Requirements on resolution of digital imaging equipment in the cardiac catheterization laboratory

We evaluated the requirements on spatial resolution of digital imaging equipment in the cardiac catheterization laboratory. Fifty cinefilms of the heart as the biological object and one film of a lead-ladder-pattern as an objective test were used. The patient films were examined for the visibility of the left ventricular angiogram, coronary arterial tree, coronary artery lesions, branching of septal arteries and the number of septal arteries. All films were viewed three times: with a 625 line TV-system, with a 1249 line TV-system and with a cineprojector. It was found that two application areas with different demands on the spatial and temporal resolution can be distinguished: 1) low spatial resolution and high temporal resolution, e.g. left ventriculography; and 2) high spatial resolution and low temporal resolution, e.g. coronary arteriography. For the diagnostic assessment of the state of the coronary system, the spatial resolution provided by the 1249 line TV-system was sufficient. Exceeding this resolution by using cinefilm quality provided no additional diagnostic information. A frame rate lower than 50 frames per second for coronary arteriography seems possible.