Gadoquatrane in Contrast-enhanced Head-and-neck and Liver Magnetic Resonance Imaging

OBJECTIVES: The objective of the study was to investigate the dose-response (signal enhancement) relationship and signal-enhancement kinetics of gadoquatrane in different anatomic regions employing different MRI pulse sequences. Gadoquatrane is a novel high-relaxivity, extracellular macrocyclic gadolinium-based contrast agent with tetrameric structure that has the potential to be used at lower Gd doses than long-established contrast agents. MATERIALS AND METHODS: In this exploratory, prospective crossover study, 7 healthy pigs underwent contrast-enhanced MRI examinations with gadoquatrane (0.01, 0.03, and 0.06 mmol Gd/kg body weight) and standard doses (0.1 mmol Gd/kg) of 2 comparators, gadobutrol and gadoterate meglumine. MRI was performed on a 1.5T scanner under conditions typically used in clinical routine. Immediately after contrast-agent injection, multiphase liver MRI was done (VIBE sequence). Steady-state head-and-neck MRI followed (spin-echo and FLASH sequences alternating from 2 to 32 min after injection). Image evaluation was based on changes in signal intensity from baseline relative signal enhancement (RSE). Simple linear regression analysis was used to investigate the relationship between RSE and gadoquatrane dose. The regression equations were used to estimate the comparator-equivalent doses of gadoquatrane. RESULTS: The RSE achieved with gadoquatrane in steady-state head-and-neck MRI and multiphase liver MRI increased with dose in all anatomic structures examined, independent of the contrast-agent distribution phase and the pulse sequence employed. Linear regression analysis showed that generally a linear model fitted the dose-response data well ( r2 ≥ 0.84). However, in spin-echo images of the cavernous sinus and VIBE images of the hepatic vein, the areas with the strongest RSE, a disproportionately low RSE was seen with the highest gadoquatrane dose ( r2 of 0.78 and 0.48, respectively).RSE equivalent to the RSE achieved with gadoterate meglumine and gadobutrol at standard dose was achieved with gadoquatrane at doses between 0.031 to 0.039 mmol Gd/kg and 0.040 to 0.049 mmol Gd/kg, respectively. Largely parallel RSE-versus-time curves suggest similar signal-enhancement kinetics for gadoquatrane and the comparators. CONCLUSIONS: The study suggests that gadoquatrane, which demonstrated signal-enhancement kinetics similar to those of gadobutrol and gadoterate meglumine, might be utilized effectively at a dose below 0.05 mmol Gd/kg body weight, independent of the anatomic structure investigated and the pulse sequence employed. Overall, the study supports and complements the results of the clinical dose-response study of gadoquatrane.