The role of three-dimensional CT in the evaluation of nasal structures and anomalies

Imaging Nasal Obstruction: An Objective Evaluation for a Subjective Complaint

Nasal obstruction (NO) is a common clinical symptom characterized by a subjective sensation of insufficient airflow through the nasal cavity and may result from various factors, including changes in nasal anatomy, inflammatory conditions, tumoral lesions, and other etiologies. While a thorough medical history and physical examination can often identify its cause, imaging is usually necessary to fully understand the problem. Computed tomography (CT) is the primary imaging modality used to evaluate the nasal cavity and paranasal sinuses, allowing for the identification of potential causes and structural abnormalities. However, when soft tissue characterization is required, magnetic resonance imaging (MRI) is also useful. Understanding the anatomical and pathological basis of NO is crucial for accurate diagnosis and appropriate management. Imaging techniques provide valuable information for identifying the underlying causes of NO and guiding treatment decisions. This article reviews the normal anatomy of the nasal cavity and adjacent paranasal sinuses as well as the several conditions that may affect breathing comfort (tumors, inflammatory diseases, bony and cartilaginous anatomical variants, and "nonobstructive" mucosal thickenings), showing their normal presentation on CT and MRI.

Evaluation of diagnostic accuracy of cone beam computed tomography and multi-detector computed tomography for detection of anatomical variations in rhinoplasty

BACKGROUND

Different imaging techniques, such as multi-detector computed tomography (MDCT) scan and cone beam computed tomography(CBCT), are used to check the structure of the nose before rhinoplasty. This study aimed to evaluate the accuracy of two imaging techniques, MDCT scan, and CBCT, in diagnosing structural Variations in rhinoplasty for the first time.

METHODS

This diagnostic accuracy study was conducted on 64 rhinoplasty candidates who complained of snoring and sleep apnea or had a positive result in the examination with Cottle's maneuver or modified Cottle technique between February 2021 and October 2022 at 15- Khordad Hospital affiliated to Beheshti University of Medical Sciences. Before rhinoplasty, patients were randomly assigned to one of the CT and CBCT techniques with an equal ratio. Scans were assessed for the presence of Nasal septum deviation (NSD), Mucocele, Concha bullosa, and nasal septal spur by two independent radiologists. The findings of the two methods were evaluated with the results during rhinoplasty as the gold standard.

RESULTS

NSD was the most common anatomical variation based on both imaging techniques. The accuracy of CBCT for diagnosing Nasal Septum Deviation and Mucocele was 80% and 75%, respectively. The sensitivity, specificity, and accuracy of CBCT in detecting Concha bullosa were 81.3% and 83.3%, respectively. The Kappa coefficient between CBCT and intraoperative findings for diagnosing NSD and Concha Bullosa was 0.76 and 0.73, respectively (p < 0.05).

CONCLUSION

CBCT can be considered a suitable method with high accuracy and quality to evaluate the anatomical variations before rhinoplasty.

The Need for Innovation in Rhinoplasty

Rhinoplasty is a challenging surgery and results are not always perfect. There are many obstacles to achieving optimal results. Among these are inadequate instrumentation, the unpredictability of healing, imprecise planning, and many more. Furthermore, selecting patients who can most benefit from surgery is equally important. In this article, some of the more pressing areas of rhinoplasty that need innovation are discussed. From proper patient selection, to advances in education, to the standardization of training programs, to the development of sophisticated implants, the future of rhinoplasty surgery lies in continued creativity and innovation.

Septoplasti ve Septorinoplasti Hastalarında Etmoid Çatı Derinliğinin ve Sinonazal Anatomik Varyasyonların Retrospektif Radyolojik Analizi

Aim: Computed tomography (CT) provides an accurate assessment of sinonasal anatomy and osseocartilaginous pathologies in patients complaining of sinonasal symptoms. Although it is not a routine practice, CT is frequently used in preoperative screening of patients planned for septoplasty and septorhinoplasty. In this study, anatomical variations and ethmoid lateral lamella depths in preoperative CT images of septoplasty and septorhinoplasty operations performed in our clinic were analyzed retrospectively and discussed with current literature. Material and Method: Septorhinoplasty and septoplasty surgeries performed in our clinic between January 2014 and August 2018 over the age of 18 years were reviewed retrospectively. Two hundred patients were included in the study. CT images were evaluated for anatomical variations and ethmoid lateral lamella depths. Results: Of the 200 patients included in the study, 158 (79%) underwent septoplasty and 42 (21%) underwent septorhinoplasty. Concha bullosa was detected in 95 (47,5%) of the patients and was determined as the most common anatomical variation. Onodi cell variation was detected in 62 (31%) of the patients. Haller cell was detected in 37 patients (18,5%). Paradoxical middle turbinate was detected in 19 patients (9,5%), pneumatized anterior clinoid process in 17 patients (8,5%), and pneumatized crista galli in 4 patients (2%). In lateral lamella measurements; the median value of the lateral lamella depth on the right was 4,20 mm (0,40-7,40 mm) and the median value of the lateral lamella depth on the left was 4,20 mm (1,70-7,30 mm). Conclusion: Anatomical variations that can be detected in CT imaging before septoplasty and septorhinoplasty operations and information about ethmoid roof anatomy will be useful in case management, surgical planning and complication management.

Endoscopic Removal of a Nasopharyngeal Foreign Body Stuck Within the Sphenoid Bone Using the Endonasal Transseptal Approach

ABSTRACT

Nasopharyngeal foreign bodies (FBs), which are generally caused by a strong, external force, are seldomly encountered. Removing these FBs is challenging for otorhinolaryngological surgeons because of the vital structures surrounding the nasopharynx, such as the skull base, cranial nerves, and internal carotid artery. Here, the authors report the case of a 69-year-old man referred to our hospital after accidentally cutting his face while using a grinder. Grinder fragments were deeply embedded in the face, thus becoming nasopharyngeal FBs. The authors evaluated three-dimensional volume rendering images and immediately removed these FBs using an endoscopic endonasal transseptal approach under general anesthesia. The postoperative course was uneventful. Using the endoscopic endonasal transseptal approach after evaluating preoperative three-dimensional volume rendering images may help eliminate nasopharyngeal FBs safely.

Preservation Rhinoplasty: Assessment of Anatomical Safe Boundaries on Computed Tomography

BACKGROUND

Nasal dorsum reconstruction is a crucial step of the rhinoplasty. For avoiding complications, techniques that preserve natural dorsal anatomy becomes popular recently. In preservation techniques, ethmoidal bone surgery may take part in the vast majority of defined techniques. Therefore, detailed anatomical knowledge is essential to avoid severe complications, especially cerebrospinal fluid leakage. Based on these, this study aimed to investigate anatomical safe boundaries of preservation techniques based on the measurements on computed tomography.

METHODS

A total of 100 patients who underwent paranasal computed tomography were enrolled in this retrospective study. Five groups were selected based on the age distribution. The distance of the dorsal osteotomy line to cranial base, amount of cartilaginous/bony septum overlaps under nasal bones, cartilaginous/bony septum length anterior and posterior to the nasal hump starting point, and anteroposterior distance of perpendicular plate was measured.

RESULTS

The mean distance between the starting point of the nasal hump and the cribriform plate was 29.5 mm. The amount of bony overlap above the cartilaginous septum was 10.9 mm in females and 10.5 mm in males. The length of septal cartilage posterior to nasal hump was 0 mm in 39 of 100 patients (39%) and the mean value was 2.38 mm in all populations. The mean distance from the starting point of the perpendicular plate to the cribriform plate was 28.17 mm.

CONCLUSIONS

Perpendicular plate may take part in the constitution of the nasal hump. Therefore, delicate surgery with appropriate tools needed for avoiding the risk of skull base injury.

LEVEL OF EVIDENCE

Level of Evidence: 3 (Therapeutic).

The Deviated Nasal Tip: A Personal Technique for Correction Using Monolateral Crural Overlay and Monolateral Dome Truncation

This study aimed to present a novel approach to correct nasal tip deviation with monolateral crural overlay or monolateral dome truncation, presenting as an isolated deformity or in complex nose deviations. Nasal tip deviation can be congenital or posttraumatic, due to a dislocated septum or cartilaginous septal or lower lateral cartilage malformations. Although some treatment strategies have been introduced, appropriate treatment remains a challenge because of the complexity and variability of such deformities. It had been assumed that in most nasal tip deviations, a lower lateral cartilage was longer than the contralateral one. The authors analyzed 158 patients from January 2015 to October 2019 with nasal tip deviation and corrected the deviated tip by using a monolateral interruptive technique (lateral crural overlay or monolateral dome truncation) on the lower lateral cartilage. Photographic comparison between preoperative and at least 1-year follow-up for nasal axis deviation variable was analyzed and a self-assessment questionnaire was administrated to the patients at 1-year follow-up. The mean nasal deviation was 6.59° (±3.1°) preoperatively and 1.56° (±0.26°) postoperatively (p < 0.05). The range of differences between pre and postoperative deviations was 2.7° to 15.1°, and the mean difference was 6.1° (±3.21°). Of the 84 patients, 47 (55.95%) were very satisfied, 33 (39.28%) were satisfied, and 4 (4.76%) were unsatisfied with surgical the results and required revision surgery. In authors' hands, monolateral interruptive techniques (lateral crural overlay or monolateral dome truncation) are a viable and feasible option to restore nasal tip symmetry. These techniques achieved high satisfaction rates among patients and resulted in reliable and reproducible symmetry immediately visible after surgery and stable over time (1-year postsurgery controls).

Assessing the Clinical Value of Performing CT Scan before Rhinoplasty Surgery

Introduction

The endonasal mucosal or anatomic pathologies could lead to poor functional results and dissatisfaction after rhinoplasty. Although computed tomography (CT) scan has become an integral part of the diagnostic paradigm for patients with pathologies of the paranasal sinuses, the use of CT scan for preoperative evaluation of patients seeking rhinoplasty is up for debate. Our aim in this study was to compare the efficacy of CT scan in diagnosing nasal pathologies with other evaluating tools in patients undergoing rhinoplasty.

Design

In this randomized controlled trial study, 74 consecutive patients seeking cosmetic rhinoplasty referred to otorhinolaryngology clinic were randomly assigned into three groups based on the perioperative evaluation method: the CT group, the nasal endoscopy group, and the control group (anterior rhinoscopy only). Surgical planning was made according to perioperative findings, and the identified endonasal pathologies were corrected during the surgery. The functional and aesthetic outcomes of the rhinoplasty were assessed by Nasal Obstruction Symptom Evaluation (NOSE), Rhinoplasty Outcome Evaluation (ROE), and the Visual Analogue Scale (VAS) tools before surgery and at 12-month follow-up.

Results

All outcome measures improved significantly in either group toward one year after rhinoplasty (all with p value <0.05). Subjects in the CT group demonstrated greater improvement in the NOSE, VAS, and ROE compared to other two groups (NOSE: p value = 0.17; VAS: p value = 0.024; ROE: p value = 0.042).

Conclusions

According to our study, perioperative CT is associated with greater patients' satisfaction and quality of life after rhinoplasty compared to either nasal endoscopy or anterior rhinoscopy. A preoperative CT scan may improve the outcomes of rhinoplasty.

Computational technology for nasal cartilage-related clinical research and application

Surgeons need to understand the effects of the nasal cartilage on facial morphology, the function of both soft tissues and hard tissues and nasal function when performing nasal surgery. In nasal cartilage-related surgery, the main goals for clinical research should include clarification of surgical goals, rationalization of surgical methods, precision and personalization of surgical design and preparation and improved convenience of doctor-patient communication. Computational technology has become an effective way to achieve these goals. Advances in three-dimensional (3D) imaging technology will promote nasal cartilage-related applications, including research on computational modelling technology, computational simulation technology, virtual surgery planning and 3D printing technology. These technologies are destined to revolutionize nasal surgery further. In this review, we summarize the advantages, latest findings and application progress of various computational technologies used in clinical nasal cartilage-related work and research. The application prospects of each technique are also discussed.

Comparison of Micro-Computed Tomography and Clinical Computed Tomography Protocols for Visualization of Nasal Cartilage Before Surgical Planning for Rhinoplasty

Importance

There is no imaging standard to model nasal cartilage for the planning of rhinoplasty procedures. Preoperative visualization of cartilage may improve objective evaluation of nasal deformities, surgical planning, and surgical reconstruction.

Objectives

To evaluate the feasibility of visualizing nasal cartilage using high resolution micro-computed tomography (CT) compared with the criterion standard of pathologic findings in a cadaveric specimen and to evaluate its accuracy compared with various clinical CT protocols.

Design, Setting, and Participants

Anatomic study at the University of Washington using single human cadaveric nasal specimens performed from July 10, 2017, to March 30, 2018.

Interventions

A micro-CT acquisition with 60-micron resolution was obtained of a nasal specimen. The specimen was then scanned with 5 different clinical CT protocols to span both clinical care and machine limits. The specimen was then sectioned in 5-mm axial slices for pathologic analysis.

Main Outcomes and Measures

Micro-CT images were registered to pathologic specimen cross-sections using a graphite fiducial system. Cartilage substructures were manually segmented and analyzed. A library of matched images across the micro-CT and various clinical CT protocols was then developed. Region of interest analysis was performed for each of the cartilage structures and their boundaries on clinical CT protocols and micro-CT, with the outcome of mean (SD) density using Hounsfield units.

Results

A single human cadaveric nasal specimen was used to obtain the following results. Lower lateral cartilage, upper lateral cartilage, and septal cartilage were accurately delineated on the micro-CT images compared with pathologic findings. The mean absolute deviation from pathologic findings was 0.30 mm for septal cartilage thickness, 0.98 mm for maximal upper lateral cartilage length, and 1.40 mm for maximal lower lateral cartilage length. On clinical CT protocols, only septal cartilage was well discriminated from boundary. Higher radiation dose resulted in more accurate density measurements of cartilage, but it did not ultimately improve ability to discriminate cartilage.

Conclusions and Relevance

The results of this anatomic study may represent a notable step toward advancing knowledge of the capabilities and pitfalls of nasal cartilage visualization on CT. Nasal cartilage visualization was feasible on the micro-CT compared with pathologic findings. Future research may further examine the barriers to accurately visualizing upper lateral cartilage and lower lateral cartilage, a prerequisite for clinical application.

Level of Evidence

NA.

Imaging of adult nasal obstruction

The commonest causes of nasal obstruction are rhinitis and chronic rhinosinusitis, which affect up to 30% and 14% of the adult population, respectively. The global financial burden is huge, estimated at $5 billion for rhinitis and $8.6 billion for chronic rhinosinusitis per annum in the USA. On referral for imaging, computed tomography (CT) is indicated initially when there is a suboptimal response to medical treatment of these mucosal diseases or there are "red flags," such as persistent unilateral obstruction, epistaxis, pain, and orbital or neurological symptoms. A mass visible at rhinoscopy or endoscopy in the nose or nasopharynx and lymphadenopathy are further indications. The anterior (cartilaginous) nose plays a key role in the aetiology of nasal obstruction as it accounts for 50-75% of the total resistance to airflow in the upper airway. It has been ignored in the imaging literature, but extensively evaluated by clinicians using a range of methods, including CT. Oblique reconstructions perpendicular to the parabolic curve of lamellar airflow provide accurate assessment of the anterior nose. A thorough and systematic approach to assessing the nose addresses the discrepancy between imaging and clinical evaluation of structural causes of nasal obstruction, especially septal deviation, reported in the surgical literature. Nasal tumours are a very uncommon cause of nasal obstruction; magnetic resonance imaging is commonly performed to assess their full extent and improve the specificity of diagnosis.

Treatment of Nasal Deviation With Underlying Bony Asymmetry Secondary to Augmentation Rhinoplasty in Asian Patients

BACKGROUND

In Asian patients, nasal deviation secondary to augmentation rhinoplasty may result from underlying bony asymmetry that was not corrected intraoperatively. Diagnosis and treatment of this condition are complicated by the masking effect of dorsal implants.

OBJECTIVES

The authors applied computed tomography (CT) to examine the causes of nasal deviation after augmentation rhinoplasty. CT results were utilized in preoperative planning for revisional surgery.

METHODS

Fifteen women with nasal deviation after augmentation rhinoplasty and CT-confirmed bony asymmetry were included in a retrospective study. To correct nasal deviation, the authors performed revisional rhinoplasty with paramedian osteotomy and unilateral placement of extended spreader grafts at the concave side of the keystone region. For patients with concomitant glabella-radix deviation, implants comprising expanded polytetrafluoroethylene or autologous fascia were placed.

RESULTS

Of the 15 patients with nasal bony asymmetry, 14 had developmental keystone asymmetry, and 1 had osteotomy-induced keystone deviation. Six patients had developmental glabella asymmetry. Patients received follow-up for an average of 11.2 months (range, 6-24 months). Revisional procedures were considered successful in 13 patients; 2 patients required additional surgery to address residual nasal deviation.

CONCLUSIONS

CT is valuable for the diagnosis of postaugmentation nasal deviation owing to underlying bony asymmetry. Paramedian osteotomy with extended spreader grafting at the concave side of the keystone area and correction of the glabella-radix deviation are effective procedures to reposition the nasal axis along the midline of the face.

LEVEL OF EVIDENCE 4

Patient-Specific Augmentation Rhinoplasty Using a Three-Dimensional Simulation Program and Three-Dimensional Printing

Background

The convergence of three-dimensional (3D) simulation, tissue engineering, and 3D printing technology is creating a paradigm shift in plastic surgery. In augmentation rhinoplasty, determining the ideal material and design method has been a critical issue for many years. Thus, these technologies are expected to make important contributions to augmentation rhinoplasty.

Objectives

We sought to validate the feasibility of the 3D carving simulation and patient-specific implant fabrication system (3D carving system) in a clinical trial using reproducibility tests.

Methods

Patient-specific implants were designed using a program developed in-house with preoperative computed tomography (CT). Negative molds of the implant were fabricated by a 3D printer and silicone was injected into these molds. Ten actual silicone implants were fabricated and compared with virtually designed implants. Seven patients underwent surgery and postoperative CT to confirm implant positioning.

Results

Virtually designed implants were produced into actual implants within 0.07 mm with a 0.17% ± 0.11% difference. The percentage within the gap was the highest at the cephalic end of the implant and reduced from the cephalic to caudal end (most cephalic point: 100%; rightmost and leftmost point of the implant at the caudal end of the nasal bone: 57.1% and 71.4%, respectively; rightmost and leftmost point at the supratip break: 28.6% and 28.6%, respectively; and most caudal point: 0%).

Conclusions

The 3D carving system can facilitate rhinoplasty by enabling the more intuitive, rapid, and accurate fabrication of implants irrespective of surgeon experience level.

Level of Evidence

4.

Multiple regression analysis of the craniofacial region of Chinese Han people using linear and angular measurements based on MRI

The purpose of this study was to measure the craniofacial region of Chinese Han people in the linear and angular dimensions, and to analyse the effects on sex, age and body parameters (height and weight). All 250 individuals (86 males, 164 females) underwent a three-dimensional magnetic resonance imaging (MRI) scan, and the MRI data were imported into VG Studio MAX 2.2 software. Each linear and angular measurement in the craniofacial region was processed directly. Using SPSS 20.0 software, nine multiple regression equations were constructed, and all the adjusted R² values were statistically significant (0.031–0.311). Multiple regression analysis showed that most craniofacial measurements of Chinese people were significantly correlated with height, weight or age. The multiple regression equations constructed will be helpful in anthropometric analysis and forensic inference.

Three-Dimensional Multidetector CT for Anatomic Evaluation of Orbital Tumors

Intricate resection and complex reconstructive procedures often required for primary and metastatic orbital tumors are facilitated by accurate imaging. A three-dimensional (3D) image can be reconstructed from source axial multidetector computed tomography (MDCT) images to visualize orbital tumors. To assess the utility of 3D images in this setting, the 3D images were reconstructed retrospectively for 20 patients with an orbital tumor and compared to two-dimensional (2D) orthogonal MDCT studies. Both types of images were assessed for their capacity to show the bony orbital walls and foramina, extraocular muscles, and optic nerve in the orbit contralateral to the tumor and, in the affected orbit, the extent of the tumor and its relationship to normal orbital contents and associated bone destruction. 3D imaging is most informative when axial images are acquired at 1.25 mm collimation. The optic nerve, extraocular muscles, and well-circumscribed orbital tumors were well visualized on 3D images. On 3D imaging, tumor-associated destruction of the lateral and superior orbital walls was fairly well demonstrated and that of the inferior and medial walls was not. The 3D images provide the surgeon with a comprehensive view of well-circumscribed orbital tumors and its relationship to extraocular muscles, exiting foramina, and the superior and lateral walls.