Measures of cardiac function in Theraphosidae spiders using in vivo magnetic resonance imaging

Abstract

We report the first in vivo cardiac magnetic resonance imaging (MRI) measurements of Theraphosidae spiders. MRI scanning is performed on six spiders under isoflurane‐induced anaesthesia. Retrospective self‐gating cine‐cardiac MRI (RG‐CINE‐MRI) is used to overcome the difficulties of prospective cardiac gating in this species. The resulting RG‐CINE‐MRI images are successfully analyzed to obtain functional cardiac parameters from live spiders at rest. Cardiac ejection fraction is found to increase with animal mass (Pearson correlation 0.849, P = 0.03) at a faster rate than myocardial tissue volume, whereas heart rate remains constant across animals. This suggests the spider heart undergoes additional biomechanical loading with age. The results of the present study demonstrate the potential for retrospective gating with respect to evaluating aspects of cardiac function in a wide range of previously inaccessible species.

MRI findings associated with clinical presentation and histopathology in a Mexican redknee tarantula (Brachypelma hamorii)

“…While ultrasound can differentiate between organs, it has inferior resolution when compared to magnetic resonance imaging (MRI) 4 . In previous studies, MRI was successfully used in tarantulas to evaluate morphology, 5 haemolymph perfusion 5 and cardiac function 6 . This case report demonstrates that MRI can be clinically used to identify lesions that correlate with physical examination and histopathological findings.…”

Theraphosid medicine: what to do when something is peculiar with the tarantula

“…A high‐frequency probe is required, and I recommend removing any ultrasound gel from the spider immediately after. More advanced imaging such as directed tomography (Fig 10), CT and MRI can all provide useful information but this is often cost prohibitive, although I have found that sometimes multiple animals can be processed at once (Merrifield and others 2018, Handberg and others 2023).…”