Visualization techniques of the facial arteries

The effect of arterial spin labeling MR angiography (ASL-MRA) in visualizing the branches of external carotid artery

This study aimed to assess the performance of arterial-spin labeling MRA (ASL-MRA) for visualizing the external carotid artery (ECA) branches in comparison with time-of-flight MRA (TOF-MRA) and CT angiography (CTA). We retrospectively selected 31 consecutive patients, who underwent both MRAs and CTA, prior to the intra-arterial chemoradiotherapy (IACRT) for head and neck cancer. Four patients underwent IACRT bilaterally, so we analyzed 35 ECAs. Pseudo-continuous, three-dimensional ASL using a turbo field echo sequence was acquired. For the TOF-MRA and CTA, clinically used parameters were applied. Two observers evaluated each ECA branch with reference to the angiogram at the IACRT, using five-point scale, in consensus. Friedman test for multiple comparisons was applied. ASL-MRA and CTA better visualized the superior thyroid, lingual, facial, submental, transverse facial, and internal maxillary arteries (IMAs) better than TOF-MRA (p < 0.05). In addition, CTA was superior to ASL-MRA in visualizing only submental artery among these arteries (p = 0.0005). Alternatively, the ASL-MRA was superior for visualizing the middle meningeal artery (MMA) and IMA, compared to the CTA (p = 0.0001 and 0.0007, respectively). ASL-MRA was superior to the TOF-MRA and similar to the CTA in visualizing most of ECA branches. Furthermore, ASL-MRA can better visualize the periphery of MMA and IMA than CTA.

Role of Robotics in Neuromodulator and Filler Injections of Face

In recent years, robots have been increasingly used in various fields of medicine, including surgery, dentistry, and ophthalmology. One of the newest and most promising applications of robotic technology in medicine is in the field of facial aesthetics, particularly in the injection of facial fillers and neuromodulators. While facial injections have traditionally been performed manually by trained physicians and nurses, the introduction of robots has the potential to revolutionize the field, offering a range of potential benefits, including increased precision, accuracy, and consistency of results. However, the significant disadvantages of robots are high cost, lack of flexibility and personal touch, limited experience, and risk of injury due to malfunction.

Visualising the individual arterial anatomy of the face through augmented reality - a useful and accurate tool during dermal filler injections

Background

The arterial anatomy of the face is extremely variable. Despite numerous cadaver dissections and anatomical descriptions, the exact location of the superficial facial arteries remains unpredictable. This ignorance is a determining factor in the pathophysiology of intravascular filler injections, potentially causing skin necrosis and blindness.

Objectives

The main objective of this study is to evaluate the accuracy of an augmented reality (AR) application that visualizes the individual arterial anatomy of the face.

Methods

A workflow was developed during which a magnetic resonance angiography (MRA) mapped the superficial arteries of the face. The images were further processed into an AR image that was visualized on the patient’s face using a specifically designed smartphone application. The accuracy of the AR image and the position of each individual artery were analyzed using duplex ultrasound (US).

Results

A total of 216 facial arteries were visualized in 20 patients. The superficial temporal (100%), supratrochlear (92.5%), facial (75%), and angular (82.5%) arteries were visualized the most. The inferior labial (17.5%), dorsal nasal (22.5%), and supraorbital (42.5%) arteries were the most difficult to visualize through MRA. The average deviation between the artery visible on the AR image and the location assessed by US was 0.30 mm (standard deviation = +/− 0.66 mm). There were no complications reported.

Conclusions

The combination of a risk-free MRA to map the individual arteries of the face and the processing into an AR image may be considered as a useful and accurate tool during dermal filler injections to potentially minimize the risk of intravascular filler injections.

The Usefulness of Magnetic Resonance Angiography to Analyze the Variable Arterial Facial Anatomy in an Effort to Reduce Filler-Associated Blindness: Anatomical Study and Visualization Through an Augmented Reality Application

BACKGROUND

The use of soft tissue fillers for facial rejuvenation is increasing rapidly and the complications, unfortunately, follow the same path. Blindness caused by intravascular filler injections is a rare but devastating complication. Knowledge of the individual arterial anatomy may aid the injector in avoiding injecting into an artery and thus to prevent blindness.

OBJECTIVES

To evaluate if the use of magnetic resonance angiography (MRA) may visualize the arterial facial anatomy in a contrast- and radiation-free way and study the individual arterial variations using an augmented reality (AR) image.

METHODS

The individual arterial anatomy of the 3 terminal branches of the ophthalmic artery (supraorbital [SO]; supratrochlear [STr]; and dorsal nasal [DN] arteries) of 20 volunteers was studied by a 3-Tesla MRI, combining infrared (IR) facial warming and 3-dimensional time-of-flight multiple overlapping thin slab acquisition MRA. The resulting visualization of the facial arteries was shown on the patient's face through AR technology.

RESULTS

The MRA was able to visualize the SO in 90.0%, STr in 92.5%, and DN arteries in 75% of the examined patients, as well as numerous variations in both vessel localization and path. Furthermore, a proof-of-concept of the AR visualization of the individual arterial anatomy was successfully implemented.

CONCLUSIONS

Dermal filler injectors should be aware of the risk of filler-induced blindness and familiarize themselves with the visualization of the variable facial vascular anatomy. The implementation of a one-time MRA and subsequent AR visualization may be useful in the accurate planning of minimally invasive facial rejuvenation procedures.

Visualization techniques of the facial arteries

BACKGROUND

As the face is known for its extreme variation in vascular anatomy and the number of filler-associated complications due to intra-arterial injection is increasing, we are in need of a method to visualize anyone's individual arterial anatomy of the face in a completely harmless way.

AIMS

The different medical imaging methods and a recently developed MRA protocol are reviewed.

METHODS

The literature of the last twenty years-with special attention for the last five years-concerning the different medical imaging modalities of the facial arteries was reviewed.

RESULTS

A harmless visualisation of the facial arteries is currently only possible with US or MRA. US may identify single vessels but never the complete arterial network. A combination of IR "heat enhancement" and a MRA 3D-TOF sequence might make it feasible to visualize a large number of facial arteries in a risk-free, radiation-free, contrast-free and non-invasive way.

CONCLUSION

Currently, a new combination of IR "heat enhancement" and a MRA 3D-TOF sequence might be the only method to visualize a large number of facial arteries.

Facial vascular danger zones for filler injections

Filler injections are widely used for facial rejuvenation. The technique is safe as long as some precautions are respected. In this review we will focus on vascular anatomy in the upper, middle and lower face. We performed a PUBMED research on "facial danger zones" and "filler injections" and "hyaluronic acid" and "vascular compromise" with a focus on the last decade. This is of particular importance since vascular compromise is one of the most severe adverse events possibly leading to tissue necrosis and in rare cases to loss of vision. We describe the danger zones in these esthetic units and provide recommendations how to avoid severe adverse events. We report on temporal region, glabella and nose, infraorbital region, nasolabial folds and nasal triangle, lips, and chin. Although we focus on hyaluronic acid fillers, our recommendations will also scope other filler types and autologous adipose tissue transfer. We also take a closer look on innovations to improve the safety of facial filler injections. Facial rejuvenation with hyaluronic acid fillers is a popular method. It is safe if the facial danger zones are recognized and proper injection techniques and fillers are used.