Densitometric studies in digital subtraction angiography: assessment of pulmonary and myocardial perfusion.

The technical improvement of digital imaging systems has provided for roentgen densitometric analysis of radiographic image sequences. Thereby, regional and temporal measurements of the amount of contrast medium have been performed for comparative studies in angiocardiography. The use of digital image subtraction for densitometric evaluation is specifically advantageous because misregistration by motion artefacts can be circumvented. Furthermore, enhancement of faintly opacified circulatory structures assists in the detection and outlining of the regions of interest. Methods of digital densitometry are described utilizing large "densitometric areas" for the evaluation of pulmonary perfusion symmetry. Similarly, coronary flow distribution data have been established in experimental studies. Regional measurements of myocardial contrast accumulation allowed for perfusion studies in absolute units of volume flow (ml/min) of the three main coronary arterial vessels. Future application of the latter technique is expected to facilitate coronary flow reserve measurements in the clinical setting.