Head and Neck Veins of the Mouse. A Magnetic Resonance, Micro Computed Tomography and High Frequency Color Doppler Ultrasound Study

Abstract

To characterize the anatomy of the venous outflow of the mouse brain using different imaging techniques. Ten C57/black male mice (age range: 7-8 weeks) were imaged with high-frequency Ultrasound, Magnetic Resonance Angiography and ex-vivo Microcomputed tomography of the head and neck. Under general anesthesia, Ultrasound of neck veins was performed with a 20MHz transducer; head and neck Magnetic Resonance Angiography data were collected on 9.4T or 7T scanners, and ex-vivo Microcomputed tomography angiography was obtained by filling the vessels with a radiopaque inert silicone rubber compound. All procedures were approved by the local ethical committee. The dorsal intracranial venous system is quite similar in mice and humans. Instead, the mouse Internal Jugular Veins are tiny vessels receiving the sigmoid sinuses and tributaries from cerebellum, occipital lobe and midbrain, while the majority of the cerebral blood, i.e. from the olfactory bulbs and fronto-parietal lobes, is apparently drained through skull base connections into the External Jugular Vein. Three main intra-extracranial anastomoses, absent in humans, are: 1) the petrosquamous sinus, draining into the posterior facial vein, 2) the veins of the olfactory bulb, draining into the superficial temporal vein through a foramen of the frontal bone 3) the cavernous sinus, draining in the External Jugular Vein through a foramen of the sphenoid bone. The anatomical structure of the mouse cranial venous outflow as depicted by Ultrasound, Microcomputed tomography and Magnetic Resonance Angiography is different from humans, with multiple connections between intra- and extra- cranial veins.

Outflow of cerebrospinal fluid is predominantly through lymphatic vessels and is reduced in aged mice

“…5a ). In rodents, the major venous outflow routes for blood from the brain and the dural sinuses exit the skull through the postglenoid (or “spurious” jugular) foramina and drain into the posterior facial veins to reach the external jugular veins, as opposed to the internal jugular veins which act in this capacity in larger mammalian species including humans 39 – 41 . Infusions into the lateral ventricle were performed in n = 5 mice and an incision of the skin on the lateral aspect of the head was made to expose the posterior facial vein.…”

Brain Vascular Imaging Techniques

“…Compared to other imaging methods, the strengths of microCT and nanoCT lay with their high-resolution scanning efficiency, velocity and relatively low cost. Additionally, it is a structural imaging modality that provides a high-resolution volumetric representation of vascular structures in brains of rodents [ 20 , 21 , 22 , 23 , 24 ] as well as measurements of cerebral blood volume (CBV) [ 25 ].…”

Correlation between volumetric oxygenation responses and electrophysiology identifies deep thalamocortical activity during epileptic seizures

“…The delayed onset of these changes in voxel 6 and the absence of fluctuations in voxels 5 and 12 (located in the confluence of sinuses and the longitudinal hippocampal vein, respectively) may suggest a link to the recently reported bidirectional flow effect in the SSS. 34 Analysis of deeper regions at anterior locations to the 4-AP injection site (traces 8 and 9) revealed no measurable changes, thus showing the final extent of the activated area in the cortex. On the other hand, similar analysis in the TA area demonstrated clear hemodynamic patterns temporally correlating with the EEG, although having generally lower magnitude as compared to the cortical activation areas (trace 10).…”