A novel intubation technique for minimally invasive longitudinal studies of rat lungs using hyperpolarized ³He magnetic resonance imaging

Abstract

Hyperpolarized noble gas (HNG) magnetic resonance imaging (MRI) has been shown to be useful for studying rodent models of lung disease. Image quality can be substantially degraded by signal loss from molecular oxygen entering the airway, requiring invasive surgery to ensure a good seal between the endotracheal (ET) tube and trachea. A modified Foley catheter having an inflatable cuff near the tip provides a novel approach for ensuring image quality for HNG MRI, thereby enabling longitudinal studies and reducing animal numbers. A Foley catheter was modified for rodent intubation and to minimize dead space. Three pairs of age-matched male Sprague Dawley rats 400 (30) g were used. Two pairs were intubated using the Foley and the third with an intravenous catheter. Leak rates were measured from pressure versus time curves within each animal. The pairs were euthanized immediately or six days postrecovery to assess the effects of the procedure on animal health, as reflected by histological examination. The Foley catheter resulted in minimal leak rates (20.20 (0.03) versus 20.16 (0.05) cmH 2 O/s), and were shown to be well below upper-limit leak rates of 20.5 and 20.7 cmH 2 O/s. Tracheal samples from rats in a separate Foley group (not mechanically ventilated) showed superficial damage six days postextubation (grade ¼ 0).3 He imaging performed using the Foley showed good image quality. Though some technical issues remain to be solved, a modified Foley catheter used as an ET tube offers the potential to enable longitudinal studies in rodents and reduce animal numbers.

Early stage radiation‐induced lung injury detected using hyperpolarized 129Xe Morphometry: Proof‐of‐concept demonstration in a rat model

“…This ensured controllable breathing cycles and breath‐holds as well as avoidance of mixing of hyperpolarized xenon with oxygen that diminishes the MR signal prior to acquisition. There has been a single demonstration of the feasibility of a longitudinal evaluation in animals ; however, the techniques described are still under development, and many of the identified shortcomings still require attention.…”

Hyperpolarized 129 Xe imaging of the rat lung using spiral IDEAL

“…All procedures followed animal use protocols approved by Western University's Animal Use Subcommittee and were consistent with the guidelines written by the Canadian Council on Animal Care (CCAC) . Five Sprague Dawley rats (390 ± 7 g, Charles River Laboratories, Saint‐Constant, Canada) were imaged in the supine position following three breaths of Hp 129 Xe using a MRI‐compatible mechanical ventilator (GE Healthcare, Malmo, Sweden) for delivery of Hp 129 Xe to the lung.…”

Transmit‐only/receive‐only radiofrequency coil configuration for hyperpolarized 129Xe MRI of rat lungs

“…The mechanical ventilation of the rat lungs has been described previously . A large surgical incision area was required across the neck for intubating the trachea and to secure the intubation catheter.…”