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

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.

Relationship between the degree of subchondral collapse and articular surface irregularities in osteonecrosis of the femoral head

Articular surface irregularities are often observed in collapsed femoral heads with osteonecrosis, while the effects of the degree of collapse on the articular surface are poorly understood. We first macroscopically assessed the articular surface irregularities on 2-mm coronal slices obtained using high-resolution microcomputed tomography of 76 surgically resected femoral heads with osteonecrosis. These irregularities were observed in 68/76 femoral heads, mainly at the lateral boundary of the necrotic region. The mean degree of collapse was significantly larger for femoral heads with articular surface irregularities than for those without (p < 0.0001). Receiver operating characteristic analysis showed that the cutoff value for the degree of collapse in femoral heads with articular surface irregularities at the lateral boundary was 1.1 mm. Next, for femoral heads with <3-mm collapse (n = 28), articular surface irregularities were quantitatively assessed based on the number of automatically counted negative curvature points. Quantitative evaluation showed that the degree of collapse was positively correlated with the presence of articular surface irregularities (r = 0.95, p < 0.0001). Histological examination of articular cartilage above the necrotic region (n = 8) revealed cell necrosis in the calcified layer and abnormal cellular arrangement in the deep and middle layers. In conclusion, articular surface irregularities of the necrotic femoral head depended on the degree of collapse, and articular cartilage was already altered even in the absence of macroscopically determined gross irregularities.

Deep causal learning for robotic intelligence

This invited Review discusses causal learning in the context of robotic intelligence. The Review introduces the psychological findings on causal learning in human cognition, as well as the traditional statistical solutions for causal discovery and causal inference. Additionally, we examine recent deep causal learning algorithms, with a focus on their architectures and the benefits of using deep nets, and discuss the gap between deep causal learning and the needs of robotic intelligence.

The Caucasian Hump: Radiologic Study of the Osteocartilaginous Vault versus Surface Anatomy. Clinical Implications in Structured and Preservation Rhinoplasty

BACKGROUND

The relation between the osteocartilaginous nasal vault and nasal hump characteristics has not been fully investigated.

METHODS

Measurements were collected from computed tomographic nasal scans in the midsagittal plane in adult Caucasian patients seeking rhinoplasty because of nasal hump from January of 2015 to December of 2018. Measurements were compared to those of sex- and age-matched patients not seeking rhinoplasty (control group). Patients with other significant nasal deformities were excluded. The correlations between nasal hump length, height, and osteocartilaginous nasal vault measurements were assessed. Distances from the beginning of the nasal hump to the kyphion and ethmoidal points were measured as well. The location of the nasal hump apex in relation to the keystone area structures was detailed.

RESULTS

The study included 134 Caucasian patients, with 67 presenting nasal hump. The mean patient age was 32.9 years and 69.6 percent were female patients. Nasal hump measured a mean 17 ± 2.7 mm in length and 1.8 mm (range, 1.1 to 3.8 mm) in height. Nasal hump length correlated with nose length and nasal bone length. Nasal hump height correlated with nose length and the angle over the kyphion. In 97 percent of patients, the nasal hump began caudal to the ethmoidal point, and in all patients, the kyphion was underneath the nasal hump. The nasal hump is not a symmetric structure and, in all patients, its apex was situated above the septal cartilage.

CONCLUSIONS

The nasal hump characteristics are mainly attributable to the septal cartilage, and this should be the cornerstone of any dorsal hump reduction strategy. The caudal aspect of the nasal bones contributes to the nasal hump, whereas the posterior ethmoidal plate rarely does.

Robotics in Pediatric Otolaryngology-Head and Neck Surgery and Advanced Surgical Planning

Robotic surgery has been shown to be feasible and successful in several areas of pediatric head and neck surgery. However, adoption has been limited. Robotic surgery may be better integrated into practice with advanced preoperative surgical planning and the design of new robotic platforms with instrumentation specific for the application. With continued investigations, computer-aided surgical planning techniques including three-dimensional printing, virtual reality, multiobjective cost function for optimization of approach, mirror image overlay, and flexible robotic instruments may demonstrate value and utility over current practice.

Dorsal Hump Reduction Based on the New Ethmoidal Point Classification: A Clinical and Radiological Study of the Keystone Area in 138 Patients

BACKGROUND

Hump resection often requires reorganization of the keystone area.

OBJECTIVES

The authors sought to describe the importance of the point where the perpendicular plate of ethmoid joins the septal cartilage (SC) and the nasal bones (NB) (Ethmoidal point [E-point]) for hump resection surgical planning.

METHODS

Measurements from mid-sagittal slices in nasal computed tomography scans taken in adult Caucasian patients between January 2015 and December 2018 were compared between patients seeking primary rhinoplasty due to a nasal hump and patients not seeking rhinoplasty (control group). Patients with previous nasal surgery or trauma, genetic or congenital facial disorders, and high septal deviation were excluded. The length of overlap between NB and SC was compared between the 2 groups. The location of the E-point in relation to the beginning of the nasal hump in the cephalocaudal direction was documented in the patients seeking rhinoplasty.

RESULTS

The study population included 138 patients, 69 seeking and 69 not seeking rhinoplasty (96 females). The mean age was 32.9 years (range, 18-55 years). The length of overlap between NB and SC was similar between both groups (11.7 ± 3.3 vs 10.8 ± 3.3; P = 0.235). The E-point was located before the beginning of the nasal hump in 97% (67/69) of nasal hump patients, and it could be found a mean distance of 2.3 (±2.3) mm cephalic to the latter.

CONCLUSIONS

As a rule, the perpendicular plate of the ethmoid does not contribute to the nasal hump; therefore, only in exceptional cases should this be addressed while performing dorsal reduction.

LEVEL OF EVIDENCE: 3

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.

Finite Element Analysis of the Septal Cartilage L-Strut

Importance: Septoplasty is one of the most commonly performed operations in the head and neck. However, the reasons for septoplasty failure and the additional stress of performing a chondrotomy on the septal cartilage are not well understood. Design, Setting, and Participants: A finite element model of the nasal septum was created using a microcomputed tomography scan of the nasoseptal complex that was reconstructed into a three-dimensional model in silico. Testing included four common chondrotomy designs: traditional L-strut, double-cornered chondrotomy (DCC), curved L-strut, and the C-curve. Tip displacement was applied in a vector parallel to the caudal strut to simulate nasal tip palpation. Main Outcomes and Measures: With finite element analysis, the maximum principal stress (MPS), von Mises stress (VMS), harvested cartilage volume, and surface area were recorded. Results: The highest MPS for the L-strut, DCC, curved L-strut, and C-curve was identified at the corner of the chondrotomy. The MPS at the corner of the chondrotomy was reduced 44% when comparing the C-curve with the traditional L-strut. The VMS patterns showed compressive stress along the caudal septum in all models, but at the corner, the stresses were highest in the chondrotomies designed with sharp-angled corners. The VMS showed a 76% decrease when comparing the C-curve with the traditional L-strut. The stress across the anterior septal angle is also higher in models with sharp-angled corners. Cartilage harvest volumetric and surface area assessments did not show meaningful differences between shapes. Conclusions and Relevance: The highest area of stress is near the transition of the dorsal to caudal septum in all models. Stresses are relatively higher in chondrotomy shapes that contain sharp-angled corners. The relative reduction in MPS and VMS utilizing a C-curve instead of an L-strut may decrease the likelihood that the septum will deform or fail in this region. The volume and surface area of the C-curve are similar to that of the L-strut technique. Avoiding sharp-angled corners reduces the stresses at the corner of the chondrotomy and across the anterior septal angle. Using a C-curve may be an improved septoplasty design.

Primary Rhinoplasty Does Not Interfere with Nasal Growth: A Long-Term Three-Dimensional Morphometric Outcome Study in Patients with Unilateral Cleft

BACKGROUND

Primary rhinoplasty has not been universally adopted because the potential for nasal growth impairment remains an unsolved issue in cleft care. This study's purpose was to assess the long-term effects of primary rhinoplasty performed by a single surgeon in a cohort of patients with a unilateral cleft lip nose deformity.

METHODS

Three-dimensional nasal morphometric measurements (linear, angular, proportional, surface area, and volume) were collected from consecutive patients (cleft group, n = 52; mean age, 19 ± 1 year) who had undergone primary rhinoplasty with the use of the Noordhoff approach between 1995 and 2002 and reached skeletal maturity. Normal age-, sex-, and ethnicity-matched subjects (control group, n = 52) were identified for comparative analyses.

RESULTS

No significant differences (all p > 0.05) were observed for most measures, including nasal height, alar width, nasal dorsum angle, columellar angle, columellar-labial angle, nasal tip/height ratio, nasal index, alar width/intercanthal distance ratio, nasal surface area, and nasal volume. The cleft group displayed significantly (all p < 0.05) lower nasal bridge length and nasal tip projection, and greater nasal protrusion, tip/midline deviation, nasal tip angle, nasal tip protrusion width index, and alar width/mouth ratio values than the control group.

CONCLUSIONS

Primary rhinoplasty does not interfere with nasal growth as measured by three-dimensional photogrammetric analysis. Further imaging studies are required for the assessment of development in other anatomical nasal structures.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.