Objective To analyze the biomechanical changes of lateral atlantoaxial articulation by means of three‐dimensional fnite element models of craniocervical junction malformation(CJVM) .Methods CT scan images of 1 patients with CJVM were ob‐tained .The analytical model was constructed by advanced three‐dimension modeling and finite element softwares .A comparison of range of motion difference between the deformity model and normal model ,referring to the experience of clinical observation ,was used to verify the validity of the model .Applying respectively the same loads and boundary conditions on finite element model .The effectiveness was verified by contrastive analysis of the variation in lateral atlantoaxial joint stresses .Results The finite CJVM ele‐ment model with high geometric accuracyand reliable parameter had built .Compared to the results of cadaver test and finite element model based in normal cranio‐cervical junction ,the segment mobility coincides with the actual clinical performance in patients .The stress distribution the lateral junction between atlas and axis of can be reasonably explained the deformation of lateral atlanto‐axial joint structure and its important role in remaining stable between atlantoaxial vertebraeunder different physiological conditions .Con‐clusion The structure of lateral atlantoaxial joint changes in patients of CJVM ,the biomechanical stability for preoperative diagno‐sis and intraoperative treatment operation has a certain value .

Objective:To evaluate the feasibility of making individualized scanning and contrast injection protocol based on body mass index (BMI) and body weight during dynamic myocardial computed perfusion (CTP) imaging in order to get high-quality images while drastically reducing radiation dose.Methods:A total of 128 patients with coronary heart disease diagnosed by coronary CTA (CCTA) performed CTP from June, 2019 to March, 2020 were prospectively enrolled. Patients were divided into six groups: group 1, BMI<24 kg/m 2, ≤60 kg, 70 kV; group 2,BMI<24 kg/m 2, 61≤kg≤70, 70 kV; group 3, BMI 24-28 kg/m 2, 61≤kg≤70, 80 kV; group 4, BMI 24-28 kg/m 2, 71≤kg≤80, 80 kV; group 5, BMI 24-28 kg/m 2,>80 kg, 80 kV;group 6, BMI>28 kg/m 2,>80 kg, 100 kV. 200 mA was fixed for all patients. Contrast agent with iodine containing 370 mg/ml was used in all patients. The iodine delivery rates (IDR) for each group was 0.8, 1.0, 1.2, 1.4, 1.6, 2.0 g/s, respectively. The attenuation and noise of left ventricle (LV) and septal myocardial were measured to calculate signal to noise ratio (SNR) and contrast to noise ratio (CNR) of the images in each group. The Shapiro-Wilk test was conducted to assess the normality of quantitative data. Quantitative variables were compared using one-way ANOVA if normally distributed. Results:The LV attenuation of the six groups were (506±85), (513±77), (510±81), (456±74), (477±111), (462±43) HU, respectively. There was no significant difference among them ( F=2.249, P=0.054). SNR values of LV were 23±8, 20±5, 21±5, 19±4, 19±7, 19±4, and CNR values were 19±7, 17±4, 17±4, 16±4, 15±6, 15±4, respectively. There were no significant differences among them ( F=1.674, 1.736, all P>0.05). Under a single CTP scan, the radiation dose of 70, 80 and 100 kV groups were 1.6, 2.3 and 4.3 mSv, respectively. The does of the 70 kV group and 80 kV group were significantly lower than that of the 100 kV group, and the dose of the 70 kV group was also significantly lower than that of the 80 kV group (all P<0.001). Conclusions:The application of individualized scanning and contrast agent injection protocol based on IDR is feasible in myocardial CTP with successful image quality, and the radiation dose decreases significantly.

Low back pain is becoming an important factor affecting people's quality of life, while the age of its onset is getting younger and younger, and the social and economic losses caused by low back pain are huge every year. Intervertebral disc degeneration (IDD) is an important cause of low back pain. Due to multiple factors, biomechanical and structural changes occur in intervertebral disc tissue, including rupture of annulus fibrosus, protrusion of nucleus pulposus, which cause compression of spinal cord and nerve root, and lower back pain. Micro-RNA (miRNA) is a kind of single-stranded non-coding small molecule RNA, with 18-24 nucleotides in length, which exists widely in eukaryotes. As one of the important regulatory molecules of gene expression, it has been proved to play a key role in the initiation and progression of many diseases, and it may also play an important role in intervertebral disc degeneration. At present, the clinical treatment for IDD is mainly surgical treatment to alleviate clinical symptoms. Even if surgical treatment can achieve good results, it will bring great physical trauma and economic burden to patients. The role of miRNA in IDD is one of the hotspots in the current academic research. Studies have shown that miRNA has abnormal expression patterns in degenerative intervertebral disc tissues and participates in a variety of pathological processes of IDD. At present, some miRNAs have been proved to be related to a variety of pathological processes in IDD, including nucleus pulposus cell apoptosis and proliferation, extracellular matrix degradation, autophagy, inflammation and cartilage endplate degeneration. The comparative study of gene chip showed that there were significant differences in the expression of some miRNAs between degenerative and normal nucleus pulposus cells. These differentially expressed miRNAs may be involved in the process of nucleus pulposus cell degeneration by regulating their respective upstream or downstream pathways. Most of the regulatory pathways are crossed and parallel, thus constructing a huge miRNA regulatory network. Understanding the target genes and mechanisms of miRNA in the pathogenic process can provide an important reference for the origin, development and prognosis of IDD. In this article, the important role of miRNA in IDD and the potential significance of clinical treatment are reviewed. With the in-depth study of miRNA and the molecular biological mechanism can provide new ideas for the diagnosis and treatment of IDD, which is likely to become a new strategy for biological treatment of IDD.

Intervertebral disc degeneration (IDD) refers to the biomechanical and structural changes of intervertebral disc tissues due to the effects of a variety of factors. Theses physical or chemical factors lead to the rupture of the annulus fibrous, protrusion of the nucleus pulposus tissue, compression of the spinal cord and nerve roots and causing the patient's back and leg pain ultimately. Degeneration of intervertebral disc is a common condition in clinical practice, which affects working ability and daily living quality of patients seriously. Due to the change of living habits, the population with IDD tend to be younger recently. The etiology, pathogenesis and diagnosis and interventions of IDD have always been hot topics in spinal surgery. Thus, animal models of IDD close to the human body has a of great clinical significance for exploring the etiology, pathological mechanism and non-surgical treatment of IDD. At present, the establishment of IDD model mainly includes two following aspects, in vitro model and in vivo model. There are two main in vitro models, cell culture and tissue or organ culture. There are seven kinds of in vivo models, which can be divided into two categories, namely spontaneous and induced model. Among them, the spontaneous degeneration model is also regarded as age-related degeneration, while the induced model refers to the construction of the animal model of IDD by injuring the structure of the intervertebral disc, changing the biomechanical structure of the vertebral body, development spinal instability caused by surgery or constructing nerve root compression and gene knockout. Although there are many methods of animal modeling and literature reports, each method has its own advantages and disadvantages. The advantages and disadvantages should be weighed when choosing the animal models.

Objective:To investigate the impact on image quality of a new deep learning image reconstruction (DLIR) algorithm in dynamic CT myocardial perfusion imaging (CTP) and to explore whether the algorithm affects the quantification of myocardial blood flow (MBF) in swine.Methods:Dynamic CTP imaging was performed in five anesthetized domestic swine [body weight (58.6±1.9) kg], at both rest and stress state. The tube voltages were fixed at 100 kV, and the low-dose and high-dose scanning tube currents were set as 150 mA and 300 mA, respectively. The low-dose (LD) scan data were reconstructed with filtered back projection (FBP) and three different DLIR strengths (low, medium, and high). High-dose (HD) scan data were reconstructed with filtered back projection (FBP) only. Subjective (5-point scale) image quality was evaluated, and objective evaluations included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) was performed. Linear regression was used to test the linear trend between DLIR algorithm strength and image quality. Data sets normality was determined by the Shapiro-Wilk test. Comparisons between groups were performed using Student′s t test for normally distributed data or the Wilcoxon rank-sum test for non-normally distributed data. Results:The mean effective radiation dose was 7.2 and 3.8 mSv for the HD protocol and the LD protocol, respectively, with statistically significant difference found between two protocols ( t=282.50, P<0.001). The image noise of the images obtained at LD protocol gradually decreased and the image SNR and CNR gradually increased with DLIR algorithm strength increased ( F=60.10,35.87,41.41; P for trend were all<0.001). As for DLIR-high strength (LD) and FBP (HD) images, the image noise values were (31.7±3.1) and (38.2±1.2) HU; SNR were 16.6±2.0 and 13.8±0.8; CNR were 14.5±1.7, 11.6±0.9, respectively, with significant differences found between two groups ( t=5.70, 4.15, 5.68; all P<0.05). The subjective scores of DLIR-high strength (LD) and FBP (HD) images were significantly different (4.8±0.4 and 4.2±0.6, Z=2.12, P<0.05). No significant differences were found between the MBF calculated from FBP (LD) and from DLIR-high strength (LD), with the values as (81.3±17.3) ml·100 ml -1·min -1 vs. (79.9±18.3)ml·100 ml -1·min -1 at rest state; and (99.4±24.9)ml·100 ml -1·min -1 vs. (100.7±27.3) ml·100 ml -1·min -1 at stress state ( t=1.10, 0.89; P>0.05). Conclusion:DLIR-high strength can improve image quality of myocardial CTP in swine, and can reduce radiation dose without influencing the MBF calculation.