High spatial resolution magnetic resonance imaging of insects covered with a hard exoskeleton

Abstract

The morphological investigation of insects is usually performed using histologic serial sections and subsequent reconstruction of the structures from these sections. The achievement of cross sections for microtomy is time-consuming and the risk of damaging sections is inevitable. Recently, X-ray computed tomography (micro-CT) was used to provide adequate spatial resolution without destroying the specimens. Micro-CT is limited by the low x-ray contrast of the insect soft tissues and image quality is relatively poor. Magnetic resonance imaging (MRI) allows the study of morphologic classification of the insects with sufficient spatial resolution and provides a noninvasive mean to determine disease abnormalities and progression in vivo and longitudinally. The morphologic classification of the insects with sufficient spatial resolution analyzed the potential of MR imaging. However, a stag beetle has a particularly hard exoskeleton protecting internal organs and nerves. It is challenge to obtain high spatial resolution images using MRI. The aim of this study was to characterize optimal MRI protocols for the investigation of stag beetles and to evaluate the morphologic characterization of the stag beetles by a 9.4 T MRI scanner. In this study, MR imaging provided the spatial resolution necessary for the examination of morphologic structures of the insects on our hardware-software platform. This study plays a significant role in providing the high spatial resolution, ideally required for routine application to the study of internal morphology of insects, arachnids and crustaceans whose organs, nerves and muscles are protected by the hard exoskeleton.