Kyung Nyeo Jeon

The aim of this study was to evaluate the actual values and ranges of conventional and spectral parameters in pulmonary thromboembolism (PE) and assess their potential for distinguishing acute PE (APE) from chronic PE (CPE) using dual-layer CT (DLCT). This retrospective study included 52 patients with central PE diagnosed with CT pulmonary angiography (CTPA) using DLCT. Patients were categorized into APE and CPE groups. Conventional and spectral parameters including Hounsfield unit (HU) and electron density (ED) values were measured at the thrombus and pulmonary trunk on both pre- and post-contrast images. Additionally, in vitro experiments were conducted to generate clots of varying compositions. Apart from D-dimer levels, no significant clinical differences were found between APE and CPE groups. APE showed significantly higher mean HU and ED values than CPE on both unenhanced and enhanced images (both p < 0.001). Thrombus enhancement, using true non-contrast (TNC) values as a reference, was similar between groups. APE showed greater variability in HU and ED values, whereas CPE consistently demonstrated lower values across all imaging phases. Unenhanced HU and ED values provided better discrimination than post-contrast values, with high AUCs ( p < 0.05). The in vitro findings were consistent with these observations and may provide a plausible explanation for the compositional differences between APE and CPE. APE showed higher HU and ED values than CPE. Conventional and spectral CT parameters could help differentiate APE from CPE, reflecting distinct thrombus compositions.

Cyst-predominant anterior mediastinal lesions are commonly attributed to benign thymic cysts. However, thymomas—the most common thymic epithelial tumor—may rarely present as a predominantly cystic mass with only a small solid component, posing a diagnostic challenge. The World Health Organization (WHO) classifies thymomas according to the morphology of tumor epithelial cells and the degree of lymphocytic infiltration, a schema that correlates with biological behavior and prognosis. Unlike low-risk subtypes, high-risk thymomas frequently require multimodal treatment because of their more aggressive clinical course. MRI has increasingly been utilized as a problem-solving modality for indeterminate lesions identified on CT. In particular, diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) measurement has emerged as a potentially useful imaging biomarker for predicting histologic subtypes of thymic epithelial tumors. We report a case of a WHO type B3 thymoma presenting as a predominantly cystic anterior mediastinal lesion, in which MRI findings suggested the possibility of a high-risk subtype. The imaging and corresponding histopathologic findings are presented in this paper.

Background/Objectives: This study aimed to assess the impact of a deep learning-based iodine contrast augmentation (DLCA) algorithm on image quality and diagnostic performance for pulmonary embolism (PE) detection in suboptimally enhanced CT pulmonary angiography (CTPA). Methods: We retrospectively included 103 suboptimal CTPA cases performed between May 2020 and March 2025. Image quality (attenuation, noise, SNR, and CNR) was compared between original and DLCA-processed images. Diagnostic performance for PE detection was assessed per segment, with and without DLCA processing. Results: DLCA increased pulmonary artery opacification by 57.7% and reduced noise by 56.7%, significantly improving SNR (13.2 → 47.5) and CNR (8.7 → 37.2; both p < 0.001). Incorporation of DLCA-processed images improved diagnostic accuracy for overall (AUC: 0.874/0.845 → 0.958/0.938), central (0.939/0.895 → 0.987/0.972), and peripheral (0.824/0.807 → 0.935/0.912) PE detection (all p ≤ 0.003). In suboptimal CTPA, a pulmonary artery attenuation threshold of 130 HU was identified, above which DLCA processing significantly improved PE detection accuracy compared with original images in both readers (p < 0.001). Conclusions: DLCA processing in suboptimal CTPA significantly enhances image quality and diagnostic accuracy for PE detection, providing a promising strategy to optimize scans without additional contrast or radiation.

Pulmonary neuroendocrine proliferations and neoplasms represent a broad spectrum of diseases, ranging from neuroendocrine cell hyperplasia and tumorlets to carcinoid tumors. Carcinoid tumorlets are most commonly located in the peripheral airways and are often incidentally detected as pulmonary micronodules on chest CT. We report the radiological, bronchoscopic, and pathological findings of a case of carcinoid tumorlets presenting as endobronchial nodules in the left main bronchus. The patient had previously undergone a left lower lobectomy five years earlier for a typical carcinoid tumor. Follow-up imaging revealed new endobronchial nodules, which were subsequently confirmed as carcinoid tumorlets through histopathologic analysis. This case highlights the rare presentation of carcinoid tumorlets in the central airways, emphasizing the importance of recognizing their potential for late recurrence and atypical localization. It underscores the necessity for physicians to be aware that pulmonary neuroendocrine tumors can recur over the long term and may present in a multicentric fashion within the disease spectrum.

Background: Acute eosinophilic pneumonia (AEP) is a rare and severe lung condition characterized by a rapid accumulation of eosinophils in the alveoli, leading to respiratory distress. This study analyzed the clinical characteristics of affected patients, aiming to shed light on the relationship between cigarette smoking and AEP.Methods: This retrospective study analyzed 17 cases of AEP, focusing on patients' smoking habits, clinical symptoms, diagnostic findings, and treatment outcomes. Data were collected from medical records, imaging studies, and bronchoalveolar lavage (BAL) findings.Results: The study cohort consisted primarily of male military personnel (94.1%), with a mean age of 20.8 years. Symptoms generally appeared approximately 2.82 days prior to hospitalization, with a mean body temperature at admission of 37.6 °C. The mean initial peripheral blood white blood cell count was 15.3×103/μL, with eosinophil percentages starting at 0.2%, peaking at a mean of 16.1%, and reaching as high as 32.4%. BAL fluid analysis showed a mean eosinophil level of 46.6%±15.1% (range, 17%–67%). In most cases, radiological examinations revealed bilateral ground-glass opacities, interlobular septal thickening, various degrees of airspace consolidation, and bilateral pleural effusions. Steroid treatment was administered to 70.5% of patients, lasting a mean of 8.3 days and resulting in significant improvements.Conclusions: These cases reinforce the strong link between cigarette smoking and AEP. Additionally, these cases demonstrate the importance of obtaining a detailed smoking history and thorough diagnostic assessments, including BAL, in order to facilitate a more rapid diagnosis and early initiation of corticosteroid treatment.

Jeong WG, et al. Korean J Radiol. 2025 Sep;26:e75. https://doi.org/10.3348/kjr.2025.0457

정원기, et al. J Korean Soc Radiol. 2025 Jul;86(4):524-536. https://doi.org/10.3348/jksr.2024.0048

Objective This study aimed to evaluate the added value of 40 keV virtual mono-energetic images (VMIs) obtained from dual-layer detector CT (DLCT) for diagnosing malignant pleural effusion (MPE) in patients presenting with unilateral pleural effusion on chest CT. Materials and methods This retrospective study included 75 patients with unilateral pleural effusion who underwent contrast-enhanced chest CT scans using DLCT. Quantitative and qualitative assessments of the visibility of pleural thickening were conducted on both conventional 120 kVp images and 40 keV VMIs. Two independent radiologists reviewed chest CT scans with or without 40 keV VMIs to detect pleural nodules or nodular thickening for the diagnosis of MPE. Diagnostic performances were compared and independent predictors of MPE were identified through multivariate logistic regression analysis using CT and clinicopathologic findings. Results Pleural thickening associated with MPE demonstrated a higher contrast-to-noise ratio value and greater visual conspicuity in 40 keV VMIs compared to benign effusions (p < 0.05). For both readers, the use of 40 keV VMIs significantly improved (p < 0.05) the diagnostic performance in terms of sensitivity and area under the curve (AUC) for diagnosing MPE through the detection of pleural nodularity. Inter-observer agreements between the two readers were substantial for both 120 kVp images alone and the combined use of 40 keV VMIs. Initial cytology results and pleural nodularity at 40 keV were identified as independent predictors of MPE. Conclusion The use of 40 keV VMIs from DLCT can improve diagnostic performance of readers in detecting MPE among patients with unilateral pleural effusion.