Frameless Stereotactic Biopsy Research Articles

5-Aminolevulinic acid-induced protoporphyrin IX fluorescence as immediate intraoperative indicator to improve the safety of malignant or high-grade brain tumor diagnosis in frameless stereotactic biopsies

BackgroundFrameless stereotactic biopsies are replacing frame-based stereotaxy as a diagnostic approach to brain lesions. In order to avoid a sampling bias or negative histology, multiple specimens are often taken. This in turn increases the risk of hemorrhagic complications.ObjectiveWe present the use of 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX fluorescence in frameless stereotaxy to improve the procedure duration and yield, and thereby reduce the risk of complications.MethodsPatients with suspected high-grade brain tumors are given 5-ALA 4 h prior to stereotactic biopsy. The biopsy needle is guided to the target using frameless stereotaxy based either on preoperative images or combined with intraoperative MRI sequences. The specimen is illuminated with blue light to look for fluorescence. In case of a positive fluorescence within the tissue sample, no frozen sections are obtained, and no further specimens are taken.ResultsThe samples of 13 patients revealed a positive fluorescence and were histologically confirmed as malignant or high-grade brain neoplasms. four cases were fluorescence-negative, requiring frozen section confirmation and/or multiple samples. In theses cases histology was either nonspecific gliotic changes or low-grade tumors. There were no complications related to the additional use of 5-ALA.Conclusion5-ALA fluorescence in stereotactic biopsies can increase the safety and accuracy of these procedures by reducing sampling errors and eliminating the need for multiple samples and/or frozen section verification, creating a more accurate, faster and safer procedure for cases of suspected malignant or high-grade brain tumors situated in deep or eloquent areas.

Management strategies after nondiagnostic results with frameless stereotactic needle biopsy: Retrospective review of 28 patients

Background:Although frameless stereotactic needle biopsy is an accepted procedure for the diagnosis of intracranial lesions, findings are nondiagnostic in 2–15% of patients and no recommendations yet exist to guide subsequent care. After reviewing the postoperative course after nondiagnostic biopsy of 28 patients, we developed a paradigm to guide management in the future.Methods:In reviewing the medical records of 284 frameless stereotactic needle biopsies (January 2000 to December 2006), we identified a subset of 28 patients who underwent 29 (10.2%) biopsies that did not yield a definitive diagnosis based on permanent pathologic samples. Postoperative treatment plans and clinical courses were further examined in 21 patients; 7 without follow-up were excluded.Results:Of the 21 patients, lesion location and characteristics guided the surgeon's decision to recommend further surgery or initiate empiric treatment. Soon after initial biopsy, five patients underwent a second procedure (biopsy or resection) that yielded diagnostic pathologic tissue. Of 16 patients who had empiric treatment, 7 (43.7%) subsequently had their treatment plan changed because of a lack of improvement and 5 underwent a second biopsy (4 diagnostic). Evolving clinical information precipitated treatment change in two patients. Of 10 patients who had a second surgery for better diagnostic information, the diagnostic yield was 90%.Conclusions:Considering the 90% diagnostic yield, we now recommend repeat surgery for most patients with nondiagnostic biopsies, especially for lesions considered potentially neoplastic or infectious. Empiric management, for lesions likely to be neurodegenerative, is an option but requires close follow-up examination.

Intraoperative magnetic resonance-guided frameless stereotactic biopsies – initial clinical experience

Background and purposeWe present our early experience in intraoperative magnetic resonance (iMRI)-guided stereotactic frameless biopsies with special regard to its safety, efficacy and diagnostic value. Material and methodsThe records of patients who underwent frameless stereotactic iMRI-guided biopsies between June 2009 and April 2011 were analysed prospectively. All the operations were performed under local anaesthesia, with the use of a passive side-cutting biopsy needle. The needle was introduced into the pathological lesion with the help of optic neuronavigation system guidance. The iMRI scans served as reference images. We analysed the patients’ demographic and epidemiological data, the preparation and surgery times, diagnostic values of collected specimens, lengths of the hospital stay (LOS) and the complication rate. ResultsFifteen iMRI-guided stereotactic biopsies were performed in the analysed period. The mean patient age was 52 ± 18 yrs, the median WHO score was 2 (range: 1–3), there were 9 (60%) males in the study group. The average preparation time was 53 ± 24 minutes and the operation time 69 ± 25 minutes. No major complications were noted. The median total length of hospital stay was 5 days. The histopathological diagnoses were as follows: glioblastoma multiforme – 6 cases, low-grade gliomas – 4 cases, lymphomas – 3 cases, and other pathologies – 2 cases. In all the cases biopsy material allowed specified histopathological diagnoses to be obtained. ConclusionsFrameless stereotactic iMRI-guided brain tumour biopsy is a safe and diagnostically effective procedure. The use of iMRI might increase the diagnostic value and safety of stereotactic biopsy and positively influence its economic balance.

An experience of frameless stereotactic technique application for biopsy of brain supratentorial lesion

16 cases of application of navigation system Stealth Station® Treon®Plus, Medtroniс (USA) for frameless stereotactic biopsy of brain supratentorial lesion were analyzed. Frameless biopsy technic with our own technological developments is described in details.

Clinical experience of stereotactic biopsy for the brain lesions

To investigate the methodology of diversified advanced image-guided stereotactic biopsy for the brain lesions, and its diagnostic significance and experience in nervous system diseases. Retrospectively reviewed 1187 cases of brain lesions underwent image-guided stereotactic biopsy from December 1987 to January 2009. There were 694 male (58.5%) and 493 female (41.5%) patients, aged from 1 to 85 years (average 39.7 years). There were 607 cases in CT-guided, including positron emission computed tomography (PET) guided stereotactic biopsy; 580 cases in MRI-guided, including proton magnetic resonance spectroscopy ((1)H-MRS) guided stereotactic biopsy. Routine frame was used in 726 cases and frameless stereotactic biopsy in 461 cases, including neuroendoscopic biopsy in 28 cases, guided by computer assisted surgery (CAS) computer-assistant robot. In the early 450 cases, CT/MRI images films were employed to measure the coordinates of the target by hand, while in the late 737 cases, computer-assistant planning software rebuilt the CT/MRI images and figured out the optimal neurosurgical path for biopsy. The positive diagnosis rate of biopsy was 97.4%, 983 (82.8%) cases were diagnosed pathologically as brain tumors, and 173 (14.6%) cases as non-tumor diseases. The tumors mainly including neuroglioma, metastatic tumor, primary central nervous system lymphoma and germ cell tumors. In non-tumor diseases, mainly including multiple sclerosis, tumefactive demyelinating lesion, neurodegenerative disease, inflammation and parasite. The biopsy operation caused small hematoma without neurological deficits in 20 cases (1.7%), and caused large hematoma (> 10 ml) which need neurosurgical treatment (catheterization or craniotomy evacuation of hematoma) in 9 cases (0.8%). Hemorrhage associated with biopsy caused 3 cases (0.3%) death. There were no severe intracranial infection cases. The stereotactic biopsy with advanced image-guided technique represents a safe, reliable and minimally invasive method for pathological diagnosis of intracranial lesions. Moreover, the developments of biochemical imaging gives a new concept to the stereotactic biopsy.

Image-guided frameless stereotactic needle biopsy in awake patients without the use of rigid head fixation

Image-guided frameless stereotactic techniques provide an alternative to traditional head-frame fixation in the performance of fine-needle biopsies. However, these techniques still require rigid head fixation, usually in the form of a head holder. The authors report on a series of fine-needle biopsies and brain abscess aspirations in which a frameless technique was used with a patient's head supported on a horseshoe headholder. To validate this technique, they performed an in vitro accuracy study. Forty-eight patients underwent fine-needle biopsy of intracranial lesions that ranged in size from 0.9 to more than 107.7 ml; a fiducial-less, frameless, image-guided technique was used without rigid head fixation. In 1 of the 48 patients a cerebral abscess was drained. The accuracy study was performed with a skull phantom that was imaged with a CT scanner and tracked with a registration mask containing light-emitting diodes. The objective was a skin fiducial marker with a 4-mm circular target to accommodate the 2.5-mm biopsy needle. A series of 50 trials was conducted. Diagnostic tissue was obtained on the first attempt in 47 of 48 brain biopsy cases. In 2 cases small hemorrhages at the biopsy site were noted as a complication on the postoperative CT scan. One of these hemorrhages resulted in hand and arm weakness. The accuracy study demonstrated a 98% success rate of the biopsy needle passing through the 4-mm circular target using the registration mask as the registration and tracking device. This demonstrates a ± 0.75-mm tolerance on the targeting method. The accuracy study demonstrated the ability of the mask to actively track the target and allow navigation to a 4-mm-diameter circular target with a 98% success rate. The frameless, pinless, fiducial-less technique described herein will likely be another safe, fast alternative to frame-based stereotactic techniques for fine-needle biopsy that avoids the potential morbidity of rigid head-pin fixation. Furthermore, it should lend itself to other image-guided applications such as the placement of ventricular catheters for shunting or Ommaya reservoirs.

Safety and efficacy of frameless stereotactic biopsy. A single-centre review of 535 cases

Safety and efficacy of frameless stereotactic biopsy. A single-centre review of 535 cases

Comparing the risks of frameless stereotactic biopsy in eloquent and noneloquent regions of the brain: a retrospective review of 284 cases

Frameless stereotactic biopsy has been shown in multiple studies to be a safe and effective tool for the diagnosis of brain lesions. However, no study has directly evaluated its safety in lesions located in eloquent regions in comparison with noneloquent locations. In this study, the authors determine whether an increased risk of neurological decline is associated with biopsy of lesions in eloquent regions of the brain. Medical records, including imaging studies, were reviewed for 284 cases in which frameless stereotactic biopsy procedures were performed by 19 neurosurgeons at 7 institutions between January 2000 and December 2006. Lesion location was classified as eloquent or noneloquent in each patient. The incidence of neurological decline was calculated for each group. During the study period, 160 of the 284 biopsies predominately involved eloquent regions of the brain. In evaluation of the complication rate with respect to biopsy site, neurological decline occurred in 9 (5.6%) of 160 biopsies in eloquent brain areas and 10 (8.1%) of 124 biopsies in noneloquent regions; this difference was not statistically significant (p = 0.416). A higher number of needle passes was associated with the presence of a postoperative hemorrhage at the biopsy site, although not with a change in the result of neurological examination. Frameless stereotactic biopsy of lesions located in eloquent brain regions is as safe and effective as biopsy of lesions in noneloquent regions. Therefore, with careful planning, frameless stereotactic biopsy remains a valuable and safe tool for diagnosis of brain lesions, independent of lesion location.

Glioblastoma multiforme with an unusual location and clinical course

We present a unique case of a brain tumor patient with atypical location and progression. He was initially presented with mood and anxiety type symptoms together with aphasia and left-sided paraesthesias. Magnetic resonance imaging and CSF were negative and the patient was diagnosed with PTSD as he recently experienced a small motor vehicle accident. Two months after the first presentation, MRI revealed multifocal juxtacortical, leptomeningeal hyperdensities in the bilateral frontal lobes. MRI-guided frameless stereotactic biopsy defined a diagnosis of GBM 1 week prior to death which occurred within 4 months. Postmortally, formalin-fixed brain demonstrated that the main tumor mass was located in the fornix, infiltrating the ventricular system and disseminating over the cortex, cerebellum and spinal cord. The authors recommend closer scrutiny of psychiatric patients presenting CNS symptomatology, negative MRI, CT and CSF.

Primary leptomeningeal oligodendrogliomatosis

Primary leptomeningeal oligodendrogliomas (PLOs) are rare intracranial malignancies where tumors grow in the subarachnoid space without an obvious connection to the brain or spinal cord parenchyma. Adding to the three previously reported cases of PLO with no parenchymal involvement we report a fourth case of the same in this paper in a 50-year-old woman presenting with unrelenting headaches. CT scan of her head revealed hydrocephalus and MRI revealed diffuse enhancement of her leptomeninges throughout her brain and spine, prominent over the basilar region. Biopsy obtained using a frameless stereotactic biopsy showed sharply defined cell borders, clear cytoplasm, and rounded nuclei consistent with an oligodendroglioma. Our case suggests that PLO can mimic diffuse forms of granulomatous meningitis and should be suspected in patients that clinically and radiographically present like granulomatous meningitis but without blood or CSF markers for the same.

Accuracy and Clinical Use of a Novel Aiming Device for Frameless Stereotactic Brain Biopsy

Aiming devices enable the use of neuronavigation systems for rigid instrument guidance mimicking the possibilities of a frame-based system without having a stereotactic frame affixed to the skull. The aim of the presented work was to investigate the phantom targeting accuracy of the Vertek aiming device (Medtronic Inc., Louisville, USA) and whether it can be safely and accurately applied in a concept of minimally invasive brain biopsy in which multi-modal image fusion, image-to-patient registration and head immobilization were based on a non-invasive vacuum mouthpiece. A plastic model of a head with 20 target beads broadly distributed around the head volume was used for determination of CT-based targeting accuracy. Every target was punctured 5 times totaling 100 needle positionings. Accuracy was evaluated on postoperative CT scans with the needles in place. The mean normal deviation (n = 100) was 1.5 +/- 0.8 mm and the mean angle of deviation was 1.1 +/- 0.7 degrees. In a preliminary clinical series in ten patients diagnostic biopsy sampling of intracranial lesions with a median diameter of 28 mm (range: 12-90 mm) could be achieved in all patients and no biopsy related complications were recorded. The experimental results showed a similar accuracy to frame-based stereotaxy. The device facilitates trajectory alignment via two pivot joints and the actual depth and location of the biopsy needle can be monitored. Within the limitations of a preliminary study, brain biopsy may be accurately and safely performed for lesions > or = 12 mm.

Stereotactic biopsy complicated by pneumocephalus and acute pulmonary edema

Background The aim of this study was to describe pneumocephalus as a rare complication of stereotactic biopsy and as a possible cause of acute neurogenic pulmonary edema. Case Description A case of frameless stereotactic biopsy complicated by pneumocephalus presenting with acute lung injury 48 hours after the procedure. A frameless stereotactic procedure was performed in the standard fashion. Immediate postoperative CT showed no intracranial air except for a gas inclusion at the biopsy site within the lesion. The skin staple placed at the end of surgery on the skin incision was removed 36 hours later. A CT scan performed 48 hours postoperatively showed new pneumocephalus. The patient exhibited acute respiratory distress but no new neurologic symptoms. There was no detectable systemic cause for the pulmonary edema. The patient received supportive respiratory treatment and fully recovered. Conclusion Pneumocephalus is apparently a rare complication of stereotactic brain biopsy and one that may result from early removal of the skin staple or suture. The occurrence of acute neurogenic pulmonary edema may be attributed to the pneumocephalus.

Photodiagnosis for frameless stereotactic biopsy of brain tumor

Stereotactic biopsy is a minimally invasive method of reaching a pathological diagnosis. However, it is not always possible with this method to obtain the tissue samples required for an exact pathological diagnosis. The factors that can make histological diagnoses uncertain are the heterogeneity of tumors and/or brain shifts in the case of small tumors. In this study, we investigated the usefulness of fluorescence in determining the existence of tumor components in obtained tissues. Six patients underwent stereotactic biopsy. 5-Aminolevulinic acid (5-ALA) was administered orally prior to operation. Frameless stereotactic biopsies were performed. The obtained samples were irradiated with 405nm light and all samples showed red light excitation. Intraoperative rapid pathological diagnosis was made in each case by microscopic examination of frozen section samples. The final pathological diagnoses were of three glioblastomas, one astrocytoma grade 3, and two malignant lymphomas. One case was initially thought to be gliosis on rapid pathological diagnosis, but the final pathological diagnosis reached by examination of a permanent HE stained section was astrocytoma grade 3. Another case, finally diagnosed as malignant lymphoma, was initially diagnosed as infiltration of lymphocytes. The discrepancies between rapid and permanent pathological diagnoses might be caused by the destruction of cells. 5-ALA photodynamic diagnosis is not influenced by the destruction of tissues, simply because it does not depend on the structure of tissues. Stereotactic fluorescence biopsy is very useful in that it enables rapid and exact biopsy and obviates the necessity of waiting for an intraoperative report from a pathologist.

Frameless image-guided stereotactic brain biopsy procedure: diagnostic yield, surgical morbidity, and comparison with the frame-based technique

The gold standard for stereotactic brain biopsy target localization has been frame-based stereotaxy. Recently, frameless stereotactic techniques have become increasingly utilized. Few authors have evaluated this procedure, analyzed preoperative predictors of diagnostic yield, or explored the differences in diagnostic yield and morbidity rate between the frameless and frame-based techniques. A consecutive series of 110 frameless and 160 frame-based image-guided stereotactic biopsy procedures was reviewed. Associated variables for both techniques were reviewed and compared. All stereotactic biopsy procedures were included in a risk factor analysis of nondiagnostic biopsy sampling. Frameless stereotaxy led to a diagnostic yield of 89%, with a total permanent morbidity rate of 6% and a mortality rate of 1%. Larger lesions were fivefold more likely to yield diagnostic tissues. Deep-seated lesions were 2.7-fold less likely to yield diagnostic tissues compared with cortical lesions. Frameless compared with frame-based stereotactic biopsy procedures showed no significant differences in diagnostic yield or transient or permanent morbidity. For cortical lesions, more than one needle trajectory was required more frequently to obtain diagnostic tissues with frame-based as opposed to frameless stereotaxy, although this factor was not associated with morbidity. With regard to diagnostic yield and complication rate, the frameless stereotactic biopsy procedure was found to be comparable to or better than the frame-based method. Smaller and deep-seated lesions together were risk factors for a nondiagnostic tissue yield. Frameless stereotaxy may represent a more efficient means of obtaining biopsy specimens of cortical lesions but is otherwise similar to the frame-based technique.

Comparative analysis of diagnostic accuracy of different brain biopsy procedures

Image-guided procedures such as computed tomography (CT) guided, neuronavigator-guided and ultrasound-guided methods can assist neurosurgeons in localizing the intraparenchymal lesion of the brain. However, despite improvements in the imaging techniques, an accurate diagnosis of intrinsic lesion requires tissue sampling and histological verification. The present study was carried out to examine the reliability of the diagnoses made on tumor sample obtained via different stereotactic and ultrasound-guided brain biopsy procedures. A retrospective analysis was conducted of all brain biopsies (frame-based and frameless stereotactic and ultrasound-guided) performed in a single tertiary care neurosciences center between 1995 and 2005. The overall diagnostic accuracy achieved on histopathology and correlation with type of biopsy technique was evaluated. A total of 130 cases were included, which consisted of 82 males and 48 females. Age ranged from 4 to 75 years (mean age 39.5 years). Twenty per cent (27 patients) were in the pediatric age group, while 12% (16 patients) were >or= 60-years of age. A definitive histological diagnosis was established in 109 cases (diagnostic yield 80.2%), which encompassed 101 neoplastic and eight nonneoplastic lesions. Frame-based, frameless stereotactic and ultrasound-guided biopsies were done in 95, 15 and 20 patients respectively. Although the numbers of cases were small there was trend for better yield with frameless image-guided stereotactic biopsy and maximum diagnostic yield was obtained i.e, 87% (13/15) in comparison to conventional frame-based CT-guided stereotactic biopsy and ultrasound-guided biopsy. Overall, a trend of higher diagnostic yield was seen in cases with frameless image-guided stereotactic biopsy. Thus, this small series confirms that frameless neuronavigator-guided stereotactic procedures represent the lesion sufficiently in order to make histopathologic diagnosis.

Frame-based stereotactic biopsy remains an important diagnostic tool with distinct advantages over frameless stereotactic biopsy

As the availability of image-guided surgical navigation systems has increased, the application of frame-based biopsy has declined at our institution, despite equivalent accuracy and safety. There are several cost issues separating the use of surgical navigation systems and stereotactic frames for simple biopsy which may have implications in this era of health care cost control. We retrospectively reviewed the UCSF experience with stereotactic brain biopsy from a 9 year period. Data were collected for 213 consecutive stereotactic brain biopsies performed at UCSF (139 frame-based and 74 frameless). There were no significant differences between the frame-based and frameless biopsy groups with regard to patient demographics, overall histopathology, proportion of nondiagnostic biopsies, or incidence of complications. General anesthesia was used for 9 (6%) and 70 (95%) of the frame-based and frameless biopsy cases, respectively. Frame-based biopsies required a mean of 114+/-3 min of operating room time, while frameless biopsies required 185+/-6 min (P<0.0001). For patients admitted to our neurosurgery service who underwent frame-based (n=110) or frameless (n=52) biopsy within 24 h of admission, the mean lengths of hospital stay were 1.8+/-0.2 and 3.2+/-0.6 days, respectively (P=0.007). Frame-based and frameless stereotactic biopsy approaches were equally effective at providing a tissue diagnosis with minimum morbidity and mortality. The frame-based approach, however, required significantly less anesthesia resources, less operating room time and shorter hospital stays, and thus should still be considered a first-line approach for stereotactic brain biopsy.

Independent predictors of morbidity after image-guided stereotactic brain biopsy: a risk assessment of 270 cases

Image-guided stereotactic brain biopsy is associated with transient and permanent incidences of morbidity in 9 and 4.5% of patients, respectively. The goal of this study was to perform a critical analysis of risk factors predictive of an enhanced operative risk in frame-based and frameless stereotactic brain biopsy. The authors reviewed the clinical and neuroimaging records of 270 patients who underwent consecutive frame-based and frameless image-guided stereotactic brain biopsies. The association between preoperative variables and biopsy-related morbidity was assessed by performing a multivariate logistic regression analysis. Transient and permanent stereotactic biopsy-related morbidity was observed in 23 (9%) and 13 (5%) patients, respectively. A hematoma occurred at the biopsy site in 25 patients (9%); 10 patients (4%) were symptomatic. Diabetes mellitus (odds ratio [OR] 3.73, 95% confidence interval [CI] 1.37-10.17, p = 0.01), thalamic lesions (OR 4.06, 95% CI 1.63-10.11, p = 0.002), and basal ganglia lesions (OR 3.29, 95% CI 1.05-10.25, p = 0.04) were in'dependent risk factors for morbidity. In diabetic patients, a serum level of glucose that was greater than 200 mg/dl on the day of biopsy had a 100% positive predictive value and a glucose level lower than 200 mg/dl on the same day had a 95% negative predictive value for biopsy-related morbidity. Pontine biopsy was not a risk factor for morbidity. Only two (4%) of 45 patients who had epilepsy before the biopsy experienced seizures postoperatively. The creation of more than one needle trajectory increased the incidence of neurological deficits from 17 to 44% when associated with the treatment of deep lesions (those in the basal ganglia or thalamus; p = 0.05), but was not associated with morbidity when associated with the treatment of cortex lesions. Basal ganglia lesions, thalamic lesions, and patients with diabetes were independent risk factors for biopsy-associated morbidity. Hyperglycemia on the day of biopsy predicted morbidity in the diabetic population. Epilepsy did not predispose to biopsy-associated seizure. For deep-seated lesions, increasing the number of biopsy samples along an established track rather than performing a second trajectory may minimize the incidence of morbidity. Close perioperative observation of glucose levels may be warranted.

799 Independent Predictors of Morbidity after Image-guided Stereotactic Brain Biopsy: A Risk Assessment of 270 Consecutive Cases

INTRODUCTION: Image-guided stereotactic brain biopsy is associated with transient morbidity in 7 to 10%, permanent morbidity in 4 to 6%, and mortality in 0.5 to 1% of patients. To date, a critical analysis of risk factors predictive of enhanced operative risk in frame-based and frameless stereotactic brain biopsy has not been performed. METHODS: We reviewed the clinical and radiological records of 270 consecutive frame-based and frameless image-guided stereotactic brain biopsies. The associations between biopsy-related morbidity and clinical, operative, and radiological variables were assessed via multivariate logistic regression analysis. RESULTS: Thirty-six patients (13%) experienced streotactic biopsy-related morbidity; 23 (8%) transient, 13 (5%) permanent, 3 (1%) mortality. Biopsy site hematoma occurred in 25 patients (9%), and 10 (4%) were symptomatic. Diabetes mellitus (OR, 3.73; 95% CI, 1.37–10.17; P = 0.01), thalamic lesions (OR, 4.06; 95% CI, 1.63–10.11; P = 0.002), and basal ganglia lesions (OR, 3.29; 95% CI, 1.05–10.25; P = 0.040) were independent risk factors for morbidity. In diabetic patients, operative-day glucose >200 mg/dl had 100% PPV; glucose <200 mg/dl 95% NPV for biopsy-related morbidity. Pontine biopsy was not a risk factor for morbidity. Only 2 of 45 patients (1%) with prebiopsy epilepsy experience seizures postoperatively. More than one needle trajectory increased the incidence of deficits from 17% to 44% in deep lesions (basal ganglia, thalamus), P = 0.05, but was not associated with morbidity in cortex lesions. Number of biopsy specimens taken per trajectory was not associated with morbidity in all lesions. CONCLUSION: Basal ganglia lesions, thalamic lesions, and diabetic patients were independent risk factors for biopsy-associated morbidity. Operative day hyperglycemia strongly predicted morbidity in the diabetic population. Epilepsy did not predispose to biopsy-associated seizure. For deep-seated lesions, increasing the number of biopsy samples along an established tract versus performing a second trajectory may minimize morbidity. Stereotactic biopsy is a safe procedure with low permanent morbidity (5%) and should be performed cautiously for lesions of the thalamus and basal ganglia. Close peri-operative glucose control is mandatory.

798 Accuracy of Image-guided Stereotactic Brain Biopsy in the Diagnosis of Glioma: Comparison of Biopsy and Open Resection Specimen

INTRODUCTION: Tissue heterogeneity and rapid tumor progression may decrease the accuracy and prognostic value of stereotactic brain biopsy in the diagnosis of gliomas. Correct tumor grading is therefore dependent on accuracy of biopsy needle placement. The accuracy of frameless and frame-based techniques in the diagnosis and grading of glioma remains unstudied. METHODS: The diagnoses of 21 astrocytic brain tumors were derived using image-guided stereotactic biopsy (12 frame-based, 9 frameless) and followed by open resection of the lesion 1.5 months (0.5–4 mo) later. The histological diagnoses yielded by biopsy were compared with subsequent histological diagnosis from open tumor resection. RESULTS: Stereotactic biopsy histology accurately represented the greater lesion at open resection a median of 45 days later in 16 patients (76%) and correctly guided therapy in 19 (91%). Biopsy accuracy of frameless versus frame-based stereotaxy was similar (89 versus 66%, P = 0.21). In 3 patients (14%), biopsy specimens were adequate to diagnose glioma; however, histology was insufficient for definitive tumor grading (grade III versus IV). Anaplastic oligodendroglioma (ODG) was undergraded as low-grade ODG in 1 patients (5%). Biopsy of new-onset GBM yielded necrosis/gliosis and was called nondiagnostic in one patient. Tumors >50 cm3 were eightfold less likely to accurately represent the grade of the entire lesion at resection compared with lesions <50 cm3 (OR, 8.8; 95% CI, 0.9–100; P = 0.05). CONCLUSION: Both frameless and frame-based magnetic resonance imaging-guided stereotactic brain biopsy are safe and accurately represent the larger glioma mass sufficiently to guide subsequent therapy. The diagnostic accuracy of frameless stereotactic brain biopsy is equivalent to the frame-based technique in the diagnosis and grading of glioma. Glioma volume >50 cm3 may be a negative prognostic indicator of biopsy accuracy.

Clinical Application of Neuro-Navigation in a Series of Single Burr-Hole Procedures

With recent developments in computer technology and the improvement of neuroimaging, modern optical neuro-navigation systems are increasingly being used in neurosurgery. In this study, we present our experience with 51 operations using a frameless optical navigation system in a variety of single burr-hole procedures. The procedures include neuroendoscopic surgery, frameless stereotactic biopsy, cyst aspiration and catheter placement. Both the VectorVision and the VectorVision(2) neuro-navigation systems (BrainLab AG, Munich, Germany) were used. The reliability and accuracy of the neuro-navigation system, postoperative complications and the clinical usefulness of image-guidance were analyzed. The navigation system worked properly in all 51 neurosurgical cases. Exact planning of the approach and determination of the ideal trajectory were possible in all cases. The mean registration error of the system, given as a computer-calculated value, was 2.1 mm (0.4-3.1 mm). Postoperative clinical evaluations and imaging were performed on every patient in order to confirm the success of the surgical procedure. All patients recovered well and without any postoperative complications. We conclude that image guidance in single burr-hole procedures provides a high degree of accuracy in lesion targeting, permits good anatomical orientation and minimizes brain trauma. The navigation system has proven to be a helpful tool since it increases the safety of single burr-hole procedures.