Objective:This study compares the magnetic resonance imaging (MRI) appearance of two types of breast tissue markers to investigate the appropriate clinical application of the markers.Methods:Breast MRI of 69 patients (78 masses) with breast tissue markers had been placed were analyzed retrospectively from November 2015 to August 2018 in our hospital. The sizes and shapes of breast tissue markers were assessed in axial fat-suppressed T2-weighted images, T1-weighted images and contrast-enhanced T1-weighed images.Results:The length of the coil nickel-free stainless steel markers were greater than ribbon titanium markers, with statistical difference in fat-suppressed T2-weighted images ( P=0.039). In contrast-enhanced T1-weighted images, all coil nickel-free stainless steel markers showed >6 mm diameter and round shape, and ribbon titanium markers showed >6 mm diameter ( n=20) or ≤6 mm diameter ( n=8), and round ( n=20), dot ( n=7) or band ( n=1) shapes. The categories of sizes and shapes in two types of breast tissue markers both had statistical significance ( P<0.001, P<0.001). Conclusions:Small breast lesions with breast tissue markers are not suitable for MRI evaluation. The artifact of ribbon titanium markers is smaller than coil nickel-free stainless steel markers, so they have less impact for lesions. The choice of the breast tissue markers and image evaluation methods should depend on the different clinical conditions.

DNA assembly is the core technology of synthetic biology. With the development of synthetic biology, researchers have developed different DNA assembly technologies that rely on DNA polymerase or DNA ligase, and also have developed some non-enzyme-dependent DNA assembly techniques to facilitate the automation of DNA assembly. The assembly of large fragments of DNA from a few hundred kb to Mb is mostly dependent on microbial recombination. In this paper, the three types of DNA assembly technologies, including enzyme-dependent, non-enzymatic and in vivo homologous recombination, are reviewed.
DNA ; Synthetic Biology