To determine optimal sample preparation conditions with potassium triiodide (I ₂ KI) and optimal imaging settings for microfocus CT (micro-CT) of excised cat hearts.

7 excised hearts (weight range, 10 to 17.6 g) obtained from healthy adult cats after euthanasia by IV injection of pentobarbital sodium.

Following excision, the hearts were preserved in 10% formaldehyde solution. Six hearts were immersed in 1.25% I ₂ KI solution (n = 3) or 2.5% I ₂ KI solution (3) for a 12-day period. Micro-CT images were acquired at time 0 (prior to iodination) then approximately every 24 and 48 hours thereafter to determine optimal sample preparation conditions (ie, immersion time and concentration of I ₂ KI solution). Identified optimal conditions were then used to prepare the seventh heart for imaging; changes in voltage, current, exposure time, and gain on image quality were evaluated to determine optimal settings (ie, maximal signal-to-noise and contrast-to-noise ratios). Images were obtained at a voxel resolution of 30 μm. A detailed morphological assessment of the main cardiac structures of the seventh heart was then performed.

Immersion in 2.5% I ₂ KI solution for 48 hours was optimal for sample preparation. The optimal imaging conditions included a tube voltage of 100 kV, current of 150 μA, and exposure time of 354 milliseconds; scan duration was 12 minutes.

Results provided an optimal micro-CT imaging protocol for excised cat hearts prepared with I ₂ KI solution that could serve as a basis for future studies of micro-CT for high resolution 3-D imaging of cat hearts.