Variability and Reliability of Normal Liver 18F-FDG Standardized Uptake Value in Relation to Placement of Volume of Interest

The impact of volume-of-interest (VOI) placement on liver standardized-uptake-value (SUV) measurement remains unclear.

To investigate variability and reliability of liver SUV in relation to placement of VOI within the right lobe of the liver.

Positron emission tomography-computed tomography (PET/CT) of 343 patients with normal liver were retrieved. Liver mean SUV (SUVmean) were measured by placing spherical VOIs at upper, portal vein and lower level of the right-lobe liver. The general linear model, Bland-Altman analysis, one-way ANOVA were performed and the intraclass correlation coefficients (ICC) were calculated to identify impacts of reader and VOI position on variations of liver SUVmean.

The liver SUVmean at the upper, lower and portal vein level were 1.85 ± 0.435, 1.88 ± 0.409, and 1.89 ± 0.414, respectively, with no significant inter-location difference (P = 0.449). The coefficients of variation were close among locations (21.9% - 23.5%). The inter-location ICCs controlling for reader were 0.955 for reader 1 and 0.980 for reader 2, while the inter-reader ICCs controlling for location were between 0.930 and 0.937, indicating great reliability and reproducibility. However, inter-reader bias of SUVmean were significantly different among locations (P < 0.001). Bias at portal vein level (0.069 ± 0.112) was significantly larger than those at the upper level (0.004 ± 0.144, P < 0.001) and lower level (0.002 ± 0.136, P < 0.001).

Liver SUVmean measured by placing VOI at the portal vein level exhibited a relatively larger variation and less precision between readers, which was not recommended.