Abstract
ObjectivesIn the early recognition of portal vein ligation (PVL) induced tumor progression, positron emission tomography and magnetic resonance imaging (PET/MRI) could improve diagnostic accuracy of conventionally used methods. It is unknown how PVL affects metabolic patterns of tumor free hepatic tissues. The aim of this preliminary study is to evaluate the effect of PVL on glucose metabolism, using PET/MRI imaging in healthy rat liver.Materials and MethodsMale Wistar rats (n = 30) underwent PVL. 2-deoxy-2-(18F)fluoro-D-glucose (FDG) PET/MRI imaging (nanoScan PET/MRI) and morphological/histological examination were performed before (Day 0) and 1, 2, 3, and 7 days after PVL. Dynamic PET data were collected and the standardized uptake values (SUV) for ligated and non-ligated liver lobes were calculated in relation to cardiac left ventricle (SUVVOI/SUVCLV) and mean liver SUV (SUVVOI/SUVLiver).ResultsPVL induced atrophy of ligated lobes, while non-ligated liver tissue showed compensatory hypertrophy. Dynamic PET scan revealed altered FDG kinetics in both ligated and non-ligated liver lobes. SUVVOI/SUVCLV significantly increased in both groups of lobes, with a maximal value at the 2nd postoperative day and returned near to the baseline 7 days after the ligation. After PVL, ligated liver lobes showed significantly higher tracer uptake compared to the non-ligated lobes (significantly higher SUVVOI/SUVLiver values were observed at postoperative day 1, 2 and 3). The homogenous tracer biodistribution observed before PVL reappeared by 7th postoperative day.ConclusionThe observed alterations in FDG uptake dynamics should be taken into account during the assessment of PET data until the PVL induced atrophic and regenerative processes are completed.
Highlights
After portal vein ligation (PVL), ligated liver lobes showed significantly higher tracer uptake compared to the non-ligated lobes
The observed alterations in FDG uptake dynamics should be taken into account during the assessment of positron emission tomography (PET) data until the PVL induced atrophic and regenerative processes are completed
Despite advances in chemotherapy regimens and ablative techniques, extended hepatectomy is considered as a gold standard for the treatment of primary and secondary liver cancers. [1,2,3] surgical resection can be accomplished only in 20– 30% of the cases, due to insufficient amount of remaining liver mass after hepatectomy
Summary
Despite advances in chemotherapy regimens and ablative techniques, extended hepatectomy is considered as a gold standard for the treatment of primary and secondary liver cancers. [1,2,3] surgical resection can be accomplished only in 20– 30% of the cases, due to insufficient amount of remaining liver mass after hepatectomy (future remnant liver volume; FRLV). [4] It is known for decades that occlusion of the portal vein results in atrophy of the occluded liver lobe, while owing to the unique regeneration capacity, the unoccluded liver tissue shows compensatory hypertrophy. [5] Based on this observation portal vein occlusion techniques, such as portal vein ligation (PVL) or embolization (PVE), have been introduced to increase the future volume of the remnant liver before major liver resection. [6] Considering that at the time of diagnosis most liver malignancies show multiple bilateral patterns, a two-stage resection with portal vein occlusion has recently been developed. [5] Based on this observation portal vein occlusion techniques, such as portal vein ligation (PVL) or embolization (PVE), have been introduced to increase the future volume of the remnant liver before major liver resection. There might be an increased risk, that portal vein occlusion could stimulate the growth of future remnant liver, and significantly affects tumor size and tumor spread in both occluded and non-occluded liver segments. [9,10,11] Tumor progression in the liver between the time of PVL/ PVE and the phase of hepatectomy is responsible for the majority of changes into irresectable state which occurs in approximately 20% of the cases of planned for two-stage surgeries. In a clinical scenario, computed tomography (CT) is currently the goldstandard method of assessing the increase in FRLV. [15] CT volumetry may not be reliable in the detection of residual tumor growth, because the accuracy of CT is poor for smaller (,0.2–1 cm) tumor sizes. [16] MRI, especially with liverspecific contrast agents, could improve the sensitivity by providing better soft-tissue contrast, but is not sufficiently specific leading to number of false positive lesions. [17] These drawbacks of morphological imaging techniques indicate the importance of additional functional imaging assays, which could recognize tumor progression during two-stage hepatectomy combined with portal vein ligation
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