Frameless stereotaxy with scalp-applied fiducial markers for brain biopsy procedures: experience in 218 cases

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.

Navigation Guided Biopsy Is as Effective as Frame-Based Stereotactic Biopsy

BACKGROUND

Stereotactic biopsy is a standard procedure for brain biopsy. However, with advances in technology, navigation-guided brain biopsy has become a well-established alternative. Previous studies have shown that frameless stereotactic brain biopsy is as effective and safe as frame-based stereotactic brain biopsy is. In this study, the authors evaluate the diagnostic yield and complication rate of frameless intracranial biopsy.

MATERIALS AND METHODS

We reviewed data from biopsy performed patients between March 2014 and April 2022. We retrospectively reviewed medical records, including imaging studies. Various intracerebral lesions were biopsied. Diagnostic yield and post-operative complications were compared with those of frame-based stereotactic biopsy.

RESULTS

Forty-two frameless navigation-guided biopsy were performed, and the most common pathology was primary central nervous system lymphoma (35.7%), followed by glioblastoma (33.3%), and anaplastic astrocytomas (16.7%), respectively. The diagnostic yield was 100%. Post-operative intracerebral hematoma occurred in 2.4% of cases, but it was not symptomatic. Thirty patients underwent frame-based stereotactic biopsy, and the diagnostic yield was 96.7%. There was no difference in diagnostic rates between two methods (Fisher's exact test, p = 0.916).

CONCLUSIONS

Frameless navigation-guided biopsy is as effective as frame-based stereotactic biopsy is, without causing further complications. We consider that frame-based stereotactic biopsy is no longer needed if frameless navigation-guided biopsy is used. A further study will be needed to generalize our results.

Successful use of stereotactic navigation in posterior spinal fusion T10-S2 with bilateral iliac screw fixation in a patient with prior spinal surgeries and osteoporosis: A case report

INTRODUCTION AND IMPORTANCE

Degenerative lumbar scoliosis is a prominent cause of adult spinal deformity with an increasing prevalence as the population ages. This pathology is associated with debilitating symptoms, including radicular back pain and lower extremity claudication. Surgical realignment of the spine and restoration of sagittal imbalance can reduce low back pain. Chronic sacroiliac dysfunction commonly causes low back radicular pain. We present a complicated case where stereotactic navigation facilitated an extensive fusion and decompression procedure for adult spinal deformity in an obese patient with multiple prior surgeries for scoliosis and sacroiliac joint pathology.

CASE PRESENTATION

A 69-year-old, obese female with scoliosis refractory to multiple interventions presented with severe, radicular lower back pain. On examination of the right lower extremity (RLE), she had mild weakness (3/5 strength) and reduced sensation to light touch over its anterolateral aspect (dermatome L4). She was unable to perform single leg stance or tandem walk. Imaging revealed moderate mid-lumbar levoscoliosis, severe degenerative disc disease and facet hypertrophy changes in the setting of prior multilevel lumbar fusion, and consecutive nerve root impingement between L1 and L5 (worst at L3-4). DEXA scan was consistent with osteoporosis. The patient underwent lumbar laminectomy with posterior fusion of T10-ilium, transforaminal lumbar interbody fusion, osteotomy, and decompression using stereotactic navigation. The presence of SI titanium dowels from her previous SI fusion procedure posed a challenge with respect to achieving pelvic fixation.

CLINICAL DISCUSSION

Iliac screw placement is a critical adjunctive to lumbosacral fusion, notably for prevention of pseudoarthrosis; however, patients with prior SI fusion may present a biomechanical challenge to surgeons due to obstruction of the surgical site. The O-arm neuronavigation system was successfully used to bypass this obstruction and provide sacroiliac fixation in this procedure.

CONCLUSION

Stereotactic navigation (The O-arm Surgical Imaging System) can effectively be used to circumvent prior SI fusion in osteoporotic bone.

Diagnostic Yield and Complication Rate of Stereotactic Biopsies in Precision Medicine of Gliomas

Background

An integrated diagnosis consisting of histology and molecular markers is the basis of the current WHO classification system of gliomas. In patients with suspected newly diagnosed or recurrent glioma, stereotactic biopsy is an alternative in cases in which microsurgical resection is deemed to not be safely feasible or indicated. In this retrospective study, we aimed to analyze both the diagnostic yield and the safety of a standardized biopsy technique.

Material and Methods

The institutional database was screened for frame-based biopsy procedures (January 2016 until March 2021). Only patients with a suspected diagnosis of glioma based on imaging were included. All tumors were classified according to the current WHO grading system. The clinical parameters, procedural complications, histology, and molecular signature of the tissues obtained were assessed.

Results

Between January 2016 and March 2021, 1,214 patients underwent a stereotactic biopsy: 617 (50.8%) for a newly diagnosed lesion and 597 (49.2%) for a suspected recurrence. The median age was 56.9 years (range 5 months−94.4 years). Magnetic resonance imaging (MRI)-guidance was used in 99.3% of cases and additional positron emission tomography (PET)-guidance in 34.3% of cases. In total, stereotactic serial biopsy provided an integrated diagnosis in 96.3% of all procedures. The most frequent diagnoses were isocitrate dehydrogenase (IDH) wildtype glioblastoma (n = 596; 49.2%), oligodendroglioma grade 2 (n = 109; 9%), astrocytoma grade 3 (n = 108; 8.9%), oligodendroglioma grade 3 (n = 76; 6.3%), and astrocytoma grade 2 (n = 66; 5.4%). A detailed determination was successful for IDH 1/2 mutation in 99.4% of cases, for 1p/19q codeletion in 97.4% of cases, for TERT mutation in 98.9% of cases, and for MGMT promoter methylation in 99.1% of cases. Next-generation sequencing was evaluable in 64/67 (95.5%) of cases and DNA methylome analysis in 41/44 (93.2%) of cases. Thirteen (1.1%) cases showed glial tumors that could not be further specified. Seventy-three tumors were different non-glioma entities, e.g., of infectious or inflammatory nature. Seventy-five out of 597 suspected recurrences turned out to be post-therapeutic changes only. The rate of post-procedural complications with clinical symptoms of the Common Terminology Criteria for Adverse Events (CTCAE) grade 3 or higher was 1.2% in overall patients and 2.6% in the subgroup of brainstem biopsies. There was no fatal outcome in the entire series.

Conclusion

Image-guided stereotactic serial biopsy enables obtaining reliable histopathological and molecular diagnoses with a very low complication rate even in tumors with critical localization. Thus, in patients not undergoing microsurgical resection, this is a valuable tool for precision medicine of patients with glioma.

Factors affecting diagnostic yield in stereotactic biopsy for brain lesions: a 5-year single-center series

The objective of this study is to determine the factors that are associated with the diagnostic yield of stereotactic brain biopsy. A retrospective analysis was performed on 50 consecutive patients who underwent stereotactic brain biopsies in a single institute from 2014 to 2019. Variables including age, gender, lesion topography and characteristics, biopsy methods, and surgeon's experience were analyzed along with diagnostic rate. This study included 31 male and 19 female patients with a mean age of 48.4 (range: 1-76). Of these, 25 underwent frameless brain-suite stereotactic biopsies, 15 were frameless Portable Brain-lab® stereotactic biopsies and 10 were frame-based CRW® stereotactic biopsies. There was no statistical difference between the diagnostic yield of the three methods. The diagnostic yield in our series was 76%. Age, gender, and biopsy methods had no impact on diagnostic yield. Periventricular and pineal lesion biopsies were significantly associated with negative diagnostic yield (p = 0.01) whereas larger lesions were significantly associated with a positive yield (p = 0.01) with the mean volume of lesions in the positive yield group (13.6 cc) being higher than the negative yield group (7 cc). The diagnostic yields seen between senior and junior neurosurgeons in the biopsy procedure were 95% and 63%, respectively (p = 0.02). Anatomical location of the lesion, volume of the lesion, and experience of the surgeon have significant impacts on the diagnostic yield in stereotactic brain biopsy. There was no statistical difference between the diagnostic yield of the three methods, age, gender, and depth of lesion.

Robotic guidance platform for laser interstitial thermal ablation and stereotactic needle biopsies: a single center experience

While laser ablation has become an increasingly important tool in the neurosurgical oncologist's armamentarium, deep seated lesions, and those located near critical structures require utmost accuracy during stereotactic laser catheter placement. Robotic devices have evolved significantly over the past two decades becoming an accurate and safe tool for stereotactic neurosurgery. Here, we present our single center experience with the MedTech ROSA ONE Brain robot for robotic guidance in laser interstitial thermal therapy (LITT) and stereotactic biopsies. We retrospectively analyzed the first 70 consecutive patients treated with ROSA device at a single academic medical center. Forty-three patients received needle biopsy immediately followed by LITT with the catheter placed with robotic guidance and 27 received stereotactic needle biopsy alone. All the procedures were performed frameless with skull bone fiducials for registration. We report data regarding intraoperative details, mortality and morbidity, diagnostic yield and lesion characteristics on MRI. Also, we describe the surgical workflow for both procedures. The mean age was 60.3 ± 15 years. The diagnostic yield was positive in 98.5% (n = 69). Sixty-three biopsies (90%) were supratentorial and seven (10%) were infratentorial. Gliomas represented 54.3% of the patients (n = 38). There were two postoperative deaths (2.8%). No permanent morbidity related to surgery were observed. We did not find intraoperative technical problems with the device. There was no need to reposition the needle after the initial placement. Stereotactic robotic guided placement of laser ablation catheters and biopsy needles is safe, accurate, and can be implemented into a neurosurgical workflow.

Frameless Stereotactic Brain Biopsies: Comparison of Minimally Invasive Robot-Guided and Manual Arm-Based Technique

BACKGROUND

Most brain biopsies are still performed with the aid of a navigation-guided mechanical arm. Due to the manual trajectory alignment without rigid skull contact, frameless aiming devices are prone to considerably lower accuracy.

OBJECTIVE

To compare a novel minimally invasive robot-guided biopsy technique with rigid skull fixation to a standard frameless manual arm biopsy procedure.

METHODS

Accuracy, procedural duration, diagnostic yield, complication rate, and cosmetic result were retrospectively assessed in 40 consecutive cases of frameless stereotactic biopsies and compared between a minimally invasive robotic technique using the iSYS1 guidance device (iSYS Medizintechnik GmbH) (robot-guided group [ROB], n = 20) and a manual arm-based technique (group MAN, n = 20).

RESULTS

Application of the robotic technique resulted in significantly higher accuracy at entry point (group ROB median 1.5 mm [0.4-3.2 mm] vs manual arm-based group (MAN) 2.2 mm [0.2-5.2 mm], P = .019) and at target point (group ROB 1.5 mm [0.4-2.8 mm] vs group MAN 2.8 mm [1.4-4.9 mm], P = .001), without increasing incision to suture time (group ROB 30.0 min [20-45 min vs group MAN 32.5 min [range 20-60 min], P = .09) and significantly shorter skin incision length (group ROB 16.3 mm [12.7-23.4 mm] vs group MAN 24.2 mm [18.0-37.0 mm], P = .008).

CONCLUSION

According to our data, the proposed technique of minimally invasive robot-guided brain biopsies can improve accuracy without increasing operating time while being equally safe and effective compared to a standard frameless arm-based manual biopsy technique.

Anatomical localization of the transverse-sigmoid sinus junction: Comparison of existing techniques

Background

Anatomical localization remains integral to neurosurgery, particularly in the posterior fossa where neuronavigation is less reliable. There have been many attempts to define the location of the transverse- sigmoid sinus junction (TSSJ) using anatomical landmarks, to aid in the placement of the "strategic burr hole" during a retrosigmoid approach. There is a paucity of research allowing direct comparison of such techniques.

Methods

Using high-resolution contrast-enhanced cranial computed tomography images, we constructed three-dimensional virtual cranial models. Fifty models (100 sides) were created from a retrospective sample of images performed in a New Zealand population. Ten methods of anatomical localization were applied to each model allowing qualitative and quantitative comparisons. The "key point" was defined as the point on the outer surface of the skull that directly overlaid the junction of the posterior fossa dura, transverse sinus (TS), and sigmoid sinus (SS). The proximity of each method to this "key point" was compared quantitatively, in addition to other descriptive observations. TSSJ localization methods analyzed included: (1) asterion; (2) emissary foramen; (3) Lang and Samii; (4) Day; (5) Rhoton; (6) Avci; (7) Ribas; (8) Tubbs; (9) Li; and (10) Teranishi.

Results

Mean distance to the "key point" showed two tiers of accuracy, those <10 mm, and those >10 mm: Li (6.3 mm), Ribas (6.6 mm), Tubbs (6.8 mm), Teranishi (7.8 mm), Day (8.4 mm), emissary foramen (12.0 mm), Avci (13.0 mm), asterion (13.9 mm), Lang and Samii (15.6 mm), and Rhoton (17.4 mm). The asterion would most frequently overlie the TS (63%) and was often supratentorial (14%).

Conclusion

Each method has a unique profile of dura or sinus exposure. There are significant differences in the accuracy of localization of the TSSJ among anatomical localization methods.

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.

Frameless stereotactic biopsy for precision neurosurgery: diagnostic value, safety, and accuracy

BACKGROUND

Stereotactic biopsy is consistently employed to characterize cerebral lesions in patients who are not suitable for microsurgical resection. In the past years, technical improvement and neuroimaging advancements contributed to increase the diagnostic yield, the safety, and the application of this procedure. Currently, in addition to histological diagnosis, the molecular analysis is considered essential in the diagnostic process to properly select therapeutic and prognostic algorithms in a personalized approach. The present study reports our experience with frameless stereotactic brain biopsy in this molecular era.

METHODS

One hundred forty consecutive patients treated from January 2013 to September 2018 were analyzed. Biopsies were performed using the Brainlab Varioguide® frameless stereotactic system. Patients' clinical and demographic data, the time of occupation of the operating room, the surgical time, the morbidity, and the diagnostic yield in providing a histological and molecular diagnosis were recorded and evaluated.

RESULTS

The overall diagnostic yield was 93.6% with nine procedures resulting non-diagnostic. Among 110 patients with glioma, the IDH-1 mutational status was characterized in 108 cases (98.2%), resulting wild-type in all subjects but 3; MGMT methylation was characterized in 96 cases (87.3%), resulting present in 60 patients, and 1p/19q codeletion was founded in 6 of the 20 cases of grade II-III gliomas analyzed. All the specimens were apt for molecular analysis when performed. Bleeding requiring surgical drainage occurred in 2.1% of the cases; 8 (5.7%) asymptomatic hemorrhages requiring no treatment were observed. No biopsy-related mortality was recorded. Median length of hospital stay was 5 days (IQR 4-8) with mean surgical time of 60.77 min (± 23.12) and 137.44 ± 24.1 min of total occupation time of the operative room.

CONCLUSIONS

Stereotactic frameless biopsy is a safe, feasible, and fast procedure to obtain a histological and molecular diagnosis.

MRI-guided frame-based stereotactic brainstem biopsy procedure: A single-center experience

INTRODUCTION AND OBJECTIVES

This study aims at presenting our experience of the MRI-guided frame-based stereotactic brainstem biopsy method, and evaluating the outcomes of the procedure.

PATIENTS AND METHODS

The current study involved 18 cases that underwent MRI-guided frame-based stereotactic biopsy for brainstem lesions between 2011 and 2018 in our clinic. The relevant data regarding the technique of the biopsy procedure, morbidity, histopathological diagnosis it yields and diagnostic accuracy was retrospectively analyzed.

RESULTS

Stereotactic biopsy procedure was performed on 18 patients, including 16 adults and two children. MRI was used as guidance for the biopsy procedure in all patients. The adult patients had the biopsy under local anesthesia; as for the pediatric patients local anesthesia plus sedation was used. All patients received diagnosis based on the histopathological examination of their biopsy samples. No equivocal or negative results, and no major morbidity or mortality was seen in the patients after the procedure.

CONCLUSIONS

MRI-guided frame-based stereotactic biopsy can be considered as a safe and efficient diagnostic method for brainstem lesions when its diagnostic yield and its morbidity and/or mortality rates are evaluated. Choosing the best trajectory for each lesion, using MRI as guidance for targeting, taking a limited number of biopsy samples are valuable criteria for the decreased morbidity rates in stereotactic brainstem biopsy procedures.

Stereotactic brain biopsy: evaluation of robot-assisted procedure in 60 patients

BACKGROUND

Frameless stereotactic biopsies, particularly robot-assisted procedures are increasing in neurosurgery centers. Results of these procedures should be at least equal to or greater than frame-based reference procedure. Evaluate robot-assisted technology is necessary in particular, when a team has chosen to switch from one to another method.

OBJECTIVE

The objective of our prospective work was (i) to evaluate the success rate of contributive robotic-assisted biopsy in 60 patients, to report the morbidity and mortality associated with the procedure and (ii) to compare it with literature data.

METHODS

We performed a prospective and descriptive study including 60 consecutive patients having had robotic-assisted stereotactic biopsy at the Rouen University Hospital, France. All patients had presurgical imaging before the procedure included Magnetic Resonance Imaging merged with Computed Tomography scan acquisition. Registration was mostly performed with a touch-free laser (57/60). A control Computed Tomography scan was always realized at day 0 or day 1 after surgery. Data collected were success rate, bleeding, clinical worsening, infection, and mortality.

RESULTS

All the biopsies were considered as contributive and lead to the final diagnosis. In 41/60 patients (68%), the lesion was glial. Six in 60 patients (10%) had visible bleeding without clinical worsening related, 5/60 patients (8.5%) showed clinical impairment following surgery, which was permanent in 2 patients, and 1/60 patient presented generalized seizures. We did not report any infection and mortality.

CONCLUSION

Robot-assisted frameless surgery is efficient and provides a reasonable alternative to frame-based procedure. The operating time can be reduced, without increasing morbidity and mortality rates.

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

BACKGROUND

Robotic technologies have been used in the neurosurgical operating rooms for the last 30 yr. They have been adopted for several stereotactic applications and, particularly, image-guided biopsy of intracranial lesions which are not amenable for open surgical resection.

OBJECTIVE

To assess feasibility, safety, accuracy, and diagnostic yield of robot-assisted frameless stereotactic brain biopsy with a recently introduced miniaturized device (iSYS1; Interventional Systems Medizintechnik GmbH, Kitzbühel, Austria), fixed to the Mayfield headholder by a jointed arm.

METHODS

Clinical and surgical data of all patients undergoing frameless stereotactic biopsies using the iSYS1 robotized system from October 2016 to December 2017 have been prospectively collected and analyzed. Facial surface registration has been adopted for optical neuronavigation.

RESULTS

Thirty-nine patients were included in the study. Neither mortality nor morbidity related to the surgical procedure performed with the robot was recorded. Diagnostic tissue samples were obtained in 38 out of 39 procedures (diagnostic yield per procedure was 97.4%). All patients received a definitive histological diagnosis. Mean target error was 1.06 mm (median 1 mm, range 0.1-4 mm).

CONCLUSION

The frameless robotic iSYS1-assisted biopsy technique was determined to be feasible, safe, and accurate procedure; moreover, the diagnostic yield was high. The surface matching registration method with computed tomography as the reference image set did not negatively affect the accuracy of the procedure.

A novel robot-guided minimally invasive technique for brain tumor biopsies

OBJECTIVE

As decisions regarding tumor diagnosis and subsequent treatment are increasingly based on molecular pathology, the frequency of brain biopsies is increasing. Robotic devices overcome limitations of frame-based and frameless techniques in terms of accuracy and usability. The aim of the present study was to present a novel, minimally invasive, robot-guided biopsy technique and compare the results with those of standard burr hole biopsy.

METHODS

A tubular minimally invasive instrument set was custom-designed for the iSYS-1 robot-guided biopsies. Feasibility, accuracy, duration, and outcome were compared in a consecutive series of 66 cases of robot-guided stereotactic biopsies between the minimally invasive (32 patients) and standard (34 patients) procedures.

RESULTS

Application of the minimally invasive instrument set was feasible in all patients. Compared with the standard burr hole technique, accuracy was significantly higher both at entry (median 1.5 mm [range 0.2-3.2 mm] vs 1.7 mm [range 0.8-5.1 mm], p = 0.008) and at target (median 1.5 mm [range 0.4-3.4 mm] vs 2.0 mm [range 0.8-3.9 mm], p = 0.019). The incision-to-suture time was significantly shorter (median 30 minutes [range 15-50 minutes] vs 37.5 minutes [range 25-105 minutes], p < 0.001). The skin incision was significantly shorter (median 16.3 mm [range 12.7-23.4 mm] vs 28.4 mm [range 20-42.2 mm], p = 0.002). A diagnostic tissue sample was obtained in all cases.

CONCLUSIONS

Application of the novel instrument set was feasible in all patients. According to the authors' data, the minimally invasive robot-guidance procedure can significantly improve accuracy, reduce operating time, and improve the cosmetic result of stereotactic biopsies.

Head-up display may facilitate safe keyhole surgery for cerebral aneurysm clipping

OBJECTIVE

The head-up display (HUD) is a modern technology that projects images or numeric information directly into the observer’s sight line. Surgeons will no longer need to look away from the surgical view using the HUD system to confirm the preoperative or navigation image. The present study investigated the usefulness of the HUD system for performing cerebral aneurysm clipping surgeries.

METHODS

Thirty-five patients underwent clipping surgery, including 20 keyhole surgeries for unruptured cerebral aneurysm, using the HUD system. Image information of structures such as the skull, cerebral vasculature, and aneurysm was integrated by the navigation software and linked with the positional coordinates of the microscope field of view. “Image injection” allowed visualization of the main structures that were concurrently tracked by the navigation image, and “closed shutter” switched the microscope field of view and the pointer image of the 3D brain image.

RESULTS

The HUD system was effective for estimating the location and 3D anatomy of the aneurysm before craniotomy or dural opening in most patients. Scheduled keyhole minicraniotomy and opening of the sylvian fissure or partial rectal gyrus resection were performed on the optimized location with a minimum size in 20 patients.

CONCLUSIONS

The HUD images superimposed on the microscope field of view were remarkably useful for less invasive and more safe aneurysm clipping and, in particular, keyhole clipping.

MRI-guided frameless biopsy robotic system with the inclusion of unfocused ultrasound transducer for brain cancer ablation

BACKGROUND

A magnetic resonance image (MRI) guided robotic system dedicated for brain biopsy was developed. The robotic system carries a biopsy needle and a small rectangular unfocused, single element, planar ultrasonic transducer which can be potentially utilized to ablate small and localized brain cancer.

MATERIALS AND METHODS

The robotic device includes six computer-controlled axes. An agar-based phantom was developed which included an olive that mimics brain target. A rectangular ultrasonic transducer operated at 4 MHz was used.

RESULTS

The functionality of the robotic system was assessed by means of ultrasound imaging, MRI imaging, and MR thermometry, demonstrating effective targeting. The heating capabilities of the ultrasonic transducer were also evaluated.

CONCLUSIONS

A functional MRI-guided robotic system was produced which can perform frameless brain biopsy. In the future, if a tumour is proven malignant, the needle can be pulled-out and a small ultrasonic transducer can be inserted to ablate the tumour.

Stereotactic Drainage of Brainstem Abscess With the BrainLab Varioguide™ System and the Airo™ Intraoperative CT Scanner: Technical Case Report

BACKGROUND AND IMPORTANCE

Stereotactic biopsies or needle aspirations of posterior fossa lesions are technically challenging. Here we report a novel technique for performing these procedures employing the Airo™ intraoperative computed tomographic (CT) scanner and the VarioGuide™ articulated arm (BrainLab, Munich, Germany).

CLINICAL PRESENTATION

A 62-yr-old woman presented with an irregularly shaped, enhancing lesion of the left pons/middle cerebellar peduncle. Slowed diffusion on magnetic resonance imaging suggested an abscess, but no definitive infectious agent/source could be identified. When the patient deteriorated despite broad-spectrum antibiotic therapy, she was taken to the operating room for stereotactic drainage of the abscess employing the described technique. A specific infectious agent (Eikenella corrodens) was identified from the aspirate, allowing for tailored antibiotic therapy. The procedure was well tolerated and the patient made a full recovery with minimal neurological sequelae.

CONCLUSION

The combination of the Airo™ intraoperative CT and the Varioguide™ articulated arm allows for safe, accurate, and efficient targeting of posterior fossa lesions.

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.

The role of biopsy in the management of patients with presumed diffuse low grade glioma: A systematic review and evidence-based clinical practice guideline

QUESTION

What is the optimal role of biopsy in the initial management of presumptive low-grade glioma in adults?

TARGET POPULATION

Adult patients with imaging suggestive of a low-grade glioma.

RECOMMENDATIONS

LEVEL III

Stereotactic biopsy is recommended when definitive surgical resection is limited by lesions that are deep-seated, not resectable, and/or located within eloquent cortex, or in patients unable to undergo craniotomy due to medical co-morbidities to obtain the critical tissue diagnosis needed for targeted treatment planning for patients with low-grade gliomas.

QUESTION

What is the best technique for brain biopsy?

TARGET POPULATION

Adult patients with imaging suggestive of a low-grade glioma.

RECOMMENDATIONS

LEVEL III

Frameless and frame-based stereotactic brain biopsy for low-grade gliomas are recommended based on clinical circumstances as they provide similar diagnostic yield, diagnostic accuracy, morbidity, and mortality. It is recommended the surgeon consider advanced imaging techniques (e.g., perfusion, spectroscopy, metabolic studies) to target specific regions of interest to potentially improve diagnostic accuracy.

Beyond the VAD: Human Factors Engineering for Mechanically Assisted Circulation in the 21st Century

Thousands of ventricular assist devices (VADs) currently provide circulatory support to patients worldwide, and dozens of heart pump designs for adults and pediatric patients are under various stages of development in preparation for translation to clinical use. The successful bench-to-bedside development of a VAD involves a structured evaluation of possible system states, including human interaction with the device and auxiliary component usage in the hospital or home environment. In this study, we review the literature and present the current landscape of preclinical design and assessment, decision support tools and procedures, and patient-centered therapy. Gaps of knowledge are identified. The study findings support the need for more attention to user-centered design approaches for medical devices, such as mechanical circulatory assist systems, that specifically involve detailed qualitative and quantitative assessments of human-device interaction to mitigate risk and failure.

Assessment of the OsteoMark-Navigation System for Oral and Maxillofacial Surgery

PURPOSE

To assess the accuracy of a novel navigation system for maxillofacial surgery using human cadavers and a live minipig model.

MATERIALS AND METHODS

We tested an electromagnetic tracking system (OsteoMark-Navigation) that uses simple sensors to determine the position and orientation of a hand-held pencil-like marking device. The device can translate 3-dimensional computed tomographic data intraoperatively to allow the surgeon to localize and draw a proposed osteotomy or the resection margins of a tumor on bone. The accuracy of the OsteoMark-Navigation system in locating and marking osteotomies and screw positions in human cadaver heads was assessed. In group 1 (n = 3, 6 sides), OsteoMark-Navigation marked osteotomies and screw positions were compared to virtual treatment plans. In group 2 (n = 3, 6 sides), marked osteotomies and screw positions for distraction osteogenesis devices were compared with those performed using fabricated guide stents. Three metrics were used to document the precision and accuracy. In group 3 (n = 1), the system was tested in a standard operating room environment.

RESULTS

For group 1, the mean error between the points was 0.7 mm (horizontal) and 1.7 mm (vertical). Compared with the posterior and inferior mandibular border, the mean error was 1.2 and 1.7 mm, respectively. For group 2, the mean discrepancy between the points marked using the OsteoMark-Navigation system and the surgical guides was 1.9 mm (range 0 to 4.1). The system maintained accuracy on a live minipig in a standard operating room environment.

CONCLUSION

Based on this research OsteoMark-Navigation is a potentially powerful tool for clinical use in maxillofacial surgery. It has accuracy and precision comparable to that of existing clinical applications.

Frameless robotic stereotactic biopsies: a consecutive series of 100 cases

OBJECT

Stereotactic biopsy procedures are an everyday part of neurosurgery. The procedure provides an accurate histological diagnosis with the least possible morbidity. Robotic stereotactic biopsy needs to be an accurate, safe, frameless, and rapid technique. This article reports the clinical results of a series of 100 frameless robotic biopsies using a Medtech ROSA device.

METHODS

The authors retrospectively analyzed their first 100 frameless stereotactic biopsies performed with the robotic ROSA device: 84 biopsies were performed by frameless robotic surface registration, 7 were performed by robotic bone fiducial marker registration, and 9 were performed by scalp fiducial marker registration. Intraoperative flat-panel CT scanning was performed concomitantly in 25 cases. The operative details of the robotic biopsies, the diagnostic yield, and mortality and morbidity data observed in this series are reported.

RESULTS

A histological diagnosis was established in 97 patients. No deaths or permanent morbidity related to surgery were observed. Six patients experienced transient neurological worsening. Six cases of bleeding within the lesion or along the biopsy trajectory were observed on postoperative CT scans but were associated with transient clinical symptoms in only 2 cases. Stereotactic surgery was performed with patients in the supine position in 93 cases and in the prone position in 7 cases. The use of fiducial markers was reserved for posterior fossa biopsy via a transcerebellar approach, via an occipital approach, or for pediatric biopsy.

CONCLUSIONS

ROSA frameless stereotactic biopsies appear to be accurate and safe robotized frameless procedures.

Validation of a magnetic resonance imaging guided stereotactic access to the ovine brainstem

Background

Anatomical differences between humans and domestic mammals preclude the use of reported stereotactic approaches to the brainstem in animals. In animals, brainstem biopsies are required both for histopathological diagnosis of neurological disorders and for research purposes. Sheep are used as a translational model for various types of brain disease and therefore a species-specific approach needs to be developed. The aim of the present study was to establish a minimally invasive, accurate and reproducible stereotactic approach to the brainstem of sheep, using the magnetic resonance imaging guided Brainsight^TM frameless stereotactic system.

Results

A transoccipital transcerebellar approach with an entry point in the occipital bone above the vermis between the transverse sinus and the external occipital protuberance was chosen. This approach provided access to the target site in all heads. The overall mean needle placement error was 1.85 ± 1.22 mm.

Conclusions

The developed transoccipital transcerebellar route is short, provides accurate access to the ovine caudal cranial fossa and is a promising approach to be further assessed in live animals.

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.

Institutional charges and disparities in outpatient brain biopsies in four US States: the State Ambulatory Database (SASD)

Several groups have demonstrated the safety of ambulatory brain biopsies, with no patients experiencing complications related to early discharge. Although they appear to be safe, the reasons factoring into the selection of patients have not been investigated. We performed a cross-sectional study involving 504 patients who underwent outpatient and 10,328 patients who underwent inpatient brain biopsies and were registered in State Ambulatory Surgery Databases and State Inpatient Databases respectively for four US States (New York, California, Florida, North Carolina). In a multivariate analysis private insurance (OR 2.45, 95 % CI, 1.85, 3.24), was significantly associated with outpatient procedures. Higher Charlson Comorbidity Index (OR 0.16, 95 % CI, 0.08, 0.32), high income (OR 0.37, 95 % CI, 0.26, 0.53), and high volume hospitals (OR 0.30, 95 % CI, 0.23, 0.39) were associated with a decreased chance of outpatient procedures. No sex, or racial disparities were observed. Institutional charges were significantly less for outpatient brain biopsies. There was no difference in the rate of 30-day postoperative readmissions among inpatient and outpatient procedures. The median charge for inpatient surgery was 51,316 as compared to 12,266 for the outpatient setting (P < 0.0001, Student's t test). Access to ambulatory brain biopsies appears to be more common for patients with private insurance and less comorbidities, in the setting of lower volume hospitals. Further investigation is needed in the direction of mapping these disparities in resource utilization.

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.

Outpatient brain tumor surgery and spinal decompression: a prospective study of 1003 patients

BACKGROUND

Outpatient craniotomy, biopsy, and spinal decompression have been performed at our center for more than a decade. Early feasibility studies suggest that they are safe, successful, cost-effective, and well-tolerated by patients. However, a large-scale study of this magnitude has not been performed.

OBJECTIVE

To characterize postoperative complications and the rate of successful discharge from the day surgery unit (DSU). We also discuss patient satisfaction and benefits to flow of care.

METHODS

From August 1996 to December 2009, 1003 consecutive patients were prospectively selected as outpatient candidates. Retrospective chart review was performed for all procedures and analyzed by intent to treat.

RESULTS

Of 249 patients who underwent a craniotomy, 92.8% were successfully discharged from the DSU, 5.2% were admitted from the DSU, and 2.0% were discharged and later readmitted. Of 602 patients who underwent spinal decompression, 97.3% were successfully discharged from the DSU, 2.5% were admitted from the DSU, and 0.2% were discharged and readmitted at a later date. Of 152 patients who underwent a brain biopsy, 94.1% were successfully discharged from the DSU, 4.6% were admitted from the DSU, and 1.3% were discharged and later readmitted. No patients experienced a negative outcome as a result of early discharge.

CONCLUSION

Outpatient craniotomy, biopsy, and spinal decompression are safe, successful, and cost-effective.

Stereotactic navigation with the O-arm for placement of S-2 alar iliac screws in pelvic lumbar fixation

Object

Pelvic fixation is a crucial adjunct to many lumbar fusions to avoid L5–S1 pseudarthrosis. It is useful for treatment of kyphoscoliosis, high-grade spondylolisthesis, L5–S1 pseudarthrosis, sacral tumors, lumbosacral dislocations, and osteomyelitis. The most popular method, iliac fixation, has drawbacks including hardware prominence, extensive muscle dissection, and the need for connection devices. S-2 alar iliac fixation provides a useful primary or salvage alternative. The authors describe their techniques for using stereotactic navigation for screw placement.

Methods

The O-arm Surgical Imaging System allowed for CT-quality multiplanar reconstructions of the pelvis, and registration to a StealthStation Treon provided intraoperative guidance. The authors describe their technique for performing computer-assisted S-2 alar iliac fixation for various indications in 18 patients during an 18-month period.

Results

All patients underwent successful bilateral placement of screws 80–100 mm in length. All placements were confirmed with a second multiplanar reconstruction. One screw was moved because of apparent anterior breach of the ilium. There were no immediate neurological or vascular complications due to screw placement. The screw length required additional instruments including a longer pedicle finder and tap.

Conclusions

Stereotactic guidance to navigate the placement of distal pelvic fixation with bilateral S-2 alar iliac fixation can be safely performed in patients with a variety of pathological conditions. Crossing the sacroiliac joint, choosing trajectory, and ensuring adequate screw length can all be enhanced with 3D image guidance. Long-term outcome studies are underway, specifically evaluating the sacroiliac joint.

A prospective study of the safety and efficacy of frameless, pinless electromagnetic image-guided biopsy of cerebral lesions

BACKGROUND

In recent years, frameless navigation techniques have been reported to be safe and effective for biopsy of cerebral lesions.

OBJECTIVE

To evaluate the safety and efficacy of a technique of frameless, pinless electromagnetic-guided biopsy for brain lesions with the Medtronic Stealth AxiEM.

METHODS

Prospective data were collected on consecutive brain biopsies performed by a single surgeon (P.L.G.) with this technology between October 2007 and May 2010. One trajectory was made per lesion with multiple specimens taken for analysis. Outcome measures included measures of accuracy, histological yield, and complication rate.

RESULTS

A total of 150 biopsies were performed in 149 patients (84 male and 65 female patients; age range, 19.8-83.8 years). The consultant performed 49 procedures, supervising a trainee in the others. In only 1 case (0.7%) was there nondiagnosis consequent of a registration error and inaccurate trajectory. In 4 other cases (2.7%), no specific diagnosis was established, but abnormal tissue was identified histologically, and postoperative imaging confirmed accurate targeting of these lesions. There were no instances of intracranial hemorrhage or significant morbidity and no deaths directly attributable to the procedure. Four patients (2.7%) died within 30 days of the procedure but not of complications of surgery. One patient suffered a transitory neurological deficit.

CONCLUSION

Electromagnetic navigation is proven to be a simple, safe, and effective innovation for frameless and pinless biopsy of cerebral lesions. This technique is time efficient, and elimination of frame placement enhances patient comfort and facilitates the use of local anesthetic technique.

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.

Factors affecting diagnostic yield in needle biopsy for brain lesions

INTRODUCTION

We analyse the factors that are associated with the diagnostic yield of needle brain biopsy.

MATERIAL AND METHODS

We present a retrospective series of 124 consecutive biopsies in a 30-month period. Patients' demographics (age, gender), lesion topography (side, location, depth), lesion characteristics (histology, volume, radiological enhancement), type of biopsy procedure (freehand, ultrasound guided, frameless and frame-based stereotactic) and the use of intraoperative histologic examination were correlated with the diagnostic rate. Descriptive statistics and a nominal logistic regression model were used to evaluate the factors influencing diagnostic yield.

RESULTS

63 men and 61 women were included in the study with mean age 59.2 (range: 16-86). 55 were frame-based stereotactic biopsies, 33 were frameless stereotactic biopsies, 29 biopsies were performed under ultrasound guidance and 7 freehand. The diagnostic yield in our series is 93.5%. The gender, lesion topography, biopsy method, use of intraoperative histology and enhancement did not correlate with the diagnostic yield. Younger age had a negative impact on diagnostic yield. 6 out of 8 inconclusive biopsies were in non-glial lesions (p < 0.05). The odds of obtaining a positive diagnosis increased sevenfold with every cc increase in lesion volume.

CONCLUSION

The age of the patient, the volume and the histology of the brain lesion had an impact on the diagnostic yield of needle biopsy. None of the other factors significantly influenced the diagnostic rate.

Frameless image-guided stereotaxy with real-time visual feedback for brain biopsy

BACKGROUND

Frame-based stereotaxy remains the "gold standard" for cerebral biopsies and functional neurosurgery though new frameless stereotactic systems are evolving continually. As the technique of frameless stereotaxy gains increasing acceptance among neurosurgeons, this study assesses the feasibility of a system for frameless image-guided stereotaxy.

METHODS

All patients biopsied for intracranial lesions between February 2007 and August 2010 using the BrainLAB VarioGuide frameless stereotactic system were evaluated prospectively. Prior to surgery, patients underwent magnetic resonance (MR) imaging; additionally, fluoroethyl-tyrosine (FET)-positron emission tomography (PET) images were acquired and fused to MR images in selected cases. Biopsy trajectory length, lesion volume, procedure duration, and diagnostic yield were assessed.

RESULTS

Ninety-six diagnostic biopsies in 91 patients were evaluated. Lesion volume ranged from 0.17 to 121.8 cm(3); trajectory length from 25.3 to 101.9 mm. Diagnostic yield was 93.8%. Mean operation time from skin incision to wound closure was 42 min; in the operating room, it was 99 min.

CONCLUSIONS

Clinical experience indicates VarioGuide to be safe and accurate. Reachable range of lesion localisation appears to be comparable to a frame-based stereotaxy system. Operation times are brief. The unique design of this frameless stereotactic system allows real-time visual feedback of needle positioning.

Increased frameless stereotactic accuracy with high-field intraoperative magnetic resonance imaging

BACKGROUND

Frameless stereotaxy commonly registers preoperative magnetic resonance imaging (MRI) to patients by using surface scalp anatomy or adhesive fiducial scalp markers. Patients' scalps may shift slightly between preoperative imaging and final surgical positioning with pinion placement, introducing error. This might be reduced when frameless stereotaxy is performed in a high-field intraoperative MRI (iMRI), as patients are positioned before imaging. This could potentially improve accuracy.

OBJECTIVE

To compare frameless stereotactic accuracy using a high-field iMRI with that using standard preoperative MRI.

METHODS

Data were obtained in 32 adult patients undergoing frameless stereotactic-guided brain tumor surgery. Stereotactic images were obtained with 1.5T MRI scanner either preoperatively (14 patients) or intraoperative (18 patients). System-generated accuracy measurements and distances from the actual center of each fiducial marker to that represented by neuronavigation were recorded. Finally, accuracy at multiple deep targets was assessed by using a life-sized human head stereotactic phantom in which fiducials were placed on deformable foam to mimic scalp.

RESULTS

: System-generated accuracy measurements were significantly better for the iMRI group (mean ± SEM = 1.04 ± 0.05 mm) than for the standard group (1.82 ± 0.09 mm; P < .001). Measured distances from the actual center of scalp fiducial markers to that represented by neuronavigation were also significantly smaller for iMRI (1.72 ± 0.10 mm) in comparison with the standard group (3.17 ± 0.22 mm; P < .001). Deep accuracy in the phantom model was significantly better with iMRI (1.67 ± 0.12 mm) than standard imaging (2.28 ± 0.14 mm; P = .003).

CONCLUSION

Frameless stereotactic accuracy is increased by using high-field iMRI compared with standard preoperative imaging.

Surgical treatment of poorly visualised and complex cerebrovascular lesions using pre-operative angiographic data as angiographic DynaCT datasets for frameless stereotactic navigation

BACKGROUND

Digital subtraction angiography (DSA) is the "gold standard" for the imaging of cerebrovascular lesions, particularly cerebral aneurysms and arteriovenous malformations (AVMs). Current stereotactic navigation is based on computed tomography (CT) and magnetic resonance (MR) images, which-even despite the use of CT angiographic (CTA) or MR angiographic (MRA) sequences-may not reveal small lesions, and may not demonstrate all the different facets of complex lesions.

OBJECTIVE

To develop frameless stereotactic protocols based on pre-operative cerebral angiograms for enhancing precision in intra-operative navigation and improve patient outcomes.

METHODS

Pre-operative angiograms were obtained for ten patients requiring surgery for complex and/or poorly visualised cerebrovascular lesions. The angiographic data were captured as an angiographic DynaCT dataset and fused to pre-operative CT or MR imaging stereotactic sequences for pre-operative planning and intra-operative navigation. The utility of the angiographic DynaCT datasets for surgical navigation and treatment were assessed by the treating neurosurgeon.

RESULTS

This technique enabled precise navigation and better treatment of cerebrovascular lesions that were either inadequately imaged or invisible to conventional pre-operative CT and/or MR imaging techniques. We found that its use in the surgical excision of a micro-AVM to be far superior to CTA and MRA datasets. Its use in seven cases was found to be superior to CTA and MRA datasets, and as useful as CTA or MRA datasets in two cases.

CONCLUSION

Pre-operative formal cerebral angiography as an angiographic DynaCT dataset can be used safely and effectively for intra-operative navigation and treatment of cerebrovascular lesions, in particular, micro-cerebral AVMs.

Frameless robotically targeted stereotactic brain biopsy: feasibility, diagnostic yield, and safety

Object

Frameless stereotactic brain biopsy has become an established procedure in many neurosurgical centers worldwide. Robotic modifications of image-guided frameless stereotaxy hold promise for making these procedures safer, more effective, and more efficient. The authors hypothesized that robotic brain biopsy is a safe, accurate procedure, with a high diagnostic yield and a safety profile comparable to other stereotactic biopsy methods.

Methods

This retrospective study included 41 patients undergoing frameless stereotactic brain biopsy of lesions (mean size 2.9 cm) for diagnostic purposes. All patients underwent image-guided, robotic biopsy in which the SurgiScope system was used in conjunction with scalp fiducial markers and a preoperatively selected target and trajectory. Forty-five procedures, with 50 supratentorial targets selected, were performed.

Results

The mean operative time was 44.6 minutes for the robotic biopsy procedures. This decreased over the second half of the study by 37%, from 54.7 to 34.5 minutes (p < 0.025). The diagnostic yield was 97.8% per procedure, with a second procedure being diagnostic in the single nondiagnostic case. Complications included one transient worsening of a preexisting deficit (2%) and another deficit that was permanent (2%). There were no infections.

Conclusions

Robotic biopsy involving a preselected target and trajectory is safe, accurate, efficient, and comparable to other procedures employing either frame-based stereotaxy or frameless, nonrobotic stereotaxy. It permits biopsy in all patients, including those with small target lesions. Robotic biopsy planning facilitates careful preoperative study and optimization of needle trajectory to avoid sulcal vessels, bridging veins, and ventricular penetration.

Frameless stereotactic cerebral biopsy: our experience in 296 cases

AIMS

To evaluate the reliability, safety and accuracy of a the frameless stereotactic system in our clinical series and the differences between head fixation by means of a standard Mayfield head holder and the pinless FESS frame, and to evaluate the usefulness of biopsy targeting on the basis of magnetic resonance spectroscopy (MRS) data.

METHODS

The spectroscopic analysis was used to facilitate the targeting of the lesion. The fusion image function embedded in the Neuronavigation Unit was used postoperatively to assess the level of accuracy of the biopsy. The grading of the glioma specimens was correlated to the spectroscopic data.

RESULTS

296 patients underwent cerebral biopsy in 8 years. The diagnostic yield was 99.7%. The spectroscopic choline/N-acetyl aspartate ratio in different areas of the same tumor correlated well with the histological grading of the lesion.

CONCLUSION

The frameless stereotactic systems guarantee excellent biopsy results. Advanced imaging, in particular MRS, facilitates the correct targeting of nonenhancing lesions.

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

Object

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.

Methods

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.

Results

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.

Conclusions

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.

A modified stereotactic frame as an instrument holder for frameless stereotaxis: Technical note

Background:

In order to improve the targeting capability and trajectory planning and provide a more secure probe-holding system, a simple method to use a stereotactic frame as an instrument holder for the frameless stereotactic system was devised.

Methods:

A modified stereotactic frame and BrainLab vector vision neuronavigation sys¬tem were used together. The patient was placed in the stereotactic head-holder to which a reference array of the neuronavigation system was attached. The pointer of the frameless system was placed in the probe-holder of the frame. An offset in distances was kept between the radius of the arch of the frame and the tip of the pointer so that the pointer was always outside the head during navigation. The offset correction was made on the BrainLab monitor so that the center of the arc of the frame was at the tip of the probe line on the monitor. Then, using the frame’s coordinate adjuster system, the center of the arc was positioned on the target. This method was used to insert depth electrodes (seven procedures) and gain access to the temporal horn (three procedures).

Results:

Post-operative scans showed that the accuracy was within 2.5 mm in all three planes for depth electrode placement, and easy access to the temporal horn was obtained in two other patients.

Conclusion:

This is a simple method to use a stereotactic frame to improve coordinate and trajectory adjustments and provides a better method to stabilize the pointer and the probe-holder during frameless stereotactic procedures.

Image-guided frameless stereotactic biopsy without intraoperative neuropathological examination

OBJECT

Stereotactic biopsy is a safe and effective technique for the diagnosis of brain tumors. The use of intraoperative neuropathological examination has been routinely advocated to increase diagnostic yield, but the procedure lengthens surgical time, may produce false-negative and -positive results, and current biopsy techniques have a very low nondiagnostic rate. Therefore, the authors questioned the need for intraoperative histological evaluation.

METHODS

The authors prospectively studied all patients undergoing image-guided biopsy under the care of a single surgeon (P.L.G.) between July 2005 and October 2007. A Stryker neuronavigation system with a trajectory guide was used to plan a single trajectory, and, using a side-cutting biopsy cannula, multiple biopsy samples were taken from between 1 and 4 sites within the tumor. Tissue was inspected macroscopically by the surgeon and was only submitted for neuropathological assessment postoperatively.

RESULTS

One hundred thirty-four biopsies were performed during the study. A positive diagnosis was established in 133 cases (99.3%). One biopsy was negative (0.7%) and postoperative imaging (performed because the tissue was macroscopically normal) demonstrated inaccurate targeting of the lesion. Significant complications were seen in 3 patients (2.2%) who all had preoperative WHO performance scores of III or IV. Two patients suffered delayed deterioration and died due to probable surgical complications--one with thalamic glioblastoma multiforme (GBM) and one with gliomatosis cerebri. One patient with GBM suffered an intracerebral hematoma that was managed conservatively. Postoperative seizures were seen in 4 patients (3%), and 2 patients (1.5%) experienced a transient neurological deficit. Histological diagnosis showed a GBM in 64 cases, Grade III glioma in 19, Grade I or II in 23, metastasis in 10, lymphoma in 13, and other disease in 4. There were 32 patients discharged to home on the same day as surgery. Compared with the authors' previous retrospective audit into 127 biopsies, this technique showed improved diagnostic yield (99.3 vs 94.5%, p = 0.032) with fewer complications (2.2 vs 4.7% [not statistically significant]).

CONCLUSIONS

This technique of image-guided biopsy has high diagnostic yield with acceptably low morbidity and may be performed as a day case. Intraoperative neuropathological examination would not have increased the diagnostic yield further in this study, and its routine use may not be necessary. In the authors' department pounds sterling 70,350 (UK)/$114,522 (US) would have been saved by not using intraoperative neuropathology in this series. Therefore, intraoperative neuropathology should no longer be routinely recommended.

Precision of navigated stereotactic probe implantation into the brainstem

OBJECT

The indications for stereotactic biopsies or implantation of probes for local chemotherapy in diffuse brainstem tumors have recently come under debate. The quality of performing these procedures significantly depends on the precision of the probes' placement in the brainstem. The authors evaluated the precision of brainstem probe positioning using a navigated frameless stereotactic system in an experimental setting.

METHODS

Using the VarioGuide stereotactic system, 33 probes were placed into a specially designed model filled with agarose. In a second experimental series, 8 anatomical specimens were implanted with a total of 32 catheters into the pontine brainstem using either a suboccipital or a precoronal entry point. Before intervention in both experimental settings, a thin-sliced CT scan for planning was obtained and fused to volumetric T1-weighted MR imaging data. After the probe positioning procedures, another CT scan and an MR image were obtained to compare the course of the catheters versus the planned trajectory. The deviation between the planned and the actual locations was measured to evaluate the precision of the navigated intervention.

RESULTS

Using the VarioGuide system, mean total target deviations of 2.8 +/- 1.2 mm on CT scanning and 3.1 +/- 1.2 mm on MR imaging were detected with a mean catheter length of 151 +/- 6.1 mm in the agarose model. The catheter placement in the anatomical specimens revealed mean total deviations of 1.95 +/- 0.6 mm on CT scanning and 1.8 +/- 0.7 mm on MR imaging for the suboccipital approach and a mean catheter length of 59.5 +/- 4.1 mm. For the precoronal approach, deviations of 2.2 +/- 1.2 mm on CT scanning and 2.1 +/- 1.1 mm on MR imaging were measured (mean catheter length 85.9 +/- 4.7 mm).

CONCLUSIONS

The system-based deviation of frameless stereotaxy using the VarioGuide system reveals good probe placement in deep-seated locations such as the brainstem. Therefore, the authors believe that the system can be accurately used to conduct biopsies and place probes in patients with brainstem lesions.