Hepatic and splenic 18 F-FDG blood clearance rates (Ki) in hepatic steatosis and diabetes mellitus.

Aim: The study aim was to investigate the relationships of blood glucose level (BGL) with hepatic and splenic blood FDG clearances (Ki) in patients with diabetes mellitus (DM) and/or hepatic steatosis (HS).
Methods: This was a retrospective study of 238 patients, including 92 with type 2 DM (DM2) and 11 with type 1 DM (DM1), having routine whole body FDG PET/CT. Patients with lymphoma were excluded. Patients were divided into the following groups: HS-DM-, HS-DM2+, HS+DM-, HS+DM2+ and 2 DM1 groups (hypoglycaemic and hyperglycaemic). ROI were placed over liver and spleen for measurement of SUV _max , and left ventricular cavity (LV) for measurement of SUV _mean . Tissue SUV _max was divided by LV SUV _mean . This division, giving Z, eliminates bias from the whole body metric used to calculate SUV and renders SUV _max a closer surrogate of Ki. HS was diagnosed when hepatic unenhanced CT was ≤40 HU.
Results: In all patients, individual hepatic Z and individual splenic Z correlated significantly with individual BGL. Highest mean hepatic Z and highest mean BGL were recorded in HS+ DM2+ group and lowest in hypoglycaemic DM1 group. Patients with DM1 and hyperglycaemia showed low hepatic Z in relation to BGL. Hepatic and splenic Z correlated inversely with CT density in patients without DM but not in those with DM2.
Conclusion: As BGL increases, hepatocyte glucokinase is up-regulated. This includes patients with HS and DM2 but not DM1. We speculate that in HS and DM2, up-regulation results from insulin resistance and hyperinsulinaemia. The data also support a hepato-splenic metabolic axis.
(© 2019 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.)