Online brain attenuation correction in PET: towards a fully automated data handling in a clinical environment

We have improved the calculation of the brain attenuation correction in positron emission tomography (PET) and set up a procedure which allows the clinician to get a fully corrected image in a single reconstruction step, without human intervention. By using a general object description scheme based on polygonal contour trees we are able to calculate the attenuation correction for brain tissue, bone and head holder. The head contour is generated from the emission sinogram. On a set of 15 adult patients, the emission values obtained using this calculated attenuation compare favorably with those obtained with an attenuation resulting from a transmission measurement. Residual discrepancies are attributed to incomplete scatter compensation between emission and transmission. The robustness of the algorithm has been tested on more than 100 brain fluorodeoxyglucose (18FDG) studies in adult patients, including pathological cases. Its applicability for 18FDG studies in children and for other tracers such as water (H2 15O) and fluoroethylspiperone (18FESP) is also presented.