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.

Rayos X y resonancia magnética en la entomología: principios y aplicaciones

“…Poco tiempo después se comenzó a utilizar este método para el estudio no destructivo ni invasivo en la entomología (Seo, 2018), que demostró tener grandes ventajas para documentar imágenes precisas de la morfología interna de los insectos respecto a las técnicas clásicas que requerían abundantes especímenes para su disección y análisis (Schilling et al, 2012). Con la RMN se hizo posible obtener información y documentar al mismo insecto varias veces para darle seguimiento en diferentes edades durante su desarrollo fisiológico, así como durante etapas fenológicas específicas como el desarrollo de los gametos o durante procesos específicos como la acumulación y flujo de las reservas de energía en función de actividades cotidianas como el vuelo (Favila et al, 2004).…”

Morphological Observation of the Pupal Body of <i>Trypoxylus dichotomus</i> Using 9.4T MR Imaging

“…Morphology of adult insects have also been investigated. 8 , 9 Between these two modalities, X-CT is powerful because of its extremely high spatial resolution, but its ionizing radiation is often fatal to the subjects, preventing this modality from aiding in continuous observation.…”

In vivocontinuous three-dimensional magnetic resonance microscopy: a study of metamorphosis in Carniolan worker honey bees (Apis mellifera carnica)

“…Their optimal water/lipid content and their size make insects one of the ideal samples for the MRM studies (Hart et al, 2003). Previously, studies on the morphologies of locusts (Gassner and Lohman, 1987), ladybirds (Geoghegan et al, 2000), honey bees (Tomanek et al, 1996), diving beetles (Wecker et al, 2002), fruit flies (Meme et al, 2013) and, more recently, stag beetles (Seo, 2018) have been reported. Several studies were also focused on the development of insects, e.g.…”