Residual gadolinium contrast agents in the urinary tract following MRI contrast-enhanced examinations often presents as elevated Hounsfield Unit (HU) values on CT scans, impeding the efficacy of CT urology procedures. This study aims to explore the feasibility of addressing this challenge through the application of the Dual-Energy Computed Tomography (DECT) Virtual Non-Contrast (VNC) technique across various energy levels. HU values of residual gadolinium contrast agent in the renal pelvis and ureter were measured in patients who underwent MRI contrast-enhanced examinations followed by non-contrast CT chest examinations. Subsequently, gadolinium contrast agent mixtures, such as Max, Mean, and Min Mixtures, were created and scanned together with normal saline using DECT at various energy levels. Additionally, an iodine mixture and a virtual stone representing urolithiasis were fabricated and evaluated. The results demonstrated a significant reduction in contrast enhancement of gadolinium contrast agent with DECT VNC at 70 kV and Sn150 kV. The Min Mixture closely resembled normal saline in both HU and Contrast-to-Noise Ratio (CNR), facilitating the differentiation between iodine contrast agent and virtual urolithiasis. Therefore, utilizing DECT VNC after a 1-hour and 30-minute interval following MRI contrast-enhanced examinations effectively eliminates gadolinium contrast agents, improving the efficacy of CT Urology imaging procedures.
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