Objective:

For an oncological tracer is relevant to know the uptake in inflamed/infected lesions. Thus, in the framework of a prospective trial aiming to compare the clinical value of 68Ga-DOTATATE and 11C-Choline PET/CT in patients with hormone-resistant prostate cancer at biochemical recurrence, we evaluated the false-positive findings of both techniques.

Methods:

The study group comprised 64 prostate cancer patients with PSA relapse under androgen deprivation therapy, with a median trigger PSA level of 4.25 ng/mL (range: 0.22-291 ng/mL). Within 1-2 weeks, a PET/CT study was performed with 68Ga-DOTATATE and 11C-Choline with an approximately dose of 100 MBq and 400 MBq, respectively, using a 64-slice PET/CT with time-of-flight correction. Correlative imaging, histopathology and/or clinical follow-up were considered as reference standard.

Results:

Both techniques showed positive local, regional and distant findings in 31 patients. Results were concordant in 57 cases (89%), with discordant findings observed in patients with bone (n=2) and regional lymph nodes lesions (n=5). On a per patient basis, sensitivity, specificity, positive and negative predictive values with their 95% confidence intervals were the same for both techniques: 0.82 (0.65-0.93), 0.90 (0.73-0.98), 0.90 (0.73-0.98) and 0.81 (0.65-0.93), respectively. False-positive lesions (n=5) were found, for both tracers, in 3 patients and were located in the prostate bed (n=1) and regional lymph nodes (n=4, being 3 discordant). In all cases, pathology revealed non-specific inflammatory lesions.

Conclusion:

This study demonstrates avid 68Ga-DOTATATE and 11C-Choline accumulation in inflammatory tissue, which may limit the specificity of these techniques for the detection of occult metastatic disease.

Keywords: Prostate cancer, biochemical recurrence, 68Ga-DOTATATE, 11C-Choline