Effect of the rate of gadolinium injection on magnetic resonance pulmonary perfusion imaging

Purpose: To determine whether the injection rate of contrast agent affects the dynamics of enhancement of the pulmonary parenchyma on magnetic resonance (MR) pulmonary perfusion imaging. Materials and Methods: Fifteen healthy volunteers underwent enhanced MR pulmonary perfusion imaging, to evaluate the effects of different injection rates. Injection rates were 1, 3, or 5 mL/second. Regions of interest (ROIs) were chosen in the lung and aorta to analyze the change in signal intensity over time. Results: As the injection rate increased, the peak enhancement occurred significantly earlier (P = 0.0012), but the peak enhancement signal-to-noise ratio (SNR) value was not affected (P = 0.25). With the 3- and 5-mL/second injection rates, images of both the pulmonary circulation and systemic circulation were obtained separately. However, with 1 mL/second, higher enhancement of the aorta was overlapped with peak enhancement of the lung tissue. Conclusion: The injection rate affects the enhancement profiles of the pulmonary parenchyma.