ENHANCED CROSS-TALK CORRECTION TECHNIQUE FOR SIMULTANEOUS DUAL-ISOTOPE IMAGING - A TL-201 TC-99M MYOCARDIAL PERFUSION SPECT DOG STUDY/

A newly developed cross-talk correction method for simultaneous dual-i sotope SPECT imaging was tested in a canine model. The method is based on the assumption that the transformations, which modify the primary energy window images into the scatter images as viewed in the other en ergy windows, are known. These transformations were found by measuring the point spread functions (PSFs) in two different energy windows for both isotopes in water. The dual-isotope correction method is describ ed by two convolution equations which were applied in frequency space. The equations take into account the different spatial distributions o f the primary and scatter cross-talk photons. The new enhancement of t he method was in applying restoration filters to the resulting correct ed images. Three separate studies were acquired in our dog study: two single-isotope and one dual-isotope study. The single isotope images w ere used as references. The contrast between the left ventricle cavity (LVC) and the myocardium was used in transaxial and short-axis slices as a parameter to evaluate results of dual-isotope correction method with restoration. The change in contrast in the dual-isotope corrected images in both energy windows, i.e., Tc-99m primary window (140 keV) and Tl-201 primary window (70 keV), was significant. The only exceptio n was for the short-axis Tc-99m window images. The corrected 140 keV d ual-isotope short-axis slice had the contrast of 0.60 vs 0.58, which w as the value in the noncorrected dual-isotope short-axis slice. For du al-isotope 140 keV transaxial slice, the contrast changed from 0.72 to 0.82 after correction. In comparison, for single-isotope Tc-99m 140 k eV transaxial slice, contrast changed from 0.62 to 0.84 after restorat ion correction. There was less change in contrast in the shea-axis Tc- 99m 140 keV slice, i.e., from 0.56 to 0.61. In the Tl-201 primary wind ow for the transaxial slices the improvement of contrast was from 0.38 to 0.64, and for short-axis slices from 0.22 to 0.32 after correction . In the same 70 keV energy window for single-isotope Tl-201 images, c ontrast improved from 0.61 to 0.69 and from 0.35 to 0.38 for transaxia l and short-axis slice, respectively, after applying restoration corre ction. In conclusion, the presented dual-isotope correction method wit h restoration improves the quality of the simultaneous rest Tl-201/str ess Tc-99m sestamibi SPECT imaging. (C) 1997 American Association of P hysicists in Medicine.