Comparison of different new ultrasonic technologies in resection assessment of neurosurgery

New ultrasound (US) techniques, such as contrast-enhanced ultrasound (CEUS) and shear wave elastography (SWE), are being used to identify artifacts, guide the interventions and evaluate the extent of resection, as it is difficult for gray-scale ultrasound to distinguish the artifacts in intraoperative ultrasound (IOUS). However, to date, no comparative study has been conducted on the role of several new US technologies in guiding brain tumor resection. Thus, this study sought to compare the roles of various new US technologies in guiding brain tumor resection to find a convenient and useful guiding technology for brain tumor resection.

From July 2022 to July 2023, 64 brain tumor patients (33 men and 31 women), with ages ranging from 26 to 78 years (53.2±11.6 years), were included in the study. Before surgery, a planned resection (pRS) was determined for all of the included patients by a multidisciplinary neuro-oncology team. All patients underwent microsurgical resection of the lesion. After the craniotomy and before the dural opening, ultrasonic techniques, including B-mode, micro-flow imaging (MFI), CEUS, and SWE, were used to evaluate the features of the brain tumor and its surrounding structure. Then, those ultrasonic techniques were applied to each patient to confirm the microsurgical margin achieving the pRS at the end of the resection. Next, 3 days after surgery, a magnetic resonance imaging (MRI) scan was performed on each patient as the reference standard. The agreement between B-mode, color Doppler flow imaging (CDFI), MFI, CEUS, SWE, and MRI was measured by Fleiss' kappa agreement.

In the evaluation of the surgical resection edges, all the included US technologies showed substantial agreement compared to the MRI results. The Kappa values were 0.717, 0.751, 0.714, and 0.892 for B-mode, MFI, SWE, and CEUS, respectively. CEUS and MRI showed the best diagnostic consistency. CEUS had the highest sensitivity, specificity, positive predictive value, and negative predictive value under the receiver operating characteristic (ROC) curve analysis (77.78%, 100%, 100%, and 86.05%, respectively), followed by MFI. B-mode and SWE showed similar accuracy in detecting tumor residue.

US is a convenient and cost-effective method for guiding the procedure and evaluating the extent of resection in neurosurgery. CEUS has the highest diagnostic accuracy for residual lesions among the new US technologies. Thus, MFI can be recommended as a technique for guiding and evaluating residues in neurosurgery in addition to CEUS.