Objective To evaluate the imaging performance and characteristics of peripheral primitive neuroectodermal tumors (pPNET), in order to raise awareness of the disease and the diagnostic accuracy. Methods Thirteen patients with pPNET who confirmed by puncture or pathology were enrolled in this study. The CT and MRI features were retrospectively analyzed. Four patients received simple routine CT examination, and 9 patients had MRI examination based on X-ray, CT examination. Results The part of body involved was more widely.Two patients occurred in the sinuses, 1 patient in the chest wall, 1 patient in the lung, and 3 patients in the abdominal and pelvic(1 patient involved the pelvic floor through the pelvic wall lesions to basins), 1 patient in the spine, and 5 patients located in the extremities. The characteristics of pPNET by CT and MRI in soft tissue of 8 patients showed single large soft tissue mass, and the biggest was 11.2 cm × 10.6 cm. In bonds and joints of 5 patients, CT and MRI showed wide range of soft tissue mass, mixed internal signal/density with obviously uneven enhancement, significant bone destruction and dissolvable osseous changes, and no obvious tumor bone and calcification. Conclusions Each site has its relative imaging characteristics of pPNET. CT and MRI can show lesions involving the scope, internal structure, with or without adjacent tissue invasion and metastasis, and provide guidance for clinical treatment and selecting treatment regimen. But in the end, it depends on the diagnosis of pathological and immunohistochemical examination.

In order to study the biological characteristics and whole-genome sequence of Streptococ-cus equi,a sheep-derived Streptococcus equi preserved in our laboratory was subjected to recovery,biochemical experiments,drug susceptibility tests and animal experiments,and followed by whole genome sequencing and annotation of the gene functions of the genome by using the biogenetic da-tabase.The biochemical identification results showed that this strain could ferment sugars,but the results of nitrate,catalase,V-P test,and M-R test were negative;the drug susceptibility test results showed that this strain was highly sensitive to most antibiotics and was resistant to kanaphylaxis.It was resistant to amikacin and amikacin;animal experiments showed that the lethality rate of this strain to mice was 100％,and the median lethal dose of this strain was measured to be 4.86X 106 CFU/kg.According to the pathological section results of mice,it showed that the lungs,liver,kidneys,and spleen all had varying degrees of lesions.The whole genome sequencing results showed that the total genome length of this strain is 2 272 497 bp,the G+C content was 41.1％,and it was predicted to contain 2 124 CDS regions.The RNA prediction results showed that the number of rRNA and tRNA was 15,and the number of tRNA was 57.There were four prophages and gene islands,and there were 362 pathogenicity-related genes in the VFDB database without CRISPR sequences.This study analyzed the complete genome of Streptococcus equi derived from sheep,and also provided a theoretical basis for the treatment,prevention and control of the disease.