Effect of oral glucose loading on the biodistribution of BMIPP in normal volunteers

We have evaluated whether myocardial uptake of the fatty acid analog 123I-15-(p-iodophenyl)-3-R,S-methyl pentadecanoic acid (BMIPP) is dependent on the dietary state.

We compared the biodistribution of 150 MBq of 123I-BMIPP in six healthy volunteers in two states: after at least 12 hr of fasting and after oral glucose loading (75 g) 60 min before tracer administration, followed by a meal enriched in carbohydrates and protein. Planar and tomographic acquisitions were performed over a 4-hr time period after tracer injection; data were corrected for radioactive decay and injected dose. Radioactivity was measured in blood samples drawn at several points.

Significant increases of glycemia and insulinemia and a significant drop in plasma nonesterified acids were documented after glucose loading. Half-time values for plasma radioactivity were significantly shorter in the glucose-loaded state than in the fasted state (4.3 +/- 1.4 min compared to 6.3 +/- 1.3 min, p < 0.05). Activity in the heart and liver tended to be higher in the glucose-loaded state than in the fasted state. SPECT images at 0.5 hr after tracer injection demonstrated that the myocardial wall-to-cavity ratio was higher after glucose than in the fasted state (2.53 +/- 0.59 compared to 2.11 +/- 0.21, p = 0.15). Washout from the liver between 1 and 4 hr after injection increased from 18.6% +/- 4.4% in the fasted study to 24.1% +/- 2.4% after glucose (p = 0.04). Washout from the myocardium between 0.5 and 3.5 hr after injection increased from 13.1% +/- 8.8% in the fasted study to 24.0% +/- 3.7% after glucose (p = 0.05).

These results indicate that fasting before BMIPP scintigraphy is not mandatory to obtain adequate SPECT images. At the tire when SPECT is usually performed, glucose loading may provide improved ratios between myocardial and blood pool activity.