MRI OF PULMONARY-EMBOLISM USING GD-DTPA-POLYETHYLENE GLYCOL POLYMER ENHANCED 3D FAST GRADIENT-ECHO TECHNIQUE IN A CANINE MODEL

This study was to evaluate the accuracy of MR angiography (MRA) using a Gd-DTPA-polyethylene glycol polymer (Gd-DTPA-PEG) with a 3D fast gra dient echo (3D fgre) technique in diagnosing pulmonary embolism in a c anine model. Pulmonary emboli were created in six mongrel dogs (20-30 kg) by injecting tantalum oxide-doped autologous blood clots into the femoral veins via cutdowns. MRI was performed with a 1.5 T GE Signa im ager using a 3D fgre sequence (11.9/2.3/15 degrees) following intraven ous injection of 0.06 mmol Gd/kg of Gd-DTPA-PEG. The dogs were euthani zed and spiral CT of the lungs were then obtained on the deceased dogs . The MRI images were reviewed independently and receiver-operating-ch aracteristic (ROC) curves were used for statistical analysis using spi ral CT results as the gold standard. The pulmonary emboli were well vi sualized on spiral CT. Out of 108 pulmonary segments in the six dogs, 24 contained emboli >2 mm and 27 contained emboli less than or equal t o 2 mm. With unblinded review, MRI detected 79% of emboli >2 mm and on ly 48% of emboli less than or equal to 2 mm. The blinded review result s were significantly worse. Gd-DTPA-PEG enhanced 3D fgre MRI is potent ially able to demonstrate pulmonary embolism with fairly high degree o f accuracy, but specialized training for the interpretations will be r equired. (C) 1997 Elsevier Science Inc.