Simultaneous technetium-99m/thallium-201 SPECT imaging with model-based compensation for cross-contaminating effects

Phys Med Biol. 1999 Jul;44(7):1843-60. doi: 10.1088/0031-9155/44/7/319.

Abstract

Simultaneous acquisition of dual-isotope SPECT data offers a number of advantages over separately acquired data; however, simultaneous acquisition can result in cross-contamination between isotopes. In this work we propose and evaluate two frameworks for iterative model-based compensation of cross-contamination in dual-isotope SPECT. The methods were applied to cardiac imaging with technetium-99m-sestamibi and thallium-201, and they were compared with a subtraction-based compensation method using a cross-talk estimate obtained from an auxiliary energy window. Monte Carlo simulations were performed to carefully study aspects of bias and noise for the methods, and a torso phantom with cardiac insert was used to evaluate the performance of the methods for experimentally acquired data. The cross-talk compensation methods substantially improved lesion contrast and significantly reduced quantitative errors for simultaneously acquired data. Thallium image normalized mean square error (NMSE) was reduced from 0.522 without cross-talk compensation to as low as 0.052 with model-based cross-talk compensation. This is compared with a NMSE of 0.091 for the subtraction-based compensation method. The application of a preliminary model for cross-talk arising from lead fluorescence x-rays and collimator scatter gave promising results, and the future development of a more accurate model for collimator interactions would probably benefit simultaneous Tc/Tl imaging. Model-based compensation methods provide feasible cross-talk compensation in clinically acceptable times, and they may ultimately make simultaneous dual-isotope protocols an effective alternative for many imaging procedures.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Drug Interactions
  • Humans
  • Image Processing, Computer-Assisted
  • Phantoms, Imaging
  • Radiopharmaceuticals*
  • Technetium Tc 99m Sestamibi*
  • Thallium Radioisotopes*
  • Tomography, Emission-Computed, Single-Photon / methods*

Substances

  • Radiopharmaceuticals
  • Thallium Radioisotopes
  • Technetium Tc 99m Sestamibi