RT Journal Article SR Electronic T1 Rising PSA after curative I125 brachytherapy in prostate cancer: patterns of 18F-Choline prostatic uptake on PET/CT. JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1549 OP 1549 VO 57 IS supplement 2 A1 Anne Laure Cazeau A1 Eivind Blais A1 Jean Luc Hoepffner A1 Thierry Piechaud A1 Celine Merino A1 Philippe Stein A1 AXELLE DUTERTRE A1 Laurence Thomas YR 2016 UL http://jnm.snmjournals.org/content/57/supplement_2/1549.abstract AB 1549Objectives [18F]-choline (FCH) positron emission tomography/computed tomography (PET/CT) is an efficient technique to assess relapse in prostate cancer. In a context of PSA bounce after I125 brachytherapy, to distinguish relapse from inflammation in case of rising PSA remains difficult. To our knowledge patterns of prostatic (FCH) PET/CT has not been described in this setting yet.The aim of this study was to describe patterns of (FCH) PET/CT prostatic uptake during rising PSA after I125 brachytherapy.Methods Among 243 patients with rising PSA referred to our center for (FCH) PET/CT between 12/2012 and 12/2015, 27 patients were previously treated by I125 brachytherapy. A two-time protocol, 30 minutes after furosemide infusion, including dynamic pelvic acquisition immediately after 3 MBq/kg FCH and a later acquisition (> 10 minutes) - was retrospectively analyzed. Imaging prostatic characteristics recorded were: diffuse versus focal and peripheral versus central uptake, for visual analysis. SUVmax from dynamic and late step were also recorded. Delta SUV absolute value (ΔSUV) - defined by the difference between late and dynamic SUVmax values - was calculated. Positive gold standard was defined by histology on biopsy and/or prostatectomy. Negative gold standard was defined by negative biopsy and spontaneously - no hormone therapy - PSA drop below nadir + 2 ng/ml during follow-up. Patients were excluded if no gold standard for prostatic status was available.Results Fourteen patients raised gold standard criteria. Median follow-up was 14.3 months [2.5-36.5]. Ten patients had intra prostatic and/or seminal vesicle relapse histologically proven, among them 5 patients were treated with salvage prostatectomy. Uptake was focal and peripheral for all positive patients with mean SUVmax 2.1[1.0-2.8] at the dynamic acquisition and 3.1[2.3-3.9] at the late step, nearby Iodine seeds. A central, diffuse with soft to intense uptake - mean SUVmax 2.3[1.1-5.8] - was observed for the 10 positive patients. Increased uptake at the late step tended to by higher in prostatic zones corresponding to histologically proven recurrence - ΔSUV 1.0 vs 0.21 (p=0.31), respectively for peripheral and central area. Histological analyses after prostatectomy found no cancer cells in the central area (n=5). Moreover, uptake only in central area was found for 3 on 4 negative patients. For the last negative patient no prostatic uptake was observed.Conclusions Local recurrence of prostate cancer after I125 brachytherapy remains challenging but can still be assessed by (FCH) PET/CT. Imaging patterns during local recurrence was a focal and peripheral uptake - even if SUVmax values were modest - increasing at the late step. A frequent central, diffuse and homogeneous uptake, probably due to post brachytherapy inflammation, should not been confused with a local recurrence.