Evaluation of X‐ray tomography contrast agents: A review of production, protocols, and biological applications

Abstract

X‐ray computed tomography is a strong tool that finds many applications both in medical applications and in the investigation of biological and nonbiological samples. In the clinics, X‐ray tomography is widely used for diagnostic purposes whose three‐dimensional imaging in high resolution helps physicians to obtain detailed image of investigated regions. Researchers in biological sciences and engineering use X‐ray tomography because it is a nondestructive method to assess the structure of their samples. In both medical and biological applications, visualization of soft tissues and structures requires special treatment, in which special contrast agents are used. In this detailed report, molecule‐based and nanoparticle‐based contrast agents used in biological applications to enhance the image quality were compiled and reported. Special contrast agent applications and protocols to enhance the contrast for the biological applications and works to develop nanoparticle contrast agents to enhance the contrast for targeted drug delivery and general imaging applications were also assessed and listed.

X-ray computed tomography in life sciences

“…While staining is well established in electron microscopy, fluorescent microscopy and histology, staining for CT imaging is in its relative infancy. To date only a few stains have been described in the literature, based mainly around those used for electron microscopy (which is also sensitive to heavy elements), including those containing iodine, tungsten, molybdenum and osmium (Table 1) [43,45,46]. The use of iodine has become commonplace, providing excellent contrast alongside ease of handling and cost effectiveness, and a range of staining protocols have been detailed [38].…”

“…Several studies have compared the relative benefits of the CT stains used to date across a range of zoological and plant specimens [43,46]. Nevertheless, there remains great scope for further CT stain development, in terms of both the library of available stains and the characterisation of staining uptake by different tissue types.…”

KI’nın Tavuk ve Kemirgen Epidermal Dokusunun Bilgisayarlı Tomografi Uygulamalarında Kontrast Ajanı Olarak Optimize Edilmesi

“…Keeping biological tissues in formalin or ethyl alcohol is well-known fixation processes that cause biological tissues to dehydrate [8]. Such dehydration protects biological samples from decomposing [4].…”

“…Since the invention of X-ray imaging, it has used in many medical applications such as diagnostics. In addition, high permeability of X-rays attracted researchers in many fields like physics, engineering and material sciences to investigate their samples in detail and understand their physical and atomic structures [1]- [4]. The invention of X-ray tomography enables people to obtain the image of samples in three dimension (3D) with the help of the computer which therefore is called computed tomography (CT) [5].…”

Connections between the internal and the external capsules and the globus pallidus in the sheep: A dichromate stain X‐ray microtomographic study

“…The use of micro‐CT (µ‐CT) has been recommended to characterize microstructural features of bone and soft tissues to obtain, in a non‐destructive manner, accurate 2D images in invertebrate and vertebrate samples (de Bournonville, Vangrunderbeeck, & Kerckhofs, 2019; de Crespigny et al., 2008; Descamps et al., 2014; Gignac & Kley, 2014; Heimel et al., 2019; Koç, Aslan, Kao, & Barber, 2019; Metscher, 2009; Pauwels, Van Loo, Cornillie, Brabant, & Van Hoorebeke, 2013; Rüegsegger, Koller, & Müller, 1996; Shearer, Bradley, Hidalgo, Sherratt, & Cartmell, 2016; Swain & Xue, 2009). In veterinary research, µ‐CT studies have mainly focused on the locomotor apparatus and associated diseases (Dedrick et al., 1993; Horbal, Smith, & Dixon, 2019; Lill, Gerlach, Eckhardt, Goldhahn, & Schneider, 2002; Salmon, 2020).…”