Contrast-free Ultrasound Microvascular Imaging for Intraoperative Detection of Human Spinal Cord Tumor: An in vivo Feasibility Study

Spinal cord tumor (SCT) is a critical disease with low incidence but high disability rate and morbidity. Surgical resection is a primary and effective treatment of SCT, but intraoperative detection of SCT highly depends on the clinical experience. Pathological studies show that microvascular proliferation (MP) occurs in some kinds of SCTs but it cannot be observed by conventional medical imaging modalities such as magnetic resonance imaging (MRI). Ultrasound microvascular imaging (UMI) has been developed to map tumor-related microvasculature. In this study, we introduced UMI into the visualization of microvessels in two types of human SCTs (i.e., ependymoma and schwannoma) and their corresponding normal tissues. For quantitative evaluation, microveseel density (MD) and power Doppler density (PDD) in the tumor region and normal tissue region of the two SCTs were calculated, respectively. Results show that the MDs and PDDs in the tumors are significantly higher than those in the normal tissues. Qualitative and quantitative results demonstrate that MP occurs in the tumor region compared with normal tissue, which is consistent with the results of immunohistochemical staining examination. In conclusion, this study demonstrate the feasibility of UMI in the intraoperative detection of human SCT.