Foreshortening display: an on-line method for spatial interpretation and projection assessment of the target coronary segment

In biplane coronary angiography, the operator frequently does not achieve a projection of the target coronary segment without foreshortening. To support the visual assessment of lesion geometry, the authors developed the Foreshortening Display (FD). With this procedure a triangle consisting of the imaged segmental axis, non-foreshortened axis and foreshortening height is calculated and displayed in each angiographic plane. The validity of FD calculation was examined by a wire grid imaged in common angiographic views. The calculated foreshortening values were compared with the true values. FD values showed an accuracy and precision of 0.05%/spl plusmn/0.62%. Alignment and shape of FD indicate spatial orientation and foreshortening of the target vessel in each angiographic plane. The authors' long-term experience with FD in the analysis of 3022 coronary angiograms showed over 30% foreshortening in 660 cases demonstrating the need for the method.