DECONVOLUTION ANALYSIS IN RADIONUCLIDE QUANTITATION OF LEFT-TO-RIGHT CARDIAC SHUNTS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 20  (6) , 502-506
Abstract
A poor bolus injection causes an unsatisfactory quantitative radionuclide angiocardiogram in 20% of children with possible left-to-right (L-R) cardiac shunts. Deconvolution analysis was applied to similar studies in experimental animals to determine whether dependence on the input bolus could be minimized. Repeated good-bolus, prolonged (> 2.5 s) or multiple-peak injections were made in 4 normal dogs and 7 dogs with surgically created atrial septal defects (ASD). QP/QS (the shunt) was determined using the gamma function. The mean QP/QS from 10 good-bolus studies in each animal was used as the standard for comparison. In 5 trials in normal animals where a prolonged or double-peak bolus led to a shunt calculation (QP/QS > 1.2:1), deconvolution caused QP/QS = 1.0. Deconvolution improved shunt quantitation in 8 of 10 trials in animals that received a prolonged bolus. The correlation between the reference QP/QS and the QP/QS calculated from uncorrected bad bolus studies was only 0.39 (P > 0.20). After deconvolution using a low pass filter the correlation improved significantly (r (correlation coefficient) = 0.77, P < 0.01). The technique gave inconsistent results with multiple-peak bolus injections. Deconvolution analysis in these studies is useful in preventing normals from being classified as shunts and in improving shunt quantitation after a prolonged bolus. Clinical testing of this technique in children with suspected L-R shunts is warranted.