Predicting Signal Intensity Profiles for Various MRI Contrast Agent Injection Strategies: Including Measurement of Relaxivities in Oxygenated Whole Human Blood for Gadopiclenol, Gadoterate Meglumine and Gadoteridol

Background Gadolinium based contrast agents (GBCAs) vary in arterial signal intensity (SI) profiles. Gadopiclenol is a high relaxivity GBCA approved at 0.05 mmol/kg. Purpose Evaluate contrast‐enhanced MRA injection strategies: measure r 1 , r 2 , and r 2 * of gadopiclenol, gadoterate meglumine, and gadoteridol in plasma and blood, and model arterial SI profiles for different injection rates. Study Type Phantom/Modeling. Phantom Vials of oxygenated whole blood and plasma, with gadopiclenol, gadoterate meglumine, and gadoteridol ranging from 1 to 18 mM. FIELDSTRENGTH/Sequence Look‐Locker, multi‐echo turbo spin echo (mTSE), multi‐echo fast field echo (mFFE) at 1.5 T and 3.0 T. Assessment R 1 derived by mono‐exponential recovery fitting of Look‐Locker data. R 2 and R 2 * derived by fitting mono‐exponential decays of mTSE and mFFE data. r 1plasma , r 2plasma,blood , r 2plasma,blood * derived by linear fitting of R 1 , R 2 , R 2 * versus GBCA concentration [GBCA]. R 1blood predicted using fast‐exchange‐regime (FXR) and ‐limit (FXL), compared with measured R 1blood . Spoiled gradient echo (SPGR) SI versus [GBCA] modeled at 1.5 T and 3.0 T for each GBCA and two SPGR protocols using these blood relaxivities, generating SI versus time curves at rates of 0.5, 1, and 2 mL/s. Statistical Tests Trust reflective least squares algorithm, Levenberg–Marquardt least squares curve fitting, FXR and FXL prediction models. Results Gadopiclenol r 1plasma , r 2plasma , r 2plasma * ~3 times greater than gadoteridol and gadoterate meglumine. R 1blood, well‐predicted by FXR (RMSE 4.6 vs. 28 s −1 for FXL). Gadopiclenol r 2blood * 20%–46% higher than the other contrast agents, with r 2 blood similar across agents (7.4–8.8 s −1 mM −1 at 1.5 T and 12.9–13.4 s −1 mM −1 at 3.0 T). CE‐MRA modeling demonstrated slight SI decrease at 1 versus 2 mL/s (0%–14% SI loss generally; 2%–6% for gadopiclenol), with a more uniform arterial enhancement profile. Conclusion SI profiles vary for different GBCAs. Modeling showed injection rates as low as 1.0 mL/s (or 0.5 mL/s for gadopiclenol and gadobutrol) may provide benefit. Level of Evidence 2. Technical Efficacy Stage 3.