3.0 Tesla magnetic resonance imaging anatomy of the central nervous system, eye, and inner ear in birds of prey

Abstract

Despite the increasing interest in the clinical neurology of birds, little is known about the magnetic resonance imaging (MRI) appearance of the avian central nervous system, eye, and inner ear. The objective of this cadaveric study was to document the MRI anatomic features of the aforementioned structures using a high-resolution 3.0 Tesla MRI system. The final study group consisted of 13 cadavers of the diurnal birds of prey belonging to six species. Images were acquired in sagittal, dorsal, and transverse planes using T1-weighted and T2-weighted turbo spin echo sequences. A necropsy with macroscopic analysis of the brain and spinal cord was performed on all cadavers. Microscopic examination of the brain was performed on one cadaver of each species; the spinal cord was examined in three subjects. Anatomic structures were identified on the magnetic resonance images based on histologic slices and available literature. Very good resolution of anatomic detail was obtained. The olfactory bulbs; cerebral hemispheres; diencephalon; optic lobe; cerebellum; pons; ventricular system; optic, trigeminal, and facial nerves; pineal and pituitary glands; as well as the semicircular canals of the inner ear were identified. Exquisite detail was achieved on the ocular structures. In the spinal cord, the gray and white matter differentiation and the glycogen body were identified. This study establishes normal MRI anatomy of the central nervous system, eye, and inner ear of the birds of prey; and may be used as a reference in the assessment of neurologic disorders or visual impairment in this group of birds.

Computed tomographic and magnetic resonance imaging anatomy of the coelomic cavity in market‐age commercial Pekin Ducks (Anas platyrhynchos domesticus)

“…This combination of signal intensities often reflects high glycogen content, as the intracytoplasmic accumulation of glycogen may shorten T1 relaxation time of the tissues, increasing the signal intensity on the T1‐weighted images (Chou et al, 2011). In the current study, the appearance of the glycogen body was not well defined on MRI images; this is in opposition to a previous publication (Stanczyk et al, 2018) which used a 3.0‐Tesla MRI and was able to visualize strong glycogen body margins. The poor visibility of the glycogen body in this study is likely due to the lower resolution of a 1.5‐Tesla MRI compared to the 3‐Tesla MRI in the previous study.…”

“…This combination of signal intensities often reflects high glycogen content, as the intracytoplasmic accumulation of glycogen may shorten T1 relaxation time of the tissues, increasing the signal intensity on the T1-weighted images (Chou et al, 2011). In the current study, the appearance of the glycogen body was not well defined on MRI images; this is in opposition to a previous publication (Stanczyk et al, 2018) The testes were present cranioventrally to each cranial-most kidney lobe. Each testis was partially distinguishable from the surrounding tissue but there was border effacement dorsally, where the testes were abutting the kidneys.…”

“…The glycogen body is found along the dorsal midline of the lumbosacral enlargement and occupies the cleft within the rhomboid sinus between the left and right dorsal columns. The glycogen body is composed of glial cells that are rich in glycogen and has previously been described as a T2-weighted hypointense structure relative to other portions of the spinal cord and as a T1-weighted hyperintense structure in the lumbosacral enlargement (Stanczyk et al, 2018). This combination of signal intensities often reflects high glycogen content, as the intracytoplasmic accumulation of glycogen may shorten T1 relaxation time of the tissues, increasing the signal intensity on the T1-weighted images (Chou et al, 2011).…”

The localization of a conjunctivoscleral foreign body via high‐resolution microscopy coil magnetic resonance imaging in a dog

“…However, one of the limiting factors in MRI of the eye and the orbit is the small size of the structures of interest, which limits their spatial resolution. As a consequence, small anatomic structures, as well as subtle lesions, cannot be displayed and detailed properly . This case report outlines the limitations of commonly available MRI sequences and the advantage of using novel diagnostic tools like microscopy coil high‐resolution MRI in selected cases.…”

Clinical, imaging, and pathologic features in cases of neurologic disease in 3 psittacine birds

“…9 Magnetic resonance imaging (MRI) is a noninvasive process that provides excellent soft tissue contrast of the CNS and spatial orientation of anatomic structures. MRI has been used increasingly in avian medicine for anatomic description of the brain 14 and also for the diagnosis of neurologic diseases. 9 We compare here MRI findings and postmortem examination in 3 psittacine birds that manifested neurologic clinical signs.…”