PURPOSE: It is known for that oxygen-enhance lung MRI (OE-MRI) may reflect the physiological conditions of oxygen delivery, solubility of oxygen, and blood volume under which oxygen may dissolve. However few reports are available about that effect of pulmonary flow on the OE-MRI. So, we investigated the effect of the change of pulmonary vascular flow on the OE-MRI.
METHODS: Total five New Zealand White Rabbits were used throughout the study. Increased pulmonary flow (i-PF) was produced by intravenous infusion of sildenafil (0.2mg/kg) for 1 hour. Decreased pulmonary flow (d-PF) was produced by single subcutaneous injection of monocrotaline (60mg/kg). MRI consisted of a velocity-encoded cine MRI for pulmonary artery flow and an OE-MRI. The OE-MRI was acquired while the animals received mechanical ventilation alternately with either room air or 100% oxygen. Arterial blood gas analysis was also performed for room air and 100% oxygen at each status. We compared baseline to i-PF status, and to d-PF status for cardiac output of pulmonary artery, PaO2-increasing ratio, and signal enhancement ratio of OE-MRI. Wilcoxon signed rank test was used for statistical analysis.
RESULTS: Our results for baseline, i-PF, and d-PF were as follows: Mean cardiac output of pulmonary artery (ml): 409.7 ± 144.9, 470 ± 133. and 335.4 ± 114.6; PaO2-increasing ratio (%): 282.0 ± 44.7, 271.0 ± 15.6, 247.3 ± 18.7; signal enhancement ratio of OE-MRI (%): 21.3 ± 14.7, 25.1 ± 10.8, and 23.0 ± 14.3, respectively. There was significant difference for cardiac output of pulmonary artery between baseline and i-PF (p=0.043), and between baseline and d-PF (p=0.043). But, there was no significant difference for PaO2-increasing ratio and signal enhancement ratio of OE-MRI between baseline and i-PF (p=0.686 and 0.138, respectively). No significant difference was also shown for PaO2 increasing ratio and signal enhancement ratio of OE-MRI between baseline and d-PF (p=0.223 and 0.893, respectively).
CONCLUSION: There was little effect of pulmonary flow change on the signal enhancement of the OE-MRI.
CLINICAL IMPLICATIONS: The OE-MRI MRI mostly reflects oxygen delivery, ventilation.
DISCLOSURE: Kyu Ok Choe, No Financial Disclosure Information; No Product/Research Disclosure Information