ACCURACY OF DIGITAL VIDEODENSITOMETRY IN QUANTITATING CONTRAST-MEDIUMCONCENTRATION

To evaluate the accuracy of digital videodensitometric technique in di rectly quantitating concentration of contrast medium, iohexol 300 mg I /ml was injected into a 2-mm-diameter plastic tube, in which clean wat er was circulated at a 190 ml/min flow, for digital subtraction angiog raphy. Altogether 27 injections were performed with 3, 4 and 5 ml volu mes at 3-, 4- and 5-ml/s flows of the contrast medium. A time-density curve was achieved by selecting a ''vessel'' region of interest (ROI) and a background ROI. Then, a frame corresponding to the maximum opaci fication of the contrast medium could be calculated. Finally, the aver age density and the time to peak density of the contrast medium were o btained. The average density was statistically higher (p<0.01) with 5 ml/s flow than with 4- and 3-ml/s flows. Times to peak density reduced as injection flows or volumes increased. The results support the conc lusion that digital videodensitometric technique is an accurate method for quantitation of contrast medium concentration during angiography. The angiographic opacification may be improved by injecting the iodin e contrast medium with higher flows or larger volumes.