Exitron nano 12000

Micro-CT scan (Inveon Micro-CT, Siemens, Germany) was performed 4 h after injection of contrast agent. The contrast agent (ExiTron nano 12000, Miltenyi Biotec, Germany) is an alkaline earth-based nanoparticulate contrast agent for mouse liver CT imaging [41 (link)]. Upon intravenous injection, the agent is taken up by cells of the reticuloendothelial system, including macrophages within the liver, termed Kupffer cells. Mice were injected with 100 µl of agent (per mouse, 25–30 g body weight) via a lateral tail vein.

MicroSPECT/CT imaging was performed as described with minor modifications14 (link)44 (link)45 (link)46 (link). In brief, under anesthesia with 1–2% isoflurane in 100% oxygen, 55.2 ± 2.6 MBq ^99mTc-labeled RP805 was injected intravenously through a jugular vein catheter. Two hours after tracer injection, animals were imaged using a high-resolution small animal imaging system (Gamma Medica X-SPECT). SPECT images were acquired using the following optimized parameters: ROR = 2.7 cm; 64 projections, 30 sec per projection; 360° rotation; matrix 82 × 82; and 140-keV photopeak ± 10% window. SPECT images were followed by a non-contrast CT followed by CT angiography using ExiTron nano 12000 (80 μL/min for 1 minute, Miltenyi Biotec, San Diego, CA) to locate the aortic valve. To quantify tracer uptake on microSPECT images a 2 × 2 mm cylindrical region of interest (ROI) was drawn at the level of the aortic valve located by CT. Background activity was defined by a ROI drawn immediately anterior to the valve, and the data were expressed as background-corrected mean activity per kBq tracer injected. After completion of in vivo imaging, the heart (with aortic valve) and aorta were harvested for ex vivo planar imaging using the following parameters: distance 28 mm, image acquisition time 30 minutes. Tracer uptake was quantified in a 2 × 2 mm square ROI drawn over the aortic valve area.

The rats were anesthetized by intraperitoneal injection of tribromoethanol (250 mg/kg). Five minutes after a single intravenous injection of 400 μL of a nanoparticulate contrast agent (ExiTron nano 12000; Miltenyi Biotec GmbH, Bergisch Gladbach, Germany), the rat was held in the cradle. The abdomen filled the field of view. The tube parameters were set to 90 kV and 160 mA (focal spot size 5 µm). The scanning protocol was programmed to acquire a total of 1200 projections per scan while continuously rotating the rat by 360°.

Micro-CT scan (Inveon Micro-CT, Siemens, Germany) was performed 1 day after injection of a contrast agent (ExiTron nano 12000, Miltenyi Biotec, Germany) which is an alkaline earth-based nanoparticulate contrast agent for mouse liver CT imaging [23 (link)]. Mice were injected with 100 μl of contrast agent via a lateral tail vein. Since this agent is taken up by cells of the reticuloendothelial system including macrophages within the liver and spleen, normal liver and spleen were enhanced and tumors were drawn as a black spot.

In vivo imaging was performed using a micro-CT system (Quantum GX, PerkinElmer, Hopkinton, MA, USA) 24 h after intra-venous injection of a contrast agent (ExiTron nano 12000, 100 μl/animal; Miltenyi Biotec, Bergisch-Gladbach, Germany). All in vivo imaging procedures were performed under inhaled isoflurane anesthesia. The analysis of the images was performed using OsiriX DICOM viewer software (version 12.0). Tumor morphological analysis was performed on sets of axial images using a slice thickness of 1 mm and manually contouring each individual tumor (regions of interest). Tumor volumes were then automatically calculated based on the regions of interest defined by the user. Analysis of tumor volume by micro-CT was performed at 24, 32 and 36 weeks of age.