Criteria for using imaging ultrasound during brain and spinal cord surgery.

Abstract

In contmdistinction to the widespread use of imaging ultrasound in exmnining many other l'egions of the body, ultrasonography of the centralnervow; system has been seriously limited because high· frequency ultrasound dues not readily penetrate the bon y covering of this organ system. The difl'iculty in using ultrasound to visualize lm1in and spinal cord structm·es is a paradox in the history of medical ultr:•sonogmphy hecause much of the interest in the early days of this field of diagnostic imaging was in the central nervous system. ~lore than 30 years ago, French et a!. used A-mode s<:anning to localize il subcortical brain tumor in an e:\+ cised postmortem specimen. U! Advances in central nervous system ultrasonography have been made, however, in applic.ltions in which the skull or vertebral bodies have not impeded the pasage of ultrasound waves. There have been three pl'incipal areas of such applkations: postoperative scanning through craniectomy portals, : l .~ imaging through the fontanels of infants,5·6 and intraoperative ultrasonography.Operative use of imaging ultrasound for brain disease was first employed in the 1960s. ' :' "-II However, the A-mode scanning available then presented problems of interpretation which prevented widespread applkation of this dia~nostic tool. ~lore recent adnmces in ultrasound technology, particularly the development of high-resolution real-time B-mode scanners, have eliminated manv of the em~ lier difHculties in operative imaf,ting. This IHL'i re· suited in u renewed trial of ultrasonic scanning in various types of operations on the hrain 1 :2 -:H and spinal cord. ~. 2l iAs part of a pro~ra m to assess the utility of op· erative ultrasonography in a number of surgical dis· ciplines. we employed ultrasound imaging during brain and spinal cord surgery. \Ve have reviewed our experience of spedfic applications in terms of the impact of ultrasonography on management during opemtion. From this analysis we have de· termined the situations in which ultrasonograph~· during neurosurgery can be most helpful. This analvsis has enabled us to establish criteria for the most productive use of ultrasound during brain and spinal cord surgery and is the basis of this report. METHODSOperative ultrasonography during neurosurgical procedures was performed with real-time B-mode instruments employing mechanically driven sectorscanning transducers. High Stoy. Philips, and Dia-155

Correlation of intra-operative ultrasound with histopathologic findings after tumour resection in supratentorial gliomas

“…In the literature on IOUS only annotations exist concerning the role of IOUS to screen resection cavity for tumour remnants [4,23,53,61,64,76]. No studies have been published so far, in which a systematic correlation between sonographically guided biopsies and histopathological examinations after tumour resection was performed.…”

“…Some authors have used IOUS to control the extension of tumour removal [44,53,56,59,61], but a histological verification has so far not been performed.…”

Delineation of brain tumor margins using intraoperative sononavigation: Implications for tumor resection

“…1 However, considerable controversy exists as to whether the echogenicity of edema can impair the mapping of brain tumors. 1,3,6,7 In the present study, sononavigation revealed that the majority of areas of brain edema were hyperechoic, while other areas of brain edema were both hyperechoic and hypoechoic. The hyperechoic nature of brain edema surrounding some tumors interfered with the assessment of tumor boundaries in lesions of types 2 and 3.…”

Intraoperative Ultrasound Technology in Neuro-Oncology Practice—Current Role and Future Applications

“…However such studies are few and more evidence needs to accumulate before conclusive inferences can be drawn.Other benefits of IOUSObjective assessment of the overall utility of IOUS as an intraoperative tool has also been described by many authors. 52,[90][91][92] Whereas the effect of the US (and for that matter, any other adjunct) on extent of resection, survival, operating times, and cost-effectiveness are easily fledged navigable US systems would cost a fraction of the cost of IOMR systems. Further, logistics and work flow during surgery is far simpler with ultrasound systems especially for awake procedures when IOMR assisted surgery becomes challenging.…”