The Rational For Simultaneous
Dual-Isotope Cardiac Imaging

The use of multi pinhole tomography for non-rotational SPECT (NRSPECT) imaging of the heart has several advantages in comparison with rotational SPECT (RSPECT).

Each individual NRSPECT image is active for the entire acquisition period resulting in a set of input images with an order of magnitude higher statistical content than RSPECT images. The improved statistical content of NRSPECT images allows:

The acquisition of multi spectral images (128 channels) with adequate statistics to allow scatter and cross-talk correction between Tl-201 and Tc-99m Sestamibi.

The high statistical content also allows motion correction for respiration and “cardiac creep”.

Greater flexibility in utilizing multiplicative first estimates followed by rapid iterative convergence (typically, three interations achieve adequate convergence).

Since all images are acquired simultaneously, gating can be performed more reliably using list-mode acquisition. The gated image sequences can be reformulated after the fact to include only the desired QRS complexes.

Pinhole collimation provides high geometric precision at very low cost and is also capable of noncoincidence positron imaging. It is also very easy to swap pinhole inserts to adjust overall system sensitivity and resolution.