EMISSION-BASED ATTENUATION CORRECTION OF MYOCARDIAL PERFUSION STUDIES

Background Nonuniform attenuation in the thorax can generate artifacts in single-photon emission computed tomographic myocardial perfusion s tudies that mimic coronary artery disease, In this article we present both phantom and simulation data, as well as clinical data, in support of an emission-based method that provides reliable correction for att enuation effects without the need for a transmission measurement, Meth ods and Results. The attenuation map is derived from the measured dist ribution of Tc-99m-labeled macroaggregated albumin in the lungs and a radioactive binder wrapped about the thorax, This information is acqui red as part of a dual-isotope acquisition during the rest (TI)-T-201 s tudy, Segmentation is used to define the interiors of lung and body co mpartments, which are assigned a single attenuation coefficient for ea ch of the two tissue types, The appropriateness of this approach was i nvestigated by examining the measured attenuation coefficients in a gr oup of 80 individuals (40 male, 40 female) from positron emission tomo graphic transmission studies, The correction technique was evaluated w ith computer simulations, a physical phantom, and clinical data acquir ed from 20 patients, Analysis of the positron emission tomographic dat a found a small SD in the mean attenuation coefficients for the body ( <5%) and lungs (<15%), The application of emission-based attenuation-c orrection technique produced a substantial reduction in the magnitude of the attenuation artifact in images obtained from both the phantom a nd the simulation studies, The emission-based attenuation-correction t echnique was easily applied to myocardial perfusion studies, where it had a significant effect, resulting in changes in interpretation for n ine of 20 patients, Conclusions. The results of this study provide str ong support for the concept that an attenuation map can be generated w ith fixed attenuation values in place of those that are directly measu red, Thus the emission-based attenuation-correction technique can be c onsidered an inexpensive alternative to transmission-based correction methods, Because the emission-based correction technique does not requ ire any additional hardware, it has the major advantage of being appli cable to all single-photon emission computed tomographic systems.