PET WITH F-18 FLUORIDE - EFFECTS OF ITERATIVE VERSUS FILTERED BACKPROJECTION RECONSTRUCTION ON KINETIC MODELING

High focal uptake in patients poses particular problems in PET imaging . Filtered backprojection (FBP) introduces disturbing streak artifacts , adversely affecting the identification of structures and delineation of regions. Iterative reconstruction methods (MLEM) provide images of superb quality, however, the accuracy of quantitative results obtaine d from MLEM images has nor been established for clinical data. Dynamic images were acquired over 1 hr with PET and F-18-fluoride in 6 patien ts with an old unilateral hip fracture. FBP and MLEM reconstruction wa s performed. Since the bladder was in the FOV and filled up with fluor ide, FBP produced streaks hampering region delineation. Bone blood flo w (k1) and fluoride influx rate (Ki) were estimated with a 3 compartme nt model. Analyzed regions (n=190) showed correlation coefficients bet ween FBP and MLEM: 0.88 for k1 and 0.97 for Ki. Affected and normal fe moral head regions (n=30) yielded r=0.89 for k1 and r=0.95 for Ki. Var iations up to 46% were seen in individual data. Conclusion: in patient s MLEM provides superior images at the expense of an increased reconst ruction duration. Our procedure appeared acceptable in clinical routin e. Quantitative estimates obtained with kinetic modeling from MLEM dat a were reliable and correlated highly to those obtained with the stand ard, validated FBP algorithm.