A transformation cross-talk technique for simultaneous dual radionuclide imaging: a myocardial perfusion 201Tl/99Tcm...

We have developed a novel transformation method for the correction of cross-talk in simultaneous dual radionuclide single photon emission CT (SPECT) imaging. It is based on the assumption that the transformations, which transform the primary energy window images into the scatter images as viewed in the other energy windows, are known. The method was tested on a dog model. These transformations were found by measuring the point response functions (prf) in different energy windows for both radionuclides in water. The dual radionuclide correction method described takes into account the different spatial distributions of the primary and scatter cross-talk photons in different energy windows. This method also includes the sequential application of restoration filters to the resulting cross-talk corrected images. We used a dog model in three separate studies: two single radionuclide studies used as references and one dual radionuclide study. Contrast between the left ventricular cavity (LVC) and the myocardium was used in horizontal long axis (HLA) slices as a parameter to evaluate the results of the dual radionuclide correction method with restoration. The increase of the contrast in the dual radionuclide corrected images in both energy windows, i.e. 201Tl primary window (70 keV) and 99Tcm primary window (140 keV), was significant. The cross-talk corrected 70 keV dual radionuclide HLA slice had a contrast of 0.62 compared with 0.35, which was the value in the non-corrected dual radionuclide HLA slice. Restoration improved the contrast to 0.68. In the single radionuclide 201Tl image, the same contrast was 0.59, improving to 0.70 after restoration. For the dual radionuclide 140 keV HLA slice, the contrast increased from 0.69 to 0.76 after cross-talk correction. Additional increase of the contrast to 0.83 resulted from restoration filtering. In the single radionuclide 99Tcm sestamibi 140 keV HLA slice the improvement of contrast was from 0.63 to 0.86 as a result of the restoration. The transformation three-window, dual radionuclide correction method with restoration improves the quality of the simultaneous rest 201Tl/stress 99Tcm sestamibi SPECT imaging.