OBJECTIVE:Liver Imaging Reporting and Data System category M (LR-M) is associated with a poor prognosis in intrahepatic cholangiocarcinoma (iCCA). However, the prognostic value of individual LR-M features across imaging modalities remains unclear. We aimed to determine, through intraindividual comparisons, whether the prognostic value of individual LR-M features differs between CT and MRI in patients with iCCA at risk for hepatocellular carcinoma. MATERIALS AND METHODS:This retrospective study included consecutive patients with cirrhosis or chronic hepatitis B who underwent curative-intent resection for iCCA and preoperative multiphasic CT and MRI between 2010 and 2019. CT and MRI images were reviewed in separate sessions ≥4 weeks apart. Cox proportional hazards regression analyses with and without adjustment for LI-RADS categorization (non-LR-M vs. single-modality LR-M or dual-modality LR-M) were performed to evaluate the associations of CT- and MRI-based targetoid and non-targetoid LR-M features and other variables with recurrence-free survival (RFS) and overall survival (OS). RESULTS:A cohort of 122 patients (mean age, 57.9 ± 10.4 years) was included. MRI demonstrated significantly higher frequencies than CT for targetoid (84.4% vs. 73.8%, P = 0.007) and non-targetoid features (43.4% vs. 20.5%, P < 0.001), resulting in a higher rate of LR-M categorization (90.2% vs. 81.1%, P = 0.003). In the multivariable analysis, CT-based targetoid features (hazard ratio [HR] = 2.31 for RFS, P = 0.010; HR = 1.85 for OS, P = 0.043) and MRI-based non-targetoid features (HR = 2.15 for RFS, P = 0.005; HR = 2.09 for OS, P = 0.008) were independently associated with poorer survival. After adjustment for LI-RADS categorization, MRI-based non-targetoid features remained independently associated with poorer RFS (HR = 1.76, P = 0.041) and OS (HR = 1.79, P = 0.038). Dual-modality LR-M designation was independently associated with poorer RFS (HR = 8.02, P = 0.042). CONCLUSION:The prognostic implications of LR-M features in iCCA vary by imaging modality and feature type. CT-based targetoid and MRI-based non-targetoid features were associated with poorer survival, and the associations between MRI-based non-targetoid features and survival remained significant after adjustment for LI-RADS categorization.
OBJECTIVE:To evaluate the sequential changes in right ventricular (RV) strain and histological vascular remodeling and their correlations during pulmonary hypertension (PH) development in a rat model by using cardiac magnetic resonance (CMR)-feature tracking (FT). MATERIALS AND METHODS:Separate cohorts of six-week-old male Wistar rats (10 per group) were allocated to a baseline group, PH induction groups assessed at 1, 2, 3, or 4 weeks after monocrotaline injection, and vehicle-injected control groups assessed at 2 and 4 weeks. Each rat underwent a single magnetic resonance imaging (MRI) examination and was subsequently euthanized for histological analysis. Cine images were acquired using a 9.4T MRI scanner, and strain was analyzed using the FT technique. Histological analysis was used to quantify pulmonary arterial wall thickness percentage (PA %WT) and RV collagen density. Overall group differences were analyzed using the Kruskal-Wallis test, which was followed by the Mann-Whitney U test with Bonferroni correction for pairwise comparisons with the baseline group. Correlations between the variables were assessed using Spearman's correlation coefficients. RESULTS:All CMR-derived RV parameters showed significant differences across the baseline and PH induction groups (all P < 0.001). RV free wall longitudinal strain (RVFWLS) showed the earliest impairment at 2 weeks, with a progressive decline thereafter. The RV free wall circumferential strain (RVFWCS) and RV ejection fraction were reduced beginning at 3 weeks, whereas the RV end-diastolic volume index increased significantly only at 4 weeks. The PA %WT increased progressively from week 2, whereas the RV collagen density did not change significantly. RVFWLS and RVFWCS showed strong positive correlations with PA %WT (r = 0.885 and r = 0.757, respectively; both P < 0.001), which were primarily driven by parallel changes across the post-induction time points. The control groups showed no significant temporal changes in the CMR or histological measurements. CONCLUSION:In this preclinical model of PH, staged CMR and histological assessments demonstrated sequential RV remodeling in parallel with PA remodeling, with RVFWLS impairment preceding overt RV dysfunction and enlargement.
OBJECTIVE:To evaluate the feasibility, safety, and treatment outcomes of single-session whole-liver yttrium-90 (Y90) transarterial radioembolization (TARE) in patients with multifocal hepatocellular carcinoma (HCC). MATERIALS AND METHODS:This retrospective study included 37 patients (age, 23-86 years; median age, 60 years) with multifocal HCC (2-21 tumors; median, 9) and preserved liver function (Child-Pugh A) who underwent planned single-session whole-liver Y90 TARE between 2017 and 2024. Treatment was performed when no substantial liver parenchyma could be spared on pretreatment imaging and angiographic evaluation. Treatment planning was based on the findings of technetium-99m macroaggregated albumin single-photon emission computed tomography and partition-model dosimetry. Tumor response was assessed using the modified Response Evaluation Criteria in Solid Tumors. Overall survival, progression-free survival, and hepatic toxicity were also evaluated, with toxicity assessed on the basis of the occurrence of adverse events, Child-Pugh class change, and the development of ascites within 3-6 months. RESULTS:Patients were followed up for 1.4-49.0 months (median, 17.8 months). At 3 months, the objective response rate was 78.4%; the disease control rate was 94.6%; and complete response was noted in 11 patients (29.7%). Successful downstaging was achieved in 19 (51.4%) patients. The median overall survival was not reached, and the median progression-free survival was 23.5 months. The 2-year overall and progression-free survival rates were 78.3% and 46.8%, respectively. Eleven patients (29.7%) subsequently underwent surgery, including one resection and 10 living-donor liver transplantations. None of the patients showed grade 3 or 4 adverse events or radioembolization-induced liver disease. One patient with cirrhosis showed worsening of the Child-Pugh class with ascites. CONCLUSION:Single-session whole-liver Y90 TARE was feasible and showed acceptable hepatic safety in carefully selected patients with multifocal HCC and preserved liver function. It achieved high response and downstaging rates and may serve as a bridge to curative surgery in selected patients.
OBJECTIVE:To clarify the qualitative and quantitative MRI features of myxoid leiomyosarcoma (MLMS) in comparison with conventional leiomyosarcoma (cLMS) and to identify the specific diagnostic pitfalls of the current consensus criteria when applied to the MLMS subtype. MATERIALS AND METHODS:This retrospective multicenter study (12 institutions) included patients with histopathologically confirmed leiomyosarcoma (MLMS or cLMS) who underwent preoperative MRI. A total of 38 women (15 with MLMS and 23 with cLMS; median age, 55 years) were evaluated. Three radiologists independently evaluated features, including T2 signal patterns (purely hyperintense, mixed, iso-to-moderately hyperintense) and a characteristic "marbled appearance" (heterogeneous signal intermingling). The tumors were classified as benign or malignant on the basis of the apparent diffusion coefficient (ADC) values in accordance with the current consensus criteria. A histogram analysis was performed using multiparametric sequences. RESULTS:MLMS frequently exhibited purely T2-hyperintense or mixed patterns (12 of 15 [80%]), whereas cLMS predominantly showed T2-isointensity to moderate hyperintensity (21 of 23 [91%]) (P < 0.001). The "marbled appearance" was identified in 11 of 15 (73%) MLMS cases and 2 of 23 (9%) cLMS cases (P < 0.001). Median ADC values of the most restricted component were significantly higher in MLMS (1.14 × 10⁻³ mm²/s) than in cLMS (0.80 × 10⁻³ mm²/s) (P < 0.001). Consequently, the consensus ADC criteria misclassified 10 of 12 (83%) MLMS cases as benign, in comparison with 3 of 21 (14%) cLMS cases (P < 0.001). Notably, among these 10 misclassified MLMS cases, 8 (80%) demonstrated the "marbled appearance." Histogram analysis confirmed that patients with MLMS had higher median normalized T2-weighted imaging signal intensity ratios (1.97 vs. 1.36; P = 0.019) and ADC ratios (1.39 vs. 0.82; P = 0.007). CONCLUSION:Strict reliance on ADC-based consensus criteria may lead to systematic under-recognition of MLMS. Recognizing the "marbled appearance" on MRI is crucial to prevent misclassifying these tumors as benign.
Artificial intelligence (AI) has rapidly transformed cardiac CT, extending its clinical utility from coronary CT angiography (CCTA) to CT myocardial perfusion imaging (CT-MPI). This review outlines the current advances in and future perspectives on AI-aided cardiac CT across anatomical, functional, and prognostic dimensions. In CCTA, AI can automate calcium scoring, vessel segmentation, and plaque characterization, markedly improving workflow efficiency and reproducibility. Deep-learning models can allow accurate detection of coronary stenosis and plaque quantification, achieving diagnostic and prognostic performances comparable to those of invasive reference standards. Beyond anatomical assessment, machine learning-based CT-derived fractional flow reserve measurements can provide lesion-specific functional evaluation directly from routine CCTA scans, substantially improving computational efficiency over conventional fluid dynamics while maintaining diagnostic accuracy. In functional imaging, AI can facilitate automated quantification of myocardial blood flow and ischemic myocardial volume, showing excellent agreement with manual measurements and strong performance for ischemia detection and risk stratification. Emerging approaches for virtual perfusion modeling and deep-learning-based denoising have further expanded the noninvasive assessment of myocardial physiology and tissue characterization. Despite these advances, challenges in aligning AI development with clinical requirements, acquiring diverse and high-quality datasets, and translating algorithms into validated tools remain unresolved. Furthermore, the current evidence is limited by retrospective designs, selected validation cohorts, and insufficient external and prospective testing in complex real-world settings. Addressing these challenges through multidisciplinary collaboration, standardized protocols, and robust validation frameworks is critical for responsible integration of AI into routine cardiovascular imaging and for realizing its full potential in precision cardiovascular care.
Magnetic resonance elastography (MRE) is widely recognized as the most accurate, non-invasive imaging technique for evaluating liver fibrosis. However, MRE requires dedicated hardware, including an external vibration device, which limits its availability. Virtual MRE (VMRE) has recently emerged as a promising alternative technique in which tissue stiffness is estimated using diffusion-weighted imaging data without the need for external mechanical vibrations. VMRE is based on the hypothesis that tissue elasticity and water diffusivity share common mechanical features at the microstructural level. By calculating the shift in the apparent diffusion coefficient from the optimized b-values (200 and 1,500 s/mm²), the virtual stiffness can be derived and calibrated against the MRE-derived stiffness. Studies in cohorts with chronic viral hepatitis have demonstrated strong correlations between VMRE and MRE findings, with both techniques showing good agreement in liver fibrosis staging. Although the utility of VMRE in patients with metabolic dysfunction-associated steatotic liver disease (MASLD) was previously considered debatable because of the confounding effects of steatosis, recent evidence suggests that VMRE performed using an optimized fat-correction method combined with MASLD-specific b-values (200 and 1,200 s/mm²) can achieve diagnostic performance comparable to that of MRE. Beyond liver fibrosis assessment, the combination of VMRE and MRE has shown potential for distinguishing hepatocellular carcinoma from metastatic liver cancers. This article provides a comprehensive overview of VMRE, including its technical basis and current clinical applications in chronic liver diseases and focal liver lesions.
Gastric cancer continues to be a significant global health challenge, particularly in East Asia, necessitating precise imaging for optimal management. Although multidetector computed tomography (MDCT) has become the primary tool for staging and response evaluation, clinical practice is hampered by a lack of standardized protocols and interpretation criteria. To address these needs, the Korean Society of Abdominal Radiology established a consensus-based guideline for gastric cancer CT. Using a modified Delphi process with a panel of experts, 10 key statements were developed and validated with a high level of agreement (≥80%). These recommendations emphasize the necessity of adequate gastric distention and a dedicated arterial phase to identify critical vascular variations, such as aberrant left hepatic arteries, for surgical planning. The guideline provides refined criteria for T, N, and M staging, including the use of multiplanar reformations and three-dimensional visualization to improve diagnostic accuracy. Furthermore, it introduces dedicated criteria for re-staging after chemotherapy, highlighting the differentiation of viable tumor from treatment-induced fibrosis. Finally, a risk-stratified approach for postoperative surveillance is proposed, suggesting that surveillance may be de-escalated in very-low-risk groups, such as pT1aN0 disease. These recommendations are intended to standardize CT practice and improve clinical decision-making in the management of gastric cancer.
Hepatocellular carcinoma (HCC) is a biologically heterogeneous malignancy staged according to tumor burden and clinical status. Molecular and histopathologic factors remain unincorporated into current staging systems, as they are usually unavailable because HCC is often diagnosed noninvasively. Emerging evidence indicates that magnetic resonance imaging (MRI) features reflect underlying tumor biology and provide prognostic information beyond diagnosis. MRI can differentiate proliferative-class HCC, which is characterized by aggressive behavior, frequent microvascular invasion (MVI), and poor outcomes, from non-proliferative-class HCC with more favorable biology. Several MRI features, including rim arterial phase hyperenhancement (APHE), non-smooth margins, necrosis, intratumoral arteries, low apparent diffusion coefficient, peritumoral APHE, and peritumoral hepatobiliary phase (HBP) hypointensity, have been associated with aggressive tumor behavior and adverse outcomes. In contrast, capsule appearance, intratumoral fat, and HBP hyperintensity are associated with more favorable biology. Although biopsy is not routinely required when characteristic imaging features of HCC are present, imaging features suggestive of aggressive tumor subtypes may identify patients who could benefit from histologic confirmation for diagnostic clarification, molecular profiling, or treatment planning. Radiomics and artificial intelligence-based analyses further enhance MVI prediction, recurrence risk stratification, and noninvasive molecular characterization. In conclusion, the emerging role of MRI in characterizing tumor biology underscores the growing importance of imaging biomarkers in clinical decision-making and selective biopsy strategies.
