[Accuracy and efficiency of 2D/3D single-vertebra spine navigation registration method based on dual-view feature fusion].

Objective: To investigate the accuracy and efficiency of spine 2D/3D preoperative CT and intraoperative X-ray registration through a framework for spine 2D/3D single-vertebra navigation registration based on the fusion of dual-position image features. Methods: The preoperative CT and intraoperative anteroposterior (AP) and lateral (LAT) X-ray images of 140 lumbar spine patients who visited Huashan Hospital Affiliated to Fudan University from January 2020 to December 2023 were selected. In order to achieve rapid and high-precision single vertebra registration in clinical orthopedic surgery, a designed transformation parameter feature extraction module combined with a lightweight module of channel and spatial attention (CBAM) was used to accurately extract the local single vertebra image transformation information. Subsequently, the fusion regression module was used to complement the features of the anterior posterior (AP) and lateral (LAT) images to improve the accuracy of the registration parameter regression. Two 1×1 convolutions were used to reduce the parameter calculation amount, improve computational efficiency, and accelerate intraoperative registration time. Finally, the regression module outputed the final transformation parameters. Comparative experiments were conducted using traditional iterative methods (Opt-MI, Opt-NCC, Opt-C2F) and existing deep learning methods convolutional neural network (CNN) as control group. The registration accuracy (mRPD), registration time, and registration success rate were compared among the iterative methods. Results: Through experiments on real CT data, the image-guided registration accuracy of the proposed method was verified. The method achieved a registration accuracy of (0.81±0.41) mm in the mRPD metric, a rotational angle error of 0.57°±0.24°, and a translation error of (0.41±0.21) mm. Through experimental comparisons on mainstream models, the selected DenseNet alignment accuracy was significantly better than ResNet as well as VGG (both P<0.05). Compared to existing deep learning methods [mRPD: (2.97±0.99) mm, rotational angle error: 2.64°±0.54°, translation error: (2.15±0.41) mm, registration time: (0.03±0.05) seconds], the proposed method significantly improved registration accuracy (all P<0.05). The registration success rate reached 97%, with an average single registration time of only (0.04±0.02) seconds. Compared to traditional iterative methods [mRPD: (0.78±0.26) mm, rotational angle error: 0.84°±0.57°, translation error: (1.05±0.28) mm, registration time: (35.5±10.5) seconds], registration efficiency of the proposed method was significantly improved (all P<0.05). The dual-position study also compensated for the limitations in the single-view perspective, and significantly outperforms both the front and side single-view perspectives in terms of positional transformation parameter errors (both P<0.05). Conclusion: Compared to existing methods, the proposed CT and X-ray registration method significantly reduces registration time while maintaining high registration accuracy, achieving efficient and precise single vertebra registration.

[The correlation of functional connectivity and structural connectivity between hippocampus and thalamus in Alzheimer's disease and amnestic mild cognitive impairment].

Objective: To investigate the correlation of functional connectivity (FC) and the integrity of connective fibres between hippocampus and thalamus in Alzheimer's disease(AD) and amnestic mild cognitive impairment (aMCI). Methods: Both resting-state functional magnetic resonance imaging (rs-fMRI) and diffusion tensor imaging (DTI) data of 40 AD patients, 37 aMCI patients and 41 normal control subjects matching with age and educational level were collected. These subjects were all recruited from outpatient Department of Neurology in the Second Medical Center of Chinese PLA General Hospital, as well as poster, from May 2016 to January 2018. The FC strength between bilateral hippocampus and thalamus, as well as the parameters representing integrity of connective fibres, including fractional anisotropy (FA) and mean diffusivity(MD),were analyzed. Also, the correlations between FC strength and FA or MD strength were analyzed in the study. Results: Compared to that of normal control subjects, the FC strength between billateral hippocampus and thalamus in patients with AD, aMCI were not significantly different(P>0.05). The integrity of bilateral connective fibres between hippocampus and thalamus were damaged in AD patients when compared to normal control subjects(P<0.01). A positive correlation of connective fibres integrity with FC strength between hippocampus and thalamus was found in the left side(r=0.25,P<0.05) but rather in the right side. Conclusion: In AD and aMCI patients, structural connectivity between left hippocampus and thalamus affects the functional connectivity between them.