Usefulness of three-dimensional navigable intraoperative ultrasound in resection of brain tumors with a special emphasis on malignant gliomas

Background

Intraoperative imaging is increasingly being used in resection of brain tumors. Navigable three-dimensional (3D)-ultrasound is a novel tool for planning and guiding such resections. We review our experience with this system and analyze our initial results, especially with respect to malignant gliomas.

Methods

A prospective database for all patients undergoing sononavigation-guided surgery at our center since this surgery’s introduction in June 2011 was queried to retrieve clinical data and technical parameters. Imaging was reviewed to categorize tumors based on enhancement and resectability. Extent of resection was also assessed.

Results

Ninety cases were operated and included in this analysis, 75 % being gliomas. The 3D ultrasound mode was used in 87 % cases (alone in 40, and combined in 38 cases). Use of combined mode function [ultrasound (US) with magnetic resonance (MR) images] facilitated orientation of anatomical data. Intraoperative power Doppler angiography was used in one-third of the cases, and was extremely beneficial in delineating the vascular anatomy in real-time. Mean duration of surgery was 4.4 hours. Image resolution was good or moderate in about 88 % cases. The use of the intraoperative imaging prompted further resection in 59 % cases. In the malignant gliomas (51 cases), gross-total resection was achieved in 47 % cases, increasing to 88 % in the “resectable” subgroup.

Conclusions

Navigable 3D US is a versatile, useful and reliable intraoperative imaging tool in resection of brain tumors, especially in resource-constrained settings where Intraoperative MR (IOMR) is not available. It has multiple functionalities that can be tailored to suit the procedure and the experience of the surgeon.     

Usefulness of multimodal examination and intraoperative magnetic resonance imaging system in glioma surgery

Extensive surgical removal of tumor tissue can contribute to longer survival for patients with gliomas. Intraoperative magnetic resonance (iMR) imaging is important for safe and maximal resection of brain tumors. A new operating room equipped with a 1.5-T MR imaging system and neuronavigation opened at Yamagata University Hospital in 2008. Using this new suite, we have safely treated over 200 cases. Use of iMR imaging improved glioma resection rates in 25 (34%) of 73 cases, and gross total resection was achieved in 48 patients (66%). Motor evoked potential (MEP) monitoring was performed in combination with iMR imaging for 32 gliomas. MEP monitoring was successful in 30 cases (94%). Transient decreases in MEP amplitude were seen in two patients. One patient showed transient motor weakness and another showed improvement of motor function. The iMR imaging system provides useful information for tumor resection that allows intraoperative modification of surgical strategies. Combining MEP monitoring with iMR imaging appears to offer the most effective method for safe glioma surgery near eloquent areas.     

Quantification of, visualization of, and compensation for brain shift using intraoperative magnetic resonance imaging

OBJECTIVE: Modern neuronavigation systems lack spatial accuracy during ongoing surgical procedures because of increasing brain deformation, known as brain shift. Intraoperative magnetic resonance imaging was used for quantitative analysis and visualization of this phenomenon. METHODS: For a total of 64 patients, we used a 0.2-T, open-configuration, magnetic resonance imaging scanner, located in an operating theater, for pre- and intraoperative imaging. The three-dimensional imaging data were aligned using rigid registration methods. The maximal displacements of the brain surface, deep tumor margin, and midline structures were measured. Brain shift was observed in two-dimensional image planes using split-screen or overlay techniques, and three-dimensional, color-coded, deformable surface-based data were computed. In selected cases, intraoperative images were transferred to the neuronavigation system to compensate for the effects of brain shift. RESULTS: The results demonstrated that there was great variability in brain shift, ranging up to 24 mm for cortical displacement and exceeding 3 mm for the deep tumor margin in 66% of all cases. Brain shift was influenced by tissue characteristics, intraoperative patient positioning, opening of the ventricular system, craniotomy size, and resected volume. Intraoperative neuronavigation updating (n = 14) compensated for brain shift, resulting in reliable navigation with high accuracy. CONCLUSION: Without brain shift compensation, neuronavigation systems cannot be trusted at critical steps of the surgical procedure, e.g., identification of the deep tumor margin. Intraoperative imaging allows not only evaluation of and compensation for brain shift but also assessment of the quality of mathematical models that attempt to describe and compensate for brain shift.     

Preoperative functional magnetic resonance imaging assessment of higher-order cognitive function in patients undergoing surgery for brain tumors

OBJECT: Resection of brain tumors has been shown to increase patient survival. The extent of the possible resection, however, depends on whether the tumor has invaded brain regions important for motor, sensory, or cognitive processes and whether the brain tissue surrounding the tumor maintains its functional role. The goal of the present study was to develop new pre- and intraoperative tools to specifically assess the function of the rostral part of the dorsal premotor cortex (PMdr) in 4 patients with brain tumors close to this region. METHODS: Using functional magnetic resonance (fMR) imaging and a task developed to assess accurate selection between competing responses based on conditional rules, the authors preoperatively assessed the function of the PMdr in 4 patients with brain tumors close to this region. In 1 patient, the authors developed an intraoperative procedure to assess performance on the task during the tumor resection. RESULTS: Preoperative fMR imaging data showed specific activity increases in the vicinity of the tumors, that is, in the PMdr. As confirmed by postoperative structural MR imaging, the extent of the tumor resection was optimal and the functional region within the PMdr was preserved. Furthermore, patients exhibited no postoperative deficits during task performance, demonstrating that the function was preserved. Intraoperative behavioral results demonstrated that the cognitive processes underlying performance on the task remained intact throughout the tumor resection. CONCLUSIONS: These findings suggest that preoperative fMR imaging, together with intraoperative behavioral evaluation, may be a useful paradigm to assist neurosurgeons in preserving cognitive function in patients with brain tumors.     

Neuronavigation by intraoperative three-dimensional ultrasound: initial experience during brain tumor resection

OBJECTIVE: Three-dimensional (3-D) ultrasound is an intraoperative imaging modality used in neuronavigation as an alternative to magnetic resonance imaging (MRI). This article summarizes 4 years of clinical experience in the use of intraoperative 3-D ultrasound integrated into neuronavigation for guidance in brain tumor resection. METHODS: Patients were selected for inclusion in the study on the basis of the size and location of their lesion. Preoperative 3-D MRI data were registered and used for planning as in other conventional neuronavigation systems. Intraoperative 3-D ultrasound images were acquired three to six times, and tumor resection was guided on the basis of these updated 3-D images. RESULTS: Intraoperative 3-D ultrasound represents a good solution to the problem of brain shift in neuronavigation because it easily provides an updated, and hence more accurate, map of the patient's true anatomy in all phases of the operation. Ultrasound makes it possible to follow the progression of the operation, and it improves the radicality of tumor resection by detecting tumor tissue that would remain if the imaging technology had not been used (in 53% of the cases). Integration of 3-D ultrasound with navigation technology solves the orientation problem experienced previously with two-dimensional ultrasound in neurosurgery. The technology makes it possible to directly compare intraoperative ultrasound and MRI data regarding visualization of the lesion. Ultrasound image quality is useful for guiding surgical procedures. CONCLUSION: Intraoperative 3-D ultrasound seems to provide a time- and cost-effective way to update high-quality 3-D maps used in neuronavigation.     

Time-domain and spectral-domain optical coherence tomography in the analysis of brain tumor tissue

INTRODUCTION: Detection of residual tumor during resection of glial brain tumors remains a challenge because of a low inherent contrast of adjacent edematous brain, the surrounding infiltration zone, and the solid tumor. Therefore, new technologies that may facilitate an intraoperative analysis of the tissue at the resection edge are of great interest to neurosurgeons. MATERIALS AND METHODS: For ex vivo imaging of gliomas in a mouse model and human biopsy specimens of brain tumors and nervous system tissue we have used a time-domain Sirius 713 Tomograph with a central wavelength of 1,310 nm and a coherence length of 15 microm equipped with a mono mode fiber and a modified optical coherence tomography (OCT) adapter containing a lens system for imaging at a working distance of 2.5 cm. A spectral-domain tomograph using 840 nm and 930 nm superluminescence diodes (SLD) with a central wavelength of 900 nm was used as a second imaging modelity. RESULTS: Both time-domain and spectral-domain coherence tomography delineated normal brain, the infiltration zone and solid tumor in murine intracerebral gliomas. Histological evaluation of H&E sections parallel to the optical plain demonstrated that tumor areas of less than a millimeter could be detected and that not only solid tumor, but also brain invaded by a low-density single tumor cells produced an OCT signal different from normal brain. Spectral-domain OCT (SD-OCT) demonstrated a significantly more detailed microstructure of tumor and normal brain up to a tissue depth of 1.5-2.0 mm, whereas the interpretation of time-domain OCT (TD-OCT) was difficult at a tissue depth >1.0 mm. Because of rapid scanning times SD-OCT data could be acquired as 3D data maps, which allowed a multi-planar analysis of the tumor to brain interface. Similar to our findings in experimental gliomas, images of human nervous system tissue acquired using SD-OCT showed a characteristic signal of normal brain tissue and a detailed microstructure of tumor parenchyma. CONCLUSION: Spectral-domain OCT of experimental gliomas and human brain tumor specimens differentiates solid tumor, diffusely invaded brain tissue, and adjacent normal brain based on microstructure and B-scan signal characteristics. In conjunction with the rapid image acquisition rates of SD-OCT, this technology carries the potential of a novel intraoperative imaging tool for the detection of residual tumor and guidance of neurosurgical tumor resections.     

Feasibility of cervical intramedullary diffuse glioma resection using intraoperative magnetic resonance imaging

Intraoperative magnetic resonance imaging (iopMRI) actually has an important role in the surgery of brain tumors, especially gliomas and pituitary adenomas. The aim of our work was to describe the advantages and drawbacks of this tool for the surgical treatment of cervical intramedullary gliomas. We describe two explicative cases including the setup, positioning, and the complete workflow of the surgical approach with intraoperative imaging. Even if the configuration of iopMRI equipment was originally designed for cranial surgery, we have demonstrated the feasibility of cervical intramedullary glioma resection with the aid of high-field iopMRI. This tool was extremely useful to evaluate the extent of tumor removal and to obtain a higher resection rate, but still need some enhancement in the configuration of the headrest coil and surgical table to allow better patient positioning.     

Integrated positron emission tomography and magnetic resonance imaging-guided resection of brain tumors: a report of 103 consecutive procedures

OBJECT: The aim of this study was to evaluate the integration of positron emission tomography (PET) scanning data into the image-guided resection of brain tumors. METHODS: Positron emission tomography scans obtained using fluorine-18 fluorodeoxyglucose (FDG) and L-[methyl-11C]methionine (MET) were combined with magnetic resonance (MR) images in the navigational planning of 103 resections of brain tumors (63 low-grade gliomas [LGGs] and 40 high-grade gliomas [HGGs]). These procedures were performed in 91 patients (57 males and 34 females) in whom tumor boundaries could not be accurately identified on MR images for navigation-based resection. The level and distribution of PET tracer uptake in the tumor were analyzed to define the lesion contours, which in turn yielded a PET volume. The PET scanning-demonstrated lesion volume was subsequently projected onto MR images and compared with MR imaging data (MR volume) to define a final target volume for navigation-based resection-the tumor contours were displayed in the microscope's eyepiece. Maximal tumor resection was accomplished in each case, with the intention of removing the entire area of abnormal metabolic activity visualized during surgical planning. Early postoperative MR imaging and PET scanning studies were performed to assess the quality of tumor resection. Both pre- and postoperative analyses of MR and PET images revealed whether integrating PET data into the navigational planning contributed to improved tumor volume definition and tumor resection. Metabolic information on tumor heterogeneity or extent was useful in planning the surgery. In 83 (80%) of 103 procedures, PET studies contributed to defining a final target volume different from that obtained with MR imaging alone. Furthermore, FDG-PET scanning, which was performed in a majority of HGG cases, showed that PET volume was less extended than the MR volume in 16 of 21 cases and contributed to targeting the resection to the hypermetabolic (anaplastic) area in 11 (69%) of 16 cases. Performed in 59 LGG cases and 23 HGG cases, MET-PET demonstrated that the PET volume did not match the MR volume and improved the tumor volume definition in 52 (88%) of 59 and 18 (78%) of 23, respectively. Total resection of the area of increased PET tracer uptake was achieved in 54 (52%) of 103 procedures. CONCLUSIONS: Imaging guidance with PET scanning provided independent and complementary information that helped to assess tumor extent and plan tumor resection better than with MR imaging guidance alone. The PET scanning guidance could help increase the amount of tumor removed and target image-guided resection to tumor portions that represent the highest evolving potential.     

光动力诊断和荧光指导切除脑恶性胶质瘤15例

目的研究光动力诊断(PDD)和荧光指导的肿瘤切除在脑恶性胶质瘤治疗中的作用。方法对手术治疗的原发和复发的15例恶性脑胶质瘤患者,在手术中进行荧光波谱诊断及其指导下的肿瘤切除。光敏剂为血卟啉衍生物,剂量为2mg/kg体重。应用激光电子波谱分析系统,光纤尖端激发激光波长632．5nm。手术前48h静脉注射光敏剂,注射后患者进行避光。手术为常规开颅手术,显微镜下切除肿瘤,在手术医师认为肿瘤完全切除后用光纤探头在瘤腔各壁进行多于4个点的光动力诊断,同时取该点样本送常规病理。如光动力诊断发现肉眼未发现的肿瘤则进一步切除。直至瘤腔各壁均确认为正常脑组织。分别记录肉眼辨别,光动力诊断和病理诊断结果,计算光动力诊断的敏感率,特异率和准确率。术后复查CT或MRI确定切除程度,记录手术死亡率和致残率。结果15例肿瘤标本均表现特异肿瘤波谱图形,其中有2例患者在光动力诊断后发现肿瘤,继续切除肿瘤。有1例显微镜下可疑肿瘤组织,经光动力诊断为脑组织,未切除,取病理证实为脑组织。2例(胶质肉瘤和胶质母细胞瘤)离体肿瘤组织和正常脑组织进行光动力诊断,均获得和术后病理诊断相一致的诊断。在瘤腔各壁取样标本106份,根据病理诊断,光动力诊断的敏感率90．60%,特异率96．8％,准确率94．3％。15例患者无手术死亡,1例术后偏瘫失语加重。9例患者肿瘤全切,6例患者肿瘤未全切,其中5例患者因肿瘤位于功能区,为保护功能未能全切肿瘤,并被手术后．MRI或CT证实。有1例术中肉眼辨认和PDD均未提示肿瘤,但样本病理提示仍为肿瘤边缘组织。结论荧光波谱分析的光动力诊断具有比较快速准确、简单客观等特点,对于提高脑恶性胶质瘤的切除程度和减少手术损伤具有积极意义。     

Histological examination of false positive tissue resection using 5-aminolevulinic acid-induced fluorescence guidance

Intraoperative 5-aminolevulinic acid (5-ALA)-induced fluorescence guidance for resection of malignant brain tumors was correlated with histological examination to investigate false positive findings in 42 patients with malignant glioma and six patients with metastatic brain tumor. Patients received a single 1 g oral dose of 5-ALA 2 hours before surgery. The tumor site was illuminated with a laser with a peak wavelength of 405 +/- 1 nm and output of 40 mW. Samples with strong fluorescence were obtained from the tumor bulk and samples with weak fluorescence from the tumor cavity. Fluorescence was observed in 36 of the 42 malignant gliomas and four of the six metastatic brain tumors. No tumor cells were found in fluorescent samples from six of the 36 malignant gliomas and all four metastatic brain tumors. Five of the six malignant gliomas were recurrent cases. Fluorescence was found in areas of peritumoral edema or inflammatory cell and reactive astrocyte infiltration. Intraoperative 5-ALA-induced fluorescence guidance is useful for the resection of initial malignant glioma since false positive results are rare, but only non-eloquent weak positive areas should be resected. In contrast, all weak positive areas of recurrent malignant gliomas must be resected. Weak positive areas of the peritumoral edema surrounding metastatic brain tumors should be removed carefully as false positive results are common.     

Functional activity within brain tumors: a magnetic source imaging study

OBJECTIVE: To determine whether low-grade gliomas contain functional cortical activity more often than high-grade gliomas within radiologically defined abnormal tissue. METHODS: Patients with intra-axial cerebral lesions located in the vicinity of eloquent brain cortex preoperatively underwent magnetic source imaging. A dual 37-channel biomagnetometer was used to perform the imaging. Evoked magnetic fields were analyzed using the single-equivalent dipole representation to ascertain the neuronal source. Stimuli included painless tactile somatosensory stimulation of fingers, toes, and lips and auditory presentation of pure sinusoidal tones. RESULTS: A retrospective analysis of 106 nonconsecutively treated patients, who had undergone preoperative magnetic source imaging between February 1996 and December 1999, revealed that 24.5% of the patients had been at risk for neurological deficits, because functionally active tissue was located within or at the border of the tumor. Functional activity was found within the radiologically defined lesion in 18% of Grade 2 tumors, in 17% of Grade 3 tumors, and in 8% of Grade 4 tumors. CONCLUSION: The results confirm that, regardless of tumor grade, intra-axial brain tumors may involve or directly border on functional cortex. The degree of involvement of functionally viable cortex appeared greater for low-grade tumors than for high-grade lesions. On the other hand, high-grade lesions were more likely to be associated with functional cortex at their margins or within peritumoral edema. To safely maximize tumor resection, preoperative functional imaging and intraoperative electrophysiological mapping of the cerebral cortex and the white matter tracts are deemed necessary.     

Reappraisal of intraoperative ultrasonography for pancreatobiliary carcinomas: assessment of malignant portal venous invasion

BACKGROUND: Conventional preoperative imaging modalities are unreliable for assessing portal venous invasion by pancreatobiliary carcinoma. We evaluated the usefulness of intraoperative ultrasonography for detecting pancreatobiliary carcinoma and assessing portal venous invasion, compared with other imaging modalities. METHODS: Ninety-one patients with pancreatic carcinoma (n = 66) or bile duct carcinoma (n = 25) underwent ultrasonography, computed tomography, angiography, and endoscopic ultrasonography preoperatively. All these patients underwent tumor resection, with (n = 23) or without (n = 68) portal vein resection, after intraoperative ultrasonography. Portal venous invasion was histologically examined in all patients. RESULTS: Intraoperative ultrasonography was significantly more sensitive (100%) than ultrasonography (79%), computed tomography (81%), and angiography (54%) for detecting carcinomas, especially bile duct carcinomas and small (< or = 2.0 cm) tumors. Portal venous invasion was confirmed histopathologically in 25 patients. For diagnosing portal venous invasion, intraoperative ultrasonography was more sensitive (92%) and specific (92%) than ultrasonography (56% and 73%), computed tomography (64% and 79%), and angiography (76% and 83%), respectively. Endoscopic ultrasonography showed a 95% detectability for carcinomas and a 92% accuracy for assessing portal venous invasion. CONCLUSIONS: Intraoperative ultrasonography is a simple and accurate procedure for detection of pancreatobiliary carcinomas and assessment of portal venous invasion.     

Clinical impact of integrated functional neuronavigation and subcortical electrical stimulation to preserve motor function during resection of brain tumors

OBJECT: The authors evaluated the clinical impact of combining functional neuronavigation with subcortical electrical stimulation to preserve motor function following the removal of brain tumors. METHODS: Forty patients underwent surgery for treatment of brain tumors located near pyramidal tracts that had been identified by fiber tracking. The distances between the electrically stimulated white matter and the pyramidal tracts were measured intraoperatively with tractography-integrated functional neuronavigation, and correlated with subcortical motor evoked potentials (MEPs) and clinical symptoms during and after resection of the tumors. Motor function was preserved after appropriate tumor resection in all cases. In 18 of 20 patients, MEPs were elicited from the subcortex within 1 cm of the pyramidal tracts as measured using intraoperative neuronavigation. During resection, improvement of motor weakness was observed in two patients, whereas transient mild motor weakness occurred in two other patients. In 20 patients, the distances between the stimulated subcortex and the estimated pyramidal tracts were more than I cm, and MEPs were detected in only three of these patients following stimulation. CONCLUSIONS: Intraoperative functional neuronavigation and subcortical electrical stimulation are complementary techniques that may facilitate the preservation of pyramidal tracts around 1 cm of resected tumors.     

Endoscopic resection of solid intraventricular brain tumors

OBJECT: Endoscopic removal of intraventricular brain tumors is well established for cystic tumors such as colloid cysts. Aspiration followed by removal or ablation of the membranous wall is possible given the constituent features of these tumors. It is generally expected that endoscopic removal of solid brain tumors from the intraventricular compartment would impose additional technical demands. In this paper, the feasibility and safety of endoscopic removal of solid intraventricular brain tumors is evaluated. METHODS: Eighty-one patients who underwent endoscopic management of an intraventricular brain tumor were identified from a prospective database. Of these patients, seven underwent attempted endoscopic surgical removal of a solid primary brain tumor. Patient selection, surgical technique, procedure-related morbidity, and extent of removal were reviewed. Five patients underwent complete resection of a solid intraventricular brain tumor, a treatment option that was based on intraoperative assessment and confirmed by postoperative imaging. No patient experienced any procedure-related morbidity. Of the individuals in whom a total endoscopic resection was successful, there has been no symptomatic or radiological evidence of recurrence (mean follow up 20 months). Maximum tumor diameter ranged from 0.5 to 1.8 cm for patients who underwent complete resection, whereas maximum tumor diameter measured 2.4 and 2.5 cm in the two patients in whom a subtotal excision was performed. CONCLUSIONS: In select patients, complete endoscopic removal of solid intraventricular brain tumors is possible and safe. Factors that influence the ability of a surgeon to perform a complete endoscopic resection include tumor size, composition, and vascularity. The procedure requires careful patient selection, the use of refined endoscopic instrumentation, and a disciplined surgical technique.     

Intraoperative compensation for brain shift.

BACKGROUND: Tumor removal, brain swelling, the use of brain retractors, and cerebrospinal-fluid drainage all result in an intraoperative brain deformation that is known as brain shift. Thus, neuronavigation systems relying on preoperative image data have a decreasing accuracy during the surgical procedure. Intraoperative image data represent the correct anatomic situation, so their use may compensate for the effects of brain shift. METHODS: In a series of 16 brain tumor patients, we used intraoperative magnetic resonance (MR) imaging to obtain 3-D data, which were then transferred to the microscope-based neuronavigation system. With the help of bone fiducial markers these images were registered intraoperatively, updating the neuronavigation system. RESULTS: In all patients the updating of the neuronavigation system with the intraoperative MR data was successful. It led to reliable neuronavigation with high accuracy; the mean registration error of the update procedure in all patients was 1.1 mm. The updating procedure added about 15 minutes to the operation time. In all patients the area suggestive of remaining tumor was reached and the additional tumor could be resected, resulting in a complete tumor removal in 14 patients. In the remaining patients extension of the tumor into eloquent brain areas prevented a complete excision. CONCLUSIONS: The update of a neuronavigation system with intraoperative MR images reliably compensates for the effects of brain shift. This method allows completion of tumor removal in some difficult brain tumors.     

Outpatient brain tumor surgery: innovation in surgical neurooncology

OBJECT: Recent studies of conventional craniotomies and image-guided biopsies have afforded a solid characterization of surgical morbidity and the timing of its occurrence. This report outlines a novel 11-year experience with outpatient image-guided biopsy and outpatient craniotomy for supratentorial intraaxial brain tumors. METHODS: During the period between August 1996 and May 2007, 117 awake image-guided biopsies and 145 elective craniotomies for tumor resection were prospectively selected to be performed as outpatient procedures. Data were recorded for each patient regarding tumor histological type, reasons for admission if planned early discharge failed, and surgical complications. RESULTS: Successful discharge from the Day Surgery Unit was possible in 109 (93%) of 117 biopsy cases and 136 (94%) of 145 craniotomy cases (only 2 of which [1.5%] required unplanned readmission after discharge). Neurological worsening occurred in 5.1% of the patients who underwent image-guided biopsies, and in 5.5% of those who underwent outpatient craniotomies (based on intent-to-treat group analysis). No patient suffered an adverse event with alteration in outcome because of planned outpatient discharge. CONCLUSIONS: Outpatient image-guided brain biopsy and outpatient craniotomy for tumor resection are safe and effective procedures in selected patients.     

Intraoperative acquisition of fMRI and DTI

Multimodal functional navigation enables removing a tumor close to eloquent brain areas with low postoperative deficits, whereas additional intraoperative imaging ensures that the maximum extent of the resection can be achieved and updates the image data compensating for the effects of brain shift. Intraoperative imaging beyond standard anatomic imaging, that is, intraoperative functional magnetic resonance imaging (fMRI) and especially intraoperative diffusion tensor imaging (DTI), add further safety for complex tumor resections. This article discusses the acquisition of intraoperative fMRI, DTI, and imaging.     

Intraoperative ultrasound assistance for excision of impalpable musculoskeletal soft tissue tumors

Intraoperative ultrasonography is a useful tool for the detection and extirpation of liver metastases, breast masses, and melanoma. However, the efficacy of this technology in intraoperative localization and resection of small soft tissue tumors has not been addressed. The purpose of this study is to report on the efficacy of intraoperative ultrasound assistance in excising impalpable musculoskeletal soft tissue tumors. Twenty-two soft tissue tumors <3 cm (range, 0.7-3 cm) were resected with intraoperative ultrasound assistance. All tumors were localized in the deep panniculus, fascia, or muscle. Surgical time and length of incisions was recorded in all the cases. Intra- and postoperative reregistration was made to confirm the tumor resection. Ultrasound assistance was successful in obtaining an accurate localization in all treated cases. Mean surgical time was 30 minutes (range, 13-87 minutes). Average incision length was 5.7 cm (range, 2.5-10.6 cm). Reregistration allowed intraoperative confirmation of the adequacy of the excision. The procedure allowed recognized and excised additional nodules not previously diagnosed in 3 cases. Postoperative echography done in all patients confirmed complete extirpation of the tumors, and histopathology confirmed adequate margins obtained. Intraoperative ultrasound can be used as an efficient tool to localize and treat impalpable small soft tissue tumors.     

Glioma resection in a shared-resource magnetic resonance operating room after optimal image-guided frameless stereotactic resection

OBJECTIVE: We describe a shared-resource intraoperative magnetic resonance imaging (MRI) design that allocates time for both surgical procedures and routine diagnostic imaging. We investigated the safety and efficacy of this design as applied to the detection of residual glioma immediately after an optimal image-guided frameless stereotactic resection (IGFSR). METHODS: Based on the twin operating rooms (ORs) concept, we installed a commercially available Hitachi AIRIS II, 0.3-tesla, vertical field, open MRI unit in its own specially designed OR (designated the magnetic resonance OR) immediately adjacent to a conventional neurosurgical OR. Between May 1998 and October 1999, this facility was used for both routine diagnostic imaging (969 diagnostic scans) and surgical procedures (50 craniotomies for tumor resection, 27 transsphenoidal explorations, and 5 biopsies). Our study group, from which prospective data were collected, consisted of 40 of these patients who had glioma (World Health Organization Grades II-IV). These 40 patients first underwent optimal IGFSRs in the adjacent conventional OR, where resection continued until the surgeon believed that all of the accessible tumor had been removed. Patients were then transferred to the magnetic resonance OR to check the completeness of the resection. If accessible residual tumor was observed, then a biopsy and an additional resection were performed. To validate intraoperative MRI findings, early postoperative MRI using a 1.5-tesla magnet was performed. RESULTS: Intraoperative images that were suitable for interpretation were obtained for all 40 patients after optimal IGFSRs. In 19 patients (47%), intraoperative MRI studies confirmed that adequate resection had been achieved after IGFSR alone. Intraoperative MRI studies showed accessible residual tumors in the remaining 21 patients (53%), all of whom underwent additional resections. Early postoperative MRI studies were obtained in 39 patients, confirming that the desired final extent of resection had been achieved in all of these patients. One patient developed a superficial wound infection, and no hazardous equipment or instrumentation problems occurred. CONCLUSION: Use of an intraoperative MRI facility that permits both diagnostic imaging and surgical procedures is safe and may represent a more cost-effective approach than dedicated intraoperative units for some hospital centers. Although we clearly demonstrate an improvement in volumetric glioma resection as compared with IGFSR alone, further study is required to determine the impact of this approach on patient survival.