Power of Mediso's nanoScan combined systems: Perfect Co-Registration

In the first published article from MSKCC (Carney, B. et al. Non-invasive PET Imaging of PARP1 Expression in Glioblastoma Models. Mol Imaging Biol 1–7 (2015)), using the nanoScan PET/MRI (1T) small animal imaging system, in vivo whole body PET/MRI imaging of [¹⁸F]PARPi in orthotopic brain tumor-bearing mice is referenced.

[¹⁸F]PARPi is a selective PARP1 imaging agent that can be used to visualize glioblastoma in xenograft and orthotopic mouse models with high precision and good signal/noise ratios offering new opportunities to non-invasively image tumor growth and monitor interventions.

Figure 6 in the article shows coronal views of contrast-enhanced MRI, [¹⁸F]PARPi PET images, and fused PET/MRI of orthotopic U251 MG tumor-bearing mice. In the top row the mouse receivied only [¹⁸F]PARPi, in the bottom row the mouse receivied [¹⁸F]PARPi after a 500-fold excess of olaparib.

The animals were injected with 200 µCi of [18F]-PARPi and a 20 minutes static PET scan was acquired 2 hours post injection. 200 µL of diluted gadopentate dimegumine in saline solution  was administered intravenously one minute prior to MRI acquisition. Tumor regions were identified on anatomic images acquired using a post-contrast T-weighted spin-echo (SE) acquisition. The co-localization of [¹⁸F]PARPi and tumor in PET/MRI studies was confirmed by ex vivo autoradiography. In PET/MRI fusion images, accumulation in the tumor was co-aligned with the orthotopic tumor on MRI. In mice receiving an injection of olaparib ahead of the radiotracer, the [¹⁸F]PARPi tumor uptake was negligible.

It's important to note that no further or manual co-registration was required at all as the PET/MRI studies performed on the nanoSCan PET/MRI are co-registered by nature due to the common gantry and automated acquisition system. The very same images are displayed in the viewer when the dual-modality study is loaded from the DICOM server after reconstruction. This gives scientists confidence when evaluating multi-modal data; changing animal physiology and data obtained at different times won't distort the findings.