Ultrasound assessment of the nose vasculature: A review of the common method of non‐surgical filler‐based rhinoplasty

With the increasing use of dermal injectable fillers in aesthetic medicine, the popularity of non‐surgical filler‐based rhinoplasty (NSR) is also growing. While performing this procedure might result in certain vascular complications, injecting deep into the midline of the nose is commonly considered the safest method for blind primary NSR.

imaging machines that are more affordable than other portable systems and can be easily carried out in physicians' pockets. 1,2The diagnostic accuracy of this group may be a concern for practitioners.
[3] Using ultrasound in clinical dermatology dates back more than four decades, but the application of ultrasound as an imaging tool in the field of aesthetic medicine does not have a long history. 4trasound devices with the frequency range of 12-20 MHz and Doppler properties enable us to differentiate anatomic layers of the face, observe its vascular pattern, and are useful for facial aesthetic purposes. 4[6] Although it has been recommended to integrate ultrasound imaging in all stages of an aesthetic practice from primary assessment and treatment planning to the management of probable complications, [4][5][6][7][8] many aesthetic practitioners still do not believe in the use of ultrasound in their routine work and keep this technology for the management of severe complications that they may face at some point.The evolution of aesthetic medicine practice is accompanied by an increasing number of complications. 4,8[16][17] In this article, based on an ultrasound study of the nasal vascular anatomy of a group of people, we declare the importance of considering personal anatomic variations during NSR, bring the commonly conducted technique of NSR into question, and provide convincing evidence for the use of ultrasound-assisted tailored aesthetic treatment of the nose to minimize complications.We believe that this study can influence the attitudes of aesthetic practitioners toward using ultrasound in their daily practice.

| MATERIAL S AND ME THODS
14]16 The arterial supply of these regions is mainly with dorsal nasal (radix, upper, and mid-dorsum), lateral nasal, and columellar (caudal dorsum, tip, and columella) arteries. 13,14[15][16][17][18] To challenge the recommended layer of injection in primary NSR (deep at midline), we studied the vascular pattern of the nose of a group of our aesthetic clinic clients using a linear portable 14 MHz handheld ultrasound transducer with Doppler properties (Silarious L14PS HD Portable Doppler Ultrasound Scanner).All study population were Iranian women selected by convenience sampling from January to March 2023.They had never undergone any surgical or non-surgical procedures in their nose and presented at our clinic for other aesthetic concerns.Written informed consent was obtained from all participants for taking part in this study and the publication of the results.During ultrasound evaluation, we focused on the midline of the nasal radix and tip, the most common points of injection during primary NSR.The laterality and depth of the vessels in the midline of the mentioned regions were evaluated.
To be more practical, the position of the studied vessels in terms of their laterality and depth were not reported as measurements and exact numbers.Instead, we developed a classification to easily describe their anatomic position by considering safety margins in millimeters (mm).If a vessel was exactly located in the midline or up to 1 mm lateral to the midline (whether right or left), it was reported as a "midline vessel."This laterality classification was used for the vessels of both the radix and nasal tip.Regarding the depth, radix vessels were classified based on their position toward the nasalis muscle as "superficial" (within or above the muscle) or "deep" (under the muscle which is in fact supraperiosteal).To describe the depth of nasal tip vessels, their position toward the perichondrium was assessed.Vessels located exactly on the perichondrium or within 2 mm distance from it were reported as "deep "and those with more than 2 mm distance from perichondrium were classified as "superficial".
The internally installed scale in the device was used for calculating distances in millimeters.
All cases were examined by an aesthetic physician who has a decade of experience in filler-based non-surgical primary and secondary rhinoplasty and 2-year experience in conducting ultrasound-assisted aesthetic procedures.Radix was studied in two views (Figure 1A,a,B,b) and tip was evaluated in one view (Figure 1C,c).
Radix in this study is defined as the deepest point of the nose in profile view.
During the ultrasound study of the above-mentioned regions, several vessels were observed, but just the nearest vessel to the midline was evaluated and reported, which could have been a branch of the aforementioned main arteries.The participants who had at least one deep vessel at midline were classified as "high risk" for blind NSR.
The rationale for setting the safety margins in this study is that we tried to take into account the inevitable uncertainties in the precise placement of the filler at the desired point during the

| RE SULTS
Twenty-one Iranian women with a mean (SD) age of 37.7 (7.2) years, ranging from 23 to 54, were enrolled in this study.By using ultrasound mapping of nasal vessels in our two target regions and based on our definitions in this study, the following findings were obtained: In the radix, 8 out of 21 cases (38%), had at least one vessel at the midline, and all these vessels were superficial.Thus, all supraperiosteal injections (deep to nasalis muscle) in the radix seem safe among our study population.In the nose tip of 18 cases (86%), at least one vessel was located at the midline, and nine (50%) of them were deep.Therefore, in nine (43%) cases of our study population, routine supraperichondrial injection at the midline of the nose tip was accompanied by a considerable likelihood of vascular events.Figures 2 and 3 show sagittal and horizontal Doppler ultrasonographic studies of the radix of two cases with superficial arteries in the midline.Figure 4 shows an axial Doppler ultrasound view of the nose tip of one studied case with a deep artery in the midline who is considered "high risk" for commonly recommended injection method in this region.

| DISCUSS ION
NSR is an alternative to surgical rhinoplasty in some patients, and if done appropriately on the right candidates, it can lead to nasal cosmetic and even functional improvements. 11,13,15,17,19,20HA fillers are the most commonly used injectables for NSR procedure. 9,13,15,17,19,206][17][18][19][20] Injecting in the midline avoids asymmetries as well. 14spite the widespread assumption of the relative avascularity and safety of filler injection in the deep supraperichondrial plane at the midline of the nose tip, in nearly half of our cases, placement of filler in the mentioned region was associated with the risk of vascular compromise and consequent catastrophic events.
The nose has an extensive network of blood vessels.
Consequently, the prospect of vessel injury is notably substantial during any injection in this area, given the dense vascularity.
aesthetic practice.Even under direct observation, several factors, including the injector's visual uncertainties, her/his position and maneuvers during conducting the procedure, the patient's position and movements, and the device of injection, can contribute to the deviations from the target points.Blind deep injections, in areas where direct observation of the target site is not possible, introduce F I G U R E 1 Assessment of the nose by 14 MHz handheld ultrasound, Doppler mode; (A, a) sagittal view of the radix; (B, b) horizontal view of the radix; (C, c) axial view of the tip.In sagittal ultrasound imaging (A), the mid-point of the footprint was located at the line perpendicular to the radix.In horizontal (B) and axial (C) ultrasound imaging, the midpoint of the footprint was located at the midline of target regions without paying attention to septal deviation.During all ultrasound imagings, the transducer was in non-contact mode, the patient was in a semi-sitting position, and her head was along the body.F I G U R E 2 Assessment of the nose by 14 MHz handheld ultrasound, Doppler mode; (A): sagittal view of the radix; (B): horizontal view of the radix.additional challenges for precise filler placement.The subjective nature of using the injector's perception to reach the periosteum, perichondrium, or muscle during NSR (especially in the absence of ultrasound guidance) can introduce variability in the injection's accuracy.The bevel's length is also a matter of consideration that may interfere with the accurate placement of filler during deep injection.
Moreover, the existence of vascular anatomical deviations within the nasal structure, as corroborated by our study findings, underscores that the suggested zones for performing NSR are not always safe.In this context, a pertinent question arises: given these considerations, what accounts for the persistently modest incidence of vascular events reported during NSR, with the majority being of a mild nature?Based on the available scientific literature so far, we can attribute the low rate of reported critical vascular events to the presence of collateral vessels in the area, cautionary injection techniques (entry points, aspirations, pressure, F I G U R E 3 Assessment of the nose by 14 MHz handheld ultrasound, Doppler mode; (A): sagittal view of the radix; (B): horizontal view of the radix.