Detection of the spatial accuracy of a magnetic resonance and surgical computed tomography scanner in the region of surgical interest.

In image-guided surgeries (IGSs) and radiology, images are the main source of information. As image data provide the differentiation between normal and abnormal tissues in the human, the images need to be reliable and they need to provide accurate spatial representation of the patient. This research concentrates on the accuracy assessment of IGS devices in general and then specifically on the spatial accuracy of a common magnetic resonance (MR) imager and a mobile three-dimensional surgical computed tomography (CT) scanner. The accuracy assessment tool had been designed to be universal and to enable its use in the hospital setting. In this study, it was used in detecting the spatial accuracy of a commercial surgical CT scanner, the O-arm, and a 1.5-T MR imager. The results show the tendency of magnetic resonance imaging to produce slight decreases in spatial accuracy toward the fringes of the images from the isocenter. Furthermore, the results indicate that the accuracy of both scanners was within pixel size and thus highly accurate in the region of surgical interest of this study.

Insomnia among brain tumor patients: a population-based prospective study of tumor patients in northern Finland.

Patients with neurological diseases often suffer from sleep disturbances. Insomnia among adult brain tumor patients has usually been studied as part of quality-of-life studies, or some case reports on insomnia in these patients have been described. The authors aimed to study insomnia in a prospective study setting among patients with primary brain tumors and evaluate whether insomnia is related to tumor laterality. Entire study population consisted of 70 patients with a solitary primary supratentorial brain tumor treated surgically at the Clinic for Neurosurgery, Oulu University Hospital. The overall functional state of the patients was assessed by the Karnofsky Performance Scale, depression was measured by Beck Depression Inventory, and insomnia by Nottingham Health Profile. Repeated measurements were assessed before tumor operation as well as 3 months and one year after surgery. Prevalence of insomnia among patients with a primary brain tumor waiting for surgery was higher compared to general population, but level of insomnia significantly decreased as soon as 3 months after tumor operation. Patients with a bilateral primary brain tumor had significantly more often insomnia without comorbid depression compared to patients with a left or right tumor for up to one year after operation. The authors suggest that insomnia among patients with a bilateral brain tumor may not be associated with depression but have other biological background.

Awake craniotomy may further improve neurological outcome of intraoperative MRI-guided brain tumor surgery.

BACKGROUND: Results of awake craniotomy are compared to results of resections done under general anesthesia in patients operated with IMRI control. We hypothesized that stimulation of the cortex and white matter during awake surgery supplements IMRI control allowing for safer resection of eloquent brain area tumors. METHODS: The study group consisted of 20 consecutive patients undergoing awake craniotomy with IMRI control. Resection outcome of these patients was compared to a control group of 20 patients operated in the same IMRI suite but under general anesthesia without cortical stimulation. The control group was composed of those patients whose age, sex, tumor location, recurrence and histology best matched to patients in study group. RESULTS: Cortical stimulation identified functional cortex in eight patients (40 %). Postoperatively the neurological condition in 16 patients (80 %) in the study group was unchanged or improved compared with 13 patients (65 %) in the control group. In both groups, three patients (15 %) had transient impairment symptoms. There was one patient (5 %) with permanent neurological impairment in the study group compared to four patients (20 %) in the control group. These differences between groups were not statistically significant. There was no surgical mortality in either group and the overall infection rate was 5 %. Mean operation time was 4 h 45 min in the study group and 3 h 15 min in the control group. CONCLUSIONS: The study consisted of a limited patient series, but it implies that awake craniotomy with bipolar cortical stimulation may help to reduce the risk of postoperative impairment following resection of tumors located in or near speech and motor areas also under IMRI control.

Technical accuracy of optical and the electromagnetic tracking systems.

Thousands of operations are annually guided with computer assisted surgery (CAS) technologies. As the use of these devices is rapidly increasing, the reliability of the devices becomes ever more critical. The problem of accuracy assessment of the devices has thus become relevant. During the past five years, over 200 hazardous situations have been documented in the MAUDE database during operations using these devices in the field of neurosurgery alone. Had the accuracy of these devices been periodically assessed pre-operatively, many of them might have been prevented. The technical accuracy of a commercial navigator enabling the use of both optical (OTS) and electromagnetic (EMTS) tracking systems was assessed in the hospital setting using accuracy assessment tools and methods developed by the authors of this paper. The technical accuracy was obtained by comparing the positions of the navigated tool tip with the phantom accuracy assessment points. Each assessment contained a total of 51 points and a region of surgical interest (ROSI) volume of 120x120x100 mm roughly mimicking the size of the human head. The error analysis provided a comprehensive understanding of the trend of accuracy of the surgical navigator modalities. This study showed that the technical accuracies of OTS and EMTS over the pre-determined ROSI were nearly equal. However, the placement of the particular modality hardware needs to be optimized for the surgical procedure. New applications of EMTS, which does not require rigid immobilization of the surgical area, are suggested.

Expression of VEGF and collagen XVIII in meningiomas: correlations with histopathological and MRI characteristics.

BACKGROUND: The objective of this study was to assess the possibility of predicting histological characteristics of meningiomas on the basis of preoperative MRI and the correlation of the expression of vascular endothelial growth factor (VEGF) and collagen XVIII with histological parameters already established as predictive of the course of these tumors. METHODS: Expression of VEGF and collagen XVIII as well as other histological characteristics was examined in meningioma tissues from 20 patients. Preoperative MRI, including dynamic imaging of contrast enhancement, was analyzed. Times to maximum enhancement and maximum intensity increase were noted from dynamic imaging. The relative intensity of the tumor in fluid-attenuated inversion recovery (FLAIR), T2-weighted and contrast enhanced T1-weighted images, as well as volumes of tumor and edema, was calculated. The edema-tumor volume ratio was defined as the edema index (EI). RESULTS: Both VEGF and collagen XVIII were expressed in all meningioma samples. Edema was present in 60 % of cases. The strongest correlation of VEGF expression was to EI. Among histological parameters, microvessel density (MVD) and cellularity correlated moderately with VEGF. Collagen XVIII expression correlated strongly with the maximal intensity increase after contrast agent administration (ρ = 0.71, P = 0.001) as well as with MVD and intensity of the meningioma on FLAIR images. CONCLUSION: Meningiomas with faster and more intense enhancement in dynamic studies, indicative of good tumor blood supply and permeability of vasculature, are associated with high levels of collagen XVIII and VEGF expression. Occurrence of peritumoral edema in meningiomas is strongly correlated with expression of VEGF.

A population based study of outcomes after evacuation of primary supratentorial intracerebral hemorrhage.

BACKGROUND AND PURPOSE: The role of surgery after primary intracerebral hemorrhage (ICH) is controversial. To explore whether hematoma evacuation after ICH had improved short-term survival or functional outcome we conducted a retrospective observational population-based study. METHODS: We identified all subjects with primary ICH between 1993 and 2008 among the population of Northern Ostrobothnia, Finland. Hematoma evacuation was carried out by using standard craniotomy or through a burr hole. We compared mortality rates and functional outcomes of patients with hematoma evacuation with those treated conservatively. RESULTS: Of 982 patients with verified ICH during the study period, 127 (13%) underwent hematoma evacuation. Surgically treated patients were significantly younger (mean±SD, 63±11 vs. 70±12 years; p<0.001), had larger hematomas (66±36 vs. 28±40 ml; p<0.001), lower Glasgow Coma Scale scores (median, 11 vs. 14; p<0.001) and more frequently subcortical hematomas (68% vs. 24%; p<0.001) than those treated conservatively. In multivariable analysis, hematoma evacuation independently lowered 3-month mortality (adjusted hazard ratio [HR], 0.62; 95% confidence interval [CI], 0.43-0.88; p<0.03), particularly among patients aged≤70 years with ≥30 ml supratentorial hematomas (adjusted HR, 0.26; 95% CI, 0.14-0.49; p<0.001). However, poor outcome was not improved by surgery (adjusted odds ratio 0.71; 95% CI 0.29-1.70). CONCLUSIONS: Improved 3-month survival was observed in patients who had undergone hematoma evacuation relative to patients not undergoing evacuation particularly in the subgroup of patients aged≤70 years with ≥30 ml supratentorial hematomas. Surgery might improve outcome if cases could be selected more precisely and if performed before deterioration.

Stereotactic operations using the o-arm.

BACKGROUND: In stereotactic operations, intraoperative imaging is crucial in several stages of the procedure. The aim was to utilize the O-arm intraoperatively for (1) planning the trajectories of stereotactic instruments, (2) calculating the coordinates of the targets, (3) identification of normal intracranial structures, (4) verification of the trajectories of the stereotactic instruments, and (5) visualization of intracranial hematoma. This is the first study using the O-arm for calculations of the target coordinates in frame-based stereotaxy. METHODS: Utilization of the O-arm as a full-scale intraoperative imaging system in stereotactic surgery required a new concept. The concept consists of the O-arm as an intraoperative imaging system and the Leksell stereotactic system with a modified CT coordinate indicator box, with the idea to widen limited imaging volume. The accuracy and feasibility of the concept were studied. RESULTS: The use of O-arm imaging was found to be clinically feasible, enabling the achievement of adequate technical accuracy for stereotactic operations with submillimeter errors in the calculation of target coordinates, and for multiple intraoperative control images when required. CONCLUSIONS: The O-arm could be used alone, with high accuracy, as an intraoperative imaging system for planning and controlling in stereotactic operations. In addition, it can be used to exclude serious complications, especially intracerebral hematoma.

Depression in relation to anxiety, obsessionality and phobia among neurosurgical patients with a primary brain tumor: a 1-year follow-up study.

Depression is found to be present in up to 44% of brain tumor patients during their illness process. Anxiety as a comorbid psychiatric disorder with depression has formerly been studied, but phobia or obsessive-compulsive symptoms among brain tumor patients have not yet been noticed. By using a clinical prospective database of primary brain tumor patients (n=77) we studied the level of depression, anxiety, obsessionality (traits and symptoms) and phobic anxiety symptoms. Psychiatric symptoms were assessed before tumor operation as well as at three months and at one year after operation. The presence of comorbid anxiety, obsessionality and phobic anxiety symptoms was assessed before operation and at follow-ups in depressed and non-depressed patients, separately. Before tumor operation 16% of the patients had depression according to Beck Depression Inventory (BDI), while 10% had depression at three months and 15% at one year after operation. The depressed patients had statistically significantly higher anxiety scores and phobic scores at all three measurement points compared to corresponding scores among non-depressed brain tumor patients. The mean obsessionality scores among depressed brain tumor patients were significantly higher when measured before operation and at one year after the operation compared to non-depressed patients. To our knowledge, this is the first study so far in which comorbidity of psychiatric symptoms has been shown among depressive brain tumor patients. Concurrent comorbid conditions have been shown to be associated with increased severity, morbidity and chronicity of depression. It is recommended that treatment of depressive patients complicated with comorbid psychiatric disorders be planned by psychiatric units.

Technical accuracy of an O-arm registered surgical navigator.

The objective of this study was to assess the accuracy of a commercial surgical navigator using optical tracking modality with automated registration between O-arm images and the scanned object. Automated registration was enabled by using the spine navigation software of the navigator. The used phantom was designed by the authors of this paper. The surgical navigators and the O-arm are routinely used at Oulu University Hospital, Oulu, Finland. The distances measured with the surgical navigator from the fixed origin of the phantom were compared to the known phantom accuracy assessment coordinates. The error of the surgical navigator was the difference between measured and true values. The mean displacement error was 0.20 mm with a standard deviation of 0.14 mm. The results show that automated registration is very reliable for image guided surgery (IGS) and that the present accuracy assessment method can be used to periodically check surgical navigator accuracy using O-arm data.

Incidence of pituitary adenomas in Northern Finland in 1992-2007.

CONTEXT: Data on the incidence of pituitary adenomas (PAs) are scant and outdated. A population-based regional cohort with thorough case identification was used to evaluate the incidence of clinically detected PAs in the era of magnetic resonance imaging. OBJECTIVE: The objective of the study was to describe the age- and sex-specific incidence of all PA subgroups, with data on incidentally found PAs, pituitary apoplexies, and time trends. DESIGN, SETTINGS, AND PATIENTS: This was a retrospective descriptive analysis of PA patients diagnosed during 1992-2007 in Northern Finland (NFi). MAIN OUTCOME MEASURE: World Health Organization 2000-standardized incidence rates (SIRs) of PAs per 100,000 were measured. RESULTS AND CONCLUSION: The final cohort consisted of 355 PAs. The incidence rates of the Oulu University Hospital regional district were used as a reference to assess the applicability of our case finding over the rest of NFi. Incidence rates of all PA subgroups except microprolactinomas were statistically equal between these areas; thus, all presented SIRs are based on the NFi's cohort except Oulu University Hospital regional district-based prolactinomas and PAs overall. Overall SIR of PAs was higher (4.0 per 100,000) than in previous reports. Prolactinomas had the highest SIR: 2.2 per 100,000, followed by clinically nonfunctioning PAs (1.0) and GH-secreting (0.34), ACTH-secreting (0.17), and TSH-secreting (0.03) PAs. The gender-specific SIR was 2.2 per 100,000 in males and 5.9 per 100,000 in females. Pituitary apoplexy occurred as a presenting symptom in 11% of clinically nonfunctioning PA patients. The SIR of incidentally discovered PAs increased significantly from 1992-1999 to 2000-2007 (0.59 to 1.6, respectively; P < 0.01), which accounted for the perceived increasing trend in the overall SIR of PAs (3.8 to 4.2; P > 0.05).

Development of an accuracy assessment phantom for surgical navigators.

The objective of this study was to design a calibration phantom for a surgical navigator used in a hospital environment. It addresses two major issues: the design of an accuracy phantom and the accuracy analysis of the surgical navigator in a hospital setting. The designed phantom was used to assess the accuracy of the optical tracking modality of the surgical navigator used at Oulu University Hospital, Oulu, Finland. The phantom functioned according to the design criteria, it was easy to use and it had enough calibration points that were localized by the navigator according to the accuracy assessment protocol to assess the accuracy error. The distances measured from a fixed origin with the surgical navigator were compared to the known phantom calibration point coordinates. The mean error was within the manufacturer specifications of 1.00 mm. The analysis done using the designed phantom and accuracy assessment protocol showed that the error increased with the distance from the center of the phantom. The accuracy assessment protocol using the present phantom proved to be a suitable method for accuracy analysis of a surgical navigator in a hospital setting.

Somatization symptoms are related to right-hemispheric primary brain tumor: a population-based prospective study of tumor patients in northern Finland.

BACKGROUND: Somatization symptoms have been found to be early symptoms of tumor among brain tumor patients. OBJECTIVE: The authors followed patients through diagnosis of brain tumor and subsequent surgery. METHOD: Patients with a supratentorial tumor were given repeated measurements for somatization with the Crown-Crisp Experiential Index. RESULTS: Before tumor operation, the patients with a tumor in the right hemisphere had significantly higher somatic anxiety scores than those with a tumor located in the left hemisphere. The specific symptoms were dizziness and palpitation among patients with a right hemispheric tumor. CONCLUSION: It is important to remember possible very unusual causes behind somatization symptoms.

Season of tumor surgery in relation to deaths among brain tumor patients: does sunlight and month of surgery play a role in brain tumor deaths?

The objective of this study is to investigate the effect at the season of the time of surgery on the survival of brain tumor patients. The population studied consisted of 101 patients (39 males and 62 females), gathered from a geographically large area in northern Finland (from 64 degrees N to 70 degrees N), aged between 20 and 82 years, with a solitary primary brain tumor treated surgically at the Oulu Clinic for Neurosurgery, Oulu University Hospital. The distribution of tumor surgery dates and mean hours of sunshine hours was analyzed by bimonthly periods. When comparing the proportion of deceased patients of all patients operated in each bimonthly period, a significant bimonthly peak in deaths was found in patients operated during the period of February to March (ratio 1.7, 95% CI 1.1-2.3). More than half of the patients who died during the peak period had grade III-IV gliomas. In 40% of the cases, the surgery time of deceased brain tumor patients occurred in the bimonthly period following the four darkest months of the year with the lowest amount of sunshine in northern Finland. The relation of low vitamin D level in the etiology and course of the disease as well as in treatment settings deserves further study.

The terminal prostaglandin synthases mPGES-1, mPGES-2, and cPGES are all overexpressed in human gliomas.

Prostaglandin E2 has been connected to processes promoting tumor growth in several human malignancies including gliomas. The terminal prostaglandin synthases mPGES-1, mPGES-2, and cPGES convert PGH2 into prostaglandin E2. The inhibition of their function could significantly reduce PGE2 levels in tumors while avoiding some side effects related to the inhibition of the upstream enzymes COX-1 and COX-2. In this study, the immunohistochemical staining of mPGES-1 and, for the first time, the staining of mPGES-2 and cPGES are characterized and compared with COX-1 and COX-2 staining in the same tumor samples of 94 human gliomas. The main results demonstrate over-expression of all three proteins, including cPGES and mPGES-2 that are commonly considered noninducible, in both low- and high-grade tumors. For all three proteins, average expression in tumor cells was higher in grade III tumors than grade II tumors. The analysis showed no correlation between tumor grade and staining of tumor cells or vascular endothelium with any of the antibodies except in oligodendrogliomas where moderate correlation (linear correlation coefficient 0.6; P < 0.01) could be found between tumor grade and tumor cell staining with mPGES-1 and cPGES. In grade II tumors which recurred and were reoperated upon during the data gathering period, average expression of COX-2, mPGES-1, and cPGES was higher than in tumors that were operated on only once. Our results demonstrate the significance of all three terminal prostaglandin synthases, mPGES-1, mPGES-2, and cPGES, as a possible future target of inhibition in glioma therapy.

3D modeling-based surgical planning in transsphenoidal pituitary surgery--preliminary results.

CONCLUSION: The preoperative three-dimensional (3D) modeling of the pituitary adenoma together with pituitary gland, optic nerves, carotid arteries, and the sphenoid sinuses was adopted for routine use in our institution for all pituitary surgery patients. It gave the surgeon a more profound orientation to the individual surgical field compared with the use of conventional 2D images only. OBJECTIVE: To demonstrate the feasibility of 3D surgical planning for pituitary adenoma surgery using readily available resources. SUBJECTS AND METHODS: The computed tomography (CT) and magnetic resonance imaging (MRI) data of 40 consecutive patients with pituitary adenoma were used to construct 3D models to be used in preoperative planning and during the surgery. A freely available, open source program (3D Slicer) downloaded to a conventional personal computer (PC) was applied. RESULTS: The authors present a brief description of the 3D reconstruction-based surgical planning workflow. In addition to the preoperative planning the 3D model was used as a 'road map' during the operation. With the 3D model the surgeon was more confident when opening the sellar wall and when evacuating the tumor from areas in contact with vital structures than when using only conventional 2D images.

Pulse repetition time and contrast enhancement: simulation study of Gd-BOPTA and conventional contrast agent at different field strengths.

OBJECTIVES: To investigate theoretically enhancement and optimal pulse repetition times for Gd-BOPTA and Gd-DTPA enhanced brain imaging at 0.23, 1.5, and 3.0 T. METHODS: The theoretical relaxation times of unenhanced, conventional contrast agent (Gd-DTPA) and new generation contrast agent (Gd-BOPTA) enhanced glioma were calculated. Then, simulation of the signals and contrasts as a function of concentration and pulse repetition time (TR) in spin echo sequence was done at 0.23, 1.5, and 3.0 T. The effect of echo time (TE) on tumor-white matter contrast was also clarified. Three patient cases were imaged at 0.23 T as a test of principle. RESULTS: Gd-BOPTA may give substantially better glioma-to-white matter contrast than Gd-DTPA but is more sensitive to the length of TR. These characteristics are accentuated at 0.23 T. Optimal TR lengths are shorter for Gd-BOPTA than for Gd-DTPA enhanced imaging at all field strengths. TR optimized for Gd-DTPA may thus give suboptimal contrast in Gd-BOPTA enhanced imaging. Higher enhancement with Gd-BOPTA is further accentuated by short TE. CONCLUSION: Appropriate TRs at 0.23 T appear to be approximately 300 to 400 milliseconds and 250 to 300 milliseconds, at 1.5 T 500 to 600 milliseconds and 400 to 450 milliseconds and at 3.0 T 550 to 650 milliseconds and 475 to 525 milliseconds using Gd-DTPA and Gd-BOPTA, respectively. For Gd-BOPTA enhanced imaging, it seems justified to optimize TR according to contrast and seek options like parallel excitation (Hadamard encoding) for increasing the number of slices and SNR.

Optically neuronavigated ultrasonography in an intraoperative magnetic resonance imaging environment.

OBJECTIVE: To develop a clinically useful method that shows the corresponding planes of intraoperative two-dimensional ultrasonography and intraoperative magnetic resonance imaging (MRI) scans determined with an optical neuronavigator from an intraoperative three-dimensional MRI scan data set, and to determine the qualitative and the quantitative spatial correspondence between the ultrasonography and MRI scans. METHODS: An ultrasound probe was interlinked with an ergonomic and MRI scan-compatible ultrasonography probe tracker to the optical neuronavigator used in a low-field intraoperative MRI scan environment for brain surgery. Spatial correspondence measurements were performed using a custom-made ultrasonography/MRI scan phantom. In this work, instruments to combine intraoperatively collected ultrasonography and MRI scan data with an optical localization method in a magnetic environment were developed. The ultrasonography transducer tracker played an important role. Furthermore, a phantom for ultrasonography and MRI scanning was produced. This is the first report, to our knowledge, regarding the possibility of combining the two most important intraoperative imaging modalities used in neurosurgery, ultrasonography and MRI scanning, to guide brain tumor surgery. RESULTS: The method was feasible and, as shown in an illustrative surgical case, has direct clinical impact on image-guided brain surgery. The spatial deviation between the ultrasonography and the MRI scans was, on average, 1.90 +/- 1.30 mm at depths of 0 to 120 mm from the ultrasonography probe. CONCLUSION: The overall result of this work is a unique method to guide the neurosurgical operation with neuronavigated ultrasonography imaging in an intraoperative MRI scanning environment. The relevance of the method is emphasized in minimally invasive neurosurgery.

Decreased quality of life and depression as predictors for shorter survival among patients with low-grade gliomas: a follow-up from 1990 to 2003.

OBJECTIVES: To assess the long-term survival of brain tumor patients, and in particular to evaluate the relation of quality of life (QOL) to survival among low-grade glioma patients. METHODS: The postoperative survival of 101 brain tumor patients was followed from surgery (1990-1992) until the end of the year 2003. Depression was evaluated by the Beck Depression Inventory (BDI) and QOL with Sintonen's 15D scale before operation and at one year as well as at five years after operation. RESULTS: The mean survival times in years (SD) were significantly related to tumor malignancy, being the shortest, 1.9 (0.6), for patients with high-grade gliomas, while patients with low-grade gliomas or a benign brain tumor had mean survival times of 9.1 (1.0) and 11.6 (0.5), respectively. At all follow-ups, depressed low-grade glioma patients had a significantly shorter survival time, 3.3-5.8 years, compared to non-depressed low-grade glioma patients, 10.0-11.7 years. A decreased level of QOL in low-grade glioma patients was significantly related to the shorter survival. CONCLUSIONS: The results suggest that depression and decreased QOL among low-grade glioma patients is related to shorter survival at long-term follow-up. Decreased QOL may serve as an indicator for poor prognosis in low-grade glioma patients.

Winter birth in association with a risk of brain tumor among a Finnish patient population.

The aim of this study was to analyze whether winter birth is related to risk of brain tumor in a clinical sample of patients from northern Finland. The study group comprised 101 patients suffering from a primary brain tumor. When comparing births in winter to births in other seasons, a 1.39-fold (95% CI 1.01-1.77) excess of winter births among patients was observed compared to respective births in the general population (p = 0.026). Especially patients with pituitary adenomas exhibited a 2.5-fold (95% CI 1.5-4.4) excess of winter births. The authors conclude that the season-of-birth effect in brain tumor patients should not be neglected when the actual and important tumorigenesis is investigated.

Cerebral edema attenuated inversion recovery MR sequence in low magnetic field: a feasibility study.

RATIONALE AND OBJECTIVES: Minimally invasive neurosurgery requires methods to specify surgical boundaries of target tissue, such as brain tumors. This study investigated technical possibilities and clinical usefulness of adapting edema attenuated inversion recovery (EDAIR) pulse sequences to suppress magnetic resonance signal from cerebral edema in brain tumor patients. MATERIALS AND METHODS: A resistive 0.23-T magnetic resonance scanner with magnitude-encoded inversion recovery sequences was used. Twenty-eight separate scanning tests in 25 neurosurgical brain tumor patients were performed on the day before surgery. An inversion recovery sequence with several inversion times between 150 and 2,200 ms was tested. The same sequences were also used intraoperatively and postoperatively. RESULTS: T(1) relaxation time of brain edema varied from case to case. An inversion recovery sequence with an inversion time of 400-800 milliseconds attenuated brain edema and seemed to help in demarcating gross brain tumor for surgical resection. These features were helpful for the evaluation of resectable tumor tissue particularly using neuronavigation techniques. CONCLUSIONS: According to these preliminary findings, inversion recovery sequences supplement other imaging modalities and assist neurosurgeons in evaluating different surgical trajectories and in estimating brain tumor volume before craniotomy.