Intraoperative Ultrasound Localization Microscopy of Human Spinal Cord: An In Vivo Feasibility Study

摘要

Spinal cord (SC) is the relay station and reflex center of central nervous system, its function is therefore very important for nerve conduction pathway. Spinal tumor (ST) is the typical disease of SC. In clinic, the standard treatment of ST is resection and a series of sequelae occur with imprecise surgical removal. Therefore, the delineation of the lesion boundaries of ST is very critical in surgery. Magnetic resonance (MR) imaging and intraoperative frozen section biopsy (IFSB) are usually used to assist in determining ST boundaries or boundary type, However, they suffer from severe limitations, such as unclear boundaries of certain types of ST in MR imaging and the inaccuracy of IFSB. Ultrasound localization microscopy (ULM) with contrast microbubbles (MBs) have been developed by several groups and may have potential in determining ST boundaries during surgery. Therefore, we apply ULM to human SC to distinguish pathological tissue from normal tissue in SC. In this study, intramedullary cavernous malformation (ICM), a typical ST, is imaged to demonstrate the feasibility of ULM of SC. Maximum intensity projection (MIP) images of filtered MBs of normal SC and ICM are obtained for comparison. Results indicate that the boundaries of normal SC and ICM in ULM images are more definite than those in MIP images. Quantitatively, the microvessel intensity (MVI) in normal SC is higher than that in ICM, while other indexes, such as direction entropy (DE), mean velocity (MEV), minimum velocity (MinV), and maximum velocity (MaxV), are similar in normal SC and ICM, which suggests the potential of ULM in surgery of SC in terms of distinguishing pathological tissue.