9.4t vnmrs horizontal bore scanner

Mice were anaesthetised with isoflurane and maintained at 37 ± 1 °C during image acquisition. For Dobutamine (40 μg kg^− 1 min^− 1) and Esmolol (5 mg kg^− 1 min^− 1) stress tests an intraperitoneal (i.p.) infusion line was prepared and connected to an infusion pump (PHP2000 Harvard Instruments, UK). Image acquisition was performed with a 39 mm diameter volume coil (Rapid Biomedical GmbH, Germany). Cardio-respiratory monitoring and gating were performed using an MR-compatible system (SA Instruments, NY). Imaging was performed using a 9.4 T VNMRS horizontal bore scanner (Agilent Technologies, CA) with a shielded gradient system (1000 mT/m). For detailed image acquisition and analysis protocols, please refer to [27] (link) and the online Supplement.

All imaging was performed using a 9.4T VNMRS horizontal bore scanner (Agilent Inc.). The key differences between the in vivo and ex vivo protocols are outlined in Table 1. For in vivo imaging, mice were anesthetized under 2% isoflurane and positioned in an MRI compatible head holder to minimize motion artifacts. Anesthesia was then maintained at 1.5% isoflurane in 100% O₂ throughout imaging. Core temperature and respiration were monitored using a rectal probe and pressure pad respectively (SA instruments). Mice were maintained at ~37°C using heated water tubing and a warm air blower with a feedback system (SA Instruments).

A total of 72 mice were imaged in this study. All experiments were performed in accordance with the UK Home Office Animals (Scientific Procedures) Act. Anaesthesia was induced using 2% isoflurane in 0.4 L/min medical air and 0.1 L/min O₂ and was maintained at 2% isoflurane whilst the animal was placed on a MRI compatible plastic probe. The head was secured using ear bars, a bite bar and a nose cone to minimise motion during the data acquisition. Once the probe was fixed in the scanner, isoflurane concentration was reduced to 1.5% in 0.4 L/min medical air and 0.1 L/min O₂. Body core temperature was measured throughout using a rectal thermometer (Small Animal Instruments Inc) and maintained at 37 ± 0.5 °C using heated water tubing during the preparation and heated water tubing and warm air flow during the data acquisition period. Eye ointment was applied and breathing rate was monitored throughout the acquisitions using a respiration pillow sensor (Small Animal Instruments Inc). A scavenger pump was fixed inside the magnet bore to prevent build up of isoflurane.
All imaging was performed using a 9.4T VNMRS horizontal bore scanner (Agilent Inc, Palo Alto, CA). A 72 mm inner diameter volume coil was used for RF transmission and signal was received using a two channel array head coil (Rapid Biomedical).