MR imaging of acute cerebral infarction: experimental study with Gd-DTPA

To evaluate the sensitivity of MR imaging for acute cerebral infarction and the effectiveness of MR enhancement with Gd-DTPA, we created a canine model of cerebral infarction by transarterial embolization (TAE). The external and internal carotid arteries were embolized respectively through a transfemoral catheter. MR imaging was performed with the Yokogawa Medical System prototype superconducting MR machine "Resona" operating at 0.35 Tesla. MR enhancement was done with 0.4 mmol/kg of Gd-DTPA. Early detectability without Gd-DTPA was 60% (3/5) two hours after TAE and 67% (4/6) at three hours. MR imaging showed high-intensity lesions on the T2-weighted sequence (SE 2000/100). The T1-weighted sequence (SR 250-600/25-35) did not reveal any lesions four hours after TAE. Five animals which received Gd-DTPA showed abnormal enhancement in the brain parenchyma within 30 min after Gd injection on the T1 weighted sequence. Gd-DTPA enhancement not only improved early sensitivity for acute cerebral infarction when MR imaging without Gd-DTPA was negative, but also enhanced the size and number of lesions compared with SE 2000/100 images without enhancement. The breakdown of the blood-brain barrier was suggested to be an important factor in Gd-DTPA enhancement.