[Densitometry determination of coronary flow rates using digital subtraction angiography (DSA). Methods, multiple examinations and interobserver comparison].

In invasive diagnostics of coronary heart disease (CHD), three each DSA examinations of the left coronary artery were performed at 2-minute intervals in ten patients subsequent to conventional examination by means of a left-side cardiac catheter and coronary angiography. While placing the patient in left anterior oblique (60 degrees) position, 6 ml each of ionic contrast medium were injected mechanically with a flow of 4 ml/sec at a pacemaker-induced heart rate of 100/min. Examinations were performed according to a standard mode and were evaluated via the image analysing computer APU of the Philips DVI-DSA system. The purpose of this approach was to analyse the examination conditions and a new improved evaluation algorithm in respect of stability, feasibility and sensitivity. 17 series were evaluated by two examiners who were independent of each other. The interobserver differences obtained were between 5% at the time of maximum density (Tmax) and 25% with exponential downward slope of the curve (lambda), with reference to the median value in each case. Scatter of the individual examinations around the median value of all the three DSA runs is 11 to 17% with the exception of lambda. A significant rise can be proven in the RCX region for the curve slope rise parameters "slope" and "RFL2". We interpret this as a genuine 1.2 to 1.3 fold regional flow increase due to the residual effect of the contrast medium. At the same time, this can be interpreted as an indicator for the good sensitivity of the method.(ABSTRACT TRUNCATED AT 250 WORDS)