A new liver functional study using Tc-99m DTPA-galactosyl human serum albumin: Evaluation of the validity of several functional parameters

Abstract

Several parameters calculated with a new functional imaging agent for the liver, Tc-99m DTPA-galactosyl human serum albumin, were evaluated in 9 patients with liver cirrhosis, one with hepatocellular carcinoma, and five with both liver cirrhosis and hepatocellular carcinoma. LU3, which represents the cumulative uptake of the tracer from 3 to 4 minutes after injection, showed a strong correlation (r = 0.858, p = 0.0001) with LHL15, which represents the count ratio for the liver to sum for the liver and heart 15 minutes after injection of the tracer. It also showed a strong correlation (r = -0.896, p = 0.0001) with the indocyanine green retention rate (ICGR15). Regional ICGR15 is therefore calculable from the regional LU3. GSAR15, which represents the radioactivity of the tracer retained in the blood 15 minutes after injection, showed a strong correlation (r = 0.878, p = 0.0001) with HH15, which represents the count ratio for the heart 15 minutes after injection of the tracer divided by the count for the heart 3 minutes after injection. In conclusion, LU3 and GSAR15 are interesting and promising parameters for assessing liver function.

ICG Clearance Test and 99mTc-GSA SPECT/CT Fusion Images

“…In addition, a decrease in hepatic ASGPR expression has been reported in patients with liver damage [64]. Thus, analysis of ASGPR expression has been widely performed using 99mTc-GSA, an analog of asialoglycoproteins, to estimate liver function in damaged livers [65][66][67][68][69]. For example, a receptor index parameter (LHL15), obtained from the liver and heart time-activity data as the ratio of radioactivity of the liver over that of the liver plus heart at 15 min after intravenous injection of Tc-GSA correlated well with classical indicators for hepatic functional capacity such as the serum albumin level, serum bilirubin level, prothrombin time, ICGR15, or CTP criteria score [65,70].…”

Estimation of fractional liver uptake and blood retention of 99mTc-DTPA-galactosyl human serum albumin: an application of a simple graphical method to dynamic SPECT

“…For this purpose, gamma camera-based liver uptake is commonly calculated from counts of an organ ROI and injected dose determined by syringe counting or whole body counting [6][7][8]. Although this camera-based organ uptake is simple to implement, the uptake value obtained by this method could be influenced directly by ROI size.…”

“…It may be affected by several factors including injected dose and patient's body size. However, conventional indexes such as gamma camera-based liver uptake and the count ratio of liver to blood pool have been used in evaluation of asialoglycoprotein receptor imaging [6,7,20]. which was about several hundred n moles in amount [3].…”

“…As the simplest quantitative index for liver asialoglycoprotein receptor density, Tc-99m-GSA liver uptake at 15 min after injection (LU15) was reported to be valuable in evaluation of hepatic function [7]. LU15 obtained by this method was therefore …”

“…In the first step of quantitative analysis of imaging data, it is usually necessary to calibrate count-based data recorded by digital gamma camera system to the concentration-based or fractional dose-based data expressed with a general unit such as percentages of the injected dose (%ID). Not only for further quantitative model analysis, fractional uptake in the liver (% liver uptake) in itself can be useful for the evaluation of hepatic function [6,7]. Standard procedures for this calibration are accomplished by determination of calibration coefficients from measured blood radioactivity and the corresponding blood pool count or from camera-based organ uptake and corresponding liver counts on the images [3,8].…”