RT Journal Article SR Electronic T1 11C-acetate PET/CT for prediction of negative lymph node involvement of prostate cancer before prostatectomy JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1444 OP 1444 VO 56 IS supplement 3 A1 Sirong Chen A1 Yim Lung Leung A1 Kam Chau Cheng A1 Ka-Nin Wong A1 William Cheung A1 Man-ki Cheung A1 Chi-Lai Ho YR 2015 UL http://jnm.snmjournals.org/content/56/supplement_3/1444.abstract AB 1444 Objectives Accurate prediction of negative lymph node (LN) involvement is essential to facilitate the confidence and success of radical prostatectomy, particularly in patients with intermediate/high-risk prostate cancer (PCa). We aim to evaluate the value of 11C-acetate PET/CT for prediction of negative LN involvement in this group of patients before prostatectomy.Methods From July 2012 to June 2014, newly diagnosed PCa patients referred for 11C-acetate PET/CT were consecutively recruited. PET/CT was performed at 20 min post injection of ~550MBq 11C-acetate. Presence/absence of LN metastasis was evaluated by 2 nuclear medicine physicians in consensus. Patients with no LN involvement on 11C-acetate PET/CT and who underwent radical prostatectomy & pelvic LN dissection within 1 month after PET/CT were analyzed. Postoperative pathology served as the gold standard. Intermediate/high-risk patients were defined as those with: Gleason score (GS)=7 & serum PSA>=10ng/mL, GS>=8, or PSA>20ng/mL.Results 52 patients (age range:54~81y, mean=67.7±7.5y) showed absence of LN metastasis on 11C-acetate PET/CT and underwent radical prostatectomy & pelvic LN dissection within 1 month after imaging. 27/52 (52%) patients (mean age=68.7±7.1y, GS=7.2±1.0, PSA=29.8±15.3ng/mL) were classified as intermediate/high-risk and 25/52 (48%, mean age=66.5±8.1y, GS=6.2±0.4, PSA=7.9±2.2ng/mL) as low-risk. Histopathology revealed LN metastases in 3/27 (11.1%) intermediate/high-risk patients with 1 LN metastasis in each patient, and 0/25 (0%) low-risk patients. The accuracy for prediction of negative LN involvement in intermediate/high-risk and low-risk patients by preoperative 11C-acetate PET/CT was 88.9% and 100%, respectively.Conclusions 11C-acetate PET/CT has a high negative predictive value for LN involvement in newly diagnosed PCa patients with intermediate/high risk comparable to those with low risk. Inclusion of this imaging as part of preoperative work-up may facilitate the confidence and success of operative treatment for these patients.