Low-field magnetic resonance imaging and cross-sectional anatomy of the rabbit head

Correlation between Cross-Sectional Anatomy and Computed Tomography of the Normal Six-Banded Armadillo (Euphractus sexcintus) Nasal Cavity and Paranasal Sinuses

This research aimed to study the rostral part of the head of the six-banded armadillo, applying advanced imaging techniques such as CT. Furthermore, by combining the images obtained through this technique with anatomical cross-sections, an adequate description of the structures that constitute the rostral part of the head of this species is presented. This anatomical information could provide a valuable diagnostic tool for the clinical evaluation of different disorders in the six-banded armadillo's nasal cavity and paranasal sinuses.

Cranial Investigations of Crested Porcupine (Hystrix cristata) by Anatomical Cross-Sections and Magnetic Resonance Imaging

This paper aimed to describe an atlas of the crested porcupine (Hystrix cristata) head by applying advanced imaging techniques such as MRI. Furthermore, by combining the images acquired through these techniques with anatomical sections, we obtained an adequate description of the structures that form the CNS and associated structures of this species. This anatomical information could serve as a valuable diagnostic tool for the clinical evaluation of different pathological processes in porcupines, such as abscesses, skull malformations, fractures, and neoplasia.

Ultrasonographic measurement of the adrenal gland-to-abdominal aortic ratio as a valuable method of estimating normal adrenal size in rabbits

A wide range has been reported for the ultrasonographic measurements of the normal adrenal gland in rabbits. Therefore, having sufficient information about the normal measurements of the adrenal gland and their relationship with indicators such as weight, sex and the diameter of the internal abdominal aorta will be of great help in diagnosing diseases of the adrenal gland. In the present study, 21 healthy adult intact rabbits were selected. The abdominal cavity of the animals was examined using ultrasound; adrenal gland parameters such as length, width, height, circumference and area on the right and left sides were measured in both sagittal and transverse planes. Additionally, the diameter of the abdominal aorta in the sagittal plane was imaged. After statistical analysis, the parameters of the adrenal glands on the right and left showed a positive significant correlation with the weight and the diameter of the abdominal aorta, although no significant correlation was found between these parameters and sex. The ratio of adrenal gland parameters to abdominal aortic diameter was calculated and the statistical analysis of the values showed that, except for the ratio of left adrenal area to aortic diameter, the other ratio of adrenal gland parameters to abdominal aortic diameter was not significantly related to weight. Therefore, these ratios can be used as suitable indicators for assessing the change in size of the adrenal gland of rabbits of different sizes. Knowing the relationship between normal adrenal measurements and the indices such as weight, sex and diameter of the abdominal aorta can help clinicians and researchers evaluate the changes in the size of the adrenal gland.

Correlation between computed tomography, magnetic resonance imaging and cross-sectional anatomy of the head of the guinea pig (Cavia porcellus, Linnaeus 1758)

The current work aimed to study the anatomical features of the guinea pig's head by two medical imaging techniques: computed tomography (CT) and magnetic resonance imaging (MRI), and their correlation with the anatomical cross-sectional images. Six adult healthy guinea pigs were used in the present study. Two heads were imaged by CT scanner and then by MRI. The examined heads were cut sagittally and transversely, and two skulls were macerated. The anatomical features were identified on the anatomical sections and compared with the tomographic and MRI images obtained. Data were presented as three-dimensional reconstructed images of the head. In addition, representative combinations of the sagittal and transverse anatomical sections and the corresponding CT scans and MRI images were also presented. Reconstruction of CT images enabled the visualization of different bony structures and airways of the guinea pig head. In addition, skull bones were easily visualized on CT scans, while different parts of the brain were identified on MRI images. Air cavities could be identified by their different contrast on the CT scans and their low intensity on MRI images. The study showed that guinea pig had poorly developed paranasal sinus system represented by rostral and caudal maxillary sinuses. On the contrary, the guinea pig had two tympanic bullae: a small dorsal and a large ventral bulla. In conclusion, this study provides one of the first investigations that uses the multislice CT scans and MRI to study the guinea pig's head and their correlation with the corresponding anatomical sections.

Mensuration of the rabbit pituitary gland from computed tomography

The aim of this retrospective reference interval observational study was to determine the mensuration of the pituitary gland (hypophysis cerebri) by analyzing CT studies in rabbits without clinical evidence of pituitary disease or central neurologic signs. Though diseases of the rabbit pituitary gland are uncommon, the pituitary gland is essential in regulation of the rabbit's endocrine system, as in other species. Currently, there are minimal published studies that detail the rabbit head anatomy on cross-sectional imaging, and even less specifically examining the pituitary gland. The pituitary gland was measured by one observer at a single time point from transverse and reconstructed sagittal CT images in a soft-tissue algorithm in 62 rabbits for a total of 66 rabbit head CT studies. The rabbits ranged from 0.84 to 14 years in age (mean ± SD: 5.46 ± 3.05 years) and 0.92 to 4.95 kg in weight (2.21 ± 0.83 kg). Linear pituitary measurements were performed using electronic calipers. The mean ± SD pituitary height was 4.22 ± 0.57 mm, width was 4.48 ± 0.71 mm, and length was 6.02 ± 0.70 mm. The pituitary gland height-to-brain area ratio was 1.10 ± 0.16 mm^-1 , which is much higher than the values reported in normal dogs and cats. The age, weight, and sex of the rabbits were not found to have a significant impact on pituitary gland mensuration. These measurements could be useful as a reference range for future rabbit head CT studies and to rule out pituitary enlargement or disease when evaluating rabbit pituitary glands.

Advances in the anatomic study of the interscapular region of the cat

Background

New clinical oriented approaches are supported by the integration of advanced imaging techniques, e.g. computed tomography and magnetic resonance, with gross anatomy imaging. The interscapular region of the cat is a typical site of a highly invasive infiltrative pathology, i.e. Feline Injection-Site Sarcoma. Even if chemotherapy and radiotherapy have been considered as pre-surgical therapies, extensive surgery is still the recommended treatment. Evidence suggested that the relationships between muscles, infiltrative mass and adjacent musculoskeletal structures could change according to the forelimb positions: a fact to be duly considered while planning the surgical approach.

Anatomic and tomographic atlases provide only images of the interscapular region from cats positioned with their forelimbs extended cranially, which means that, they do not record musculoskeletal modifications due to the forelimb movements.

Aim of this study was to provide detailed images of the changes occurring in the musculoskeletal structures of the interscapular region of cats according to their forelimb position by comparing cross-sectional gross anatomy, computed tomography and magnetic resonance imaging.

Results

We provide an atlas of normal cross-sectional anatomy, computed tomography and magnetic resonance imaging of the interscapular region of the cat, from the fifth cervical vertebra to the fifth thoracic vertebra. We compare and couple the slices obtained both in flexed and extended forelimb positioning with the animal maintained in sternal recumbency.

Conclusion

This study shows a new and dynamic way to investigate the interscapular region of the cat and provides anatomical references for in vivo computed tomography and magnetic resonance imaging, considering changes in the muscular form according to the forelimb positioning. We believe that an in-depth anatomical knowledge of the interscapular region may be helpful to approach the study of any pathology located there and, in particular, to set up an appropriate therapy for the feline injection-site sarcoma.

Magnetic resonance imaging anatomy of the rabbit brain at 3 T

BACKGROUND

Rabbits are widely accepted as an animal model in neuroscience research. They also represent very popular pet animals, and, in selected clinical cases with neurological signs, magnetic resonance imaging (MRI) may be indicated for imaging the rabbit brain. Literature on the normal MRI anatomy of the rabbit brain and associated structures as well as related reference values is sparse. Therefore, it was the purpose of this study to generate an MRI atlas of the normal rabbit brain including the pituitary gland, the cranial nerves and major vessels by the use of a 3 T magnet.

RESULTS

Based on transverse, dorsal and sagittal T2-weighted (T2w) and pre- and post-contrast 3D T1-weighted (T1w) sequences, 60 intracranial structures were identified and labeled. Typical features of a lissencephalic brain type were described. In the 5 investigated rabbits, on T1w images a crescent-shaped hyperintense area caudodorsally in the pituitary gland most likely corresponded to a part of the neurohypophysis. The optic, trigeminal, and in part, the facial, vestibulocochlear and trochlear nerves were identified. Mild contrast enhancement of the trigeminal nerve was present in all rabbits. Absolute and relative size of the pituitary gland, midline area of the cranial and caudal cranial fossa and height of the tel- and diencephalon, 3rd and 4th ventricles were also determined.

CONCLUSIONS

These data established normal MRI appearance and measurements of the rabbit brain. Results provide reference for research studies in rabbits and, in rare instances, clinical cases in veterinary medicine.

Cross-sectional anatomy, computed tomography and magnetic resonance imaging of the head of common dolphin (Delphinus delphis) and striped dolphin (Stenella coeruleoalba)

Computed tomography (CT) and low-field magnetic resonance imaging (MRI) were used to scan seven by-caught dolphin cadavers, belonging to two species: four common dolphins (Delphinus delphis) and three striped dolphins (Stenella coeruleoalba). CT and MRI were obtained with the animals in ventral recumbency. After the imaging procedures, six dolphins were frozen at -20°C and sliced in the same position they were examined. Not only CT and MRI scans, but also cross sections of the heads were obtained in three body planes: transverse (slices of 1 cm thickness) in three dolphins, sagittal (5 cm thickness) in two dolphins and dorsal (5 cm thickness) in two dolphins. Relevant anatomical structures were identified and labelled on each cross section, obtaining a comprehensive bi-dimensional topographical anatomy guide of the main features of the common and the striped dolphin head. Furthermore, the anatomical cross sections were compared with their corresponding CT and MRI images, allowing an imaging identification of most of the anatomical features. CT scans produced an excellent definition of the bony and air-filled structures, while MRI allowed us to successfully identify most of the soft tissue structures in the dolphin's head. This paper provides a detailed anatomical description of the head structures of common and striped dolphins and compares anatomical cross sections with CT and MRI scans, becoming a reference guide for the interpretation of imaging studies.

Effect of intratonsillar injection of steroids on the palatine tonsils of rabbits

OBJECTIVES/HYPOTHESIS

Nasal steroids may significantly improve nasal obstructive symptoms with a reduction of adenoid size in children, but they do not consistently yield the same concurrent effect on enlarged palatine tonsils. Failure of nasal steroids to decrease the size of palatine tonsils is believed to be attributable to location and washout by saliva. The purpose of this study was to determine if direct application of steroid via intratonsillar injection would reduce the size of palatine tonsils in the rabbit model.

STUDY DESIGN

Prospective animal study.

METHODS

Eight rabbits (16 tonsils) were administered intratonsillar injections of fluticasone (n = 8, 1 mg/ml) or saline (n = 8, 0.1 ml) on days 0, 3, 7, 10, 14, and 17. Two rabbits (4 tonsils) received a single steroid injection to compare single versus multiple steroid injections. The rabbit's tonsil size was measured before each injection. After the fifty injections, the tonsils were harvested for histologic analysis.

RESULTS

A total of 16 tonsils were analyzed. After five steroid injections, the reduction (-7.7 mm(2)  ± 4.27) in size was statistically significant when compared to reduction (6.12 mm(2)  ± 6.57) in the saline injected group (P = 0.001). Repeated steroid injection was more potent than a single injection (-3.00 mm(2)  ± 3.08) in reducing the size (P = 0.006). In histologic analysis, tonsils after repeated steroid injections were significantly smaller than saline-injected tonsils (P = 0.014), without obvious lymphoid follicles.

CONCLUSION

Repeated focal tonsillar injections of corticosteroids significantly reduced the size of palatine tonsils as compared to saline-injected controls. A single injection of corticosteroids appears to be effective, but not as effective, as multiple injections.

LEVEL OF EVIDENCE

N/A.