[Examination of R-L shunt ratio mensuration using dynamic images in lung perfusion scintigraphy]

We examined a method of quantitative analysis that used dynamic and static images to measure the Right-left (R-L) shunt ratio in lung perfusion scintigraphy.

A total of 18 patients suspected of having R-L shunt brought on by congenital heart disease were referred for lung perfusion scintigraphy from November 2005 to February 2007 at our hospital. We acquired anterior dynamic images, set ROIs in all fields of view, and measured the highest count. We acquired anterior and posterior static images of the chest and measured lung counts. We considered the highest count on dynamic images to be the total injection dose per one second, normalized the acquisition time of static images, and calculated the R-L shunt ratio. We weighed the measurement results of the R-L shunt ratio obtained by the dynamic method against that of the whole-body method by t-test and the least-squares method.

When we used a posterior static image in the dynamic method, we found that the coefficient of correlation (r) was 0.9831. The result of the t-test was that there was no significant difference at a level of significance of 1%.

We think the use of the dynamic method is possible in R-L shunt ratio measurement and can shorten the examination time.