Scenium software

SPECT, with technetium-99m hexamethylpropyleneamine oxime (^99mTc-HMPAO) as a radiotracer, was used for the evaluation of regional cerebral blood flow. Then, 740 MBq of radiotracer was administered in patients placed in a quiet, dimly lit room in supine position. Examinations were performed with SPECT/CT scan (Symbia T6, Siemens) on dual-head gamma camera with low-energy high-resolution parallel-hole collimator. Step and shoot acquisition mode was used, and sequences of 128 frames on a 128 × 128 matrix were obtained (64 projections per head, 30 s per projection). The photopeak was set at 140 keV with 10% window on either site of the photopeak. Iterative reconstruction (eight iterations, eight subsets, 7 mm Gauss filter), scatter correction, and CT attenuation correction were performed. Post-processing analysis was performed with Scenium software (Siemens Medical Solutions USA, Inc.). The regions of interest (ROIs) were predefined on a high-resolution T1 MRI volume scan. Perfusion in the basal ganglia, frontal lobes, hemispheres of cerebella, and thalami was subsequently examined among all patients. Values of variances from ROIs in individual parts of the frontal lobe on both sides (right and left separately) were taken for statistical analysis.

Image processing was performed, and the results were visually evaluated by two experienced nuclear medicine physicians blinded to the final clinical diagnosis. Quantitative analysis of axial, coronal, and sagittal slices of the brain PET images was performed using Scenium software (Siemens Healthcare), as previously described (29 (link)). This software uses a standard template containing multiple 3D anatomical regions of interest (ROIs) to find an accurate match for each cortical structure. To analyze the concentration of tracer in the brain, we quantified the activity concentration for the following nine regional volume of interests (VOIs): basal ganglia, central region, cerebellum, cingulate and paracingulate gyri, frontal lobe, mesial temporal lobe, occipital lobe, parietal lobe, and temporal lobe. The ¹⁸F-FDG concentration in the whole brain was also calculated as a reference. Averages of the mean standardized uptake value (SUVmean) and the asymmetry index [2 × 100 (L–R)/(L + R)] were calculated in each of the selected brain regions. SUVmean values of all ROIs were divided by the mediastinal blood pool in order to correct for inter-individual variability.