Imaging of midfacial and orbital trauma

The midface’s central location, nasal projection anteriorly, and zygomas laterally make it commonly involved in trauma. The midface has singular bony elements including the vomer, ethmoid, sphenoid, mandible and paired bony maxilla, inferior nasal concha, palatine, nasal, lacrimal, and zygomatic bones. The bones form the facial skeleton with four transverse and four paired vertical buttresses. Fractures of the midfacial bones usually involve the nasal bones, followed by zygomatic complex fractures, and often occur from blunt trauma secondary to falls, altercations, or motor vehicle collisions and less commonly in penetrating trauma from gunshots or foreign bodies. Computed tomography (CT) is the imaging modality of choice to delineate fractures and can be used for orbital volumetric measurements and preoperative planning. MRI can be used to supplement CT in assessing intracranial and optic nerve involvement. Although utilized for over a century, the Le Fort classification of midfacial trauma is anachronistic and less relevant for high-speed trauma and does not include orbital and zygomaticofacial complex involvement; therefore, more recent classification schemes may be more relevant for surgical planning. This chapter reviews midface and orbit anatomy, key radiographic features from trauma including the importance of multi-planar imaging, and awareness of critical adjacent structures including the nasolacrimal ducts, orbital musculature, and sinonasal passageways that may be become displaced or obstructed. Importantly, this chapter highlights relevant fracture patterns in midfacial subunits including the nose, naso-orbito-ethmoidal region (NOE), orbital complex, and zygomaticomaxillary complex (ZMC). For each subunit, there is a brief review of relevant epidemiology, clinical features, and critical anatomy affected, highlighting radiographic findings that should be assessed, with a summary of key points, to facilitate optimal treatment

Semi-automated segmentation and quantification of perivascular spaces at 7 Tesla in COVID-19

While COVID-19 is primarily considered a respiratory disease, it has been shown to affect the central nervous system. Mounting evidence shows that COVID-19 is associated with neurological complications as well as effects thought to be related to neuroinflammatory processes. Due to the novelty of COVID-19, there is a need to better understand the possible long-term effects it may have on patients, particularly linkage to neuroinflammatory processes. Perivascular spaces (PVS) are small fluid-filled spaces in the brain that appear on MRI scans near blood vessels and are believed to play a role in modulation of the immune response, leukocyte trafficking, and glymphatic drainage. Some studies have suggested that increased number or presence of PVS could be considered a marker of increased blood-brain barrier permeability or dysfunction and may be involved in or precede cascades leading to neuroinflammatory processes. Due to their size, PVS are better detected on MRI at ultrahigh magnetic field strengths such as 7 Tesla, with improved sensitivity and resolution to quantify both concentration and size. As such, the objective of this prospective study was to leverage a semi-automated detection tool to identify and quantify differences in perivascular spaces between a group of 10 COVID-19 patients and a similar subset of controls to determine whether PVS might be biomarkers of COVID-19-mediated neuroinflammation. Results demonstrate a detectable difference in neuroinflammatory measures in the patient group compared to controls. PVS count and white matter volume were significantly different in the patient group compared to controls, yet there was no significant association between PVS count and symptom measures. Our findings suggest that the PVS count may be a viable marker for neuroinflammation in COVID-19, and other diseases which may be linked to neuroinflammatory processes