Radiology

Global CAD imaging study highlights wide, modality- and region-dependent variation in radiation dose

In this 19,302-patient, 101-country cross-sectional study, effective dose varied markedly across noninvasive CAD imaging modalities and regions. Median effective dose was 1.2 mSv for coronary calcium scoring, 2.0 mSv for PET, 6.5 mSv for SPECT, and 7.4 mSv for CCTA. More nuclear cardiology centers and patients met the ≤9 mSv guideline target compared with CCTA (81% vs 56% of centers; 79% vs 56% of patients). Doses for the same procedure differed substantially by region, lowest in Western Europe and highest in Latin America (nuclear) and Africa (CCTA). Compared with high-income countries, patient dose was 20% higher for nuclear studies and up to 96% higher for CCTA in lower-income settings. 1

Multifrequency MR elastography improves Crohn fibrosis assessment beyond standard MR enterography

This prospective study enrolled 56 Crohn disease patients undergoing preoperative multifrequency MR elastography plus MR enterography, with histologic fibrosis as reference. Shear-wave speed correlated strongly with histologic fibrosis score and collagen proportion (r up to 0.67) and achieved AUC 0.87 for moderate-to-severe fibrosis. Loss angle showed weaker but significant correlations and lower diagnostic accuracy (AUC 0.73). Shear-wave speed also correlated with Piezo1 expression, supporting its role as a biomechanical imaging biomarker of intestinal stiffness. XGBoost models incorporating elastography, advanced, and conventional MR features (complete model AUC 0.89) outperformed models using conventional features alone (AUC 0.54). 2

Serial CMR with mapping in acute myocarditis links persistent inflammation to long-term MACE

In this multicenter cohort of 105 MRI-confirmed acute myocarditis patients, CMR was performed at baseline, ~1 month, and ~1 year with 5‑year follow-up. Active disease by LLc 2018 criteria persisted in 91% at short term and 61.5% at long term, indicating frequent chronic inflammation. Greater long-term scar burden was associated with higher MACE risk, while a lateral LGE pattern was linked to better prognosis. Native T1 at short-term CMR and T2 mapping at long-term CMR were independent predictors of adverse events in multivariate analysis. Temporal changes in CMR parameters between time points did not add prognostic value beyond absolute values. 3

Commercial ICH AI underperforms on-call residents on emergency noncontrast head CT

This single-center, real-world study evaluated 2,153 emergency unenhanced head CTs for suspected intracranial hemorrhage using a commercial AI and on-call residents. ICH prevalence was 15.4%, with board-certified radiologists providing the reference standard. Overall, AI sensitivity and specificity were 84% and 94.4%, versus 96.4% and 99.6% for radiology residents (both p < 0.001). In cases with multiple hemorrhage types or multiple sites, AI sensitivity approached residents, but without performance superiority. Findings indicate AI is not ready to replace residents for ICH detection in emergency workflow and should be integrated cautiously. 4