Reproducibility of [11C]Choline-Positron Emission Tomography and Effect of Trastuzumab

Purpose: This study sought to evaluate the reproducibility of [ 11 C]choline-positron emission tomography and the effect of trastuzumab in breast cancer. Experimental Design: Twenty-one patients with newly diagnosed and recurrent breast cancer stage II-IV had a baseline dynamic [ 11 C]choline-PET scan, 10 patients had a second [ 11 C]choline-PET scan to examine reproducibility, and 6 patients had a second scan within a month after trastuzumab. Analysis of [ 11 C]choline uptake was measured as the semiquantitative standardized uptake value at 30 and 60 minutes (SUV 30 and SUV 60 ), and quantitatively as the net irreversible retention of the radiotracer at steady-state (Ki) and plasma to tissue exchange at 60 minutes (IRF60min). Results: Breast tumor lesions in all patients were visualized by [ 11 C]choline PET. The difference in tumor versus normal tissue uptake was significant for SUV 30 , SUV 60 , Ki, and IRF60 minutes (Wilcoxon P 11 C]choline radioactivity. [ 11 C]Choline uptake was reproducible in breast tumor lesions ( r 2 = 0.9 for SUV, 0.9 for Ki, and 0.8 for IRF60). Early responses to trastuzumab measured by [ 11 C]choline-PET were significant in three lesions occurring in two patients who responded clinically. Conclusions: [ 11 C]Choline-PET uptake variables can be reproducibly assessed. Initial studies show that trastuzumab decreases [ 11 C]choline uptake. Clin Cancer Res; 16(16); 4236–45. ©2010 AACR.