| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1996: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1995: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
The magnetization transfer contrast (MTC) is a relatively new technique to generate additional tissue contrast. The purpose of this study was to evaluate the effectiveness of MTC technique in experimental hyperacute brain ischemia after Gd-DTPA administration at 7 T.
In the preliminary study, we investigated optimal combinations of the wave type, duration, amplitude, and offset frequency of MTC pulse in vitro. The optimal MTC pulse was the gauss pulse with longer duration, maximal amplitude and approximately 3 kHz off resonance. In 7 T MR system the signal intensity reduction with MTC pulse cannot be avoided.
In the animal study, MTC pulse used was a 20 msec gauss pulse, the amplitude of 12.6muT,and the offset frequency of 1 kHz. Mongolian gerbils after temporarily occlusion of common carotid artery were administrated intravenously with 0.2 mmol/kg of Gd-DTPA and the T1-weighted images without and with the MTC pulse were obtained.
No abnormal enhancements were observed in the control group without carotid occlusion. In the group with 30 minutes of bilateral temporary occlusion, the contrast enhanced T1-weighted images showed abnormal enhancement around the bilateral ventricles after one hour from carotid occlusion. Contrast between the enhancing area and the normal brian tissues was improved with MTC pulse, although the moderately signal intensity reduction was observed. In the group with 3 hours of unilateral occlusion, abnormal enhancement was also observed around the lateral ventricle dominantly in temporarily occluded side. As time passed, the area of abnormal contrast enhancement began to spread in the basal ganglia. The enhancement of basal ganglia was more conspicuous with application of the MTC pulse.
MTC technique and Gd-DTPA can synergistically improve the depiction of hyperacute brain ischemia.
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