Quantitation of PET data with the EM reconstruction technique

The capability of a modified EM (expectation maximization) algorithm to quantify image data has been tested in phantom studies and in two clinical cases, cerebral blood flow studies and dopamine D2-receptor studies. Data from phantom studies indicate the superiority of images reconstructed with the EM technique compared to images reconstructed with the conventional filtered back-projection (FB) technique in areas with low statistics. At higher statistics the noise characteristics to the two technique coincide. Clinical data support these findings. Functional image data were generated regarding cerebral blood flow and receptor/dissociation constant (B_max/ kD). The functional data based on EM reconstructed images show generally less noise and higher spatial resolution than functional data generated by FB reconstructed images