Finite element analysis of characteristics of spinal cord compression in patients with early cervical spondylotic myelopathy under dynamic position / 中国组织工程研究

BACKGROUND:Cervical spondylotic myelopathy is a progressive disease leading to dysfunction in the middle-aged and elderly,and early diagnosis is difficult.In recent years,some clinical scholars have found that dynamic magnetic resonance imaging technology can detect spinal cord compression in a dynamic position earlier,but its specific biomechanical mechanism needs to be clarified. OBJECTIVE:To investigate the biomechanical compression characteristics of early cervical spondylotic myelopathy in hyperextension and flexion position,and to verify the effectiveness of dynamic magnetic resonance imaging in the diagnosis of early cervical spondylotic myelopathy. METHODS:A retrospective analysis was made on the patients who underwent cervical dynamic magnetic resonance imaging in the Department of Orthopedics of First Affiliated Hospital of Guangxi University of Chinese Medicine from January to June 2022.16 subjects were selected and divided into two groups.The pathological group included 8 patients with early cervical spondylotic myelopathy with hypertrophy of ligamentum flavum as the main sign,with 5 male patients and 3 female patients.The normal group included 8 normal degenerative people,with 4 male patients and 4 female patients.All patients were photographed with cervical CT plain scan,magnetic resonance imaging plain scan,and dynamic magnetic resonance imaging plain scan.This study was divided into the following three parts:(1)collect the dynamic magnetic resonance imaging image DCOM data of two groups of subjects,and collect the cervical vertebra CT and neutral magnetic resonance imaging image DCOM data to understand the bone and soft tissue of the two groups of subjects in the neutral position.(2)Based on the DCOM data of magnetic resonance imaging and CT plain scan,the three-dimensional finite element models of lower cervical vertebra(C3-7)of normal degenerative population and early cervical spondylotic myelopathy patients were established by reverse engineering software.The equivalent stress and equivalent elastic strain of the spinal cord and posterior dura were analyzed,and the distribution of stress and strain was observed.(3)After obtaining the stress and strain data,the data between groups were compared to analyze the mechanical characteristics of spinal cord compression caused by early cervical spondylotic myelopathy in a dynamic position and to verify the effectiveness of dynamic magnetic resonance imaging in the diagnosis of early cervical spondylotic myelopathy. RESULTS AND CONCLUSION:(1)When simulating the posterior extension,flexion and neutral position of the lower cervical vertebrae(C3-7)in the two groups,the values of stress and strain in the posterior part of the spinal cord were in the following order:extension>flexion>neutral(P<0.05).The strain values from large to small were as follows:extension>flexion>neutral(P<0.05).(2)Compared with the normal degenerative population model,the equivalent stress and strain of the spinal cord in the pathological group were higher than those in the normal group under two degrees of freedom of flexion and extension(P<0.05).The distribution area of stress and strain in the posterior part of the spinal cord was irregular.(3)In the neutral position,there was no significant difference in the strain value of the spinal cord between the two groups(P>0.05),and the strain distribution was uniform and regular.(4)It is indicated that in the cervical extension position,the dural sac and the posterior part of the spinal cord were compressed and deformed in the early cervical spondylotic myelopathy patients with the hypertrophy of ligamentum flavum as the main sign,and the degree of compression deformation of the spinal cord was significantly higher than that in the anterior flexion position and neutral position.In the neutral position,there were no obvious signs of spinal cord deformation in patients with early cervical spondylotic myelopathy.This study verified the role of dynamic magnetic resonance imaging in the diagnosis of early cervical spondylotic myelopathy from the point of view of biomechanics.

Effects of dynamic transperineal ultrasound and dynamic magnetic resonance imaging defecography in the diagnosis of rectocele / 中华消化外科杂志

Objective To evaluate the agreement between dynamic transperineal ultrasound (DTP-US)and dynamic magnetic resonance imaging defecography (DMRD) in the diagnosis of rectocele,and to compare the correlation and difference between the depth of rectocele measured by DTP-US and DMRD.Methods The clinical data of 18 female patients with rectocele who were admitted to the Third Affiliated Hospital of Nanjing University of Chinese Medicine from September 2011 to May 2012 were retrospectively analyzed.All patients received examination via DTP-US and DMRD,and the agreement of the 2 diagnosing methods was analysed.The accurate rates of the detection of other pelvic floor abnormalities by the 2 methods were calculated.The agreement of DTP-US and DMRD in diagnosing rectocele was analysed by Cohen's kappa test.The difference of the depth of rectocele measured by DTP-US and DMRD was compared by paired samplet test,and the correlation of the depth of rectocele measured by DTP-US and DMRD was analyzed by using the Pearson correlation coefficient.Results Of the 14 patients diagnosed by DTP-US,there were 7 patients with bladder prolapse,5 with unrelaxed pelvic floor,2 with uterine prolapse,2 with rectal internal mucous intussusception and 1 with enterocele; of the 18 patients diagnosed by DMRD,there were 12 patients with bladder prolapse,8 with unrelaxed pelvic floor,8 with uterine prolapse,6 with rectal internal mucous intussusception and 1 with enterocele.The agreement coefficient between DTP-US and DMRD in diagnosing rectocele was obvious (κ =0.737,P ＜ 0.05).The depth of the rectocele detected by DTP-US and DMRD were (15 ±6)mm (range,7-24 mm) and (27 ±7)mm (range,20-41 mm),with significant difference between the 2 groups (t =-16.124,P ＜0.05).There was a high coefficient between DTP-US and DMRD in detecting the depth of rectocele (| r | =0.874,P ＜ 0.05).The depth of rectocele detected by DMRD increased as the increase of depth of rectocele detected by DTP-US (| r | =1.000,P ＜ 0.05).Conclusions The agreement between DTP-US and DMRD in diagnosing rectocele is high.The depth of rectocele measured by the 2 methods not only has statistically significance,but also exists a high degree of correlation.While DTP-US is superior to DMRD in terms of quick diagnosis and better telerance of patients.

Evaluation of craniofacial morphology in patients with obstructive sleep apnea using lateral cephalometry and dynamic MRI.

Context: Obstructive sleep apnea (OSA) is a potentially life-threatening disorder, characterized by repeated collapse of the upper airway during sleep with cessation of breathing. The altered mouth breathing produces morphological changes in craniofacial region. Aim: This study was designed to compare and validate the craniofacial morphological characteristics in patients with OSA using lateral cephalometry and to investigate the dentofacial characteristics of patients with OSA with respect to the obstructive sites determined by dynamic magnetic resonance imaging (MRI) to more accurately clarify the pathophysiological features. Materials and Methods: 10 patients with OSA were divided into two groups of five each according to their obstructive site determined by dynamic MRI. (1) Obstruction at the retropalatal and retroglossal region (Rp + Rg group) and (2) obstruction at the retropalatal region (Rp group). Lateral cephalogram both in upright and supine position was taken for all the subjects. In addition, dynamic MRI was performed to identify the sites of obstruction of the upper airway. Statistical analysis used: Independent t-test was performed to evaluate the significant difference in the upright cephalometric variables between the study and control group and between the two groups. The changes in skeletal and soft tissue parameters with change in posture was assessed within the study and control group by paired t test. P value of ≤0.05 was considered as statistically significant. Results: The study indicated that the first group of patients with both retropalatal and retroglossal obstruction showed signs of skeletal discrepancy that predisposed to obstruction at the retroglossal level and the soft tissue components like the soft palate and tongue that contributed to retropalatal obstruction. However, the second group of patients with only retropalatal obstruction had primarily soft tissue components associated with increased BMI that contributed to retropalatal obstruction. Conclusion: Evaluation of craniofacial morphology in OSA patients is bound to help the concerned specialist in recognizing the morphological changes induced by altered sleep pattern so as to provide the appropriate treatment.

Role of dynamic magnetic resonance imaging in the diagnosis of female stress urinary incontinence / 中华泌尿外科杂志

Objective To evaluate the application of dynamic magnetic resonance imaging in the diagnosis of female stress urinary incontinence(SUI). Methods Dynamic magnetic resonance imaging(DMRI)were performed on 30 healthy female volunteers and 35 female SUI patients.DMRI of the pelvic floor at rest and OR maximal strain were performed by using sagittal T2-weighted fast gradient sequences.The distance of Urethra-vesical junction to the pubococcygeal line,the posterior vesicourethral angle and angle of inclination of the urethral axis were measured at rest and on maximal strain position.The t-value exact test were used to analyze the data. Results At rest the Urethravesical junction laid above pubococcygeal line on both control and SUI groups.Mean distance from the Urethra-vesical junction to pubococcygeal line at rest had no difference between the two groups.On straining,the mean Urethra-vesical junction descent distance in the SUI group(-0.9±1.1cm)was significantly higher than in control group(-0.14±0.3 cm),(P＜0.001).On straining,the mean angle of urethral inclination in the SUI group(65±37°)was significantly bigger than in control groups (17±21°),(P＜0.05).The posterior vesicourethral angle in the SUI groups(156±36°)was significantly bigger than in control groups(113±28°),(P＜0.05). Conclusion Dynamic magnetic resonance imaging is a non-invasive.easily applied method in the diagnosis of SUI.