Real-Time Glottis Detection Framework via Spatial-decoupled Feature Learning for Nasal Transnasal Intubation
Authors: Jinyu Liu, Gaoyang Zhang, Yang Zhou, Ruoyi Hao, Yang Zhang, Hongliang Ren
Organizations: Hubei Key Laboratory of Modern Manufacturing Quality Engineering, Hubei University of Technology, Nanhu Avenue 28, Wuhan, 430068, Hubei, China · School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, 430074, Hubei, China · Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, 999077, China · Key Laboratory of Symbolic Computation and Knowledge Engineering, Ministry of Education, Jilin University, Changchun, 130012, Jilin, China · National Key Laboratory for Novel Software Technology, Nanjing University, Hankou Road 22, Nanjing, 210023, Jiangsu, China
Nasotracheal intubation (NTI) is a vital procedure in emergency airway management, where rapid and accurate glottis detection is essential to ensure patient safety. However, existing machine assisted visual detection systems often rely on high performance computational resources and suffer from significant inference delays, which limits their applicability in time critical and resource constrained scenarios. To overcome these limitations, we propose Mobile GlottisNet, a lightweight and efficient glottis detection framework designed for real time inference on embedded and edge devices. The model incorporates structural awareness and spatial alignment mechanisms, enabling robust glottis localization under complex anatomical and visual conditions. We implement a hierarchical dynamic thresholding strategy to enhance sample assignment, and introduce an adaptive feature decoupling module based on deformable convolution to support dynamic spatial reconstruction. A cross layer dynamic weighting scheme further facilitates the fusion of semantic and detail features across multiple scales. Experimental results demonstrate that the model, with a size of only 5MB on both our PID dataset and Clinical datasets, achieves inference speeds of over 62 FPS on devices and 33 FPS on edge platforms, showing great potential in the application of emergency NTI.
Figures & tables
Fig. 1 : The comparative visualization with state-of-the-art methods on the PID dataset is illustrated, where the vertical axis represents the inference speed (FPS) measured on terminal devices. The bubble chart shows that our method achieves a favorable balance between AP50 and FPS while maintaining a compact model size. The area of each bubble corresponds to the model size.
Fig. 2 : Overview of the proposed Mobile GlottisNet. The input image is first processed by the backbone network to generate multi-scale feature maps, which are then fused through the FPN to produce enhanced multi-scale feature representations. Subsequently, the classification and regression tasks are decoupled, and dynamic label assignment strategies are applied to adjust anchor point allocation. The mean IoU of candidate boxes is calculated to set an adaptive threshold. Finally, convolutional kernel sampling positions are adjusted based on the Offset Field in the adaptive feature decoupling module, and the final detection results are derived from class scores and bounding box offsets.
Require : - Predicted bounding boxes {bi} across L FPN scales,
- Ground-truth class Cj for the j -th glottis,
- Hyperparameters: balance factor λ , top- K count.
Ensure : Selected candidate set Tj for training classification/regression.
Algorithm 1 Glottis Candidate Selection with Dynamic Thresholding
Fig. 3 : Attention heatmaps throughout the network. Feature disentanglement progressively refines spatial attention, culminating in accurate focus on the anatomical glottic aperture.
Fig. 4 : The nasotracheal intubation robot system is an advanced medical system that improves intubation accuracy and minimizes human error. It utilizes a fiberoptic bronchoscope with a bendable robotic arm, dynamically adjusting insertion paths through real-time feedback control.
Fig. 5 : Sample images from the Glottis dataset. The dataset includes high-speed videoendoscopic recordings from both healthy individuals and patients with laryngeal disorders, collected across different clinical settings and imaging devices.
Fig. 6 : During NTI, the glottis undergoes substantial scale variation under complex and low-light conditions, and the surrounding anatomy is intricate. These factors often degrade the accuracy of conventional detectors.
Methods
Backbone
PID (%)
Clinical (%)
Model size (MB)
Infer (FPS)
mAP
AP50
AP75
mAP
AP50
AP75
Device
Edge
ATSS Zhang et al. [2020]
ResNet50
30.3
59.5
28.4
17.8
39.5
13.6
251
21.6
12.1
CenterNet Zhou et al. [2019]
ResNet18
25.5
54.9
24.0
12.6
25.9
10.9
114
50.0
25.3
CentripetalNet Zhou et al. [2020]
Hourglass104
28.0
49.2
26.5
5.3
9.9
4.7
2416
11.2
5.9
Faster RCNN Ren et al. [2017]
ResNet50
29.1
55.1
27.6
32.4
61.0
29.3
323
51.3
26.1
GFL Li et al. [2020]
ResNet101
33.1
61.3
32.7
34.9
61.5
35.7
401
30.1
16.4
Table 1: Comparison of accuracy with the state-of-the-art methods on the PID and clinical datasets.
Methods
Backbone
Glottis (%)
Model size (MB)
Inference (FPS)
mAP
AP50
AP75
ATSS Zhang et al. [2020]
ResNet50
53.7
84.8
60.1
251
21.6
BoxInst Tian et al. [2021]
ResNet101
53.3
82.7
58.5
447
45.7
CondInst Tian et al. [2020]
ResNet50
41.1
79.1
36.9
279
46.8
CMask RCNN Cai and Vasconcelos [2021]
ResNet50
55.9
83.2
62.9
201
16.4
Conditional DETR Meng et al. [2021]
ResNet50
7.1
21.9
3.0
512
34.4
Table 2: Comparison of accuracy with the state-of-the-art methods on the Glottis dataset.
Backbone
mAP
AP50
AP75
Inference (FPS)
Model Size (MB)
ResNet101
38.8
72.5
35.4
26.6
205
ResNet50
33.3
66.3
30.6
31.5
129
ResNet18
30.1
61.6
29.2
40.2
77
ShuffleNet
18.7
42.4
11.6
65.4
73
Swin-T
35.3
63.7
28.6
21.2
285
EfficientNet
28.7
54.4
21.9
51.4
92
Table 3: Performance of various backbones on the PID dataset.
TopK
mAP
AP50
AP75
TopK
mAP
AP50
AP75
1
27.4
51.0
26.7
11
33.5
63.0
32.5
3
32.3
57.0
31.5
13
30.6
58.6
30.0
5
31.7
57.5
31.8
15
30.2
57.2
27.9
7
35.0
63.4
34.6
17
32.0
59.6
31.1
9
33.3
66.3
30.6
19
35.7
66.0
35.5
Table 4: Comparison of TopK in dynamic thresholding & hierarchical sample allocation on PID dataset.
Channels
mAP
AP50
AP75
Infer (FPS)
Model Size (MB)
256
33.3
66.3
30.6
31.5
129.1
128
32.4
68.2
26.8
36.4
104.1
64
32.7
66.6
27.9
43.9
97.3
32
28.2
57.1
25.1
48.6
95.3
16
25.7
54.0
20.8
50.5
94.7
8
20.5
45.7
16.5
51.7
94.5
Table 5: Performance of Mobile GlotissNet with MobileNetv3 in various channels on PID dataset.
Fig. 7 : Qualitative comparison among ground-truth labels, model predictions, and video detection results across glottis, clinical, and phantom datasets.
Nasotracheal intubation (NTI) is a critical clinical procedure for establishing and maintaining patient airway patency. Machine-assisted NTI has emerged as a pivotal approach for optimizing procedural efficiency and minimizing manual intervention. However, visual detection algorithms employed for NTI navigation encounter significant challenges, including complex anatomical environments and suboptimal illumination conditions surrounding the glottis. Additionally, the glottis presents considerable scale variability throughout the procedure, initially appearing as a small, difficult-to-capture structure before expanding to occupy nearly the entire field of view. Moreover, traditional visual detection methods often have high computational costs, making real-time, high-precision detection on portable devices challenging. To enhance NTI efficacy and address these challenges, this paper proposes a novel glottis segmentation framework optimized for vision-assisted NTI applications. First, we designed a lightweight, multi-receptive field feature extraction module to reduce intra-class differences, achieving robustness to scale variations of the glottis. This module was then stacked to form the backbone and neck of our network. Subsequently, we developed an advanced label assignment method and redefined the number of samples to further reduce intra-class differences and enhance accuracy in the complex NTI environment. Experiments on three distinct datasets demonstrate that our network surpasses state-of-the-art algorithms, achieving a segmentation mDice of 92.9% with a compact model size of 19 MB and an inference speed exceeding 170 frames per second. % Our code and datasets will be open-sourced on GitHub after the manuscript is accepted. Our code and datasets are available at https://github.com/HBUT-CV/GlottisNet.
Yang Zhou, Chaoyong Zhang, Ruoyi Hao +3
School of Mechanical Science & Engineering Huazhong University of Science and Technology, Wuhan 430074, China · Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong, China · Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Hong Kong 999077, China +5
We present a fully automated, two-stage modular glottal area segmentation framework for high-speed videoendoscopy (HSV) designed for accuracy, generalizability, and real-time playback. Our detection-gated pipeline combines a YOLOv8n glottis localizer with a U-Net segmenter; the localizer defines a tight crop to ensure a consistent field of view and gates the output to reduce spurious segmentations during glottal closure. The models were trained on the GIRAFE (N=600) and BAGLS (N=55,750) datasets. Cross-dataset portability was evaluated by benchmarking GIRAFE-trained models on the BAGLS test set without fine-tuning. In these evaluations, the pipeline achieved a Dice Similarity Coefficient (DSC) of 0.745 (87% of the in-domain ceiling). On in-distribution test sets, the system achieved DSCs of 0.81 (GIRAFE) and 0.856 (BAGLS), outperforming or competing with state-of-the-art methods. An exploratory clinical study of 40 subjects demonstrated that the glottal area Coefficient of Variation (CV distinguished healthy from pathological function (p=0.006). The system processes ~35 frames per second on commodity hardware, enabling interactive clinical review. This design supports uniform extraction of laryngeal kinematic measures across varying acquisition settings. Code, weights, and software are available at https://github.com/hari-krishnan/openglottal.
Harikrishnan Unnikrishnan, Rita Patel
¹Orchard Robotics, San Francisco, California, USA. · ²Department of Speech, Language, and Hearing Sciences, Indiana University, Bloomington, Indiana, USA. · ³Department of Otolaryngology–Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana, USA.
Real-time object detection has achieved substantial progress through meticulously designed architectures and optimization strategies. However, the pursuit of high-speed inference via lightweight network designs often leads to degraded feature representation, which hinders further performance improvements and practical on-device deployment. In this paper, we propose a cost-effective and highly adaptable distillation framework that harnesses the rapidly evolving capabilities of Vision Foundation Models (VFMs) to enhance lightweight object detectors. Given the significant architectural and learning objective disparities between VFMs and resource-constrained detectors, achieving stable and task-aligned semantic transfer is challenging. To address this, on one hand, we introduce a Deep Semantic Injector (DSI) module that facilitates the integration of high-level representations from VFMs into the deep layers of the detector. On the other hand, we devise a Gradient-guided Adaptive Modulation (GAM) strategy, which dynamically adjusts the intensity of semantic transfer based on gradient norm ratios. Without increasing deployment and inference overhead, our approach painlessly delivers striking and consistent performance gains across diverse DETR-based models, underscoring its practical utility for real-time detection. Our new model family, RT-DETRv4, achieves state-of-the-art results on COCO, attaining AP scores of 49.8/53.7/55.4/57.0 at corresponding speeds of 273/169/124/78 FPS. Code is publicly available at https://github.com/RT-DETRs/RT-DETRv4.
Zijun Liao, Yian Zhao, Xin Shan +5
School of Electronic and Computer Engineering, Peking University, Shenzhen, China · Department of Automation and BNRist, Tsinghua University, Beijing, China