TY - JOUR T1 - Quantitative fluctuation of a new Bayesian penalized-likelihood reconstruction algorithm in Ga-68 DOTATOC PET/CT. JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 385 LP - 385 VL - 59 IS - supplement 1 AU - Takayoshi Ishimori AU - Yuji Nakamoto AU - Kanae Miyake AU - Tsuneo Saga AU - Kaori Togashi Y1 - 2018/05/01 UR - http://jnm.snmjournals.org/content/59/supplement_1/385.abstract N2 - 385Objectives: Quantitative analysis using standardized uptake value (SUV) is commonly used in oncological PET imaging. Recently, a new Bayesian penalized-likelihood (PL) reconstruction algorithm has been developed to generate images with reduced noise and improved signal-to-noise ratio compared to conventional ordered subsets expectation maximization (OSEM) algorithm. However, it is not clear how the new PL reconstruction affects quantification of PET. The purpose of this study was to investigate the effect of the new Bayesian penalized-likelihood (PL) algorithm on quantitative parameters in Ga-68 DOTATOC PET for somatostatin receptor imaging Methods: In 6 patients (pts) suspected of having DOTATOC-avid tumor (3pts; neuroendocrine tumor, 2pts; renal cell carcinoma, 1pt; thymic cancer), whole body PET/CT scans were performed at 60 min after iv injection of averagely 121.2 (range 59.5-188.5) MBq of Ga-68 DOTATOC with a dedicated PET/CT scanner with 5-ring BGO detectors, 26 cm axial field of view. The PET images were reconstructed by PL and conventional OSEM (iteration 4, subsets 12) methods. In PL reconstruction, the noise reduction parameter (β) was determined as 300, by which the image quality was comparable with conventional OSEM. Maximum SUV (SUVmax) and highest mean SUV of 1cm3 spherical volume (SUVpeak) by PL and those by conventional OSEM were calculated for 12 DOTATOC-avid tumors averagely 35.4mm (range 9-110mm). Metabolic tumor volume (MTV: volume of DOTATOC-avid region greater than 40% of SUVmax), mean SUV in MTV (SUVmean) and total lesion uptake (TLU: MTV[asterisk]SUVmean) by PL and those by conventional OSEM were calculated and compared with each other. PL reconstructions with different β values (300, 400, 500, 600) were added and the parameters were compared with one another. Results: All parameters by PL showed strong correlation with those by conventional OSEM. SUVmax, SUVmean and SUVpeak by PL were significantly greater than those by conventional OSEM (p<0.01). However, the differences in MTV and TLU by the two reconstructions were not significant. Increasing β values decreased SUVmax, SUVmean and SUVpeak, but increased MTV. Coefficient of variation (CV) of all parameters among different β values did not show significant correlation with the size of the tumor. CV of SUVpeak was significantly smaller than that of other parameters (p<0.01). Conclusions: Although all quantitative parameters of PL method had strong correlation with those of conventional OSEM, significant differences in SUV parameters between the two methods should be noted for quantification of Ga-68 DOTATOC PET. Although parameters fluctuate with β values, SUVpeak could be a reproducible parameter because of the smallest variance among different β values. View this table:Quantitative parameters (mean±SD) View this table:Coefficient of variation among β=300-600 (mean±SD) ER -