RT Journal Article
SR Electronic
T1 An Analytic Study of the Effects of Attenuation on Tumor Detection in Whole-Body PET Oncology Imaging
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1855
OP 1861
VO 44
IS 11
A1 Chuanyong Bai
A1 Paul E. Kinahan
A1 David Brasse
A1 Claude Comtat
A1 David W. Townsend
A1 Carolyn C. Meltzer
A1 Victor Villemagne
A1 Martin Charron
A1 Michel Defrise
YR 2003
UL http://jnm.snmjournals.org/content/44/11/1855.abstract
AB There has been considerable debate about the desirability of attenuation correction in whole-body PET oncology imaging. The advantages of attenuation correction are quantitative accuracy, whereas the perceived disadvantages are loss of contrast, noise amplification, and increased scanning time. In this work, we explain contrast changes between images reconstructed with and without attenuation correction. Methods: To analytically explain both well-known and surprising phenomena in images reconstructed without attenuation correction, we performed a series of simulation studies, a phantom experiment, and a patient experiment. Results: We showed that it is possible to calculate a priori the appearance of images reconstructed without attenuation correction. Compared with attenuation-corrected images, images without attenuation correction may have locally enhanced contrast in the abdomen or other regions of uniform attenuation, although the amount of enhancement varies with position in a complex manner. In regions of nonuniform attenuation, such as the thorax, it is possible that foci of increased tracer uptake disappear in images reconstructed without attenuation correction. The critical tracer concentration for this zero-contrast effect depends on the size, location, and density of the foci. Above the critical value, foci are visible in images with and without attenuation correction, whereas below the critical value, foci are visible in attenuation-corrected images but appear as photopenic regions in images without attenuation correction. Conclusion: Even though images without attenuation correction may be desired, these results suggest that all studies should at least be reconstructed with attenuation correction to avoid missing regions of elevated tracer uptake.