Objective image analysis of real-time three-dimensional intraoperative ultrasound for intrinsic brain tumour surgery

Abstract

BackgroundThere is growing evidence that maximal surgical resection of primary intrinsic brain tumours is beneficial, both by improving progression free and overall survival and also by facilitating postoperative chemotherapy and radiotherapy. Hence, there has been an increase in the popularity of real-time intraoperative imaging in brain tumour surgery. The complex theatre arrangements, prohibitive cost and prolonged theatre time of intraoperative MRI have restricted its application. By comparison, intraoperative three-dimensional ultrasound (i3DUS) is user friendly, cost-effective and portable and adds little to surgical time. However, operator-dependent image quality and image interpretation remain limiting factors to the wider application of this technique. The aim of this study was to explore objective i3DUS image analysis and its potential therapeutic role in brain tumour surgery.MethodsA prospective, observational study was undertaken (approved by the local Research and Ethics Committee prior to recruitment). Biopsies were taken from the solid, necrotic, periphery and brain/tumour interface of intrinsic primary brain tumours. Digital i3DUS images were analysed to extract quantitative parameters from these regions of interest (ROI) in the i3DUS images. These were then correlated with the histology of the relevant specimens. The histopathologist was blinded to the imaging findings.ResultsNinety-seven patients (62 males; mean 54 years) with varying gliomas (84 high grade) were included. Two hundred and ninety regions of interest were analysed. Mean pixel brightness (MPB) and standard deviation (SD) were correlated with histological features. Close correlations were noted between MPB and cellularity, and SD and intrinsic cellular diversity.ConclusionsMPB and SD are objective measures reflecting the sensitivity of i3DUS in detecting the presence and extent of intrinsic brain tumours. They indirectly suggest heterogeneity, cellularity and invasiveness, providing information of the nature of the tumour, and also reflect the sensitivity of intraoperative US to detect the presence of residual intrinsic brain tumours. Development of this paradigm will enhance i3DUS use as an adjunct in brain tumour surgery. Optimizing its intraoperative application will impact surgical resection and, hence, patient outcome.

Application of Multiparametric Intraoperative Ultrasound in Glioma Surgery

“…Three-dimensional ultrasound (3DUS) is based on two-dimensional ultrasound (2DUS) imaging with the addition of the coronal section. Intraoperative 3DUS is a portable imaging technique that provides real-time imaging, which can be integrated into existing theater infrastructure without the need for its own dedicated suite [7]. Recently, 3DUS imaging has already been used for cardiac, obstetric, and gynecological applications [42].…”

“…Given that reconstructed images are clear and intuitive, they can be used to measure the size and volume of gliomas, as well as clearly display the 3D shape and spatial location of the lesion. This technique could provide accurate visualization of blood vessels, the ventricular system, lesions, and immediate complications, such as hematomas [7]. 3DUS can not only make up for the spatial imaging deficiency of two-dimensional ultrasound but also reduce artifacts produced after tumor resection [44].…”

“…Studies have shown that gross total resection (GTR) can positively influence quality of life, as well as progression-free survival (PFS) and overall survival (OS) [5]. Hence, the ability to achieve GTR, including precise localization and accurate tumor border description, has promoted an increase in the popularity of real-time intraoperative imaging, which is crucial for each surgical step [6,7]. Common intraoperative diagnostic imaging techniques include intraoperative magnetic resonance (IOMR), intraoperative computed tomography (IOCT), intraoperative ultrasound (IOUS), and dyes (fluorescence).…”

“…Unlike IOMR, an established imaging tool for tumor visualization and resection, IOUS has been highly regarded for its ease of use, real-time capability, portability, and affordability [7]. Moreover, IOUS adds little to the operative time.…”

The role of intraoperative ultrasound in gross total resection of brain mass lesions and outcome

“…Several studies showed the benefits of intraoperative ultrasound for achieving maximal safe resection in brain tumor surgery [10].…”