Effect of position and volume of spaceoccupying liver lesions on liver function index in 99mTc-GSA scintigraphy.

Background: The authors aimed to elucidate the effect of liver space-occupying lesions (SOL) on the quantitative index of the hepatic reserve, calculated using the dynamic planar image (LHLplanar), and a three-dimensional quantitative index (LHLSPECT) calculated using quantitative combined modality single-photon emission computed tomography (SPECT/CT).

Material and methods: Water balloons of different volumes that simulated liver SOL were placed in various positions in the combined cardiac-liver phantom to examine the effects of liver SOL on visualization and quantitative indicators (LHLplanar and LHLSPECT). A 200 mL water balloon was placed in the anterior right, posterior right, left medial and left lateral lobes in the liver phantom to compare LHLplanar and LHLSPECT values with and without liver SOL at each position. Subsequently, volumes of those in the front of the right lobe were changed to 50 mL, 100 mL, 200 mL, and 400 mL, followed by statistically comparing LHLplanar and LHLSPECT values in the presence and absence of liver SOL.

Results: Despite the variation in the degree of defect accumulation with the location of the balloon when using frontal planar imaging, quantitative SPECT/CT imaging identified all defects. Multiple comparison analysis revealed that unlike LHLSPECT, the LHLplanar values changed according to liver SOL position and volume.

Conclusions: Liver SOL position and volume may affect the hepatic reserve assessments performed using LHLplanar values. In contrast, LHLSPECT is calculated using quantitative SPECT/CT and considers the effects of scattering and attenuation corrections. Therefore, LHLSPECT is a more accurate quantitative indicator of hepatic reserve than LHLplanar and is expected to facilitate future clinical research.