Contrast enhanced ultrasound (CEUS) is a dynamic intraoperative ultrasound and continuous modality providing real-time view of vascularization and flow distribution patterns of different organs and tumors.

Contrast-enhanced ultrasound (CEUS) is a relatively new technique that has become progressively more common because it allows, among other things, highlighting of neoplastic lesions:

Prada et al., performed CEUS in an off-label setting in 69 patients undergoing surgery for cerebral glioma. An intraoperative qualitative analysis was performed comparing intraoperative contrast enhanced ultrasound (iCEUS) with B-mode imaging. A postprocedural semiquantitative analysis was then performed for each case, according to EFSUMB criteria. Results were related to histopathology.

They observed different CE patterns: LGG show a mild, dotted CE with diffuse appearance and slower, delayed arterial and venous phase. HGG have a high CE with a more nodular, nonhomogeneous appearance and fast perfusion patterns.

This study characterizes for the first time human brain glioma with CEUS, providing further insight regarding these tumors' biology. CEUS is a fast, safe, dynamic, real-time, and economic tool that might be helpful during surgery in differentiating malignant and benign gliomas and refining surgical strategy ^{1) 2)}.

Ultrasound contrast agents might be a safe and effective option in highlighting tumor bulk and borders, differentiating it from healthy brain tissue, in different kinds of lesions.

In our experience, all of the 6 metastasis cases described in our article and other 7 new cases were clearly depicted using contrast-enhanced ultrasound (CEUS) along with their afferent and efferent vessels. However, all of these cases were already quite visible on standard B-mode ultrasound, particularly in comparison with lesions with ill-defined borders such as high-grade gliomas. This might depend, to a certain extent, on the available ultrasound equipment (probes, settings, virtual navigation), but also on the operators' training on ultrasound and his/her experience. We believe that a specific training on ultrasound, and particularly in specific techniques such as CEUS, is very important, addressing both the setup of the equipment and the execution of the examination (performed in a stressful situation compared with diagnostic ultrasound) for the successful visualization of the target.5

It also has to be stressed that other ultrasound techniques are useful to achieve a thorough evaluation of a neoplastic lesion. High-frequency ultrasound allows for an impressive spatial resolution, comparable to that achieved with magnetic resonance imaging.6 High-frequency ultrasound, however, has its best performance in exploring superficial lesions, in any case not deeper than 4 to 5 cm. Another useful tool is fusion imaging between ioUS and preoperative imaging that allows for virtual navigation, providing real-time ultrasound imaging coupled with the panoramic view and orientation offered by the preoperative magnetic resonance imaging.

We definitely agree with de Lima Oliveira et al that “iCEUS could potentially enhance border definition…,” therefore guiding tumor resection. Furthermore, intraoperative CEUS (iCEUS) adds valuable biological information such as vascularization, microcirculation, tissue perfusion dynamic to those obtained with standard B-mode imaging, and might also guide the surgical strategy and lead to an iCEUS characterization of cerebral metastasis as already obtained for cerebral gliomas.8 Further studies are warranted to evaluate the role of iCEUS in highlighting tumor remnants after gross tumor removal, thus maximizing resection avoiding neurological sequelae due to damaged healthy brain tissue.

1. Schakert G, Schimiedel K, Lindner C, Leimert N, Kirsh M. Surgery of recurrent brain metastasis: retrospective of 67 patients. Acta Neurochir (Wien). 2013;155(10):1823–1832. Recursos Complementarios Solicitud de Documentos Catalogos C17 [Context Link]

2. Sanai N, Berger MS. Recent surgical management of gliomas. Adv Exp Med Biol. 2012;746:12–25. Review. [Context Link]

3. Selbekk T, Jakola AS, Solheim O, et al.. Ultrasound imaging in neurosurgery: approaches to minimize surgically induced image artefacts for improved resection control. Acta Neurochir (Wien). 2013;155(6):973–980. Recursos Complementarios Solicitud de Documentos Catalogos C17 [Context Link]

4. Prada F, Perin A, Martegani A, et al.. Intraoperative contrast-enhanced ultrasound for brain tumor surgery. Neurosurgery. 2014;74(5):542–552. Ovid Full Text Recursos Complementarios Enlaces Bibliograficos Catalogos C17 [Context Link]

5. Piscaglia F, Nolsøe C, Dietrich CF, et al.. The EFSUMB Guidelines and Recommendations on the Clinical Practice of Contrast Enhanced Ultrasound (CEUS): update 2011 on non-hepatic applications. Ultraschall Med. 2012;33(1):33–59. Recursos Complementarios Solicitud de Documentos Enlaces Bibliograficos Catalogos C17 [Context Link]

6. Serra C, Stauffer A, Actor B, et al.. Intraoperative high frequency ultrasound in intracerebral high-grade tumors. Ultraschall Med. 2012;33(7):E306–E312. Recursos Complementarios Solicitud de Documentos Enlaces Bibliograficos Catalogos C17 [Context Link]

7. Prada F, Del Bene M, Mattei L, et al.. Fusion imaging for intra-operative ultrasound-based navigation in neurosurgery. J Ultrasound. 2014;17(3):243–251. Solicitud de Documentos [Context Link]

8. Prada F, Mattei L, Del Bene M, et al.. Intraoperative cerebral glioma characterization with contrast enhanced ultrasound. Biomed Res Int. 2014;2014:484261. Epub 2014 Jun 12. [Context Link]