PERFUSION-WEIGHTED MRI USING GADOBUTROL AS A CONTRAST AGENT IN A RAT STROKE MODEL

The purpose of this study was to examine the new nonionic contrast age nt gadobutrol in MR perfusion-weighted imaging, including the influenc e of different concentrations and dosages of the agent on the sensitiv ity to perfusion alterations, Sixteen rats were examined within 35 to 105 minutes after endovascular occlusion of the middle cerebral artery . A fast T2-weighted fast low-angle shot (FLASH) sequence was used to acquire four images before and 16 images after bolus injection of .1, .2, .3, and .4 mmol/kg gadobutrol as .5 molar and 1.0 molar formulati on. From user-defined regions, we obtained the maximum signal decrease , the relative regional cerebral blood volume, and the bolus delay. Co ntrast between ischemic and nonischemic regions during bolus passage i ncreased with dose and concentration of the contrast agent. For low do ses (.1 and .2 mmol/kg), the ischemic lesion could not or could barely be discerned, For higher doses (.3 and .4 mmol/kg), administration of the 1 molar contrast agent yielded a better contrast between ischemic and nonischemic tissue. Our results suggest that administration of ga dobutrol at higher dosage and higher concentration increases sensitivi ty to perfusion alterations, These results are potentially useful for perfusion-weighted imaging of the human brain, because the volume of c ontrast agent will be reduced if a solution with higher concentration is used. When using contrast agents in higher concentrations for human examinations, a significant signal decrease may be achieved also with the low doses (.1-.15 mmol/kg).