS = deep brain stimulation; DRTT = dentatorubrothalamic tract; ET = essential tremor; ML = medial lemniscus; MRgFUS = MR-guided focused ultrasound; VIM = ventral intermediate nucleus; PT = pyramidal tract; QSM = quantitative susceptibility mapping; WM = white matter.

BACKGROUND:The alcohol-induced facial flushing phenotype (flushing) is common among East Asians. Despite a small intake of alcohol, they experience heightened levels of acetaldehyde, a group-1 carcinogen, which, in turn, causes unpleasant symptoms such as redness, acting as a robust protective mechanism against consuming alcohol. However, some individuals with this genetic trait exhibit weakened alcohol restraint, which increases the risk of developing alcohol-related cancers, such as esophageal and head or neck cancer, by several times. Although this flushing phenomenon is crucial for public health, there is a paucity of studies that have comprehensively investigated the effect of flushing or its genotype on alcohol consumption in a large group of East Asians while controlling for various sociodemographic and health-related variables at a country level. OBJECTIVE:This 2-year cross-sectional study aims to explore the effect of flushing on drinking behavior in Koreans and to examine whether the effect varies across sociodemographic and health-related factors. METHODS:test, 2-tailed t test, and multinomial logistic regression analysis. RESULTS:The suppressive effect of flushing was significant (P<.001) across all pronounced categories of alcohol consumption in 2019. The ranges of standardized regression slopes and odds ratios (ORs) were -6.70≥β≥-11.25 and 0.78≥OR≥0.50 for frequency and -5.37≥β≥-17.64 and 0.73≥OR≥0.36 for amount, respectively. The effect became somewhat stronger when adjusted for confounders. The effect also exhibited an overall stronger trend as the severity of alcohol consumption increased. The β values and ORs were consistently smaller in 2020 compared to the previous year. A simple effect analysis revealed a diminished alcohol-suppressive effect of flushing on alcohol consumption for specific groups (eg, those with low levels of education, limited family support, physical labor, or health-related issues). CONCLUSIONS:Our findings suggest that flushing suppresses drinking in Koreans overall but has little or no effect in certain susceptible populations. Therefore, health authorities should conduct targeted epidemiological studies to assess drinking patterns and disease profiles, particularly regarding alcohol-related cancers, and establish effective preventive measures tailored to this population.

OBJECTIVES/OBJECTIVE:Studies evaluating weight changes during the coronavirus disease 2019 (COVID-19) pandemic have yielded inconsistent results, and most of those studies were based on self-reported anthropometric measures. We investigated changes in body mass index (BMI), professionally measured waist circumference (WC), and metabolic syndrome components from before to during the pandemic in a sample of the adult population in Korea. METHODS:This retrospective study included 1,118 male and female (age≥18 years) who underwent health checkups at a university medical center between January 1, 2016 and March 31, 2022. Changes in BMI, lifestyles, and metabolic syndrome components during the pandemic were analyzed using the paired t-test, McNemar test, generalized estimating equations, and repeated-measures analysis of variance. RESULTS:Changes in body weight, BMI, and body fat percentage during the pandemic were not clinically significant. However, statistically significant results were found for decreased physical activity (p<0.001) and WC (p<0.001), and exacerbation of all metabolic syndrome components (except serum triglyceride levels). Moreover, the metabolic syndrome prevalence increased significantly from 20.2% to 31.2% during the pandemic (p<0.001). The prevalence of abdominal obesity and high fasting blood glucose levels also significantly increased from 2019 to 2021. CONCLUSIONS:Metabolic syndrome, its components, and fat distribution worsened significantly after the implementation of social distancing and lockdowns, despite no clinically significant changes in body weight and BMI. Further studies on the post- pandemic period should investigate the long-term impact of social lockdowns on BMI and the prevalence of metabolic syndrome.

BACKGROUND:Liver Imaging Reporting and Data System M (LR-M) lesions may appear targetoid or nontargetoid, but their clinicopathologic and prognostic differences remain unclear. PURPOSE/OBJECTIVE:To compare clinical, pathological, and prognostic features of targetoid and nontargetoid LR-M lesions on dynamic contrast enhanced-MRI (DCE-MRI). STUDY TYPE/METHODS:Retrospective. SUBJECTS/METHODS:119 consecutive patients (82 male, mean age = 62.9 ± 10.3 years) with 119 LR-M observations (75 targetoid, 44 nontargetoid) and at least 2 years of follow-up. FIELD STRENGTH/SEQUENCE/UNASSIGNED:1.5T and 3.0T; T2-weighted fast spin echo sequence, diffusion-weighted image, and dynamic T1-weighted-gradient-echo sequence using an extracellular contrast agent. ASSESSMENT/RESULTS:Three radiologists categorized lesions as targetoid or nontargetoid. Clinical, laboratory, imaging, and histopathologic data were collected. STATISTICAL TESTS/METHODS:Group differences were evaluated using t-tests and chi-square/Fisher's exact tests. Survival outcomes were assessed using Kaplan-Meier method with log-rank test and Cox proportional hazards regression. Inverse probability of treatment weighting (IPTW) was applied before survival analysis. A p-value < 0.05 was considered significant. RESULTS:The nontargetoid group had significantly higher serum AFP (6684.7 ± 15,988 vs. 194.9 ± 898.4 ng/mL), larger lesion size (9.10 ± 5.55 cm vs. 3.55 ± 2.96 cm), cirrhosis (95% vs. 76%), extrahepatic disease (50% vs. 19%), and malignancy (95% vs. 82%). Nontargetoid group showed significantly higher mortality (75% vs. 41%), progression (77% vs. 45%), shorter overall survival (477 ± 629 vs. 1226 ± 1147 days), and time-to-progression (333 vs. 1003 days). On multivariable analysis with Cox proportional hazards regression, targetoid morphology was significantly associated with improved overall survival (HR = 0.28) and progression-free survival (HR = 0.36), whereas histology was not significant (HCC vs. non-HCC). DATA CONCLUSION/CONCLUSIONS:Targetoid morphology is significantly associated with improved survival and delayed progression, supporting its role as a prognostic imaging biomarker. EVIDENCE LEVEL/METHODS:3. TECHNICAL EFFICACY/UNASSIGNED:Stage 5.

PURPOSE/OBJECTIVE:To improve 0.55T T2-weighted PROPELLER lung MRI by developing a self-supervised framework for joint reconstruction and denoising. METHODS:T2-weighted 0.55T lung MRI datasets from 44 patients with prior COVID-19 infection were used. Each PROPELLER blade was split along the readout direction into two disjoint subsets: one subset for training an unrolled network, and the other for loss calculation. Following the Noise2Noise paradigm, this framework split k-space into two subsets with independent, matched noise but identical underlying signal, enabling joint reconstruction and denoising without external training references. For comparison, coil-wise Marchenko-Pastur Principal Component Analysis (MPPCA) denoising followed by parallel imaging reconstruction was performed. The reconstructed images were evaluated by two experienced chest radiologists. RESULTS:The self-supervised model generated lung images with improved clarity, better delineation of parenchymal and airway structures, and maintained high fidelity in cases with available CT references. In addition, the proposed framework also enabled further reduction of scan time by reconstructing images with adequate diagnostic quality from only half the number of blades. The reader study confirmed that the proposed method outperformed MPPCA across all categories (Wilcoxon signed-rank test, p < 0.001), with moderate inter-reader agreement (weighted Cohen's kappa = 0.55; percentage of exact and within ±1 point agreement = 91%). CONCLUSION/CONCLUSIONS:By leveraging the intrinsic data redundancy in PROPELLER sampling and extending the Noise2Noise concept, the proposed self-supervised framework enabled simultaneous reconstruction and denoising of lung images at 0.55T to address the low-SNR challenge at low-field. It holds great potential for broad use in other low-field MRI applications.

BACKGROUND:The cumulative risk of contralateral breast cancer (CBC) in BRCA1/2 carriers is remarkably higher than in non-carriers. This study aimed to investigate the clinicopathological predictors associated with the risk of metachronous CBC among breast cancer patients with BRCA1/2 mutations using correspondence analysis. METHODS:This retrospective study included patients who underwent BRCA testing between January 2008 and December 2018. The inclusion criterion was patients being between 20 and 80-years-old with invasive breast cancer (pT1-3, N0-3). We performed univariate and multivariate survival analyses to assess the risks associated with BRCA mutations, and conducted correspondence analysis to identify contributing factors for CBC among subgroup by age and BRCA mutations. RESULTS:Total of 4009 patients were included in this analysis. After median follow-up of 93 months, 278 cases of CBC were documented. Among 576 patients with BRCA mutations, there was no difference in the incidence of CBC between BRCA1 and BRCA2 carriers (P = 0.07). Correspondence analysis revealed that, in younger patients (< 50 years) with BRCA1 mutations, the triple-negative subtype (r = 0.93) and high grade (r = 0.74) showed the closest geometric proximity associated with CBC. In BRCA2 carriers, high Ki-67 labeling index (≥ 20%) demonstrated prominent geometric association in the biplot related to CBC, regardless of age (r = 0.93). CONCLUSION/CONCLUSIONS:Although no difference was found in the risk of CBC between BRCA 1/2 mutations, correspondence analysis revealed different contributing factors. For young BRCA carriers with a triple-negative subtype and poor pathologic parameters such as high grade and Ki-67 index, risk-reducing contralateral prophylactic mastectomy could be considered as a treatment strategy.