Experimental pancreas imaging study with 13N-glutamate using positron computer tomography.

Accumulation of 13N-L-glutamate in the pancreas was experimentally evaluated by tissue distribution studies and by positron computer tomography imaging studies. The pancreas and salivary gland of Donryu rats exhibited a high rate of 13N-glutamate uptake. The percent administered dose/g of pancreas was 3.8 at 20 min, 4.4 at 30 min after injection, and the pancreas to liver ratio was 1.9 and 2.5, respectively. The same results were obtained with Golden hamsters. The role of the feeding protocols was studied to optimize the technique. The fasting group showed a significantly higher uptake in the pancreas than in the free feeding group. The uptake in the fasting followed by a high protein meal group was higher than fasting only group, but the difference was not significant. Positron emission tomography of a miniature-pig with 13N-glutamate showed a clear image of the pancreas with the highest activity. It was concluded that 13N-glutamate was quite useful in positron imaging of the pancreas.