Surgical anatomy for Asian rhinoplasty: Part II

Cone-Beam Computerized Tomography Evaluation of the Relationship between Orthodontic Vertical Direction Parameters and the Distance from the Apex of the Upper Central Tooth to the Nasal Floor and Anterior Nasal Spine

The aim of this study was to examine the relationship between the vertical cephalometric values and the distance from the apex tip of the upper central tooth (U1A) to the anterior nasal spine (ANS) and nasal floor (NF) using cone-beam computerized tomography (CBCT). One hundred and twenty-two patients who applied to the Department of Orthodontics between January 2011 and June 2019 were included. The distances between the U1A and the NF and ANS were measured using CBCT. Statistical significance was considered as p < 0.05. Of the 122 individuals, 73.8% (n = 90) were female and 26.2% (n = 32) were male, with a mean age of 22.8 ± 3.3 years. A statistically significant moderate positive correlation was found between the mean NF-U1A values and the N-Me, ANS-Me, ANS-Gn, S-Go, and N-ANS measurements (p < 0.01). A statistically significant positive correlation was found between the mean ANS-U1A values and the Ar-Go-Me, total posterior angles, N-Me, SN/GoGn and Y-axis angle, ANS-Me, and ANS-Gn measurements (p < 0.01). The distance from the U1A to the ANS and NF was related to the orthodontic vertical direction parameters. The ANS-U1A and NF-U1A distances can serve as reference points for identifying the orthodontic vertical growth pattern from CBCT scans.

Nasal Osteotomies Revisited in Asians: Surface Aesthetics, Anatomical and Technical Considerations

Background  Although osteotomy is commonly performed in rhinoplasty, it is difficult for less experienced surgeon to understand mechanism of the procedure. The primary goal of this study is to improve understanding of nasal osteotomy in Asians by considering the surface aesthetics and anatomy of the nose as well as their relationships with the surgical procedure. Methods  Surface aesthetics, anatomic considerations, kinetics of medial and lateral osteotomy, fracture levels of osteotomy were discussed in detail by reviewing the previous publications and 18 years of our experience. Moreover, the technical details of osteotomy were explained and personal tips for performing successful osteotomy were described. Results  Dorsal and lateral aesthetic lines, dorsal and basal widths are main characteristics related to the surface aesthetics of nose to perform the osteotomy. In addition, these features are different in Asian population due to the anatomic difference with Caucasians, which makes the procedure difficult and requires more attention to perform osteotomy. Conclusion  Because osteotomy is one of the most traumatic and invasive part of the rhinoplasty, it is crucial for the rhinoplasty surgeon to understand the relationship between surface aesthetics and osteotomy techniques to produce consistent and reproducible results.

Usefulness of T2-Weighted Images with Deep-Learning-Based Reconstruction in Nasal Cartilage

OBJECTIVE

This study aims to evaluate the feasibility of visualizing nasal cartilage using deep-learning-based reconstruction (DLR) fast spin-echo (FSE) imaging in comparison to three-dimensional fast spoiled gradient-echo (3D FSPGR) images.

MATERIALS AND METHODS

This retrospective study included 190 set images of 38 participants, including axial T1- and T2-weighted FSE images using DLR (T1WIDL and T2WIDL, belong to FSEDL) and without using DLR (T1WIO and T2WIO, belong to FSEO) and 3D FSPGR images. Subjective evaluation (overall image quality, noise, contrast, artifacts, and identification of anatomical structures) was independently conducted by two radiologists. Objective evaluation including signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) was conducted using manual region-of-interest (ROI)-based analysis. Coefficient of variation (CV) and Bland-Altman plots were used to demonstrate the intra-rater repeatability of measurements for cartilage thickness on five different images.

RESULTS

Both qualitative and quantitative results confirmed superior FSEDL to 3D FSPGR images (both p < 0.05), improving the diagnosis confidence of the observers. Lower lateral cartilage (LLC), upper lateral cartilage (ULC), and septal cartilage (SP) were relatively well delineated on the T2WIDL, while 3D FSPGR showed poorly on the septal cartilage. For the repeatability of cartilage thickness measurements, T2WIDL showed the highest intra-observer (%CV = 8.7% for SP, 9.5% for ULC, and 9.7% for LLC) agreements. In addition, the acquisition time for T1WIDL and T2WIDL was respectively reduced by 14.2% to 29% compared to 3D FSPGR (both p < 0.05).

CONCLUSIONS

Two-dimensional equivalent-thin-slice T1- and T2-weighted images using DLR showed better image quality and shorter scan time than 3D FSPGR and conventional construction images in nasal cartilages. The anatomical details were preserved without losing clinical performance on diagnosis and prognosis, especially for pre-rhinoplasty planning.

Efficacy and safety of equine cartilage for rhinoplasty: a multicenter double-blind non-inferiority randomized confirmatory clinical trial

Background

The efficacy and safety of equine cartilage as a competent xenograft material for rhinoplasty were evaluated and compared to the outcomes of rhinoplasty using silicone implants.

Methods

We performed a multicenter, double-blind, non-inferiority, and randomized confirmatory study. Fifty-six patients were randomized 1:1 to the study group (using MegaCartilage-E) and control group (using silicone implants). The Rhinoplasty Outcome Evaluation (ROE) score, photo documentation, Global Aesthetic Improvement Scale (GAIS), and adverse event data were obtained until 12 months after surgery. The primary efficacy, which is the change in ROE score 6 months after surgery, was assessed in the modified intention-to-treat set. The secondary efficacy was evaluated in the per-protocol set by assessing the change in ROE score 6 and 12 months after surgery and nasofrontal angle, the height of the nasion, and GAIS 1, 6, and 12 months after surgery.

Results

The change in ROE score of the study group was non-inferior to that of the control group; it increased by 24.26±17.24 in the study group and 18.27±17.60 in the control group (p=0.213). In both groups, all secondary outcome measures increased, but there was no statistical difference. In the safety set, treatment-emergent adverse events occurred in 10 patients (35.71%) in the study group and six patients (21.43%) in the control group (p=0.237). There were 13 adverse device events in the study group and six adverse device events in the control group (p=0.515).

Conclusion

Processed equine cartilage can be used effectively and safely as xenograft material for rhinoplasty.

Vasculature of the Nasal Cartilage Region Related to Filler Injection

BACKGROUND

A filler injection in the nose can be essential but is also dangerous, especially in the nasal cartilage region. To safely and accurately perform a filler injection, surgeons must have detailed knowledge of nasal anatomy.

OBJECTIVES

Associated the vessel branches and the characteristics of different nasal regions to provide suggestions for more suitable injection sites.

METHODS

Fifty specimens underwent computed tomography (CT) after contrast infusion. Qualified specimens were selected for 3D CT reconstruction. Dissection was performed to confirm the accuracy of the CT data.

RESULTS

The branches of arteries with large diameters, the dorsal nasal artery (DNA) and the lateral nasal artery (LNA) were distributed within the superficial musculoaponeurotic system layer. The DNA was seen in only 58% of specimens. The artery crossed the midline over the upper lateral cartilage in 16% of specimens. The LNA was a constant branch that traversed the nasal tip. The LNA crossed the midline to the contralateral side in 18% of patients. We divided the nasal cartilage dorsum into two regions for easy handling: the supratip region (STR) and the nasal tip region (NTR). The branches distributed in the STR mostly originated from the DNA (81.6%, 40/49), while those in the NTR mostly originated from the LNA.

CONCLUSIONS

The vasculature of the nasal cartilage region observed in this study is similar to that observed in previous studies. However, we found that the STR was an advantageous area for filler injection. At the same time, we provided suggestions for more suitable injection methods.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Shape Prediction of Nasal Bones by Digital 2D-Photogrammetry of the Nose Based on Convolution and Back-Propagation Neural Network

In rhinoplasty, it is necessary to consider the correlation between the anthropometric indicators of the nasal bone, so that it prevents surgical complications and enhances the patient's satisfaction. The penetrating form of high-energy electromagnetic radiation is highly impacted on human health, which has often raised concerns of alternative method for facial analysis. The critical stage to assess nasal morphology is the nasal analysis on its anthropology that is highly reliant on the understanding of the structural features of the nasal radix. For example, the shape and size of nasal bone features, skin thickness, and also body factors aggregated from different facial anthropology values. In medical diagnosis, however, the morphology of the nasal bone is determined manually and significantly relies on the clinician's expertise. Furthermore, the evaluation anthropological keypoint of the nasal bone is nonrepeatable and laborious, also finding widely differ and intralaboratory variability in the results because of facial soft tissue and equipment defects. In order to overcome these problems, we propose specialized convolutional neural network (CNN) architecture to accurately predict nasal measurement based on digital 2D photogrammetry. To boost performance and efficacy, it is deliberately constructed with many layers and different filter sizes, with less filters and optimizing parameters. Through its result, the back-propagation neural network (BPNN) indicated the correlation between differences in human body factors mentioned are height, weight known as body mass index (BMI), age, gender, and the nasal bone dimension of the participant. With full of parameters could the nasal morphology be diagnostic continuously. The model's performance is evaluated on various newest architecture models such as DenseNet, ConvNet, Inception, VGG, and MobileNet. Experiments were directly conducted on different facials. The results show the proposed architecture worked well in terms of nasal properties achieved which utilize four statistical criteria named mean average precision (mAP), mean absolute error (MAE), R-square (R²), and T-test analyzed. Data has also shown that the nasal shape of Southeast Asians, especially Vietnamese, could be divided into different types in two perspective views. From cadavers for bony datasets, nasal bones can be classified into 2 morphological types in the lateral view which “V” shape was presented by 78.8% and the remains were “S” shape evaluated based on Lazovic (2015). With 2 angular dimension averages are 136.41 ± 7.99 and 104.25 ± 5.95 represented by the nasofrontal angle (g-n-prn) and the nasomental angle (n-prn-sn), respectively. For frontal view, classified by Hwang, Tae-Sun, et al. (2005), nasal morphology of Vietnamese participants could be divided into three types: type A was present in 57.6% and type B was present in 30.3% of the noses. In particular, types C, D, and E were not a common form of Vietnamese which includes the remaining number of participants. In conclusion, the proposed model performed the potential hybrid of CNN and BPNN with its application to give expected accuracy in terms of keypoint localization and nasal morphology regression. Nasal analysis can replace MRI imaging diagnostics that are reflected by the risk to human body.

A practical approach to nasal reconstruction in Asian patients

Background

The study aimed to evaluate nasal reconstruction techniques customized for Asians. The currently available nasal reconstruction guidelines are based on Caucasian patients, and their applicability is limited in Asian patients due to differences in anatomical and structural features.

Methods

A retrospective analysis was performed of the medical records of 76 patients who underwent nasal reconstruction at a single center between January 2010 and June 2020. A comprehensive evaluation was conducted of patients’ baseline demographics and clinical characteristics, including age, sex, medical history, defect size and location, reconstructive procedure, pathological diagnosis, postoperative complications, and recurrence.

Results

In 59 cases (77%), nasal defects resulted from tumor ablation, and the remaining 17 cases involved post-traumatic (20%) and infection-induced (3%) tissue damage. The most common defect location was the alae, followed by the sidewalls, tip, and dorsum. Forehead flaps were the most commonly used reconstructive technique, followed by nasolabial advancement flaps, rotation flaps, and skin grafts. Each procedure was applied considering aspects of structural anatomy and healing physiology specific to Asians. Complications included nasal deformity, hypertrophic scarring, secondary infection, and partial flap necrosis, but no cases required additional surgical procedures. Tumors recurred in two cases, but tumor recurrence did not significantly affect flap integrity.

Conclusion

Nasal reconstruction techniques applied considering Asians’ facial features resulted in fewer postoperative complications and higher patient satisfaction than the approaches that are currently in widespread use. Therefore, this study is expected to serve as an essential reference for establishing treatment guidelines for nasal reconstruction in Asians.

Deviated nose: Physiological and pathological changes of the nasal cavity

Deviated nose is highly challenging in rhinoplasty since the surgeon should consider both aesthetic and functional aspects of the nose. Deviated nose correction is surgically complex, and a thorough understanding of the mechanical and physiological changes of intranasal structures, including the septum and turbinates, is necessary for functional improvement.