PT - JOURNAL ARTICLE AU - Manuela Hoffmann AU - Hans-Georg Buchholz AU - Helmut Wieler AU - Nicolas Fischer AU - Matthias Miederer AU - Florian Rosar AU - Mathias Schreckenberger TI - <strong>Dual-time point <sup>68</sup>Ga-PSMA PET/CT imaging for staging and restaging of prostate cancer</strong> DP - 2020 May 01 TA - Journal of Nuclear Medicine PG - 1250--1250 VI - 61 IP - supplement 1 4099 - http://jnm.snmjournals.org/content/61/supplement_1/1250.short 4100 - http://jnm.snmjournals.org/content/61/supplement_1/1250.full SO - J Nucl Med2020 May 01; 61 AB - 1250Objectives: 68Ga-PSMA PET/CT hybrid imaging has been shown to be a valuable method for the detection of prostate cancer (PC) lesions, when the scan is performed one hour after injection of the tracer, particularly in lymph node metastases. The goal of this study is to evaluate the advantages of a dual-time point imaging modality for staging and restaging of PC patients. Methods: We retrospectively studied biphasic 68Ga-PSMA-11 PET/CT scans of 243 patients. 225 patients with biochemical recurrence (BC), previously treated for localized PC and 18 patients with elevated prostate-specific antigen (PSA) serum levels (&gt; 4.0 ng/mL), suspected of having primary PC. The prostatectomized patients were assessed separately from the irradiated patients. All patients underwent early and late scans: whole body, one hour post injection as well as pelvic and suspicious regions, three hours post injection. Tumor uptake was quantified by SUVmax and the biphasic detected PC lesions were compared. Results: 68Ga-PSMA-11 PET/CT detected PC lesions in 149 of 225 patients with BC (66%) and in 13 of 18 patients with elevated PSA (72%). The overall tumor lesion rate at early scans in the prostatectomized patients (PP) was 567 in 116 patients, in the irradiated patients (IP) 186 in 33 patients and 48 in the 13 staging patients (SP). In the delayed scans, the rate was 570/116 (PP), 187/33 (IP) and 48/13 (SP), respectively. In most patients,108 RP, 32 IP and 13 SP, no additional PC lesions were identified by late imaging. However, 11 PSMA-avid lesions were only detected in the delayed images. In addition, 30 lesions suspected of being malignant were confirmed as malignant due to the increase in SUVmax in the late scans. By contrast, 7 PSMA-avid findings were demonstrated in the early but not in the late pictures. Overall, SUVmax of malignant lesions in the delayed scans was higher in 22.0% (PP), 22.5% (IP) and 17.8% (SP) (each p&lt;0.001) than SUVmax in the early scans. The mean SUVmax of local and distant lymph node metastases was 25% (p&lt;0.001) and 14% higher (p=0.003) comparing early and late imaging. Conclusions: This study demonstrates high positivity rates from routine 68Ga-PSMA-11 PET/CT scans (one hour post injection) in biochemically recurrent patients as well as in primary PC patients. However, the additional implementation of delayed scans (dual-time point imaging) offers an information advantage in the detection of PC lesions due to a higher tracer uptake and an improved contrast which may be important for therapy management decisions at least in individual cases. Keywords: 68Ga-PSMA PET/CT, prostate cancer, positivity rate, biphasic imaging, dual-time point imaging