Magnetic resonance imaging

Anatomical magnetic resonance imaging (MRI) of ß-cell cancers in RIP1-Tag2 mice. 

MRI of ß-cell cancers of 10 weeks old Rip1-Tag2 mice was performed under 1.5% isoflurane anaesthesia using a dedicated 7 T small animal magnetic resonance scanner (ClinScan, Bruker BioSpin MRI, Ettlingen, Germany) with a proton (¹H) operating frequency of 300 MHz and a magnet with a 300 mm clear bore. The gradient and shim system (200 mm inner diameter) offers a maximum gradient strength of 300 mT/m. The system was equipped with a quadrature mouse whole- body coil (inner diameter 35 mm; Bruker BioSpin MRI) used for transmission and reception of the MRI data(1). To determine the correct position of the animals in the field of view of the MRI, short localizer-protocols were applied before each measurement.

For detection of the β-cancers and general anatomic information, a T2-weighted 3D turbo spin-echo-sequence (TE/TR 205/3,000 ms, image matrix of 160 × 256, slice thickness 0.22 mm) was used. Respiration was monitored and used for triggering MRI data acquisition to reduce artifacts caused by movements of the thoracic cavity. Additional sequence parameters are provided in the Table below.T2 maps were generated using integrated Syngo software (Siemens Healthcare) based on multicontrast spin-echo (se-mc) data, and T2 values were calculated based on signal decay with echo time. The acquired MRI data was visualised using Inveon Research Workplace software (Siemens Preclinical Solutions, Knoxville, TN, USA)(2, 3).

References:

1. Judenhofer MS, et al. (2008) Simultaneous PET-MRI: a new approach for functional and morphological imaging. Nature medicine 14(4):459-465.
2. Schmid A, Braumuller H, Wehrl HF, Rocken M, & Pichler BJ (2013) Non-invasive monitoring of pancreatic tumor progression in the RIP1-Tag2 mouse by magnetic resonance imaging. Mol Imaging Biol 15(2):186-193.
3. Brenner E, et al. (2020) Cancer immune control needs senescence induction by interferon- dependent cell cycle regulator pathways in tumours. Nature Communications 11(1):1335.

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