Quantitative coronary arteriography: the impact of image zoom and reference object size on diameter measurements

The authors studied the effect various catheter sizes and floating image zoom on catheter calibrated vessel diameters. The pixel sizes of vessel phantoms (0.3-4.5 mm ø) were obtained by optimum weighted edge detection. The 2.0 mm and the 3.0 mm phantom served as scaling device for catheter calibration. Image zoom varied from 1 to 6 fold. The authors found, that reference object calibration causes a rotation of measured native pixel diameter curves, whereby the amount of rotation depends on the size of the scaling catheter and affects especially diameters in the normal range of coronaries. It is concluded that using different catheter sizes and varying image zoom should be discouraged in long-term studies of coronary artery disease, since they feign non-existent lesion changes