Carbon-11-acetate PET imaging in renal disease

The purpose of this study was to investigate the use of [1-¹¹C]acetate as a metabolic tracer for renal imaging in human subjects. Methods: Eighteen patients underwent dynamic PET imaging of the kidneys after intravenous bolus injection of 10-20 mCi [1-¹¹C]acetate. Time-activity curves of renal parenchyma tracer activity were fitted to a two-compartment model using direct arterial blood sampling for the arterial input function. Results: Renal uptake of [1-¹¹C]acetate is prompt and high target-to-background ratios are achieved even in the presence of markedly reduced renal function. Carbon-11-acetate is cleared from the renal parenchyma without any urinary excretion and the rate of clearance is comparable to myocardial clearance rates. Among normal subjects, K₁ ranged from 0.653 to 1.37 ml/min-g, and was reduced to as low as 0.363 ml/min-g in severe renal disease (serum creatinine greater than 5 mg/dl), while k₂ ranged from 0.114 to 0.166 min^-1 among normal subjects and was reduced to as low as 0.053 min^-1 in severe renal disease. Kinetic parameters K₁ and k₂ were both reduced in the presence of intrinsic renal disease or significant renal artery stenosis. Renal cell carcinoma demonstrated similar uptake of [1-¹¹C]acetate, but substantially reduced the rate of clearance compared to normal and diseased non-neoplastic renal tissue, allowing for ready differentiation of renal cell carcinoma from non-neoplastic renal tissue on images acquired beyond 10 min of tracer administration. Conclusion: Carbon-11-acetate is a promising physiologic tracer for the study of renal disease.