Interview fusion

Experimental
animals under isoflurane
anesthesia were r.o. injected with [⁶⁸Ga]Ga-ORNB (approximately
∼0.5 μg of ORNB) at a dose of 2–7 MBq per animal
and placed in a dorsoventral position in the Mediso NanoScan PET/CT
imaging system for small animals (Mediso Medical Imaging Systems,
Budapest, Hungary). After the administration of [⁶⁸Ga]Ga-ORNB,
static imaging was initiated 30 and 90 min p.i. for non-infection
imaging studies and 45 min p.i. for infection imaging studies. Dynamic
imaging studies were started ∼5 min p.i. Single FOV PET scans
(98.5 mm) for mice and double FOV PET scans (2 × 98.5 mm) for
rats were performed, followed by whole body helical CT scan (50 kVp/980
μA, 720 projections). Image reconstruction was performed via Mediso Tera-Tomo 3D PET iterative reconstruction (Mediso
Medical Imaging Systems, Budapest, Hungary). The images were visualized,
processed, and quantified in the Mediso InterView FUSION (Mediso Medical
Imaging Systems, Budapest, Hungary). Quantitative analyses were performed
on images of non-infected rats and rats with lung infections. The
images were normalized to injected activity and animal weight. The
results were expressed as percentage of injected dose per gram tissue
(% ID/g).

The experimental animals under isoflurane anaesthesia were injected r.o. with [⁶⁸Ga]Ga-FR or [⁶⁸Ga]Ga-FRH (approximately ∼ 0.5 μg of siderophore) at a dose of 5–8 MBq per animal and placed in the prone position in the Mediso NanoScan PET/CT small animal imaging system (Mediso Medical Imaging Systems, Budapest, Hungary). After the administration of [⁶⁸Ga]Ga-FR or [⁶⁸Ga]Ga-FRH, static imaging was initiated at 30 and 90 min p.i. Dynamic imaging studies were started ∼ 5 min p.i. Single field-of-view PET scans (98.5 mm) were performed, followed by whole-body helical CT scans (50 kVp/980 μA, 720 projections). Image reconstruction was performed using Mediso Tera-Tomo 3D PET iterative reconstruction (Mediso Medical Imaging Systems, Budapest, Hungary). Images were visualised, processed, and quantified using Mediso InterView FUSION (Mediso Medical Imaging Systems, Budapest, Hungary). Final images were normalised to injected activity and animal weight.

Image analysis was performed with InterView Fusion (Mediso Medical Imaging Systems, Budapest, Hungary). Tumor volumes (volumes of interest - VOIs) were defined by a 3D standardized uptake value (SUV) 2.0 isocontour around the hottest voxel, with manual corrections where necessary. For comparison, VOIs based on SUV 2.5 isocontours were also defined. The maximum SUV (SUV_max), mean SUV (SUV_mean), metabolic tumor volume (MTV), and coefficient of variation (COV) were calculated on floating-point SUV data. The SUV used for calculations was the measured activity concentration normalized to decay corrected injected activity and body weight of the patient. For determination of textural parameters, SUV values were normalized and discretized to a total of 64 bins by the formula $R\left(x\right)=64\times \left[I\left(x\right)-SU{V}_{\mathit{min}}\right]/\left[SU{V}_{\mathit{max}}-SU{V}_{\mathit{min}}\right]$
where I(x) is the SUV of voxel x in the original image and R(x) is its resampled value. Subsequently, an analysis via neighborhood gray-tone difference matrices (NGTDM) and gray-level co-occurence matrices (GLCM) in 13 directions (3D) was carried out as described earlier [15 (link)]. From these matrices, local entropy, correlation, contrast, coarseness and busyness were derived. Additionally, tumor diameters were measured in the low-dose CT image.