TY - JOUR T1 - Triphasic 18F-Choline- PET/CT in prostate cancer patients: Optimization of imaging protocol JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1554 LP - 1554 VL - 57 IS - supplement 2 AU - Ankit Watts AU - Rajender Kumar AU - Baljinder Singh AU - Bhagwant Mittal Y1 - 2016/05/01 UR - http://jnm.snmjournals.org/content/57/supplement_2/1554.abstract N2 - 1554Objectives To evaluate the usefulness and feasibility of new acquisition protocol of 18F-Choline (FCH) PET/CT in prostate cancer (PC) patients.Methods New acquisition protocol was evaluated on 22 PC patients (mean age 69 years, range 51-75) who were referred for 18-FCH PET/CT scan as part of diagnostic workup. The acquisition protocol consisted of three phases: a) Early Dynamic scan of the pelvis b) Whole body scan 1hr post injection (p.i) c) Delayed static scan of the pelvis 2hr p.i. Qualitative & Quantitative analysis was done to evaluate various phases of acquisition. Qualitative analysis was done by blinded visual scoring criteria based on activity accumulation in the urinary tract (bladder, ureters, and urethra) and whether it interferes with the reading of the scan, especially focused to the prostatic bed, using a 3- scale score: 0: no accumulation; 1: mild accumulation not interfering with the reading; 2: intense accumulation that could interfere with the reading. Any additional pathological findings in various phases were also documented. Semi-quantitative analysis was done by drawing fixed ROI’s over the prostate/prostatic bed (Lesion), bladder (urine activity) to compute SUVmax values. Quantitative measure of image contrast (focused on prostate/prostatic bed) was computed by calculating SUV ratio of prostate to bladder.Results Early dynamic static images showed absence of radioactive urine in the bladder in all the patients (mean visual score 0), hence allowing clear interpretation of the prostate/prostatic bed. One hr image had maximum interference (mean visual score = 1.27 ± 0.63) & delayed 2 hr image had moderate interface (mean visual score = 0.81 ± 0.50) of radioactive urine with the prostate/ prostatic bed. Additional lymph nodes findings were observed in 5/22 patients in early dynamic images as compared to other set of images. Similarly better image contrast was found in 6/22 in early static image as compared to the delayed images. Concurrent finding were noted in 3/22 patient between early & 2-hr delayed image whereas 1 hr image lacked this information. Similar findings were noted in all the set of images in 1/22 patients while 7/22 patients showed no loco regional disease. On quantitative assessment, no significant difference was observed between SUV (prostate) of early dynamic image with that of SUV (prostate) 1 hr image (p value= 0.852) or SUV(prostate) 2 hr (p value= 0.207). Quantitative measure of radioactive urine (SUV (bladder) showed least in early image (0.86±0.38) followed by delayed 2 hr image (3.65± 3.63) & maximum for 1 hr image (5.55± 6.53). Highest SUV (Prostate to bladder) ratio (7.4) was seen in early dynamic image followed by 2hr (2.4) & least in 1hr (1.43) images. On computing SUV ratio of prostate to bladder significant difference was found between early dynamic with 1hr image (p=0.010) & 2hr image (p=0.025). This validated the qualitative results.Conclusions The major limitation of use of 18-FCH in PC patients is its variable urinary excretion. This limitation can be overcome by an early acquisition of the pelvic region before the arrival of the tracer in the urinary pathways. Early dynamic image also gives additional advantage in identifying small lymph node lesions with only marginal to moderate tracer uptake lying in close proximity to pelvic vessels/bladder. Hence a three-phase protocol helps increasing the diagnostic assessment of local recurrence disease. ER -