Imaging of Cartilage and Mimic Muscles With MRI: Anatomic Study in Healthy Volunteers and Patients With Unilateral Cleft Lip and Palate

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.

Cleft lip, alveolus and palate: Defect or dislocation malformation? Importance of adopting a physiological concept for surgical repair in achieving optimal outcomes in LMICs. Part 1: Physiological processes in facial development

The conventional surgical procedures for the closure of cleft-lip and palate are based on proven plastic-surgical procedures from tumour surgery or traumatology. These flap surgeries take little account of the fact that the treatment of such malformations takes place during the time of a child's increased growth and is known to lead to pronounced scarring and skeletal growth disorders. It is therefore imperative to develop modified surgical procedures based on physiological growth processes. These physiological procedures must include the reconstruction of all facial structures such as orofacial, palatal and pharyngeal muscles, complete nose, upper jaw and palate. Transfer of this know how to low resource LMIC and training is essential if optimal outcomes are to be achieved.

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.

MRI and Additive Manufacturing of Nasal Alar Constructs for Patient-specific Reconstruction

Surgical reconstruction of cartilaginous defects remains a major challenge. In the current study, we aimed to identify an imaging strategy for the development of patient-specific constructs that aid in the reconstruction of nasal deformities. Magnetic Resonance Imaging (MRI) was performed on a human cadaver head to find the optimal MRI sequence for nasal cartilage. This sequence was subsequently used on a volunteer. Images of both were assessed by three independent researchers to determine measurement error and total segmentation time. Three dimensionally (3D) reconstructed alar cartilage was then additively manufactured. Validity was assessed by comparing manually segmented MR images to the gold standard (micro-CT). Manual segmentation allowed delineation of the nasal cartilages. Inter- and intra-observer agreement was acceptable in the cadaver (coefficient of variation 4.6–12.5%), but less in the volunteer (coefficient of variation 0.6–21.9%). Segmentation times did not differ between observers (cadaver P = 0.36; volunteer P = 0.6). The lateral crus of the alar cartilage was consistently identified by all observers, whereas part of the medial crus was consistently missed. This study suggests that MRI is a feasible imaging modality for the development of 3D alar constructs for patient-specific reconstruction.

Electrophysiological method to examine muscle fiber architecture in the upper lip in cleft-lip patients

OBJECTIVES

The upper lip's musculature comprises several muscle fiber groups with different spatial orientations for various lip movements. In the past, it has not been possible to describe these various groups and their motor units in detail with traditional methods of electromyography (EMG). The purpose of this investigation was to create a viable method for studying the architecture of upper-lip muscle fibers in patients with surgically closed cleft lip by refining the design of a flexible electrode array for multichannel EMG.

METHODS

Calibrated perioral photographs of 36 adult subjects were used to determine the basic geometry of an electrode array for use on different facial shapes. A total of 256 chloride silver electrodes, 1 mm in diameter, were distributed over this geometry to form a grid with interelectrode distances of 2.5 mm. Technical implementation of the electrode array was based on a modified technique used for flexible printed circuit boards. A double-sided adhesive tape with perforations was used to apply the array to the skin in the upper-lip area. Surface EMG signals were recorded while the subjects were performing various lip movements and exerting specific lip forces. The latter were recorded with a specially developed transducer.

RESULTS

Despite an extremely dense grid of electrodes associated with downsized contacts, the electrode array could be precisely applied to the perforated adhesive tape. The electrode array remained firmly attached to the skin even during extensive lip movements. The recorded EMG signals offered high baseline stability and a strong signal-to-noise ratio, thus, allowing us to extract individual motor unit action potentials (MUAPs). Spatiotemporal tracking of MUAPs succeeded in demonstrating the course of muscle fibers belonging to individual motor units. Pilot measurements taken on subjects with surgically closed unilateral cleft lip revealed an asymmetric distribution of muscle activity surrounding the closed cleft-lip segments.

CONCLUSION

Our refined noninvasive electrophysiological method is capable of providing detailed information about muscle fiber architecture and the position, size, and organization of motor units in the lip area. It is thus feasible to conduct further studies to analyze differences in muscle morphology and motor control between surgically treated cleft-lip patients and noncleft individuals.

Functional 3-D analysis of patients with unilateral cleft of lip, alveolus and palate (UCLAP) following lip repair

INTRODUCTION

Particular importance is attached to lip repair cleft surgery, as numerous functional and aesthetic aspects have to be taken into account simultaneously. Spatial assessment of function and depiction of dynamic deviations is reasonable for describing surgical outcome in addition to long standing static analysis. This study aimed at 3D analysis of the oral area after reconstruction in patients with unilateral cleft lip, alveolus and palate.

PATIENTS AND METHODS

Twelve patients with unilateral cleft lip, alveolus and palate who underwent surgery according to Tennison-Randall were enrolled in this study. Soft tissue dynamics was analysed during passive stretching and active contraction of the lips, and photogrammetry was used for comparing relative changes of length and displacement vectors. The spatial coordinates of surgically significant and reproducible landmarks along the red-white lip junction were analyzed.

RESULTS

Static analysis of the lips revealed a good result with far-reaching symmetry in all cases. Regarding dynamic behaviour, two groups could be distinguished showing clear differences of passive distension and contraction behaviour.

CONCLUSION

Despite nominally identical surgical techniques and comparable static-morphological outcomes, dynamic analysis revealed differences pointing to a need for optimization.