The experimental study of oxygen contrast MR ventilation imaging

Objective: To study the feasibility and basic technology of the oxygen contrast MR ventilation imaging in lung. Methods: Six canine lungs were scanned by using inversion recovery pulse sequence with turbo spin echo acquisition before and after inhalation of the 100% oxygen as T1 contrast agent, and the T1 values were measured. The contrast-to-noise ratio (CNR) for each inversion recovery time was compared and the relationship between arterial blood oxygen pressure (PaO2) and T1 relaxation rate was observed. Subtraction technique was employed in the postprocessing of pre- and post-oxygen conditions. Results: Molecular oxygen could shorten the pulmonary T1 value (average 13.37%, t=2.683, P<0.025). The optimized inversion delay time for the best CNR was about the average between the T1 value of pre- and post-oxygen conditions. The relaxtivity of T1 resulted in excellent linear correlation (r2=0.9974) with PaO2. Through the subtraction of pre- and post-oxygen image, the oxygen contrast MR ventilation -image was obtained. Conclusion: The oxygen contrast MR ventilation imaging has the feasibility and clinical potential for the assessment of regional pulmonary function