FDG-PET standardized uptake values in normal anatomical structures using iterative reconstruction segmented attenuation correction and filtered back-projection

Filtered back-projection (FBP) is the most commonly used reconstruction met hod for PET images, which are usually noisy. The iterative reconstruction s egmented attenuation correction (IRSAC) algorithm improves image quality wi thout reducing image resolution. The standardized uptake value (SUV) is the most clinically utilized quantitative parameter of [fluorine-18]fluoro-2-d eoxy-D-glucose (FDG) accumulation. The objective of this study was to obtai n a table of SUVs for several normal anatomical structures from both routin ely used FBP and IRSAC reconstructed images and to compare the data obtaine d with both methods. Twenty whole-body PET scans performed in consecutive p atients with proven or suspected non-small cell lung cancer were retrospect ively analyzed. Images were processed using both IRSAC and FBP algorithms. Nonquantitative or gaussian filters were used to smooth the transmission sc an when using FBP or IRSAC algorithms, respectively. A phantom study was pe rformed to evaluate the effect of different filters on SUV. Maximum and ave rage SUVs (SUVmax and SUVavg) were calculated in 28 normal anatomical struc tures and in one pathological site. The phantom study showed that the use o f a nonquantitative smoothing filter in the transmission scan results in a less accurate quantification and in a 20% underestimation of the actual mea surement. Most anatomical structures were identified in all patients using the IRSAC images. On average, SUVavg and SUVmax measured on IRSAC images us ing a gaussian filter in the transmission scan were respectively 20% and 8% higher than the SUVs calculated from conventional FBP images. Scatterplots of the data values showed an overall strong relationship between IRSAC and FBP SUVs. Individual scatterplots of each site demonstrated a weaker relat ionship for lower SUVs and for SUVmax than for higher SUVs and SUVavg. A se t of reference values was obtained for SUVmax and SUVavg of normal anatomic al structures, calculated with both IRSAC and FBP image reconstruction algo rithms. The use of IRSAC and a gaussian filter for the transmission scan se ems to give more accurate SUVs than are obtained from conventional FBP imag es using a nonquantitative filter for the transmission scan.