Use of [11C]Choline PET-CT as a Noninvasive Method for Detecting Pelvic Lymph Node Status from Prostate Cancer and Relationship with Choline Kinase Expression

Purpose: To evaluate the accuracy and biological basis for [C-11]choline-PET-CT in the nodal staging of high risk localized prostate cancer patients. Experimental Design: Twenty-eight patients underwent dynamic [C-11] choline-PET-CT of the pelvis and lower abdomen prior to extended laparoscopic pelvic lymph node dissection (eLPL). The sensitivity and specificity of [C-11]choline PET, [C-11]choline PET-CT, and MRI for nodal detection were calculated. Average and maximal standardized uptake values (SUVave, SUVmax) were compared with choline kinase alpha (CHK alpha) and Ki67 immunohistochemistry scores. Results: Four hundred and six lymph nodes (LN), in 26 patients, were assessable. Twenty-seven (6.7%) involved pelvic nodes at eLPL were detected in 9 patients. Seventeen of the 27 involved nodes were subcentimeter. The sensitivity and specificity on a per nodal basis were 18.5% and 98.7%, 40.7% and 98.4%, and 51.9% and 98.4% for MRI, [C-11]choline PET, and [C-11]choline PET-CT, respectively. Sensitivity was higher for [C-11]choline PET-CT compared with MRI (P = 0.007). A higher nodal detection rate, including subcentimeter nodes, was seen with [C-11]choline PET-CT than MRI. Malignant lesions showed CHKa expression in both cytoplasm and nucleus. SUVave and SUVmax strongly correlated with CHKa staining intensity (r = 0.68, P < 0.0001 and r = 0.63, P = 0.0004, respectively). In contrast, Ki67 expression was generally low in all tumors. Conclusion: This study establishes the relationship between [C-11]choline PET-CT uptake with choline kinase expression in prostate cancer and allows it to be used as a noninvasive means of staging pelvic LNs, being highly specific and more sensitive than MRI, including the detection of subcentimeter disease. Clin Cancer Res; 17(24); 7673-83. (C)2011 AACR.