Comparative study of the value of dual tracer PET/CT in evaluating breast cancer

The present study was conducted to assess the relationship between tumor uptake and pathologic findings using dual-tracer PET/computed tomography (CT) in patients with breast cancer. Seventy-four patients with breast cancer (mean age 54 years) who underwent ¹¹C-choline and 2-[ ¹⁸F]fluoro-2-deoxy-d-glucose ( ¹⁸F-FDG) PET/CT prior to surgery on the same day were enrolled in the present study. Images were reviewed by a board-certified radiologist and two nuclear medicine specialists who were unaware of any clinical information and a consensus was reached. Uptake patterns and measurements of dual tracers were compared with the pathologic findings of resected specimens as the reference standard. Mean (±SD) tumor size was 5.9 ± 3.2 cm. All primary tumors were identified on ¹⁸F-FDG PET/CT and ¹¹C-choline PET/CT. However, ¹⁸F-FDG PET/CT demonstrated focal uptake of the primary tumor with (n = 38; 51%) or without (n = 36; 49%) diffuse background breast uptake. Of the pathologic findings, multiple logistic regression analysis revealed an independent association between fibrocystic change and diffuse background breast uptake (odds ratio [OR] 8.57; 95% confidence interval [CI] 2.86-25.66; P < 0.0001). Tumors with higher histologic grade, nuclear grade, structural grade, nuclear atypia, and mitosis had significantly higher maximum standardized uptake values (SUV _max) and tumor-to-background ratios (TBR) for both tracers. Multiple logistic regression analysis revealed that only the degree of mitosis was independently associated with a high SUV _max (OR 7.45; 95%CI 2.21-25.11; P = 0.001) and a high TBR (OR 5.41; 95%CI 1.13-25.96; P = 0.035) of ¹¹C-choline PET/CT. In conclusion, ¹¹C-choline may improve tumor delineation and reflect tumor aggressiveness on PET/CT in patients with breast cancer.