AIM: To cxplore the diagnostic effect of pulmonary ventilation-perfnsionfMRI for pulmonary embolism(PE).METMODS: Gelatin sponge was intraduced into the left fewer lobar pal-monary arteries of 4 dogs through catheter under distal subtraction an#ag-raphy(DSA) so as to establish PE model. Before PE, the dogs inhaled roomair(21%O2) and 99.5%02 respectively and inhaled 99.5% 02 again afterPE. Then MRI scanning was performed for pulmonatT ventilation. The signalintersitites (SI) of left lower lobe wore meesured and its variation was oh-sexved. The dogs were undergone MRI scanning before and efiex PE to ob-serve the perfusion of ]eft lower lobe.RESULTS: Both before and ofter PE the SI of left lower lobe after inhalationof 99.5% O2 increased significantly much more than after inhalation of indoorair. However, there was no significant difference in the increase of SI valuehctween the emhollc left lower lobe and non-mhdiio region of the right lowerlobe (t=3.685, P>0.05), indicating that pulmonary ventilation was notinfluenced in the emholic region of left lower loho. During perfusion MRscanning and after injection of contrast media, the SI of non-embelic re#on inthe fight lower lobe rapidly inched and reached the peak 6.8 aconds atinrinjection of contrast media. Bm the time-signal intensity curve of die embeficregion of left fower lube rpmained at lower level and had no apparont peakvalue all the time. CONCLUSION: Oxygen-enhanced ventilation fMRI combining pexlnsionfMRI provide a new diagnostic means for PE. The method is feasible andbeneficial for PE diagnosis.