Peri-operative prognostic factors for primary skull base chordomas: results from a single-center cohort.

BACKGROUND: Skull base chordomas (SBC) are rare malignant tumors and few factors have been found to be reliable markers for clinical decision making and survival prognostication. The aim of the present work was to identify specific prognostic factors potentially useful for the management of SBC patients. METHODS: A retrospective review of all the patients diagnosed and treated for SBC at the Fondazione IRCCS Istituto Neurologico "Carlo Besta" between January 1992 and December 2017 has been performed. Survival analysis was performed and a logistic regression model was used. Statistically significant predictors were rated based on their log odds in order to preliminarily build a personalized grading scale-the Peri-Operative Chordoma Scale (POCS). RESULTS: Fifty-nine primary chordoma patients were included. The average follow-up from the first treatment was 82.6 months (95% CI, 65.5-99.7). POCS was built over PFS and MR contrast enhancement (intense vs mild/no, value 4), preoperative motor deficit (yes vs no, value 3), and the development of any postoperative complications (yes vs no, value 2). POCS ranges between 0 and 9, with higher scores being associated with reduced likelihood of survival and progression-free state. CONCLUSIONS: Our results show that preoperative clinical symptoms (motor deficits), surgical features (extent of tumor resection and surgeon's experience), development of postoperative complications, and KPS decline represent significant prognostic factors. The degree of MR contrast enhancement significantly correlated to both OS and PFS. We also preliminarily developed the POCS as a prognostic grading scale which may help neurosurgeons in the personalized management of patients undergoing potential adjuvant therapies.

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

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. 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.

Intraoperative cerebral angiosonography with ultrasound contrast agents: how I do it.

BACKGROUND: Intraoperative vessel visualization is highly desirable, especially when the target is related to or close to main vessels, such as in the skull base and vascular surgery. Contrast-enhanced ultrasound (CEUS) is an imaging technique that allows visualization of tissue perfusion and vascularization through the infusion of purely intravascular ultrasound contrast agents (UCA). METHODS: After cerebral scanning with B-mode ultrasound (US) CEUS is performed, UCA are injected and insonated with low mechanical index US. A UCA-specific harmonic signal is transduced using a contrast-specific algorithm to obtain real-time angiosonography (ASG). CONCLUSIONS: Real-time intraoperative ASG is a rapid, reliable, repeatable method for vessel visualization and evaluation of tissue perfusion.

Risk of seizures during intraoperative electrocortical stimulation of brain motor areas: a retrospective study on 50 patients.

Tumours close to cerebral cortices involved in motor and language functions represent a major challenge for neurosurgeons. Intraoperative neurophysiologic monitoring is useful to gain insight into the anatomy of and the relationship between pathological and normal tissues. In this study we report on the experience of electrocortical stimulation in the surgery of tumours adjacent to the motor cortex in 50 patients under general anaesthesia (26 under propofol, 24 under sevoflurane), and on EMG responses from contralateral muscles. In 18 patients stimulation evoked seizures, which were controlled only with antiepileptic drugs (36%). No difference was found in the incidence of intra-operative seizures between the patients with (10 out of 27) or without (8 out of 23) pre-operative epilepsy (p = 0.8685). The majority of the patients (13 out of 18) with intraoperative seizures were under sevoflurane (p = 0.01) and there was a statistically significant difference in the mean electrical intensity used between the two groups, sevoflurane and propofol, respectively 5.3 ± 1.3 mA and 3.6 ± 2 mA (p = 0.03). Regarding pre-operative anti-epileptic drugs, the use of levitiracetam was associated with a high incidence of intraoperative seizure (5 out of 6 patients). 4 patients developed new, unwanted, permanent neurological deficits, of which 2 had intraoperative seizures controlled only with antiepileptic drugs. Electrocortical stimulation is a powerful tool to understand the functional organization of patients' eloquent areas. Intraoperative epileptic seizures may represent an unwanted complication preventing further stimulation and possibly worsening neurological results. The choice of anaesthetics according to the patients' characteristics, pre-op symptoms and medical therapy is pivotal.

FABP4 is a candidate marker of cerebellar liponeurocytomas.

Cerebellar liponeurocytoma (cLPN) is a very rare central nervous system (CNS) tumour recently recognized as a clinical and pathological entity distinct from medulloblastoma (MB), and included in the WHO classification of CNS tumours under the heading "glioneuronal tumours". cLPN typically develop in adult age and have a favourable prognosis compared with MB. In this work, we reviewed the clinical and neuroradiological data of two novel cases of adult cLPN diagnosed at our institution; one patient developed distant metastases. We tried to identify novel molecular markers for this malignancy. We found that the transcription factor NEUROG1 (but not ATOH1) is expressed in cLPN, unlike normal adult cerebellum, and that fatty acid binding protein 4 (FABP4), typically found in adipocytes, is significantly overexpressed compared with both normal adult cerebellum and human MB. These findings suggest cLPN occur as a result of transformation of cerebellar progenitors, which are distinct from cerebellar granule progenitors, and aberrantly differentiate into adipocyte-like tumour cells. They also suggest that analysis of FABP4 expression is of help to differentiate cLPN from MB.

Spinal cord herniation: management and outcome in a series of 12 consecutive patients and review of the literature.

BACKGROUND: Spinal cord herniation is a rare entity that has been recognized and described with increasing frequency in the past few years. It is characterized by herniation of the spinal cord through an anterior dural defect. In their study of 12 cases, the authors attempt to develop management and treatment guidelines for patients suffering from this condition. METHODS: A retrospective analysis of the medical files was carried out in a series of 12 consecutive patients treated at our Institution between 1998 and 2011 for spinal cord herniation. The clinical, radiological and surgical findings, management and outcome were reviewed. RESULTS: The male:female ratio was 5:7, with a mean age of 47 years (range 26­71 years). All patients presented a progressively worsening symptomatology. Symptoms at presentation included progressive myelopathy, corticospinal tract sign, algoparesthesia and sphincter dysfunction. The radiological appearance was uniform. All the lesions were located between the T2 and T8 vertebrae. One patient was initially managed conservatively. All patients underwent surgical correction via a posterior approach, with reduction of the herniated spinal cord, the positioning of a muscular autograft to fill the anterior cavity and closure of the dural defect with an artificial dural patch. Six patients showed improvement of preoperative symptomatology at follow-up, while the others remained free from symptom progression. CONCLUSIONS: The authors present one of the largest studies to date regarding patients with spinal cord herniation and emphasize that the possibility of this condition must be kept in mind when addressing all patients with progressive myelopathy.

Navigated Intraoperative 2-Dimensional Ultrasound in High-Grade Glioma Surgery: Impact on Extent of Resection and Patient Outcome.

BACKGROUND: Maximizing extent of resection (EOR) and reducing residual tumor volume (RTV) while preserving neurological functions is the main goal in the surgical treatment of gliomas. Navigated intraoperative ultrasound (N-ioUS) combining the advantages of ultrasound and conventional neuronavigation (NN) allows for overcoming the limitations of the latter. OBJECTIVE: To evaluate the impact of real-time NN combining ioUS and preoperative magnetic resonance imaging (MRI) on maximizing EOR in glioma surgery compared to standard NN. METHODS: We retrospectively reviewed a series of 60 cases operated on for supratentorial gliomas: 31 operated under the guidance of N-ioUS and 29 resected with standard NN. Age, location of the tumor, pre- and postoperative Karnofsky Performance Status (KPS), EOR, RTV, and, if any, postoperative complications were evaluated. RESULTS: The rate of gross total resection (GTR) in NN group was 44.8% vs 61.2% in N-ioUS group. The rate of RTV > 1 cm3 for glioblastomas was significantly lower for the N-ioUS group (P < .01). In 13/31 (42%), RTV was detected at the end of surgery with N-ioUS. In 8 of 13 cases, (25.8% of the cohort) surgeons continued with the operation until complete resection. Specificity was greater in N-ioUS (42% vs 31%) and negative predictive value (73% vs 54%). At discharge, the difference between pre- and postoperative KPS was significantly higher for the N-ioUS (P < .01). CONCLUSION: The use of an N-ioUS-based real-time has been beneficial for resection in noneloquent high-grade glioma in terms of both EOR and neurological outcome, compared to standard NN. N-ioUS has proven usefulness in detecting RTV > 1 cm3.

Piezosurgery for Infra- and Supratentorial Craniotomies in Brain Tumor Surgery.

OBJECTIVE: Piezoelectric surgery represents an innovative technique to perform safe and effective osteotomies and is an alternative to traditional bony tissue management using rotating or perforating instruments. We evaluated the safety and feasibility of craniotomies using an ultrasonic device that allows the selective cut of mineralized structures, avoiding damages to the vascular, dural, and parenchymal structures. METHODS: We analyzed a series of 300 patients (age range, 1-81 years; SD ± 15.2) who underwent elective cranial surgery for brain tumors, in which the craniotomy was performed using a piezoelectric device. Pre- and postoperative imaging, clinical notes, and intraoperative details were collected. RESULTS: There were 197 patients (66%) who underwent surgery for supratentorial tumors; the remaining 103 patients (34%) underwent surgery for infratentorial ones. Tumors involved the skull base in 125 cases. Meningiomas, gliomas, and schwannomas represented the most common histotypes. Duraplasty for dural damages was not necessary in all cases; no venous sinuses or parenchymal injuries were reported during bone work. We noted in 13 cases (4.3%) a minor dural tear, requiring only direct sutures. Bone flaps were always intact after craniotomy. No subgaleal cerebrospinal fluid (CSF) collection or CSF leak was recorded. Because of the minimal bone gap, we always achieved correct bone flap ossification. No reabsorption or mobilization of bone flap was noted. CONCLUSIONS: We illustrate the feasibility and safety of a piezosurgical cutter to perform craniotomies. This alternative technique appears to be safe, with excellent cosmetic effects, adding another tool to the neurosurgical armamentarium.

Image-Guided Biopsy of Intracranial Lesions with a Small Robotic Device (iSYS1): A Prospective, Exploratory Pilot Study.

BACKGROUND: Robotic technologies have been used in the neurosurgical operating rooms for the last 30 yr. They have been adopted for several stereotactic applications and, particularly, image-guided biopsy of intracranial lesions which are not amenable for open surgical resection. OBJECTIVE: To assess feasibility, safety, accuracy, and diagnostic yield of robot-assisted frameless stereotactic brain biopsy with a recently introduced miniaturized device (iSYS1; Interventional Systems Medizintechnik GmbH, Kitzbühel, Austria), fixed to the Mayfield headholder by a jointed arm. METHODS: Clinical and surgical data of all patients undergoing frameless stereotactic biopsies using the iSYS1 robotized system from October 2016 to December 2017 have been prospectively collected and analyzed. Facial surface registration has been adopted for optical neuronavigation. RESULTS: Thirty-nine patients were included in the study. Neither mortality nor morbidity related to the surgical procedure performed with the robot was recorded. Diagnostic tissue samples were obtained in 38 out of 39 procedures (diagnostic yield per procedure was 97.4%). All patients received a definitive histological diagnosis. Mean target error was 1.06 mm (median 1 mm, range 0.1-4 mm). CONCLUSION: The frameless robotic iSYS1-assisted biopsy technique was determined to be feasible, safe, and accurate procedure; moreover, the diagnostic yield was high. The surface matching registration method with computed tomography as the reference image set did not negatively affect the accuracy of the procedure.

Brain Tectal Tumors: A Flexible Approach.

BACKGROUND AND IMPORTANCE: Mesencephalic tectal gliomas represent a subset of midbrain tumors, which are more frequent in children than in adults. They usually become symptomatic when causing hydrocephalus by occluding the aqueduct. Because of their slow progression, due to their benign histology, they are characterized by a relatively good prognosis, although hydrocephalus might jeopardize patients' prognosis. Treatment is usually represented by cerebrospinal fluid diversion associated or not with biopsy. CLINICAL PRESENTATION: We report 2 illustrative cases of tectal gliomas in adults where endoscopic third ventriculostomy (ETV) and simultaneous endoscopic biopsy were obtained during the same operation by means of a single burr hole with a flexible endoscope. CONCLUSION: We recommend using this overlooked neurosurgical tool for such cases, since it allows the surgeon to safely perform an ETV, then judge whether biopsy can be done or not, without harming the patient, and possibly achieving an important piece of information (histopathological diagnosis) to manage this subset of oncological patients.

Intraoperative Strain Elastosonography in Brain Tumor Surgery.

BACKGROUND: Sonoelastography is an ultrasound imaging technique able to assess mechanical properties of tissues. Strain elastography (SE) is a qualitative sonoelastographic modality with a wide range of clinical applications, but its use in brain tumor surgery has been so far very limited. OBJECTIVE: To describe the first large-scale implementation of SE in oncological neurosurgery for lesions discrimination and characterization. METHODS: We analyzed retrospective data from 64 patients aiming at (i) evaluating the stiffness of the lesion and of the surrounding brain, (ii) assessing the correspondence between B-mode and SE, and (iii) performing subgroup analysis for gliomas characterization. RESULTS: (i) In all cases, we visualized the lesion and the surrounding brain with SE, permitting a qualitative stiffness assessment. (ii) In 90% of cases, lesion representations in B-mode and SE were superimposable with identical morphology and margins. In 64% of cases, lesion margins were sharper in SE than in B-mode. (iii) In 76% of cases, glioma margins were sharper in SE than in B-mode. Lesions morphology/dimensions in SE and in B-mode were superimposable in 89%. Low-grade (LGG) and high-grade (HGG) gliomas were significantly different in terms of stiffness and stiffness contrast between tumors and brain, LGG appearing stiffer while HGG softer than brain (all P < ·001). A threshold of 2.5 SE score had 85.7% sensitivity and 94.7% specificity in differentiating LGG from HGG. CONCLUSION: SE allows to understand mechanical properties of the brain and lesions in examination and permits a better discrimination between different tissues compared to B-mode. Additionally, SE can differentiate between LGG and HGG.

Advanced Ultrasound Imaging in Glioma Surgery: Beyond Gray-Scale B-mode.

Introduction: Glioma surgery is aimed at obtaining maximal safe tumor resection while preserving or improving patient's neurological status. For this reason, there is growing interest for intra-operative imaging in neuro-oncological surgery. Intra-operative ultrasound (ioUS) provides the surgeon with real-time, anatomical and functional information. Despite this, in neurosurgery ioUS mainly relies only on gray-scale brightness mode (B-mode). Many other ultrasound imaging modalities, such as Fusion Imaging with pre-operative acquired magnetic resonance imaging (MRI), Doppler modes, Contrast Enhanced Ultrasound (CEUS), and elastosonography have been developed and have been extensively used in other organs. Although these modalities offer valuable real-time intra-operative information, so far their usage during neurosurgical procedures is still limited. Purpose: To present an US-based multimodal approach for image-guidance in glioma surgery, highlighting the different features of advanced US modalities: fusion imaging with pre-operative acquired MRI for Virtual Navigation, B-mode, Doppler (power-, color-, spectral-), CEUS, and elastosonography. Methods: We describe, in a step-by-step fashion, the applications of the most relevant advanced US modalities during different stages of surgery and their implications for surgical decision-making. Each US modality is illustrated from a technical standpoint and its application during glioma surgery is discussed. Results: B-mode offers dynamic morphological information, which can be further implemented with fusion imaging to improve image understanding and orientation. Doppler imaging permits to evaluate anatomy and function of the vascular tree. CEUS allows to perform a real-time angiosonography, providing valuable information in regards of parenchyma and tumor vascularization and perfusion. This facilitates tumor detection and surgical strategy, also allowing to characterize tumor grade and to identify residual tumor. Elastosonography is a promising tool able to better define tumor margins, parenchymal infiltration, tumor consistency and permitting differentiation of high grade and low grade lesions. Conclusions: Multimodal ioUS represents a valuable tool for glioma surgery being highly informative, rapid, repeatable, and real-time. It is able to differentiate low grade from high grade tumors and to provide the surgeon with relevant information for surgical decision-making. ioUS could be integrated with other intra-operative imaging and functional approaches in a synergistic manner to offer the best image guidance for each patient.

Multisession Radiosurgery for Sellar and Parasellar Benign Meningiomas: Long-term Tumor Growth Control and Visual Outcome.

BACKGROUND: Concern about radiation-induced optic neuropathy (RION) has governed recent thinking about the role of radiation therapy in the treatment of meningiomas involving the anterior optic pathways. Despite this concern, during the last few years, the use of radiosurgery for such lesions has increased steadily. OBJECTIVE: To define both the tumor control rate and the risk of RION over a long-term follow-up period in a large cohort of patients treated with multisession radiosurgery. METHODS: The local control and visual outcome of 143 patients who underwent multisession radiosurgery (mRS) were evaluated. Neurological outcome was also analyzed. The data for the present study were obtained from a prospectively maintained database. RESULTS: The mean follow-up was 44 months (range, 12-113 months). All patients underwent mRS. The median prescription dose was 25 Gy delivered in 3 to 5 fractions. The prescription isodose, which typically encompassed at least 95% of the tumor, ranged from 65% to 86% (median, 80%). The mean tumor volume was 11.0 cm (range, 0.1-126.3 cm; median, 8 cm). The progression-free survival at 3, 5, and 8 years was 100%, 93%, and 90%, respectively. Compared with baseline, visual function improved in 36% of patients, whereas 7.4% experienced a worsening in visual function (5.1% excluding the patients with progressive disease). CONCLUSION: Good local control rate and a low risk of RION indicate that mRS is a safe and effective treatment option in cases of large meningiomas.

From Grey Scale B-Mode to Elastosonography: Multimodal Ultrasound Imaging in Meningioma Surgery-Pictorial Essay and Literature Review.

The main goal in meningioma surgery is to achieve complete tumor removal, when possible, while improving or preserving patient neurological functions. Intraoperative imaging guidance is one fundamental tool for such achievement. In this regard, intra-operative ultrasound (ioUS) is a reliable solution to obtain real-time information during surgery and it has been applied in many different aspect of neurosurgery. In the last years, different ioUS modalities have been described: B-mode, Fusion Imaging with pre-operative acquired MRI, Doppler, contrast enhanced ultrasound (CEUS), and elastosonography. In this paper, we present our US based multimodal approach in meningioma surgery. We describe all the most relevant ioUS modalities and their intraoperative application to obtain precise and specific information regarding the lesion for a tailored approach in meningioma surgery. For each modality, we perform a review of the literature accompanied by a pictorial essay based on our routinely use of ioUS for meningioma resection.

Intraoperative Navigated Angiosonography for Skull Base Tumor Surgery.

BACKGROUND: One of the main challenges during skull base tumor surgery is identifying the relationships between the lesion and the principal intracranial vessels. To this end, neuronavigation systems based on preoperative imaging lack accuracy because of brain shift and brain deformation. Intraoperative navigated B-mode ultrasonography is useful in defining the extent of brain tumor. Doppler imaging adds information regarding flow entity in neighboring vessels. Second-generation ultrasound contrast agents improve the signal-to-noise ratio of B-mode imaging and permit the study of the vessel's course, blood flow, and perfusion characteristics of focal lesions. We report our experience using intraoperative navigated contrast-enhanced ultrasound to perform a navigated angiosonography (N-ASG) for the visualization of vessels in a series of 18 skull base tumors. METHODS: We performed N-ASG in a series of 18 skull base tumors (10 meningiomas, 3 craniopharyngiomas, 2 giant pituitary adenomas, 1 posterior fossa epidermoid, 2 dermoid cysts). N-ASG was obtained after craniotomy before resecting each lesion and during tumor removal, after intravenous injection of ultrasound contrast agent. RESULTS: In all 18 cases, major vessels and their branches were simultaneously identified (both high and low flow) using N-ASG, which allowed to visualize the whole length of each vessels. N-ASG was also useful in highlighting the lesion, compared with standard B-mode imaging, and showing its perfusion patterns. CONCLUSIONS: N-ASG can be applied to skull base tumor surgery, providing helpful information about the relationship between principal intracranial vessels and tumors. This technique could be of assistance in approaching the tumor and avoiding vascular damages.

Apoptosis, vascularity, and proliferation in primary central nervous system lymphomas (PCNSL): a histopathological study.

BACKGROUND: In the present study apoptosis, vascularity, and proliferation were quantitatively analyzed with immunohistopathological techniques in primary central nervous system lymphomas (PCNSL). Statistical analysis of these parameters was performed to evaluate their possible relationship with the unfavorable outcome of this tumor. METHODS: A series of 32 PCNSL patients for a total of 33 tumors treated from 1984 to 2000 in the Neurosurgical Department were reviewed, and their histologic specimens examined for apoptosis, vascularity, and proliferation. RESULTS: Patients were treated with either gross total/subtotal tumor removal or stereotactic biopsy. Vascularity was studied by means of FVIII staining, proliferative index with Ki-67 staining, and apoptosis with the TUNEL technique. Most tumors could be classified as immunoblastic or centroblastic B-Cell NHL. Mean Mib-1 Labeling Index was 35.34% (5-80), blood vessel density of 40.8 per 10 high power fields. Apoptotic cells were zero or less than 8 cells per 10 high power fields. CONCLUSION: No statistically significant correlation between survival and histopathological parameters could be shown. However, the apoptosis index was found to be negatively correlated with proliferative index and may account for a more aggressive clinical course of PCNSL.

Intraoperative contrast-enhanced ultrasound for brain tumor surgery.

BACKGROUND: Contrast-enhanced ultrasound (CEUS) is a dynamic and continuous modality that offers a real-time, direct view of vascularization patterns and tissue resistance for many organs. Thanks to newer ultrasound contrast agents, CEUS has become a well-established, live-imaging technique in many contexts, but it has never been used extensively for brain imaging. The use of intraoperative CEUS (iCEUS) imaging in neurosurgery is limited. OBJECTIVE: To provide the first dynamic and continuous iCEUS evaluation of a variety of brain lesions. METHODS: We evaluated 71 patients undergoing iCEUS imaging in an off-label setting while being operated on for different brain lesions; iCEUS imaging was obtained before resecting each lesion, after intravenous injection of ultrasound contrast agent. A semiquantitative, offline interobserver analysis was performed to visualize each brain lesion and to characterize its perfusion features, correlated with histopathology. RESULTS: In all cases, the brain lesion was visualized intraoperatively with iCEUS. The afferent and efferent blood vessels were identified, allowing evaluation of the time and features of the arterial and venous phases and facilitating the surgical strategy. iCEUS also proved to be useful in highlighting the lesion compared with standard B-mode imaging and showing its perfusion patterns. No adverse effects were observed. CONCLUSION: Our study is the first large-scale implementation of iCEUS in neurosurgery as a dynamic and continuous real-time imaging tool for brain surgery and provides the first iCEUS characterization of different brain neoplasms. The ability of CEUS to highlight and characterize brain tumor will possibly provide the neurosurgeon with important information anytime during a surgical procedure.

Intraoperative ultrasound in spinal tumor surgery.

PURPOSE: Intraoperative ultrasound (ioUS) has become increasingly widespread in brain tumor surgery but it is not yet a standard procedure in spinal surgery. We analyzed intraoperative ultrasonographic findings of different spinal tumors and their influence on the surgical strategy. METHODS: We evaluated patients who underwent surgery for spinal tumor (extradural, intradural extramedullary, intradural intramedullary) removal, with ultrasound (US) guidance. Intraoperative standard B-mode images were acquired using a 3-11 MHz linear US probe. Before tumor removal the lesion was identified on the two axes and measured and defined as hyperechoic, isoechoic or hypoechoic. Other characteristics of the lesions were considered: the presence of calcifications, cystic/necrotic areas, diffuse or circumscribed appearance, and the relationships with the surrounding anatomical structures. RESULTS: In all 34 cases it was possible to visualize the lesion, as well as the surrounding neural structures (like dura mater, dentate ligament, arachnoid membranes) and vascular structures. In 9 out of 34 cases, ioUS showed that the surgical approach was not wide enough: therefore it was necessary to enlarge the bony approach before dural opening. In 8 intramedullary cases, ioUS was used to correctly tailor the myelotomy. CONCLUSIONS: We present our ioUS series findings along with some pictorial essays of different spinal tumors treated at our institution. IoUS is a valuable tool to detect spinal lesions, evaluate the surgical approach and plan the surgical strategy considering the position and relationships of the lesion with bony, neural and vascular structures.

Intraoperative cerebral glioma characterization with contrast enhanced ultrasound.

BACKGROUND: Contrast enhanced ultrasound (CEUS) is a dynamic and continuous modality providing real-time view of vascularization and flow distribution patterns of different organs and tumors. Nevertheless its intraoperative use for brain tumors visualization has been performed few times, and a thorough characterization of cerebral glioma had never been performed before. AIM: To perform the first characterization of cerebral glioma using CEUS and to possibly achieve an intraoperative differentiation of different gliomas. METHODS: We performed CEUS in an off-label setting in 69 patients undergoing surgery for cerebral glioma. An intraoperative qualitative analysis was performed comparing iCEUS with B-mode imaging. A postprocedural semiquantitative analysis was then performed for each case, according to EFSUMB criteria. Results were related to histopathology. RESULTS: We 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. CONCLUSION: Our 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.

Fusion imaging for intra-operative ultrasound-based navigation in neurosurgery.

The major shortcoming of image-guided navigation systems is the use of presurgically acquired image data, which does not account for intra-operative changes such as brain shift, tissue deformation and tissue removal occurring during the surgical procedure. Intra-operative ultrasound (iUS) is becoming widely used in neurosurgery but they lack orientation and panoramic view. In this article, we describe our procedure for US-based real-time neuro-navigation during surgery. We used fusion imaging between preoperative magnetic resonance imaging (MRI) and iUS for brain lesion removal in 67 patients so far. Surgical planning is based on preoperative MRI only. iUS images obtained during surgery are fused with the preoperative MRI. Surgery is performed under intra-operative US control. Relying on US imaging, it is possible to recalibrate navigated MRI imaging, adjusting distortion due to brain shift and tissue resection, continuously updating the two modalities. Ultrasound imaging provides excellent visualization of targets, their margins and surrounding structures. The use of navigated MRI is helpful in better understanding cerebral ultrasound images, providing orientation and panoramic view. Intraoperative US-guided neuro-navigation adjustments are very accurate and helpful in the event of brain shift. The use of this integrated system allows for a true real-time feedback during surgery.