Correlation of diagnostic yield of stereotactic brain biopsy with number of biopsy bits and site of the lesion

Diagnostic yield of postmortem brain examination following premortem brain biopsy for neoplastic and nonneoplastic disease

Medical autopsies have decreased in frequency due in part to advances in radiological techniques and increased availability of molecular and other ancillary testing. However, premortem diagnosis of CNS disease remains challenging; while ∼90% of brain tumor biopsies are diagnostic, only 20%-70% of biopsies for presumed nonneoplastic disease result in a specific diagnosis. The added benefits of performing an autopsy following surgical brain biopsy are not well defined. A retrospective analysis was performed of patients who underwent brain biopsy and autopsy at Brigham and Women's Hospital from 2003 to 2022. A total of 135 cases were identified, including 95 (70%) patients with primary CNS neoplasms, 16 (12%) with metastatic tumors, and 24 (18%) with nonneoplastic neurological disease. Diagnostic concordance between biopsy and autopsy diagnosis was excellent both for primary CNS neoplasms (98%) and metastatic tumors (94%). Conversely, patients with nonneoplastic disease received definitive premortem diagnoses in 7/24 (29%) cases. Five (21%) additional patients received conclusive diagnoses following autopsy; 8 (33%) received a more specific differential diagnosis compared to the biopsy. Overall, autopsy confirmed premortem diagnoses or provided new diagnostic information in 131/135 (97%) cases, highlighting the value in performing postmortem brain examination in patients with both neoplastic and nonneoplastic diseases.

Comparison meta-analysis of intraoperative MRI-guided needle biopsy versus conventional stereotactic needle biopsies

Background

MRI-guided needle biopsy (INB) is an emerging alternative to conventional frame-based or frameless stereotactic needle biopsy (SNB). Studies of INB have been limited to select case series, and comparative studies between INB and SNB remain a missing gap in the literature. We performed a meta-analysis to compare INB and SNB literature in terms of diagnostic yield, surgical morbidity and mortality, tumor size, and procedural time.

Methods

We identified 36 separate cohorts in 26 studies of SNB (including both frameless and frame-based biopsies, 3374 patients) and 27 studies of INB (977 patients). Meta-regression and meta-analysis by proportions were performed.

Results

Relative to publications that studied SNB, publications studying INB more likely involved brain tumors located in the eloquent cerebrum (79.4% versus 62.6%, P = 0.004) or are smaller in maximal diameter (2.7 cm in INB group versus 3.6 cm in the SNB group, P = .032). Despite these differences, the pooled estimate of diagnostic yield for INB was higher than SNB (95.4% versus 92.3%, P = .026). The pooled estimate of surgical morbidity was higher in the SNB group (12.0%) relative to the INB group (6.1%) (P = .004). Mortality after the procedure was comparable between INB and SNB (1.7% versus 2.3%, P = .288). Procedural time was statistically comparable at 90.3 min (INB) and 103.7 min (SNB), respectively (P = .526).

Conclusions

Our meta-analysis indicates that, relative to SNB, INB is more often performed for the challenging, smaller-sized brain tumors located in the eloquent cerebrum. INB is associated with lower surgical morbidity and improved diagnostic yield.

Stereotactic biopsy for brain lesions: Doing more with less

Objectives

Stereotactic biopsy (STB) is a potential diagnostic tool considering its minimal invasiveness, high diagnostic yield, and minimal associated complications. Over the years, various frame-based instrument systems and frameless stereotactic biopsy systems have emerged to be employed in clinical use. With this study, we intend to get more by doing less in the form of STB for the patients of doubtful intracranial lesions treated over the past 5 years. We also want to highlight the technique of performing the procedure under scalp block, which can be used as a versatile tool in many clinical scenarios. Stereotactic biopsies may be planned even in rural district-level health facilities. One-time investment to procure instruments and avail existing imaging can lead to establishing definitive diagnoses in many doubtful cases. This will result in lesser cost and early establishment of treatment. Independent risk factors determining the outcome, such as deep-seated lesions, associated edema, and intraoperative hypertension, were studied. Establishing the diagnosis helped in prognosticating the disease, explaining the natural progression of symptoms, and starting adjuvant therapy. This tissue biopsy would also help secure samples for research and molecular analysis.

Materials and Methods

Twenty patients underwent STBs at our institution between January 2018 and December 2022. We retrospectively analyzed patient characteristics, tumor pathology, surgical procedures, and outcomes, including the diagnostic value and surgery-related complications. These patients were followed up, and their progression-free and overall survival were analyzed. The need for adjuvant treatment was noted and analyzed. All procedures were performed using Cosman Roberts Wells® stereotactic frame. Pre-procedure magnetic resonance scans were performed at the time of admission. Contrast-enhanced computerized tomography (CT) scan after frame application was performed to identify targets and calculate the coordinates. A post-procedure CT scan was done to confirm the accessibility of the targeted lesion.

Results

The most common location of the tumor was a deep-seated thalamic lesion. A definitive diagnosis was established in 19 patients (95%) at the first STB. The diagnoses were glioma in 55% of cases, primary central nervous system lymphoma, tuberculosis, and demyelinating disorders in 10% of each, and a metastatic brain tumor in 1 (5%). The post-operative complications were all transient except in one patient with deterioration of motor weakness. The follow-up was noted, and modes of adjuvant treatment needed in these patients were recorded.

Conclusion

Stereotactic biopsy is a useful and effective method for achieving a definitive diagnosis and aiding in treating multifocal or small deep-seated lesions in or around eloquent regions.

Computed tomography-guided stereotactic surgery in the management of brain lesions: A single-center experience

Background

The present study presents our experience with computed tomography (CT)-guided stereotactic surgery in managing deep-seated brain lesions and provides a background in the expanding fields of morphological stereotactic neurosurgery.

Methods

We conducted this retrospective cohort study on 80 patients managed at the Department of Neurosurgery, Zagazig University Hospitals, Zagazig, Egypt, between January 2019 to January 2021. We targeted patients with morphological stereotactic surgeries performed as the primary management modality of their treatment.

Results

A total of 80 patients, with a mean age of 44.3 years, were included in the study. The stereotactic targets were supratentorial in 71 patients (88.75%), infratentorial in seven patients (8.75%), and both supraand infratentorial in two patients (2.5%). The lesions showed enhancements with IV contrast in 55 patients (68.75%). Stereotactic procedures were performed under local anesthesia in 64 patients and general anesthesia in 16 patients. Of the 80 stereotactic procedures, 52 were biopsies (65%). We observed a significant improvement in the postoperative Karnofsky performance score compared to the postoperative score (63.4 ± 19.8 vs. 56.7 ± 15.4, P = 0.001). The level of agreement between clinical, radiological, and final pathological diagnosis was assessed; it was complete in 47.5% of the patients. The postprocedural CT scan demonstrated intracranial hemorrhage in five patients (6.25%); four (5%) were silent with no neurological complications.

Conclusion

This study provided evidence that the stereotactic procedure is easy to perform, accurate in targeting the lesion, and spares patients from undergoing major surgical procedures. Stereotactic applications of spontaneous intracerebral hemorrhage, deep-seated abscesses, encysted tumors, or medically refractory benign intracranial hypertension can improve the outcome even in medically high-risk patients.

Fluorescein sodium fluorescence: role in stereotactic brain biopsy

BACKGROUND

Stereotactic brain biopsy for eloquent area brain tumours is associated with complications like hemorrhage due to multiple sampling and increased operative time due to dependence on neuropathologist for frozen section assessment. In order to curb these limitations, we investigated the use of Fluorescein sodium fluorescence in confirming pathological tissue samples in stereotactic brain biopsy of gadolinium-enhancing tumours.

METHODS

This prospective observational study included 23 consecutive patients who underwent stereotactic biopsy of gadolinium-contrast-enhancing brain lesions with intravenous fluorescein sodium administration. 93 specimens were obtained and examined for the presence of fluorescence using a microscope with fluorescence visualisation capability. Later the nature of the samples was confirmed on histopathology. The sensitivity and specificity of flourescein sodium fluorescence were calculated based on histopathological confirmation.

RESULTS

58 (62.3%) fluorescent and 35 (37.6%) nonfluorescent samples were obtained. All fluorescent specimens contained diagnostic tissue appropriate for tumor grading. Of 35 nonfluorescent specimens, 12 (34.3%) did not contain tumor, 11 (31.4%) contained minor hypercellularity or gliosis, and 12 (34.3%) contained tumor with a high proportion of necrosis. The sensitivity and specificity for fluorescein fluorescence were 83% and 100%, respectively.

CONCLUSIONS

Fluorescein fluorescence is a handy tool to detect the pathological tissue in stereotactic brain biopsy and may improve its diagnostic accuracy and expedite the procedure.

Circulating tumor DNA in B-cell lymphoma: technical advances, clinical applications, and perspectives for translational research

Noninvasive disease monitoring and risk stratification by circulating tumor DNA (ctDNA) profiling has become a potential novel strategy for patient management in B-cell lymphoma. Emerging innovative therapeutic options and an unprecedented growth in our understanding of biological and molecular factors underlying lymphoma heterogeneity have fundamentally increased the need for precision-based tools facilitating personalized and accurate disease profiling and quantification. By capturing the entire mutational landscape of tumors, ctDNA assessment has some decisive advantages over conventional tissue biopsies, which usually target only one single tumor site. Due to its non- or minimal-invasive nature, serial and repeated ctDNA profiling provides a real-time picture of the genetic composition and facilitates quantification of tumor burden any time during the course of the disease. In this review, we present a comprehensive overview of technologies used for ctDNA detection and genotyping in B-cell lymphoma, focusing on pre-analytical and technical requirements, the advantages and limitations of various approaches, and highlight recent advances around improving sensitivity and suppressing technical errors. We broadly review potential applications of ctDNA in clinical practice and for translational research by describing how ctDNA might enhance lymphoma subtype classification, treatment response assessment, outcome prediction, and monitoring of measurable residual disease. We finally discuss how ctDNA could be implemented in prospective clinical trials as a novel surrogate endpoint and be utilized as a decision-making tool to guide lymphoma treatment in the future.

Clinical use of a new frameless optical neuronavigation system for brain biopsies: 10 cases (2013-2020)

OBJECTIVES

The aim of the retrospective study was to describe the brain biopsy procedure using a new frameless optical neuronavigation system and to report diagnostic yield and complications associated with the procedure.

MATERIALS AND METHODS

The medical records for all dogs with forebrain lesions that underwent brain biopsy with a frameless optical neuronavigation system in a single referral hospital between 2013 and 2020 were retrospectively analysed. Following data were collected: signalment, neurological signs, diagnostic findings, number of brain biopsy samples, sampled region, complications, duration of hospitalisation, whether the samples were diagnostic and histopathological diagnoses. The device consists of a computer workstation with navigation software, an infrared camera, patient tracker and reflective instruments. The biopsy needle was equipped with reflective spheres, so the surgeon could see the position of the needle during sampling the intracranial lesion free handed through a mini-burr hole.

RESULTS

Ten dogs were included. Absolute diagnostic yield based on specific histopathological diagnosis was 73.9%. Three dogs had immune-mediated necrotizing encephalitis, two dogs showed a necrotizing leukoencephalitis and two dogs a meningoencephalitis of unknown origin. In two dogs, the brain specimen showed unspecific changes. In one dog, the samples were non-diagnostic. Seven dogs showed no neurological deterioration, one dog mild temporary ataxia and two dogs died within 36 hours post brain biopsy.

CLINICAL SIGNIFICANCE

In these 10 dogs, the frameless optical neuronavigation system employed was useful to gain diagnostic brain biopsy samples. Considering the mortality rate observed, further studies are needed to confirm the safety of this procedure and prove its actual clinical effectiveness.

Related factors with diagnostic yield and intracranial hemorrhagic complications in frame-based stereotactic biopsy. Review

The frame-based stereotactic biopsy is a minimally invasive technique that allows us to obtain a sample of brain tissue for subsequent diagnosis and treatment. The scope of this article is to review the published data related to the factors that could condition its diagnostic yield, and the appearance of post-biopsy hemorrhagic complications. PubMed search, last updated June 2020, was conducted using the terms "stereotactic biopsy", "diagnostic yield" and "intracranial post-biopsy hemorrhage". A total of 38 studies, that showed descriptive or analytical results, were included, and reviewed. Our literature review show that some characteristics of the lesion and surgical procedure peculiarities are significantly related with the effectiveness and safety of the technique. In this way, they must be taken into account in order to optimize its results.

Clinical outcomes as a function of the number of samples taken during stereotactic needle biopsies: a meta-analysis

BACKGROUND

Stereotactic needle biopsy remains the cornerstone for tissue diagnosis for tumors located in regions of the brain that are difficult to access through open surgery.

OBJECTIVE

We perform a meta-analysis of the literature to examine the relation between number of samples taken during biopsy and diagnostic yield, morbidity and mortality.

METHODS

We identified 2416 patients from 28 cohorts in studies published in PubMed database that studied stereotactic needle biopsies for tumor indications. Meta-analysis by proportions and meta-regression analyses were performed.

RESULTS

On meta-analysis, the morbidity profile of the published needle biopsy studies clustered into three groups: studies that performed < 3 samples (n = 8), 3-6 samples (n = 13), and > 6 samples during biopsy (n = 7). Pooled estimates for biopsy related morbidity were 4.3%, 16.3%, and 17% for studies reporting < 3, 3-6, and > 6 biopsy samples, respectively. While these morbidity estimates significantly differed (p < 0.001), the diagnostic yields reported for studies performing < 3 biopsies, 3-6 samples, and > 6 samples were comparable. Pooled estimates of diagnostic yield for these three groups were 90.4%, 93.8%, and 88.1%, respectively. Mortality did not significantly differ between studies reporting differing number of samples taken during biopsy.

CONCLUSIONS

Our meta-analysis suggests that morbidity risk in needle biopsy is non-linearly associated with the number of samples taken. There was no association between the number of biopsies taken, and diagnostic yield or mortality.

Comparison of frame-less robotic versus frame-based stereotactic biopsy of intracranial lesions

OBJECTIVE

Robotic guidance might be an alternative to classic stereotaxy for biopsies of intracranial lesions. Both methods were compared regarding time efficacy, histopathological results and complications.

METHODS

A retrospective analysis enrolling all patients undergoing robotic- or stereotactic biopsies between 01/2015 and 12/2018 was conducted. Trajectory planning was performed on magnetic resonance imaging (MRI). With the Robotic Surgery Assistant (ROSA), patient registration was accomplished using a facial laser scan in the operating room (OR), immediately followed by biopsy. In stereotaxy, patients were transported to the CT for Leksell Frame registration, followed by biopsy in the OR.

RESULTS

The average overall procedure time amounted in robotics to 169 min and in stereotaxy to 179 min (p = 0.005). The difference was greatest for temporal targets, amounting in robotics to 161 min and in stereotaxy to 188 min (p = 0,0007). However, the average time spent purely in the OR amounted in robotics to 140 min and in stereotaxy to 113 min (p < 0.001). In 150 robotic biopsies, diagnostic yield amounted to 98%, in 266 stereotactic biopsies to 91%. Symptomatic postoperative hemorrhages were observed in 3 patients (2%) in robotic biopsy and 7 patients (2,7%) in stereotactic biopsy.

CONCLUSION

Robotics showed a shorter overall procedure time as there is no need for a transport to the CT whereas the pure OR time was shorter in stereotaxy due to skipping the laser registration process. Diagnostic yield was higher in robotics, most likely due to case selection, complication rates were equal.

Toward a standard pathological and molecular characterization of recurrent glioma in adults: a Response Assessment in Neuro-Oncology effort

Regardless of subtype, diffuse gliomas of adulthood are characterized by inexorable progression through treatment. Cancer recurrence in the context of therapy is by no means unique to gliomas. For many tumors residing outside the central nervous system (CNS), tissue-based analyses are routinely employed to document the molecular and cellular features of disease recurrence. Such interventions are inconsistently applied for gliomas, however, and lack rigorous standardization when they are. While many of the reasons underlying these discrepancies reflect pragmatic realities inherent to CNS disease, the suboptimal employment of histological and molecular assessment at recurrence nevertheless represents a missed opportunity to proactively guide patient management and increase knowledge. Herein, we address this quandary by pairing a succinct description of the histological, biological, and molecular characteristics of recurrent glioma with recommendations for how to better standardize and implement quality pathological assessment into patient management. We hope this review will prompt thoughtful revision of standard operating procedures to maximize the utility of glioma re-biopsy.

Related factors with diagnostic yield and intracranial hemorrhagic complications in frame-based stereotactic biopsy. Review

The frame-based stereotactic biopsy is a minimally invasive technique that allows us to obtain a sample of brain tissue for subsequent diagnosis and treatment. The scope of this article is to review the published data related to the factors that could condition its diagnostic yield, and the appearance of post-biopsy hemorrhagic complications. PubMed search, last updated June 2020, was conducted using the terms "stereotactic biopsy", "diagnostic yield" and "intracranial post-biopsy hemorrhage". A total of 38 studies, that showed descriptive or analytical results, were included, and reviewed. Our literature review show that some characteristics of the lesion and surgical procedure peculiarities are significantly related with the effectiveness and safety of the technique. In this way, they must be taken into account in order to optimize its results.

Treatment-induced brain tissue necrosis: a clinical challenge in neuro-oncology

Cancer therapy-induced adverse effects on the brain are a major challenge in neuro-oncology. Brain tissue necrosis (treatment necrosis [TN]) as a consequence of brain directed cancer therapy remains an insufficiently characterized condition with diagnostic and therapeutic difficulties and is frequently associated with significant patient morbidity. A better understanding of the underlying mechanisms, improvement of diagnostic tools, development of preventive strategies, and implementation of evidence-based therapeutic practices are pivotal to improve patient management. In this comprehensive review, we address existing challenges associated with current TN-related clinical and research practices and highlight unanswered questions and areas in need of further research with the ultimate goal to improve management of patients affected by this important neuro-oncological condition.

Evaluation of 311 contemporary cases of stereotactic biopsies in patients with neoplastic and non-neoplastic lesions-diagnostic yield and management of non-diagnostic cases

Stereotactic biopsies are an established tool for obtaining diagnosis of unclear brain lesions. However, non-diagnostic biopsies still occur. We aimed to analyze the contemporary diagnostic yield of stereotactic biopsies, predictors for non-diagnostic biopsies, outcome, and follow-up strategy after non-diagnostic biopsy. We conducted a single-center retrospective study of 311 adult patients undergoing stereotactic biopsies due to a newly diagnosed lesion at our department between 2012 and 2018. Patient data regarding comorbidities, presenting symptoms, imaging features, and non-invasive diagnostic procedures were obtained. The overall diagnostic yield was 86.2% and differed significantly between the various suspected diagnosis groups and was the highest when suspecting primary brain tumor compared with non-neoplastic lesions (91.2% vs. 73.3%, p > 0.001). Predicators for non-diagnostic biopsies were small lesion size, lack of contrast-enhancement, presence of sepsis, or underlying hemato-oncological disease. In case of non-diagnostic biopsy, a re-biopsy was performed in 12 cases, revealing a final diagnosis in 75%. In 16 cases, empiric therapy was started based on the suspected underlying disease. Close follow-up was performed in the remaining 15 cases. We showed that stereotactic biopsy is a safe procedure with reasonable diagnostic yield even for non-neoplastic lesions, when non-invasive diagnostic was inconclusive. In addition, we developed treatment recommendations for cases of non-diagnostic biopsies.

Capturing Tumor Heterogeneity and Clonal Evolution by Circulating Tumor DNA Profiling

Most malignancies are characterized by remarkable molecular heterogeneity. The understanding of genetic and epigenetic processes underlying tumor heterogeneity has become increasingly important for the clinical management of cancer patients. This includes the identification of patients who likely benefit from conventional or targeted therapies, classification of patients into risk groups based on their mutational landscape, and the detection of molecular mechanisms that drive treatment resistance and cancer progression. Detection of tumor heterogeneity by tumor tissue genotyping is hampered by the fact that tissue sampling is often insufficient for comprehensive genetic assessment and is associated with a higher risk of surgical complications. Detection and profiling of circulating tumor DNA (ctDNA) have emerged as a promising alternative to direct tumor genotyping. It potentially enables noninvasive and quantitative characterization of the full genetic landscape and identification of clonal evolution during treatment and towards disease progression in cancer patients. In the present chapter, we explore the role of noninvasive genotyping and ctDNA profiling for accurate and robust characterization of various types of tumor heterogeneity and its relevance for management of patients with hematologic and solid cancers.

Factors Affecting the Diagnostic Yield of Frame-Based Stereotactic Intracranial Biopsies

OBJECTIVE

Frame-based stereotactic biopsy (FSB) remains the "gold standard" for obtaining diagnostic samples of intracranial lesions to guide therapy. Nevertheless, diagnostic yield is highly variable. This study aims to provide an analysis of diagnostic yield, surgical complications, and factors associated with obtaining nondiagnostic samples in a contemporary FSB series.

METHODS

A retrospective cohort study was conducted of all adult patients with imaging-documented lesions undergoing FSB at our institution between 2013 and 2018. Diagnostic accuracy, lesion characteristics associated with nondiagnostic biopsy, and surgical complications were evaluated. A biopsy was considered nondiagnostic if all frozen samples and the final pathology yielded normal brain tissue or nonspecific reactive tissue unless the "reactive" pathology was consistent with radiation injury from prior therapy.

RESULTS

Our search identified 198 FSB patients. Mean (standard deviation) age was 62 ± 17 years, and 44.2% were female. Median procedure time was 32 minutes. A definitive histologic diagnosis was established in 187 cases (94.4% diagnostic yield). Mean lesion diameter was 31.9 ± 16.8 mm. Multivariable logistic regression revealed only lesion diameter to be significantly associated with diagnostic result (odds ratio for nondiagnostic result: 0.94 per mm diameter decrease, 95% confidence interval 0.87-0.99, P = 0.028). On univariable analysis, diagnosis of central nervous system lymphoma appeared to increase the risk of a nondiagnostic biopsy (P = 0.025), but this association disappeared when controlling for lesion size and steroid administration before biopsy. Eight patients (4.0%) developed postoperative hemorrhagic complications, 3 of whom required reoperation, and another expired.

CONCLUSIONS

This study demonstrates that diagnostic yield from contemporary FSB is high and depends predominantly on lesion size.

Diagnostic Yield and Complication of Frameless Stereotactic Brain Biopsy

Background:

With the advancement of neuronavigation technologies, frameless stereotactic brain biopsy has been developed. Previous studies proved that frameless stereotactic brain biopsy was as effective and safe as frame-based stereotactic brain biopsy. The authors aimed to find the factors associated with diagnostic yield and complication rate of frameless intracranial biopsy.

Materials and Methods:

Frameless stereotactic brain biopsy procedures, between March 2009 and April 2017, were retrospectively reviewed from medical records including imaging studies. Using logistic regression analysis, various factors were analyzed for association with diagnostic yield and postoperative complications.

Results:

Eighty-nine frameless stereotactic brain biopsy procedures were performed on 85 patients. The most common pathology was primary central nervous system lymphoma (43.8%), followed by low-grade glioma (15.7%), and high-grade glioma (15%), respectively. The diagnostic yield was 87.6%. Postoperative intracerebral hematoma occurred in 19% of cases; however, it was symptomatic in only one case. The size of the lesion was associated with both diagnostic yield and postoperative intracerebral hematoma complication. Lesions, larger than 3 cm in diameter, were associated with a higher rate of positive biopsy result (P = 0.01). Lesion 3 cm or smaller than 3 cm in diameter, and intraoperative bleeding associated with a higher percentage of postoperative intracerebral hematoma complications (P = 0.01).

Conclusions:

For frameless stereotactic brain biopsy, the size of the lesion is the essential factor determining diagnostic yield and postoperative intracerebral hematoma complication.

Diagnostic accuracy of stereotactic brain biopsy for intracranial neoplasia in dogs: Comparison of biopsy, surgical resection, and necropsy specimens

Background

Stereotactic brain biopsy (SBB) is a technique that allows for definitive diagnosis of brain lesions. Little information is available regarding the diagnostic utility of SBB in dogs with intracranial diseases.

Objective

To investigate the diagnostic accuracy (DA) of SBB in dogs with brain tumors.

Animals

Thirty‐one client‐owned dogs that underwent SBB followed by surgical resection or necropsy examinations.

Methods

Retrospective observational study. Two pathologists blinded to SBB and reference standard diagnoses reviewed histologic specimens and typed and graded tumors according to World Health Organization and revised canine glioma classification criteria. Agreement between tumor type and grade from SBB were compared to reference standards and assessed using kappa statistics. Patient and technical factors associated with agreement also were examined.

Results

Stereotactic brain biopsy specimens were obtained from 24 dogs with gliomas and 7 with meningiomas. Tumor type agreement between SBB and the reference standard was observed in 30/31 cases (κ = 0.95). Diagnostic concordance was perfect for meningiomas. Grade agreement among gliomas was observed in 18/23 cases (κ = 0.47). Stereotactic brain biopsy underrepresented the reference standard glioma grade in cases with disagreement. The DA of SBB was 81%, with agreement noted in 56/69 biopsy samples. Smaller tumors and fewer SBB specimens obtained were significantly associated with diagnostic discordance.

Conclusions and Clinical Importance

The DA of SBB readily allows for the diagnosis of common brain tumors in dogs. Although glioma grade discordance was frequent, diagnoses obtained from SBB are sufficient to currently inform therapeutic decisions. Multiple SBB specimens should be collected to maximize DA.

Venture in 101 Cranial Punctures: A Comparative Study between Frame-based versus Frameless Biopsy of 101 Intracranial Space Occupying Lesion

Background:

Presumptive diagnosis based solely on the clinical picture and imaging is not sufficient to provide appropriate treatment with certainty and hence histopathological confirmation of intracranial space occupying lesion (ICSOL) is essential. Needle biopsy via stereotactic frame-based or frameless neuronavigation technique is efficient procedure. The objective of this study is to compare their accuracy and efficacy and safety.

Methods:

This is a retrospective comparative study conducted among 101 biopsies of ICSOL. Patients data were retrieved from medical record. Data were analyzed in SPSS ver. 20. P value of <0.05 was considered significant.

Results:

Out of 101 patients, Frame-based stereotactic biopsy was done among 55 patients (54.4%) while 46 patients (45.6%) underwent frameless stealth neuronavigation guided biopsy. Male to female ration was 2.1:1. Age ranged from 5 to 82 years. 54.5% (55 patients) have deeper location of tumor while 45.5% (46 patients) have lobar location of tumor. Frontal (16.8%) and Thalamic (13.8%) were the common site. Mean size of tumor was 3.09±0.85cms. There was statistically significant difference in operative duration among study groups. Overall Diagnostic yield was 89.1%. Glioma was the most common (50.5%) diagnosis. Glioblastoma WHO Grade IV was 37.6% followed by lymphoma (12.8%).

Conclusion:

Needle biopsy via stereotactic frame-based or neuronavigation frameless technique is a safe and efficient procedure having high diagnostic yield. Reasons for negative biopsy could be missed target or retrieval of gliotic tissue.

Intraoperative detection of blood vessels with an imaging needle during neurosurgery in humans

Intracranial hemorrhage can be a devastating complication associated with needle biopsies of the brain. Hemorrhage can occur to vessels located adjacent to the biopsy needle as tissue is aspirated into the needle and removed. No intraoperative technology exists to reliably identify blood vessels that are at risk of damage. To address this problem, we developed an "imaging needle" that can visualize nearby blood vessels in real time. The imaging needle contains a miniaturized optical coherence tomography probe that allows differentiation of blood flow and tissue. In 11 patients, we were able to intraoperatively detect blood vessels (diameter, >500 μm) with a sensitivity of 91.2% and a specificity of 97.7%. This is the first reported use of an optical coherence tomography needle probe in human brain in vivo. These results suggest that imaging needles may serve as a valuable tool in a range of neurosurgical needle interventions.

Frame-based stereotactic biopsies using an intraoperative MR-scanner are as safe and effective as conventional stereotactic procedures

Background

Frame-based stereotactic biopsy (FBSB) is a minimally-invasive and effective procedure for the diagnosis of brain lesions and will likely gain clinical importance. Since FBSB procedures comprise a variety of imaging and sampling methods, it is necessary to compare the safety and effectiveness of individual techniques.

Objective

To assess the safety and effectiveness of FBSB using 1.5T iMRI as a one-stop procedure under general anesthesia without intraoperative histological examination.

Methods

In this single-center, retrospective analysis, 500 consecutive FBSBs using iMRI were compared to a historic control of 100 biopsies with traditional workflows (computed tomography (CT) with MRI image fusion). All procedures were performed under general anesthesia. Data on surgical procedures, pre- and postoperative neurologic patient status, complications and diagnostic yield were extracted from clinical records.

Results

Complication rates and diagnostic yield showed no significant differences between both groups. Mortality was 0.6%, 95% CI = [0.12%, 1.74%], in the iMRI and 0.0% [0.00%, 3.62%], in the control group with a morbidity of 5.4% [3.6%, 7.8%] and 6.0% [2.2%, 12.6%] and a diagnostic yield of 96.8% [94.9%, 98.2%] and 96.0% [90.1%, 98.9%]. Mean procedure duration was 124 [121, 127] minutes using iMRI and 112 [106, 118] minutes in the control group.

Conclusion

FBSB using 1.5T iMRI under general anesthesia is a safe and effective procedure and is equivalent to traditional stereotactic workflows with respect to complication rate and diagnostic yield.

Preoperative assessment of haemostasis in patients undergoing stereotactic brain biopsy

Parenchymal hemorrhage is considered a major risk factor for perioperative morbidity in patients undergoing stereotactic brain biopsy. Studies on patients undergoing surgical procedures have suggested that evaluation of prothrombin time (PT) and activated partial thromboplastin time (aPTT) is of limited value with regard to prevention of haemorrhagic complications. However, this issue has not yet been addressed in patients undergoing stereotactic biopsy of intracranial lesions. We retrospectively analysed the medical records of 159 consecutive patients undergoing stereotactic biopsy of supratentorial intracranial lesions during a three-year period. Laboratory values (PT, aPTT, platelet count) were reviewed as well as clinical characteristics, modalities of surgical treatment, histopathological results and the postoperative course of patients. The overall diagnostic yield was 93.7%. Histopathological examination revealed glioma (WHO°I: 5, WHO°II: 25, WHO°III: 23, WHO°IV: 65), lymphoma (n = 14), inflammation (n = 8) and other entities (n = 6). Surgery-associated neurological deficits occurred in 7 patients (4.4%) and completely resolved in 6 of these patients. CT-confirmed intracranial hemorrhage occurred in 2 patients (1.3%) and in both cases, histopathological examination revealed glioblastoma. Results of hemostatic parameters (PT: 99 ± 13%, aPTT: 24 ± 3s, platelet count: 274 ± 87 10³/μL) were within normal range values in all patients and did not correlate with postsurgical morbidity. Standard assessment of haemostasis seems to be of limited value in patients with intracranial lesions undergoing stereotactic biopsy. Further studies regarding the intratumoural vasculature's impact on the risk of biopsy-related bleeding are necessary.

Investigation of the usefulness of fluorescein sodium fluorescence in stereotactic brain biopsy

BACKGROUND

Intraoperative frozen section assessment, to confirm acquisition of pathological tissues, is used in stereotactic brain biopsy to minimise sampling errors. Limitations include the dependence on dedicated neuro-oncology pathologists and an increase in operative duration. We investigated the use of intraoperative fluorescein sodium, and compared it to frozen section assessment, for confirming pathological tissue samples in the stereotactic biopsy of gadolinium-contrast-enhancing brain lesions.

METHODS

This prospective observational study consisted of 18 consecutive patients (12 men; median age, 63 years) who underwent stereotactic biopsy of gadolinium-contrast-enhancing brain lesions with intravenous fluorescein sodium administration. Twenty-three specimens were obtained and examined for the presence of fluorescence using a microscope with fluorescence visualisation capability. Positive and negative predictive values were calculated based on the fluorescence status of the biopsy samples with its corresponding intraoperative frozen section and definitive histopathological diagnosis.

RESULTS

Nineteen specimens (83%) were fluorescent and four (17%) were non-fluorescent. All 19 fluorescent specimens were confirmed to be lesional on intraoperative frozen section assessment and were suitable for histopathological diagnosis. Three of the non-fluorescent specimens were confirmed to be lesional on intraoperative frozen section assessment. One non-fluorescent specimen was non-diagnostic on frozen section and histological assessments. The positive predictive value was 100% and the negative predictive value was 25%.

CONCLUSIONS

Fluorescein sodium fluorescence is as accurate as frozen section assessment in confirming sampling of pathological tissue in the stereotactic biopsy of gadolinium-contrast-enhancing brain lesions. Fluorescein sodium fluorescence-guided stereotactic biopsy is a useful addition to the neurosurgical armamentarium.

Assessment of molecular markers demonstrates concordance between samples acquired via stereotactic biopsy and open craniotomy in both anaplastic astrocytomas and glioblastomas

The classification, treatment and prognosis of high-grade gliomas has been shown to correlate with the expression of molecular markers (e.g. MGMT promotor methylation and IDH1 mutations). Acquisition of tumor samples may be obtained via stereotactic biopsy or open craniotomy. Between the years 2009 and 2013, 22 patients initially diagnosed with HGGs via stereotactic biopsy, that ultimately underwent open craniotomy for resection of their tumor were prospectively included in an institutional glioma database. MGMT promotor analysis was performed using methylation-specific (MS)-PCR and IDH1R132H mutation analysis was performed using immunohistochemistry. Three patients (13.7%) exhibited IDH1R132H mutations in samples obtained via stereotactic biopsy. Tissue derived from stereotaxic biopsy was demonstrated to have MGMT promotor methylation in ten patients (45.5%), while a non-methylated MGMT promotor was demonstrated in ten patients (45.5%); inconclusive results were obtained for the remaining two patients (9%) within our cohort. The initial histologic grading, IDH1R132H mutation and MGMT promotor methylation results were confirmed using samples obtained during open craniotomy in all but one patient; here inconclusive MGMT promotor analysis was obtained in contrast to that which was obtained via stereotactic biopsy. Tumor samples acquired via stereotactic biopsy provide accurate information with regard to clinically relevant molecular markers that have been shown to impact patient care decisions. The profile of markers analyzed in our cohort was nearly concordant between those samples obtained via stereotactic biopsy or open craniotomy thereby suggesting that clinical decisions may be based on the molecular profile of the tumor samples obtained via stereotactic biopsy.

A novel miniature robotic guidance device for stereotactic neurosurgical interventions: preliminary experience with the iSYS1 robot

OBJECTIVE

Robotic devices have recently been introduced in stereotactic neurosurgery in order to overcome the limitations of frame-based and frameless techniques in terms of accuracy and safety. The aim of this study is to evaluate the feasibility and accuracy of the novel, miniature, iSYS1 robotic guidance device in stereotactic neurosurgery.

METHODS

A preclinical phantom trial was conducted to compare the accuracy and duration of needle positioning between the robotic and manual technique in 162 cadaver biopsies. Second, 25 consecutive cases of tumor biopsies and intracranial catheter placements were performed with robotic guidance to evaluate the feasibility, accuracy, and duration of system setup and application in a clinical setting.

RESULTS

The preclinical phantom trial revealed a mean target error of 0.6 mm (range 0.1–0.9 mm) for robotic guidance versus 1.2 mm (range 0.1–2.6 mm) for manual positioning of the biopsy needle (p < 0.001). The mean duration was 2.6 minutes (range 1.3–5.5 minutes) with robotic guidance versus 3.7 minutes (range 2.0–10.5 minutes) with manual positioning (p < 0.001). Clinical application of the iSYS1 robotic guidance device was feasible in all but 1 case. The median real target error was 1.3 mm (range 0.2–2.6 mm) at entry and 0.9 mm (range 0.0–3.1 mm) at the target point. The median setup and instrument positioning times were 11.8 minutes (range 4.2–26.7 minutes) and 4.9 minutes (range 3.1–14.0 minutes), respectively.

CONCLUSIONS

According to the preclinical data, application of the iSYS1 robot can significantly improve accuracy and reduce instrument positioning time. During clinical application, the robot proved its high accuracy, short setup time, and short instrument positioning time, as well as demonstrating a short learning curve.

405 nm versus 633 nm for protoporphyrin IX excitation in fluorescence-guided stereotactic biopsy of brain tumors

Fluorescence diagnosis may be used to improve the safety and reliability of stereotactic brain tumor biopsies using biopsy needles with integrated fiber optics. Based on 5-aminolevulinic-acid-induced protoporphyrin IX (PpIX) fluorescence, vital tumor tissue can be localized in vivo during the excision procedure to reduce the number of necessary samples for a reliable diagnosis. In this study, the practical suitability of two different PpIX excitation wavelengths (405 nm, 633 nm) was investigated on optical phantoms. Violet excitation at 405 nm provides a 50-fold higher sensitivity for the bulk tumor; this factor increases up to 100 with decreasing fluorescent volume as shown by ray tracing simulations. Red excitation at 633 nm, however, is noticeably superior with regard to blood layers obscuring the fluorescence. Experimental results on the signal attenuation through blood layers of well-defined thicknesses could be confirmed by ray tracing simulations. Typical interstitial fiber probe measurements were mimicked on agarose-gel phantoms. Even in direct contact, blood layers of 20-40 µm between probe and tissue must be expected, obscuring 405-nm-excited PpIX fluorescence almost completely, but reducing the 633-nm-excited signal only by 25.5%. Thus, 633 nm seems to be the wavelength of choice for PpIX-assisted detection of high-grade gliomas in stereotactic biopsy. PpIX signal attenuation through clinically relevant blood layers for 405 nm (violet) and 633 nm (red) excitation.

Frame-Based Stereotactic Biopsy of Canine Brain Masses: Technique and Clinical Results in 26 Cases

This report describes the methodology, diagnostic yield, and adverse events (AE) associated with frame-based stereotactic brain biopsies (FBSB) obtained from 26 dogs with solitary forebrain lesions. Medical records were reviewed from dogs that underwent FBSB using two stereotactic headframes designed for use in small animals and compatible with computed tomographic (CT) and magnetic resonance (MR) imaging. Stereotactic plans were generated from MR and CT images using commercial software, and FBSB performed both with (14/26) and without intraoperative image guidance. Records were reviewed for diagnostic yield, defined as the proportion of biopsies producing a specific neuropathological diagnosis, AE associated with FBSB, and risk factors for the development of AE. Postprocedural AE were evaluated in 19/26 dogs that did not proceed to a therapeutic intervention immediately following biopsy. Biopsy targets included intra-axial telencephalic masses (24/26), one intra-axial diencephalic mass, and one extra-axial parasellar mass. The median target volume was 1.99 cm³. No differences in patient, lesion, or outcome variables were observed between the two headframe systems used or between FBSB performed with or without intraoperative CT guidance. The diagnostic yield of FBSB was 94.6%. Needle placement error was a significant risk factor associated with procurement of non-diagnostic biopsy specimens. Gliomas were diagnosed in 24/26 dogs, and meningioma and granulomatous meningoencephalitis in 1 dog each. AE directly related to FBSB were observed in a total of 7/26 (27%) of dogs. Biopsy-associated clinical morbidity, manifesting as seizures and transient neurological deterioration, occurred in 3/19 (16%) of dogs. The case fatality rate was 5.2% (1/19 dogs), with death attributable to intracranial hemorrhage. FBSB using the described apparatus was relatively safe and effective at providing neuropathological diagnoses in dogs with focal forebrain lesions.

The basics of intraoperative diagnosis in neuropathology

Intraoperative pathologic consultation continues to be an essential tool during neurosurgical procedures, helping to ensure adequacy of material for achieving a pathologic diagnosis and to guide surgeons. For pathologists, successful consultation with central nervous system lesions involves not only a basic familiarity with the pathologic features of such lesions but also an understanding of their clinical and radiologic context. This review discusses a basic approach to intraoperative diagnosis for practicing pathologists, including preparation for, performance of, and interpretation of an intraoperative neuropathologic evaluation. The cytologic and frozen section features of select examples of common pathologic entities are described.

Achieving Higher Diagnostic Results in Stereotactic Brain Biopsy by Simple and Novel Technique

BACKGROUND:

Neurosurgeons have preferred to perform the stereotactic biopsy for pathologic diagnosis when the intracranial pathology located eloquent areas and deep sites of the brain.

AIM:

To get a higher ratio of definite pathologic diagnosis during stereotactic biopsy and develop practical method.

MATERIAL AND METHODS:

We determined at least two different target points and two different trajectories to take brain biopsy during stereotactic biopsy. It is a different way from the conventional stereotactic biopsy method in which one point has been selected to take a biopsy. We separated our patients into two groups, group 1 (N=10), and group 2 (N= 19). We chose one target to take a biopsy in group 1, and two different targets and two different trajectories in group 2. In group 2, one patient underwent craniotomy due to hemorrhage at the site of the biopsy during tissue biting. However, none of the patients in both groups suffered any neurological complication related biopsy procedure.

RESULTS:

In group 1, two of 10 cases, and, in group 2, fourteen of 19 cases had positive biopsy harvesting. These results showed statistically significant difference between group 1 and group 2 (P<0.05).

CONCLUSIONS:

Regarding these results, choosing more than one trajectories and taking at least six specimens from each target provides higher diagnostic rate in stereotaxic biopsy taking method.

Frameless image-guided stereotactic brain biopsies: emphasis on diagnostic yield

BACKGROUND

Studies regarding frameless stereotactic brain biopsy mainly report high diagnostic yield (DY) as opposed to relatively low diagnostic accuracy. This discrepancy raises the question of the certainty and precision of obtained diagnoses. This article proposes a DY definition encompassing diagnostic certainty and precision according to the World Health Organization (WHO) central nervous system (CNS) tumour classification system. Furthermore, our eight-year experience with this procedure is reviewed and evaluated.

METHODS

A consecutive series of 235 frameless biopsy procedures was reviewed. Criteria were set up for categorising obtained diagnoses. All cases were included in a predictive factor analysis of inconclusive biopsy and postoperative complications.

RESULTS

According to our predefined DY criteria, the DY was 72.8 %. The inconclusive biopsy outcome measured 21.7 %; the non-diagnostic biopsy outcome was 5.5 %. The only predictive factor found for inconclusive biopsy procedures was age under 30. Predictive factors for postoperative complications, which were found statistically significant after multivariable analysis, were glucose level and intra-operative haemorrhage. The total morbidity rate was 8.5 %, including a mortality rate of 0.9 %.

CONCLUSIONS

Although frameless stereotactic brain biopsy procedures are considered to be relatively safe, the true DY is significantly less than previously reported, most probably due to the lack of standardised DY criteria. Based on our DY definition and subsequent DY findings, standardisation of DY criteria and definition is paramount for biopsy diagnosis interpretation.

Stereotactic biopsy of brainstem lesions: Techniques, efficacy, safety, and disease variation between adults and children: A single institutional series and review

BACKGROUND

Stereotactic biopsy of brainstem lesions have been performed with varying indications, with most of the literature reporting on children.

MATERIALS AND METHODS

The present study retrospectively analyzed all cases that underwent stereotactic biopsy for brainstem lesion in both adult and pediatric population between 1994 and 2009 in a single tertiary neurosurgical center. The clinical and radiological features, technique of the procedure, morbidity, diagnostic accuracy, spectrum of diagnosis, and variations in adult and pediatric population were analyzed.

RESULTS

Eighty-two patients were included in the study. Computed tomography (CT) was used as guidance in 73 (38 children and 35 adults) patients and magnetic resonance imaging (MRI) in 9 (3 children and 6 adults). The biopsy was performed in a procedure room under local anesthesia in most adults, while children required sedation. Glioblastoma comprised 29.3% of all pathologies in children, compared with only 4.9% of the pathologies in adult population (P = 0.007). Tuberculosis was the next major diagnosis (9.8%). In 12 patients, initial biopsy was inconclusive. Following a repeat biopsy in 5 of these patients, a diagnosis was possible for 75/82 (91.5%) patients by STB. The location of the target, the choice of entry, the radiological characteristic of the lesion, enhancement pattern, and age group did not significantly correlate with the occurrence of inconclusive biopsy. Permanent complications occurred in two patients (2.4%). There was no mortality in this series.

CONCLUSION

Stereotactic biopsy has an important role in brainstem lesions, more significantly in adults, due to wider pathological spectrum. It can be performed safely under local anesthesia through a twist drill craniostomy in most of the adults.

Role of stereotactic biopsy in histological diagnosis of multiple brain lesions

Background and Aim:

The current advances in diagnostic and therapeutic modalities and increasing in survival of patients with systemic diseases and immunosuppressive cases have caused to increasing frequency and variety of Central Nervous System neuropathologic processes indicating the necessary need for accurate localization of space-occupying lesions by cytology and histology. This study was aimed to evaluate the usefulness and safety of stereotactic biopsy in histological diagnosis of such lesions.

Materials and Methods:

Of 2081 patients underwent stereotactic biopsy of brain lesions using Riechert-Mundinger system, 158 had multifocal brain lesions, and were enrolled.

Results:

The ages of studied cases were ranged from 2 years to 75 years (Mean age: 41.3 year), 114 were male and 44 were females. Incidence of histopathologic diagnosis of multifocal brain lesions included Astrocytoma grade II (41.3%), Astrocytoma grade I (12.9%), glioblastoma multiform (11.1%), Astrocytoma grade III (10.2%), malignant lymphoma (10.2%), metastasis (4.6%), pilocytic Astrocytoma (2.7%), abscess (2.7%), craniopharyngioma (1.8%) vascular malformations (0.9%), and tuberculosis (0.9%). Mortality due to operation is none.

Conclusions:

Histopathologic diagnosis of multiple brain lesions is necessary for decision of appropriate management and stereotactic biopsy of brain lesion is a useful and safe method for histological diagnosis.

Diagnostic yield of stereotactic needle-biopsies of sub-cubic centimeter intracranial lesions

Background:

Stereotactic brain biopsies are widely used for establishing the diagnosis of intracranial lesions. Here we examine whether stereotactic biopsy of smaller brain lesions, defined for this study as being less than 1 cubic centimeter (1 cc) in volume, are associated with lowered diagnostic yield.

Methods:

We conducted a retrospective analysis of 267 consecutive patients who underwent stereotactic brain biopsy between 2007 and 2011. Lesion volumes were calculated and were stratified by <1 or >1 cc.

Results:

A total of 13 of 246 (5.2%) biopsies for lesions >1 cc resulted in nondiagnostic tissue or an incorrect diagnosis. In contrast, 5 of 21 (23.8%) biopsies for <1 cc lesions yielded nondiagnostic or incorrect diagnosis. Posthoc review of tissue from the <1 cc lesions suggests the neuropathologist's expertise in the handling and analysis of limited specimen as a critical parameter of successful diagnosis. The operative morbidities were low for both the <1 and >1 cc biopsies (0% and 1%, respectively).

Conclusion:

This study demonstrates that stereotactic cerebral biopsy of lesions less than a cubic centimeter in volume results in a lower diagnostic yield versus larger lesions (76.2% versus 94.8%). While auxiliary measures may be taken to improve diagnostic yield, these patients may be best managed in a specialized center with experienced stereotactic neurosurgeons and neuropathologists.

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.

Diagnostic yield and adverse effects of MRI-guided free-hand brain biopsies through a mini-burr hole in dogs with encephalitis

BACKGROUND

The diagnosis of encephalitis is usually presumptive based on MRI, cerebrospinal fluid analysis, or both. A definitive diagnosis based on histopathology, however, is required for optimizing treatment strategies.

OBJECTIVE

To investigate the diagnostic yield and adverse effects of minimally invasive brain biopsies in dogs with encephalitis.

ANIMALS

Seventeen dogs with suspected encephalitis, based on MR imaging and cerebrospinal fluid analysis.

METHODS

Retrospective study. Minimally invasive, free-hand brain biopsy specimens were taken from forebrain lesions through a 4-mm burr hole using a Sedan side-cutting needle. Routine histopathological examination was performed. The adverse effects were assessed by MRI evaluations after biopsy procedure (12/17) and by sequential neurological examinations.

RESULTS

The overall diagnostic yield with regard to a specific type of encephalitis was 82%. Encephalitis was evident in an additional 12%, but a specific disease could not be determined. There were no deaths caused by the biopsy procedure itself, but the indirect case fatality rate was 6%. Morbidity was 29%, including stupor, seizures, tetraparesis, hemiparesis, ataxia, and loss of conscious proprioception. All these signs resolved within 3-14 days.

CONCLUSIONS AND CLINICAL IMPORTANCE

Minimally invasive brain biopsy in dogs with suspected encephalitis leads to a definite diagnosis in the majority of dogs, allowing for a specific treatment. The advantages of a definite diagnosis outweigh potential case fatality rate and temporary neurological deficits.

Perfusion MRI as a neurosurgical tool for improved targeting in stereotactic tumor biopsies

OBJECTIVE

Stereotactic biopsies are subject to sampling errors (essentially due to target selection). The presence of contrast enhancement is not a reliable marker of malignancy. The goal of the present study was to determine whether perfusion-weighted imaging can improve target selection in stereotactic biopsies.

METHODS

We studied 21 consecutive stereotactic biopsies between June 2009 and March 2010. Perfusion-weighted magnetic resonance imaging (MRI) was integrated into our neuronavigator. Perfusion-weighted imaging was used as an adjunct to conventional MRI data for target determination. Conventional MRI alone was used to determine the trajectory.

RESULTS

We found a linear correlation between regional cerebral blood volume (rCBV) and vessel density (number of vessels per mm(2); R = 0.64; p < 0.001). Perfusion-weighted imaging facilitated target determination in 11 cases (52.4%), all of which were histopathologically diagnosed as glial tumors. For glial tumors, which presented with contrast enhancement, perfusion-weighted imaging identified a more precisely delimited target in 9 cases, a different target in 1 case, and exactly the same target in 1 other case. In all cases, perfusion-selected sampling provided information on cellular features and tumor grading. rCBV was significantly associated with grading (p < 0.01), endothelial proliferation (p < 0.01), and vessel density (p < 0.01). For lesions with rCBV values ≤1, perfusion-weighted MRI did not help to determine the target but was useful for surgical management.

CONCLUSIONS

For stereotactic biopsies, targeting based on perfusion-weighted imaging is a feasible method for reducing the sampling error and improving target selection in the histopathological diagnosis of tumors with high rCBVs.

Stereotactic versus endoscopic surgery in periventricular lesions

OBJECT

Endoscopic and stereotactic surgery have gained widespread acceptance as minimally invasive tools for the diagnosis of intracerebral pathologies. We investigated the specific advantages and disadvantages of each technique in the assessment of periventricular lesions.

METHOD

This study included a retrospective series of 70 patients with periventricular lesions. Endoscopic surgery was performed in 17 patients (mean age, 37 years; range, 4 months-78 years) and stereotactic biopsy in 55 patients (mean age, 63 years; range, 23-80 years), including two patients who underwent both procedures.

RESULTS

Hydrocephalus was present in 13/17 patients in the endoscopic group (77%) and in 11/55 patients in the stereotactic group (20%). Diagnosis was achieved in all patients in the endoscopic group and in all but one patient in the stereotactic group, in whom histological diagnosis was obtained by endoscopic biopsy during a second operation. In the endoscopic group, additional procedures performed included ventriculostomy (2/17), cyst fenestration (3/17), endoscopic shunt revision (3/17) and placement of Rickham reservoirs or external cerebrospinal fluid drains (6/17). Adverse events occurred in one patient after endoscopy (chronic subdural hematoma) and in two patients after stereotactic surgery (one mild hemiparesis and one transitory paresis of the contralateral leg).

CONCLUSIONS

Endoscopic and stereotactic surgery have distinct advantages and disadvantages in approaching periventricular lesions. The advantages of endoscopy encompass the possibility to perform additional surgical procedures during the same session (e.g. tumour reduction, third ventriculostomy, fenestration of a cyst). The visual control reduces the hazard of injury to anatomical structures and allows for a better control of bleeding although there is a considerable blind-out in such situations. The advantages of stereotactic surgery include a smaller approach and precise planning of the trajectory. It is usually performed under local anaesthesia. Both methods provide a safe and efficient therapeutic option in periventricular lesions with low surgical-related morbidity.

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

Object

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.

Methods

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.

Results

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.

Conclusions

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.