Animal anatomy has traditionally relied on detailed dissections to produce anatomical illustrations, but modern imaging modalities, such as MRI and CT, now represent an enormous resource that allows for fast non-invasive visualizations of animal anatomy in living animals. These modalities also allow for creation of three-dimensional representations that can be of considerable value in the dissemination of anatomical studies. In this methodological review, we present our experiences using MRI, CT and μCT to create advanced representation of animal anatomy, including bones, inner organs and blood vessels in a variety of animals, including fish, amphibians, reptiles, mammals, and spiders. The images have a similar quality to most traditional anatomical drawings and are presented together with interactive movies of the anatomical structures, where the object can be viewed from different angles. Given that clinical scanners found in the majority of larger hospitals are fully suitable for these purposes, we encourage biologists to take advantage of these imaging techniques in creation of three-dimensional graphical representations of internal structures.

Although myocardial architecture has been investigated extensively, as yet no evidence exists for the anatomic segregation of discrete myocardial pathways. We performed post‐mortem diffusion tensor imaging on 14 pig hearts. Pathway tracking was done from 22 standardized voxel groups from within the left ventricle, the left ventricular papillary muscles, and the right ventricular outflow tract. We generated pathways with comparable patterns in the different hearts when tracking from all chosen voxels. We were unable to demonstrate discrete circular or longitudinal pathways, nor to trace any solitary tract of myocardial cells extending throughout the ventricular mass. Instead, each pathway possessed endocardial, midwall, and epicardial components, merging one into another in consistent fashion. Endocardial tracks, when followed towards the basal or apical parts of the left ventricle, changed smoothly their helical and transmural angulations, becoming continuous with circular pathways in the midwall, these circular tracks further transforming into epicardial tracks, again by smooth change of the helical and transmural angles. Tracks originating from voxels in the papillary muscles behaved similarly to endocardial tracks. This is the first study to show myocardial pathways that run through the mammalian left and right ventricles in a highly reproducible manner according to varying local helical and transmural intrusion angles. The patterns generated are an inherent feature of the three‐dimensional arrangement of the individual myocytes aggregated within the walls, differing according to the regional orientation and branching of individual myocytes. We found no evidence to support the existence of individual muscles or bands. Anat Rec, 2009.

The three‐dimensional architecture of the right ventricular myocardium is a major determinant of function, but as yet no investigator‐independent methods have been used to characterize either the normal or hypertrophied state. We aimed to assess and compare, using diffusion tensor magnetic resonance imaging, the normal architecture with the arrangement induced by chronic hypertrophy. We randomized 20 female 5 kg piglets into pulmonary trunk banding (N = 16) and sham operation (N = 4). Right ventricular hypertrophy was assessed after 8 weeks. The excised and fixed hearts were subject to diffusion tensor imaging to determine myocyte helical angles, and the presence of any reproducible tracks formed by the aggregated myocytes. All banding animals developed significant right ventricular hypertrophy, albeit that no difference was observed in terms of helical angles or myocardial pathways between the banded animals and sham group animals. Helical angles varied from ∼70 degrees endocardially to −50 degrees epicardially. Very few tracks were circular, with helical angles approximating zero. Reproducible patterns of chains of aggregated myocytes were observed in all hearts, regardless of group. The architecture of the myocytes aggregated in the walls of the right ventricle is comparable to that found in the left ventricle in terms of endocardial and epicardial helical angles, however the right ventricle both in the normal and the hypertrophied state lacks the extensive zone of circular myocytes seen in the mid‐portion of the left ventricular walls. Without such beneficial architectural remodelling, the porcine right ventricle seems unsuited structurally to sustain a permanent increase in afterload. Anat Rec, 2009.

In heart failure, myocardial overload causes vast metabolic changes that impair cardiac energy production and contribute to deterioration of contractile function. However, metabolic therapy is not used in heart failure care. We aimed to investigate the interplay between cardiac function and myocardial carbohydrate metabolism in a large animal heart failure model. Using magnetic resonance spectroscopy with hyperpolarized pyruvate and magnetic resonance imaging at rest and during pharmacological stress, we investigated the in-vivo cardiac pyruvate metabolism and contractility in a porcine model of chronic pulmonary insufficiency causing right ventricular volume overload. To assess if increasing the carbohydrate metabolic reserve improves the contractile reserve, a group of animals were fed dichloroacetate, an activator of pyruvate oxidation. Volume overload caused heart failure with decreased pyruvate dehydrogenase flux and poor ejection fraction reserve. The animals treated with dichloroacetate had a larger contractile response to dobutamine stress than non-treated animals. Further, dichloroacetate prevented myocardial hypertrophy. The in-vivo metabolic data were validated by mitochondrial respirometry, enzyme activity assays and gene expression analyses. Our results show that pyruvate dehydrogenase kinase inhibition improves the contractile reserve and decreases hypertrophy by augmenting carbohydrate metabolism in porcine heart failure. The approach is promising for metabolic heart failure therapy.