Gold 3 hermes hybrid viewer

MET PET was performed using a dedicated full-ring GE Advance PET scanner (General Electric Medical Systems, field of view: 14.875 cm, 35 slices per PET examination with a slice thickness of 4.25 mm). Image acquisition started 20 min after intravenous application of ~740 MBq MET (produced in-house with a radiochemical purity of >97%). Data reconstruction was performed by filtered back projection using a Hanning filter with a cutoff value of 6.2 mm and a 128 × 128 matrix. Image evaluation was performed by 2 experienced nuclear medicine physicians using Hermes software (Gold 3 Hermes Hybrid Viewer, Hermes Medical Solutions, Stockholm, Sweden) manually drawing volumes of interest containing the highest tracer uptake in the tumor and in the contralateral hemisphere for calculating the Tumor/Normal cerebrum (T/N) ratio. Further details see also Poetsch et al. [22 (link)].

All reconstructed PET data were transferred from the GE system and evaluated by experienced nuclear medicine physicians using a dedicated Hermes software (Gold 3 Hermes Hybrid Viewer, Hermes Medical Solutions). For visual assessment, brain tumors were analyzed for hypo-, iso-, or hypermetabolism of MET, as described previously [24 (link)]. Hypo- or isometabolism of brain tumors was summarized as MET-negative brain tumors. For semiquantitative analysis, cuboid VOIs (20 mm × 20 mm × 20 mm) were manually generated containing the highest tracer uptake of the tumor and for background estimation in the contralateral brain. For the calculation of the T/N ratio, the maximal standardized uptake value (SUV) of the tumor was divided by the mean SUV of the background VOI. If no tracer uptake was seen, VOIs were drawn based on MRI.