Kyungsoo Bae

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.

The appearance of sclerotic bone lesions in contrast-enhanced computed tomography (CT) scans is often a significant concern for the possible presence of metastatic disease, especially in individuals with a known history of cancer. Prior research has demonstrated that in cases where patients suffer from thrombosis in major veins like the superior vena cava or the brachiocephalic vein, vertebral venous congestion can create imaging patterns on CT scans that resemble sclerotic bone metastases. However, instances of such imaging findings in patients without any form of venous obstruction are not commonly reported. In this study, we present cases of pseudopathologic vertebral enhancement observed consistently following left-side contrast injections in cancer patients devoid of venous obstruction. We aim to discuss and propose a potential mechanism for this phenomenon, drawing attention to a less commonly recognized diagnostic consideration in oncological imaging.

Osteosarcoma commonly occurs in the intramedullary cavity of long bones such as the femur, tibia, and humerus in children and adolescents. Osteosarcoma occurring as a primary tumor in the chest wall is rare. Only a limited number of such cases have been documented in the existing literature. Herein, we present radiologic and pathologic findings of a high-grade surface osteosarcoma of the rib mimicking a neurogenic tumor in a 44-year-old woman.

The tracheal bronchus is a congenital bronchial branching anomaly defined as an aberrant bronchus arising in either the trachea or a main bronchus. Left bronchial isomerism is characterized by two bilobed lungs, bilateral long main bronchi, and both pulmonary arteries passing superiorly to their respective upper lobe bronchi. Left bronchial isomerism with a right-sided tracheal bronchus is a very rare combination of tracheobronchial anomalies. It has not been previously reported. We present multi-detector CT findings of a left bronchial isomerism with a right-sided tracheal bronchus of a 74 year old man.

The widespread use of computed tomography (CT) has led to the increased recognition of cystic lung lesions. Multiple pulmonary cysts can be observed in heterogeneous disorders called diffuse cystic lung diseases (DCLDs), which include pulmonary Langerhans cell histiocytosis, lymphangioleiomyomatosis, lymphocytic interstitial pneumonia, and Birt–Hogg–Dubé syndrome. Recently, airspace enlargement with fibrosis (AEF) has been recognized as an entity on the spectrum of smoking-related lung diseases. We report a young male heavy smoker presenting diffuse pulmonary cysts on chest CT with suspected DCLD. However, histopathological examination of the surgical biopsy specimen revealed dilated emphysematous cysts with prominent mural fibrosis, consistent with AEF.

(1) Background: Highly flexible adaptive image receive (AIR) coil has become available for clinical use. The present study aimed to evaluate the performance of AIR anterior array coil in lung MR imaging using a zero echo time (ZTE) sequence compared with conventional anterior array (CAA) coil. (2) Methods: Sixty-six patients who underwent lung MR imaging using both AIR coil (ZTE-AIR) and CAA coil (ZTE-CAA) were enrolled. Image quality of ZTE-AIR and ZTE-CAA was quantified by calculating blur metric value, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of lung parenchyma. Image quality was qualitatively assessed by two independent radiologists. Lesion detection capabilities for lung nodules and emphysema and/or lung cysts were evaluated. Patients’ comfort levels during examinations were assessed. (3) Results: SNR and CNR of lung parenchyma were higher (both p < 0.001) in ZTE-AIR than in ZTE-CAA. Image sharpness was superior in ZTE-AIR (p < 0.001). Subjective image quality assessed by two independent readers was superior (all p < 0.05) in ZTE-AIR. AIR coil was preferred by 64 of 66 patients. ZTE-AIR showed higher (all p < 0.05) sensitivity for sub-centimeter nodules than ZTE-CAA by both readers. ZTE-AIR showed higher (all p < 0.05) sensitivity and accuracy for detecting emphysema and/or cysts than ZTE-CAA by both readers. (4) Conclusions: The use of highly flexible AIR coil in ZTE lung MR imaging can improve image quality and patient comfort. Application of AIR coil in parenchymal imaging has potential for improving delineation of low-density parenchymal lesions and tiny nodules.

Dual-energy computed tomography (CT) is a promising tool, providing both anatomical information and material properties. Using spectral information such as iodine mapping and virtual monoenergetic reconstruction, dual-energy CT showed added value over pulmonary CT angiography in the diagnosis of pulmonary embolism. However, the role of non-contrast-enhanced dual energy CT in pulmonary embolism has never been reported. Here, we report a case of acute pulmonary embolism detected on an electron density image from an unenhanced dual-energy CT using a dual-layer detector system.