Bridging the Allergy–Radiology Gap in Radiocontrast Media Hypersensitivity: A Patient-Level Linkage Study on Diagnostic Stewardship and Re-Exposure Outcomes

Background/Objectives: We examined how allergy findings related to candidate-agent identification, subsequent real-world imaging and clinical outcomes. Methods: This single-centre retrospective cohort included 29 adults evaluated between January 2019 and May 2025 for contrast media hypersensitivity. Imaging and outcomes between allergy evaluation and a structured telephone interview in July 2026 were assessed retrospectively and verified in national electronic health records, without prospective follow-up. Primary outcomes were skin test positivity and new hypersensitivity reactions during subsequent contrast administration. Results: The culprit contrast agent was not documented by name in 18 patients (62.1%); median evaluation delay was 60 months. Skin tests were positive in 1/20 patients (5.0%); skin-test-negative candidate agents were identified in 19/20 (95.0%). New reactions occurred in 3/14 contrast recipients (21.4%), all with immediate Brown Grade III index reactions to iohexol. Subsequent reactions included one cardiac arrest after iohexol and two Grade II reactions after iodixanol. Of seven patients imaged without contrast, four had candidate agents but reported continuing patient and physician concerns. No Holm-adjusted comparison was significant. Conclusions: Skin testing identified a candidate agent in most tested patients, but candidate identification did not establish clinical tolerance or independent protection. A shared, individualised imaging plan should communicate agent selection, premedication decisions, test limitations and precautions to patients and radiologists while preserving access to necessary imaging.