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This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Sawamoto, H. Articles by Wahl, R. PubMed Articles by Sawamoto, H. Articles by Wahl, R.

Comparison of acetate and L-methionine as potential pancreatic imaging agents: Pre-clinical studies

¹ Radiology, The Johns Hopkins Medical Institutions, Baltimore, Maryland

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Objectives: Non-invasive imaging of pancreatic exocrine function remains a critical unmet clinical need. We compared the biodistribution of 14C-acetate and 3H-L-methionine under fasting conditions in rats to determine which of these agents is more suitable for exocrine pancreatic imaging.

Methods: Eight female Lewis rats were divided into 2 groups (acetate group: n=4, methionine group: n=4). Each rat was fasted overnight, but had free access to water. 14C-acetate or 3H-L-methionine (5uCi per rat) were injected into the tail veins after anesthesia with a ketamine/acepromazine cocktail. The animals were sacrificed 30 minutes after the tracer injection. Pancreas, other major organs and blood were removed for beta-counting. Tracer uptake was determined by percentage injected dose (%ID)/(gram of tissue)x(kilogram of body weight) from the biodistribution study.

Results: The mean tracer uptake of pancreas in the acetate group and the methionine group was 0.24±0.12 and 0.41±0.15, respectively (P=0.25). However, the mean %ID/g of pancreas normalized to %ID/g of liver in the acetate group and the methionine group was 8.55±5.09 and 1.67±0.64, respectively (P<0.05). Background blood activity levels were 0.01±0.00 (acetate group) and 0.03±0.01 (methionine group), and the mean %ID/g of pancreas normalized to %ID/g of blood was 16.35±6.76 (acetate group) and 15.04±7.26 (methionine group).

Conclusions: Although both of these tracers had high absolute uptake in the exocrine pancreas, with high pancreas/blood uptake ratios, 14C-acetate appears more suitable and advantageous than 3H-L-methionine. This suggests that 11C-acetate would be preferable as an exocrine pancreatic imaging agent due to its superior target/background contrast, especially between the pancreas and the liver.

This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Sawamoto, H. Articles by Wahl, R. PubMed Articles by Sawamoto, H. Articles by Wahl, R.