Objective To investigate and design a coincidence detection system for an all-digital small animal PET scanner and evaluate its preliminary performance properties.Methods This coincidence module adopted a coincidence identification mode based on singles data in list-mode.Using digital signal processing technology,energy calibration,crystal identification,timing alignment and coincidence events extraction were performed on singles data in list-mode.The obtained data could be used for image reconstruction.Results The 13 × 13 crystal array was well recognized by the position histogram of one lutetium yttrium orthosilicate (LYSO) crystal block.In the coincidence timing histogram of the micro-Derenzo phantom,1.36 ns full width at half maximum was obtained.The rods with a diameter of 1.2 mm were clearly displayed in the reconstructed image of the micro-Derenzo phantom.Conclusion The coincidence module can provide satisfactory performance to meet the design needs of an all-digital small animal PET scanner.

Objective:To investigate the role of p21 gene in the radiation-induced heart disease (RIHD) and to evaluate the effect on p21 gene knockout on RIHD phenotype in mouse models.Methods:p21 -/-mice were utilized in the experimental group, and p21 + /-mice were allocated in the control group. RIHD mouse models were established by exposure to 10 Gy whole heart irradiation by using a small animal radiation research platform. The heart samples were collected at 6 weeks after irradiation, the gross specimens were measured and subject to HE staining. The wall thickness and left ventricular ejection fraction of the mice were detected by the Vevo2100 ultrasound imaging system. The hypoxia in cardiac tissues was detected by the hypoxia probe method. The apoptosis of cardiac cells was determined by Tunel method. Results:Compared with the p21 + /-mice, the survival of p21 -/-mice was significantly shortened ( P=0.004), the interventricular septum was significantly thinned during the diastolic and systolic phases ( P=0.049, P=0.006), the left ventricular posterior wall was remarkably thickened ( P<0.001) and the left ventricular ejection fraction was significantly decreased ( P=0.004). The gross heart tissue was enlarged in the p21 -/-mice. HE staining showed the aggregation of inflammatory cells in cardiac tissues and disordered arrangement of myocardial cells. Significant hypoxia and apoptosis could be observed in the p21 -/-mouse heart tissues. Conclusions:p21 -/-mice are prone to more severe RIHD after irradiation, manifested with shortened cardiac survival, weakened cardiac function, abnormal cardiac structure, hypoxia and apoptosis of cardiac tissues. p21 plays an important role in the repair after cardiac irradiation.

Objective:To evaluate the effect of resveratrol on radiation-induced myocardial injury in mice.Methods:A total of 80 C57BL/6 mice were randomly divided into the control group, resveratrol (Res) group, radiation (RT) group and radiation+resveratrol (RT+Res) group. In the RT group, mice were given with heart radiation and mice in the Res group were given with resveratrol by gavage for 3 months. Cardiac ultrasound was used to evaluate cardiac function at 3 months after cardiac radiation. The hearts of mice were collected for HE staining, immunofluorescence, TUNEL staining, Masson staining and Western blot to evaluate the expression of silent information regulator 1 (SIRT1), the level of oxidative stress, inflammatory response, apoptosis and the degree of fibrosis in myocardial tissues. Experimental data were expressed as Mean ± SD. Continous data were statistically analyzed by t-test. Results:After 3 months of irradiation, compared with the control group, the ejection fraction (EF) and fractional shortening (FS) of cardiac function were decreased, and myocardial degeneration and disorder, reactive oxygen species (ROS) and inflammatory levels (interleukin-1β, interleukin-6, tumor necrosis factor-α), myocardial apoptosis (TUNEL positive cell rate) and fibrosis were increased in the RT group. In the RT+Res group, the cardiac function was improved, the expression of SIRT1 was increased, and the levels of oxidative stress, inflammation, myocardial apoptosis and fibrosis were decreased.Conclusions:Resveratrol can reduce oxidative stress, inflammatory infiltration, apoptosis and fibrosis of myocardium in mice with radiation-induced myocardial injury, thereby improving cardiac structural abnormalities and cardiac dysfunction. This protective effect can be mediated by upregulation of SIRT1 expression.