Navigated intraoperative ultrasonography for brain tumors: a pictorial essay on the technique, its utility, and its benefits in neuro-oncology

Abstract

Intraoperative imaging has become one of the most important adjuncts in neurosurgery, especially in the surgical treatment of intra-axial tumors. Navigation and intraoperative magnetic resonance imaging have limitations, and intraoperative ultrasonography (IOUS) has emerged as a versatile and multifaceted alternative. With technological advances in ultrasound scanners and newer multifunctional probes, the potential of IOUS is increasingly being utilized in the resection of tumors. The addition of image guidance to IOUS has exponentially increased the power of this technique. Navigated ultrasonography (nUS) can now overcome many of the limitations of conventional standalone two-dimensional ultrasonography. In this pictorial essay, we outline our nUS technique (both two-and three-dimensional) for the resection of intra-axial tumors with illustrated examples highlighting the various steps and corresponding benefits of the technique.

Surgical considerations for maximal safe resection of exophytic brainstem glioma in the pediatric age group

“…[ 3 ] According to Vougioukas et al ., the supracerebellar infratentorial approach provides a feasible and reliable surgical option with a very low morbidity rate for tumors originating from the pontomesencephalic region. [ 20 ]…”

“…Many studies concluded that intraoperative US is more effective than the other types of image-guided navigation systems, such as MR-based neuronavigation and intraoperative MRI, especially when working with limited resources, as US is cheaper and accurate and could be used repetitively before starting tumor excision and frequently during excision to have an estimate about the proximity of the brainstem and to ensure maximal possible resection [ Figure 7 ]. [ 18 , 21 ] MRI-based navigation is limited by the brain shift that occurs after the opening of the dura, manipulations, or CSF drainage. Intraoperative MRI is logistically and financially not attractive for most surgical theaters.…”

“…Intraoperative MRI is logistically and financially not attractive for most surgical theaters. [ 19 , 21 ] Intraoperative US could delineate the surrounding anatomical landmarks for better orientation: the falx (a linear hyperechoic structure), ventricles (anechoic), and choroid plexus (densely hyperechoic tufts within the ventricles). [ 21 ] Many considerations should be taken for obtaining more accurate and clear US images as keeping the surgical field parallel to the floor when positioning the patient for ability to fill it with clear fluid instead of blood and debris before imaging and making the tumor or its cavity in perpendicular axis to US.…”

“…[ 21 ] Many considerations should be taken for obtaining more accurate and clear US images as keeping the surgical field parallel to the floor when positioning the patient for ability to fill it with clear fluid instead of blood and debris before imaging and making the tumor or its cavity in perpendicular axis to US. [ 21 ]…”

Intraoperative MR Imaging during Glioma Resection

“…Gliomata appear hypoechoic on ioUS, and this characteristic can be a reliable method to navigate toward glioma during surgical procedure. 5,11,157,[171][172][173][174][175][176][177][178][179][180][181][182][183] The use of ioUS is gaining popularity due to accuracy in localizing glioma, evaluating the extent of resection and cost-effectiveness. 12 In particular, ioUS may be used to provide information on brain shift.…”