Purpose To establish myocardial infarction model in rabbits and to evaluate cardiac function and pathological changes.Materials and Methods In 35 New Zealand white rabbits, the left anterior descending branch (LAD) of the coronary artery was ligated. The cardiac function was evaluated using echocardiography, and the blood serum brain natriuretic peptide (BNP) level was examined preoperatively, on postoperative day 1, and in 1 week, 2 weeks, 4 weeks and 8 weeks for comparison. Pathological sections and HE staining were performed to observe pathological changes. Results The death rate was 28.6% (10/35). There was progressive increase in left ventricular end systolic diameter (LVESD) and left ventricular end diastolic diameter (LVEDD) at 1 week, 2 weeks and 4 weeks (P<0.05). There was progressive decrease in left ventricular ejection fraction (LVEF) and left ventricular fractional shortening fraction (LVFS) at 1 day, 1 week, 2 weeks and 4 weeks (P<0.05). The BNP level started increasing in 1 day, peaked in 1 week, then gradually decreased but remained higher than preoperative level in 8 weeks (P<0.01). Pathological section showed typical myocardial cell degeneration, necrosis, ifbrosis, calciifcation and scar formation. Conclusion This myocardial infarction model is satisfactory with signiifcant decrease of cardiac function and increase of BNP level.

To improve the part of the hardware about Xin Hua SL-IC model X-ray radiotherapy simulative position finder, using CR and PACS, so that located-picture shooting for the simulative position finder have been realized digital upgrade.
Automatic Data Processing ; Radiographic Image Enhancement ; Radiotherapy ; methods ; Tomography, Spiral Computed ; methods

Objective:To explore the feasibility of quantitative evaluation of extracellular volume (ECV) fraction in acute ST-segment elevation myocardial infarction (STEMI) by dual-layer spectral detector CT.Methods:The clinical and imaging data of 20 patients with STEMI who underwent cardiac contrast-enhanced CT and MRI from January to October 2019 in Renji Hospital affiliated to Shanghai Jiaotong University School of Medicine were retrospectively analyzed.The dual spectral detector was used in the enhanced CT scan of the coronary artery with retrospectively gate and the late iodine enhancement with prospective gate. Conventional image and holographic spectral image were obtained by iterative and spectral reconstruction. The short axis image of the heart matched with MR image was obtained by multiplanar reconstruction. Based on the data of spectral based image, the IDD map was reconstructed for the calculation of myocardial CT-ECV during the late iodine enhancement. ECV of infarcted myocardium, salvageable myocardium and remote myocardium based on CT and MRI were calculated respectively. Bland-Altman consistency test and intra group correlation coefficient analysis (ICC) were used to compare the consistency of two measurements and different methods. The correlation between CT-ECV and MRI-ECV was compared by Spearman method.Results:The CT-ECV values of infarcted, salvageable, and remote myocardium were 51.21 (49.27, 53)%, 38.64 (36.17, 40)%, and 51.21 (49.27, 53)%, respectively. The difference was statistically significant ( H= 43.17, P<0.01). The CT-ECV value of infarcted myocardium was significantly higher than that of salvageable myocardium and remote myocardium ( Z=-24.60, 35.40, P<0.01), but there was no significant difference between salvageable myocardium and remote myocardium ( Z= 10.80, P=0.15). The T 1 values of infarcted myocardium, salvageable myocardium and remote myocardium were (1 554.85±70.94), (1 443.85±67.28) and (1 307.05±91.73) ms respectively, the difference was statistically significant ( F=51.35, P<0.01). The T 1 value of infarcted myocardium was higher than that of salvageable myocardium and remote myocardium ( t=-5.07, 9.55, P<0.01), and salvageable myocardium was significantly higher than that of remote myocardium ( t=5.38, P<0.01). The MRI-ECV values of infarcted myocardium, salvageable myocardium and remote myocardium were 55.00 (49.27, 57.75)%, 33.50 (29.00, 35.00)%,and 27.00 (26.00, 29.00)%, respectively. The difference was statistically significant ( Z= 47.12, P<0.01). MRI-ECV of infarcted myocardium was significantly higher than that of salvageable myocardium and remote myocardium ( Z=37.45, -20.30, P< 0.01), and salvageable myocardium was significantly higher than that of remote myocardium ( Z = 17.15, P<0.05). The difference between CT-ECV and MRI-ECV measured by two physicians was good. The bias of Bland-Altman analysis was -0.1% (95% CI:-5.5%-5.2%), 0.8% (95% CI:-9.8%-8.2%), and the ICC values were 0.92 and 0.94, respectively. The bias of Bland-Altman analysis in CT-ECV and MRI-ECV consistency test was 4.00% (95% CI:-9.0%-16.9%) and ICC value was 0.88, which had a good correlation ( r=0.75, P=0.001). Conclusions:The iodine density based ECV fromdual-layer spectral detector CT can be used to quantitatively evaluate the changes of extracellular space after acute STEMI, which is helpful to quantitatively evaluate the histological changes after myocardial ischemia.