Advantage window workstation

Standardized uptake values were determined using an SUV function integrated into a GE Advantage Window Workstation. In order to obtain the SUV measurement, a 1.5-cm region of interest (ROI) was deposited on the image slice that had the most intense ¹⁸F-FDG activity determined by visual inspection. By definition, an SUV is a reflection of the amount of ¹⁸F-FDG activity in an ROI per the following formula:
$$\mathrm{SUV}=\left[\text{activity}/\mathrm{mL}\text{tissue}\left(\text{decay}‐\text{corrected}\right)\right]/\left(\text{injected dose}/\text{body weight}\right).$$

The perfusion parameter maps were generated using CT perfusion software based on Lawrence-Lee model (GE Healthcare). Dual blood supply of liver was taken into consideration and the measurement of blood flow has been validated against the gold standard radioactive microsphere in the same liver tumor model. Details were described in previous publications [8 (link), 9 (link)]. Image registration between the perfusion maps and axial CT acquired during oxygen probe insertion was performed using free open-source software—3D slicer 4.4 (http://www.slicer.org). Several circular regions of interests (ROIs), each of 5 mm diameter and at 5 mm interval, were used to measure perfusion measurements including blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability surface (PS) along the oxygen sampling track. The ¹⁸F-FDG uptake within each ROI was determined from the automatically registered PET images (with respect to the perfusion CT maps) with PET-CT review software on an Advantage Window workstation (GE Healthcare). Standardized uptake value (SUV) was calculated by the following formula: SUV = mean ROI activity × body weight / Injected activity. The flow—metabolism ratio (FMR) was calculated as BF divided by SUV.