Dynamic assessment of venous anatomy and function in neurosurgery with real-time intraoperative multimodal ultrasound: technical note

Abstract

<jats:p>The relevance of the cerebral venous system is often underestimated during neurosurgical procedures. Damage to this draining system can have catastrophic implications for the patient. Surgical decision-making and planning must consider each component of the venous compartment, from the medullary draining vein to the dural sinuses and extracranial veins. Intraoperative ultrasound (ioUS) permits the real-time study of venous compartments using different modalities, thus allowing complete characterization of their anatomical and functional features. The B-mode (brightness mode) offers a high-resolution anatomical representation of veins and their relationships with lesions. Doppler modalities (color, power, spectral) allow the study of blood flow and identification of vessels to distinguish their functional characteristics. Contrast-enhanced US allows one to perform real-time angiosonography showing both the functional and the anatomical aspects of vessels.</jats:p><jats:p>In this technical report, the authors demonstrate the different applications of multimodal ioUS in neurosurgery for identifying the anatomical and functional characteristics of the venous compartment. They discuss the general principles and technical nuances of ioUS and analyze their potential implications for the study of various venous districts during neurosurgical procedures.</jats:p>

Oncological, Vascular, and Spinal Uses of Contrast-Enhanced Ultrasound in Neurosurgery

“…Thanks to their structure, sulfur hexafluoride-filled lipidic microbubbles cannot diffuse to the interstitial space, giving a representation of the vascular district only. The degree of contrast enhancement (CE) is a consequence of the density of the capillaries, which in turn is proportional to tissue activity [19,21].…”

The role of contrast-enhanced ultrasound in neurosurgical disease

“…When CEUS is coupled with B-mode ultrasonography, surgeons can visualize the lesion, the feeding and draining vasculature, and changes in the surrounding anatomy attributable to mass effect. 23,33 CEUS is notably useful in identifying the primary feeding artery and any concealed vasculature within dural arteriovenous fistulas (DAVFs). In a recent study, Prada et al evaluated the role of CEUS in spinal DAVF surgery.…”

“…8,33 Thus, CEUS can be repeated several times intraoperatively to evaluate the vascular anatomy as the surgery progresses. 7,8,23 This is particularly useful when it becomes necessary to evaluate the extent of tumor excision, by highlighting any residual tumor perfusion after the initial surgical removal. 2,5,7,21 The metabolic products of the contrast agent used in this modality are expelled through the lungs rather than the kidneys, as happens with MRI and CT, and can be safely used in patients with chronic kidney disease.…”

“…28 CEUS allows for the visualization of both superficial and deep vascular structures, reducing the need for invasive surgical exposure while also decreasing the overall time of surgery. 23,24,33 Particularly when guided by prior B-mode ultrasound, CEUS provides a broader view of the anatomical relationship among the lesion of interest, the surrounding parenchyma, and vessels of any diameter and flow velocity. 21 In most cases, CEUS can clarify borders between the tumor mass and peritumoral edema that are otherwise ill-defined on regular B-mode ultrasound imaging.…”

“…21,25 Brain perfusion and parenchymal anatomy are measured using an algorithm that measures the echo intensity of these reflected harmonics over time. 21,23 This algorithm suppresses linear ultrasound echogenicity of the surrounding parenchyma, isolating the nonlinear echogenicity of blood flow and allowing for visualization of the vascular architecture. 6 In this article, we outline the advantages of CEUS in several categories of neurosurgical disease.…”