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Investigation of optimal sample preparation conditions with potassium triiodide and optimal imaging settings for microfocus computed tomography of excised cat hearts

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  • 1 1Departments of Radiology, Great Ormond Street Hospital for Children, National Health Service Foundation Trust, London WC1N 3JH, England.
  • | 2 2Pathology, Great Ormond Street Hospital for Children, National Health Service Foundation Trust, London WC1N 3JH, England.
  • | 3 3National Institute for Health Research, Great Ormond Street Hospital, Biomedical Research Centre, University College London, Great Ormond Street Institute of Child Health, Research and Development Office, London WC1N 1EH, England.
  • | 4 4Department of Clinical Sciences, Royal Veterinary College, University of London, London NW1 0TU, England.

Abstract

OBJECTIVE

To determine optimal sample preparation conditions with potassium triiodide (I2KI) and optimal imaging settings for microfocus CT (micro-CT) of excised cat hearts.

SAMPLE

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

PROCEDURES

Following excision, the hearts were preserved in 10% formaldehyde solution. Six hearts were immersed in 1.25% I2KI solution (n = 3) or 2.5% I2KI 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 I2KI 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.

RESULTS

Immersion in 2.5% I2KI 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.

CONCLUSIONS AND CLINICAL RELEVANCE

Results provided an optimal micro-CT imaging protocol for excised cat hearts prepared with I2KI solution that could serve as a basis for future studies of micro-CT for high resolution 3-D imaging of cat hearts.

Contributor Notes

Dr. Matos’ present address is the Clinical Department, Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, England.

Address correspondence to Mr. Simcock (ian.simcock@gosh.nhs.uk).