Discussion of PET Workshop Reports, Including Recommendations of PET Data Analysis Working Group

Abstract

Summary: On May 1-2, 1989, a PET Data Analysis Working Group convened to consider positron emission tomography (PET) methodology and data analysis. The papers presented and the recommendations of the Group are reviewed. The Group recommended that a standard phantom of the human brain be used by different institu tions to examine machine and data reconstruction PET variables. Interinstitutional comparisons could be aided by using a standard three-dimensional coordinate system. Deformations within individual diseased or atypical brains would require nonlinear as well as linear transfor mations to the standard space, using magnetic resonance I shall review some of the issues discussed in this Workshop and shall address related ones. If I refer frequently to work done in the Laboratory of N eu rosciences, National Institute on Aging, it is be cause I am most familiar with this work. I also shall summarize (see Appendix) the recommendations of the PET Data Analysis Working Group, concerning future directions for relevant positron emission to mography (PET) research.In the last 15 years, PET has provided measure ments of metabolism, blood flow, blood-brain bar rier permeability, pH, and receptor distribution within the human brain. Advances have been sub stantial in the three areas discussed in this Work shop: (1) camera development and image recon struction; (2) identification and use of regions of images in register with the PET images. Methods for intersubject averaging of pixel-by-pixel or region of-interest data, as well as appropriate statistical meth ods, need to be developed. PET data may first be explor atory and hypothesis-generating (with less stringent sta tistical theory), then later used to test hypotheses (with more stringent statistical criteria). Common databases, obtained by computer simulation models with known in herent structure, or directly by PET measurements on different groups, could be used to compare analytical and statistical methods among institutions. Key Words: Posi tron emission tomography-Brain metabolism-Imaging.interest (ROIs); and (3) development of experimen tal and statistical models. These accomplishments have allowed us to employ PET to characterize con trol and experimental groups, to distinguish group differences with various degrees of statistical reli ability, and, to a limited extent, to identify individ uals having a brain pattern specific to a disease or behavioral state. Hoffman et al. (1991) summarized recent prog ress in minimizing machine-and technique-related errors, particularly those involving resolution (par tial voluming), dead time (for optimizing kinetic studies), and scatter and attenuation. Their newly developed phantom of the human brain could be used as a reference for interinstitutional compari sons of machine variables (see Appendix). Alpert et al. (1991) calculated that the variance due to the purely technical aspects of PET-resulting from ra dioactive decay and other sources of random er ror-can be reduced to < 10%, by using appropriate transmission co...

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