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

ABSTRACT 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.