Measurement of the regional exposure quality in quantitative coronary angiography

This study determines the regional exposure quality and the impact of specific exposure types on size measurement errors in quantitative coronary angiography. The regional brightness distribution of the edge detection intensity matrix is calculated and presented as a histogram. Images of interventional devices were used to define the brightness distribution of 4 exposure types: (1) optimal quality (2) low contrast, (3) under- and (4) over-exposure. The size and brightness distribution of 254 imaged PTCA or stent carrier balloons were measured using QCA. The differences (in percent) between the measured and listed size were assigned to the identified exposure types. Optimal exposure (n=88) allowed the most valid measurements (accuracy/spl plusmn/precision 1.1/spl plusmn/3.3%). Low contrast (n=107) led to the least precise measurements (2.4/spl plusmn/12.2%). Under-exposure (n=55) caused an evident size under-estimation (-12.2/spl plusmn/9.20%). Overexposure (n=3) was under-represented in the study The regional brightness distribution provides an objective assessment of vessel exposure quality and predicts measurement errors.