LAUSR

Dear Editor, We read with great interest the technical note by Della Pepa GM, Mattogno LL et al. entitled BReal-time intraoperative contrastenhanced ultrasound (CEUS) in vascularized spinal tumors: a technical note^ which appeared recently as BOnline First Articles^ inActaNeurochirurgica [3], describingCEUS findings in a case of spinal tumor. CEUS is indeed an imaging modality that is gaining popularity: the use of contrast agents, as for computed tomography (CT) and magnetic resonance imaging (MRI), is becoming well established for ultrasound (US). The European Federation for Ultrasound in Medicine and Biology (EFSUMB) published the first BGuidelines for the use of contrast agents in ultrasound^ in 2004 [1]. Since then, many updates, mainly on liver applications, have been published [2, 6]. Recently, our group in Milan had the opportunity to contribute to the new EFSUMB update BGuidelines and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound (CEUS) in Non-Hepatic Applications^ which deal with the use of UCA outside the liver in many established and emerging applications, including for the first time neurosurgery for both cranial and spinal diseases [10]. We praise Della Pepa, Mattogno et al. for their effort in implementing their intraoperative imaging tools using CEUS, adding valuable contributions to the growing body of evidence supporting the use of CEUS during neurosurgical procedures, as they already showed in a case of spinal dural artero-venous fistula [4]. In their article, the Authors describe in convincing detail the application of this intraoperative image technique on a highly vascularized tumor diagnosed as a thoracic hemangiopericytoma (HCP). However, it is important to point out for completeness that, different from what was stated in one paragraph of their paper, there were already some previously published papers and book chapters on the use of intraoperative ultrasound (IoUS), and specifically CEUS, for neoplastic and non-neoplastic medullary lesions [7–9, 11–13]. In August 2015, we reported a case of a dorsal schwannoma in which the preoperativeMRI showed findings compatible with an intramedullary lesion with an exophitic component. However, intraoperative ultrasonography with the adjunct of contrastenhanced ultrasound helped us to understand, prior dural opening, that the lesion was completely extramedullary [12]. That report was the first description of CEUS application during spinal tumor surgery in an intradural extramedullary tumor. Again in 2015, in another paper, we showed the case of an intramedullary cervico-dorsal multinodular tumor [13]. The lesion was highly vascularized and constituted by three different nodules. B-mode examination, Doppler, and CEUS permitted us to accurately localize all three nodules, thus limiting spinal cord manipulation, and allowing complete surgical resection of the lesions, with an uneventful post-operative neurological course. The final histopathological diagnosis was that of a hemangioblastoma. The use of CEUS in surgery involving the spinal cord was also described in 2017 in a case of a spinal dural artero-venous fistula (FAVD), in which microbubbles were able to show the abnormal shunt and its pathological medullary venous drainage, both in axial and sagittal scans, prior dural opening, and the normalization of the pathological findings after interruption of the shunt [7]. The synergistic use of imaging with fluorescent agents along with the tomographic sections offered by ioUS combines a direct view of the surface with indirect sectional views. Furthermore, in the recently released updated EFSUMB guidelines for the clinical use of CEUS in non-hepatic applications [10], the use of intraoperative CEUS for the evaluation of This article is part of the Topical Collection on Tumor Other