[Visual evaluation of liver function with 99mTc-GSA scintigraphy: interobserver variation and intraobserver...

We introduced a new imaging grade to evaluate liver function with 99mTc-GSA and studied its diagnostic value using interobserver variation and intraobserver variation. One hundred four patients with liver disease were injected 185 MBq/3 mg of 99mTc-GSA. Anterior images of cardiac blood-pool and liver at 5 min after injection were divided into four grades on the basis of following four categories. Faint cardiac blood-pool image, without clear demonstration of its peripheral boundary was classed in grade I; weaker cardiac blood-pool than liver was grade II; almost same appearance of blood-pool with liver was grade III and stronger blood-pool than liver was grade IV. Three radiologists reviewed the images independently. They followed the same process three months after initial evaluation. kappa-Test was employed to evaluate the goodness of agreement. Three pairs in the first reading showed excellent interobserver agreement (0.88, mean kappa-value) and another three pairs in the first and second reading also showed excellent intraobserver agreement (0.87, mean kappa-value). Quantitative indices obtained from time-activity curves for blood-pool and liver showed significant differences across four groups. Plasma retention rate of indocyanine green also showed significant difference between grade II and grade III. Imaging grade possesses high intra- and interobserver agreement and provides a good discrimination for liver function.