VISUALIZATION OF BLOOD-BRAIN-BARRIER DISRUPTION ON NIR IMAGES OF CATSWITH ACUTE CEREBRAL INFARCTION - VALUE OF ADMINISTERING A HIGH-DOSE OF CONTRAST MATERIAL

OBJECTIVE. The detection of blood-brain barrier disruption in patients with cerebral infarction by means of contrast-enhanced MR images impr oves the specificity of diagnosis, enables lesion dating, and on occas ion improves lesion detection. Accordingly, we performed a study to de termine the extent of visualization of disruption of the blood-brain b arrier on contrast-enhanced MR images, with specific attention to cont rast dose, in a cat model of acute cerebral infarction. We used doses of 0.1 and 0.3 mmol/kg of a gadolinium chelate, gadoteridol, which is characterized by extracellular distribution and renal excretion, and w as approved by the Food and Drug Administration for clinical use at th ese doses. MATERIALS AND METHODS. Blood flow in the middle cerebral ar tery was occluded unilaterally in seven cats for 1 hr, followed by 4 h r of reperfusion. T2- and T1-weighted MR images were obtained before t he injection of contrast material. After injection, the time course of enhancement was observed for 1 hr by repeated sequential acquisition of T1-weighted images. Five cats received an initial injection of 0.1 mmol/kg of contrast material, supplemented 33 min later by 0.2 mmol/kg (cumulative dose, 0.3 mmol/kg). Two cats received a single injection of contrast material, either 0.1 or 0.3 mmol/kg. The images were revie wed in a prospective fashion by a single observer, who was blinded to the dose of contrast material and the timing of image acquisition, in order to detect abnormal contrast enhancement. Changes in signal inten sity were quantified by region-of-interest measurements. RESULTS. Enha ncement at 4 and 13 min, respectively, after injection of contrast mat erial was 25 +/- 10% and 38 +/- 7% with 0.1 mmol/kg, vs 80 +/- 12% and 100 +/- 15% with 0.3 mmol/kg (n = 5). The difference between doses wa s statistically significant (p < .002) for all time points. Abnormal c ontrast enhancement was visible in three of six cats that received 0.1 mmol/kg and in all cats that received 0.3 mmol/kg. By 13 min after in jection, enhancement had peaked with a dose of 0.1 mmol/kg and was wit hin 20% of maximum with a dose of 0.3 mmol/kg. CONCLUSION. Detection o f disruption of the blood-brain barrier in acute cerebral infarction i n cats is improved when high doses (0.3 mmol/kg) of contrast material are used. Disruption may not be visualized when 0.1 mmol/kg, the curre ntly accepted standard dose, is used.