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PubMed1996

[Gamma knife versus stereotactic linear accelerator. Utilization, clinical results and cost-benefit relations].

INTRODUCTION: The principles of radiosurgery were developed in 1951 by Leksell. Their technical realization led to the development of the gamma knife and stereotactically modified linear accelerator. METHODS: In addition to the gamma knife, we present the different principles of convergent beam irradiation (radiosurgery with linear accelerator), the further development to fractionated stereotactic conformal radiotherapy, and the necessary quality-assurance steps. RESULTS: The greatest uncertainties in the precision of radiosurgery result from medical imaging (CT 0.7 x 0.7 x 1 mm; DSA 1-5 mm; MR angiography < 2 mm). The focusing accuracy of the gamma knife (+/- 0.3 mm) can also be achieved today by linear accelerators using a stereotactic floorstand. For the same indication and the same dosage for the target volume, there are no clinical differences between the gamma knife and the linear accelerator (AVM: 80% complete obliteration; metastases: 85% local tumor control; AN: 90% tumor control). However, there are greater differences in costs. There is no constellation where the gamma knife is just as expensive or more cost-effective than the linear accelerator treatment. The most cost-effective solution is modification of an available linear accelerator, resulting in treatment costs per patient of 9,201.25 DM (50 patients/year). CONCLUSION: There seem to be no methodological, physical, clinical or cost reasons for using a gamma knife, especially because the trend is going towards fractionated conformation radiotherapy instead of the application of high single doses.

Brain Neoplasms↗

PubMed2002

Antiepileptic effect of high-frequency stimulation of the subthalamic nucleus (corpus luysi) in a case of medically intractable epilepsy caused by focal dysplasia: a 30-month follow-up: technical case report.

OBJECTIVE AND IMPORTANCE: Currently, some forms of epilepsy are resistant to both pharmacological and surgical interventions. As a result, there is a need for new therapeutic strategies. Because the nigral system modulates neuronal excitability in animal models of epilepsy, we considered therapeutic high-frequency stimulation of the subthalamic nucleus (STN). We were encouraged by the known relationship between the STN and the nigral system, as well as by our experience with high-frequency stimulation of the STN in Parkinsonian patients. CLINICAL PRESENTATION: A 5-year-old girl with pharmacologically resistant, inoperable epilepsy caused by focal centroparietal dysplasia underwent implantation with a permanent electrode in the left STN and was chronically stimulated. To date, we have followed up this patient for 30 months postoperatively. TECHNIQUE: High-frequency stimulation of the STN induced a significant voltage-dependent reduction (by 80%) in the number and severity of seizures. In addition, consistent improvement in both motor and cognitive functions was noted as a result of reduced postictal states. The effect was more prominent for seizures occurring in clusters (89% reduction) and during the day (88% reduction) than for those that occurred during sleep (53% reduction). CONCLUSION: This is the first report of epilepsy control using chronic high-frequency stimulation of the STN. Preliminary observations in three other operated patients (at 2, 12, and 18 mo) confirm these data. We think that high-frequency stimulation of the STN may hold significant future potential as a treatment for epilepsy, similar to its established role in the treatment of Parkinson's disease. This finding opens completely new experimental and therapeutic avenues for the treatment of surgically and medically intractable epilepsy.

Brain↗

PubMed1995

A noninvasive, reattachable skull fiducial marker system. Technical note.

As computer-interactive technologies become more widely used in neurosurgery, radiology, and radiation therapy, the need for an optimum skull fiducial marker system increases. In the past, intracranial localization methods required precisely machined metal frames and rigid pin fixation to the skull. Recently, this function has been performed using "frameless" computer-based systems that calculate brain position relative to a series of external reference points, the most accurate of which are screwed directly into the skull. A penetrating fiducial marker system, however, is not well suited for applications requiring multiple volume registrations over an extended time period. We describe a new skull fiducial marker system that attaches to the maxillary teeth and can be used repeatedly on different occasions. A curved bar, known as a Banana Bar (BB) extends backward from a custom mouthpiece around the side of the patient's head; the bar contains sites of attachment for screw-in radiographic fiducial markers. Repositioning accuracy was quantitated using a photographic technique. A BB prototype was constructed and tested in three subjects. The BB weighs less than 100 g and can be comfortably held in position for up to 30 minutes. It takes less than 1 minute to screw in the mouthpiece and only seconds to secure the BB to the teeth. One hundred twenty photographic measurements were analyzed from 60 repositionings over a minimum 3-week period. Standard deviations for the measurement series ranged from 0.29 to 0.86 mm. Results suggest that the BB may be an inexpensive, efficient, and accurate method for providing the external reference points needed for a wide range of emerging computer-interactive applications.

Brain↗

PubMedDate not supplied

MR-guided procedures using contemporaneous imaging frameless stereotaxis in an open-configuration system.

Frameless MR-guided procedures have had limited application using conventional closed magnets, due largely to the technical difficulties involved. As a result of in-room MR image-monitoring capabilities, new open-design magnets now allow frameless stereotaxis using contemporaneous imaging to guide more invasive procedures. We evaluate our clinical experience with this new technique. An open-design 0.2 T magnet (Siemens OPEN) combined with an in-room monitor was used for 33 frameless MR-guided procedures (aspiration cytology, biopsy, and/or treatment) in a variety of locations in the head, neck, spine, brain, pelvis, and abdomen. Success of the procedure was based on the ability to accurately position the instrument in the target region to allow biopsy and/or treatment. The open-design magnet allowed the physician to directly access the patient for frameless stereotaxis as the procedure was performed. The in-room monitor provided contemporaneous imaging feedback during the procedure for successful placement of the instrument in the target region. Twenty-eight biopsy and five treatment procedures were performed. In all cases the technique resulted in successful placement of the instrument within the target tissue to complete the procedure. MR-guided procedures using contemporaneous imaging frameless stereotaxis are possible in an open-design magnet with in-room image monitoring and offer exciting possibilities for further development.

Adolescent↗

PubMed2002

Dual channel deep brain stimulation system (Kinetra) for Parkinson's disease and essential tremor: a prospective multicentre open label clinical study.

OBJECTIVES: To evaluate the safety and efficacy of a new dual channel stimulator (Kinetra) in patients with severe Parkinson's disease (PD) or essential tremor (ET). METHODS: 111 patients with PD and 18 with ET were studied. Leads were implanted into the subthalamic nucleus (STN) or internal globus pallidus of patients with the akinetic/rigid type of PD. Leads were implanted into the ventral intermediate nucleus (VIM) of the thalamus or the STN in patients with the tremor dominant type of PD and in those with ET. Technical data on the device and adverse events occurring during the study were documented. Patients were assessed with established and validated clinical scales before surgery and at three and six months' follow up. RESULTS: No device failure or unexpected adverse events occurred during the study. The dual channel stimulator used in stimulation of the STN, internal globus pallidus, and VIM in PD and ET was as safe and effective as the single channel stimulators in use. Mortality, morbidity, and infections were documented in the 129 treated patients. The parameter settings were similar to those usually programmed with single channel stimulators. Time spent in the operating room to implant the Kinetra system was systematically documented. In the PD group, improvement in the unified Parkinson's disease rating scale motor score, decrease in medication OFF periods, and reduced levodopa induced dyskinesia by bilateral STN stimulation were similar to those previously reported with bilaterally applied single channel stimulators. In the ET group upper and lower limb tremor scores were reduced by VIM stimulation. Activities of daily living improved in both disease groups. CONCLUSION: The Kinetra facilitated bilateral deep brain stimulation implantation surgery and is easy to use. It offers more advantages for the patient than the single channel stimulators; consequently, this new device may be recommended to treat patients with severe PD and ET.

Brain↗

PubMed2006

Experience with microelectrode guided subthalamic nucleus deep brain stimulation.

OBJECTIVE: Subthalamic deep brain stimulation (DBS) has rapidly become the standard surgical therapy for medically refractory Parkinson disease. However, in spite of its wide acceptance, there is considerable variability in the technical approach. This study details our technique and experience in performing microelectrode recording (MER) guided subthalamic nucleus (STN) DBS in the treatment of Parkinson disease. METHODS: Forty patients underwent surgery for the implantation of 70 STN DBS electrodes. Stereotactic localization was performed using a combination of magnetic resonance and computed tomographic imaging. We used an array of three microelectrodes, separated by 2 mm, for physiological localization of the STN. The final location was selected based on MER and macrostimulation through the DBS electrode. RESULTS: The trajectory selected for the DBS electrode had an average pass through the STN of 5.6 +/- 0.4 mm on the left and 5.7 +/- 0.4 mm on the right. The predicted location was used in 42% of the cases but was modified by MER in the remaining 58%. Patients were typically discharged on the second postoperative day. Eighty-five percent of patients were sent home, 13% required short-term rehabilitation, and one patient required long-term nursing services. Seven complications occurred over 4 years. Four patients suffered small hemorrhages, one patient experienced a lead migration, one developed an infection of the pulse generator, and one patient suffered from a superficial cranial infection. CONCLUSION: Simultaneous bilateral MER-guided subthalamic DBS is a relatively safe and well-tolerated procedure. MER plays an important role in optimal localization of the DBS electrodes.

Aged↗

PubMed2001

Early experiences with image-guided transoral surgery for the pathologies of the upper cervical spine.

STUDY DESIGN: Technical note. OBJECTIVES: Three years of convincing experience with cranial neuronavigation suggested the application of the cranial software and registration method for the transoral access to the C1-C2 vertebrae. BACKGROUND DATA: The C1-C2 vertebrae are located in close vicinity to the cranial base. If the intersegmental movements of the C0-C1/C1-C2 segments are prevented with HALO fixation, the upper cervical spine can be considered as a caudal part of the skull base and included in the extended navigation space of the skull. METHODS: Three patients were selected for navigation-assisted transoral odontoidectomy. Before surgery the patients were fixed and scanned in a HALO device. The fiducials were attached supraorbitally and to both mastoids, determining a wide registration area and allowing the caudal extension of the navigation space. The BrainLAB VectorVision navigation system was used in cranial mode during the operations. RESULTS: Neuronavigation and fluoroscopy-controlled transoral surgery were performed with success in all three cases. The registration accuracy was 1.5, 2.7, and 3.1 mm. CONCLUSION: Image guidance during transoral exposure of the upper cervical spine offered excellent three-dimensional guidance on the ventral surface of the craniocervical junction, allowing a safer, more controlled surgery. As the targets of the transoral spinal surgery are fixed bony and ligamentous structures, no shifting occurs and continuous high navigation accuracy can be achieved. The use of the navigation can reduce the significance of the intraoperative fluoroscopy, diminishing the radiograph load of the patient and the operating room team.

Cervical Vertebrae↗

PubMed2000

Frameless stereotactically guided catheter placement and fibrinolytic therapy for spontaneous intracerebral hematomas: technical aspects and initial clinical results.

OBJECTIVE: Frame-based stereotactic puncture and catheter placement followed by fibrinolytic therapy and drainage is one treatment option in the management of spontaneous intracerebral hemorrhage (sICH). This minimally invasive procedure could even be simplified by frameless stereotaxy. The authors present their experiences with frameless stereotactic image-guided catheter placement for lysis and drainage of sICH, with emphasis on technical aspects. METHOD: In 27 patients with sICH, an infrared-based frameless stereotactic device was used for selecting trajectory and target point of hematoma drainage. A trajectory along the main axis of the hematoma was considered to be optimal for fibrinolytic therapy. An articulated arm served to maintain the predetermined trajectory during surgery and to guide catheter advancement. Clot lysis with recombinant tissue plasminogen activator (rt-PA) was initiated after radiological confirmation of correct catheter positioning. RESULTS: In all cases, selection of the optimal trajectory was not restricted by the frameless stereotactic device. In 25 of the 27 patients, the catheter was placed accurately along the predetermined trajectory into the target point. In two patients, the catheter was positioned at the lateral margin of the hematoma, excluding fibrinolytic therapy in one case. In 24 of 27 patients, the mean hematoma volume could be reduced from initially 52 ml to 17 ml in an average of two days. Hematoma enlargement following rt-PA injection was observed in two patients. Further complications were culture negative pleocytosis of cerebrospinal fluid in two and meningitis in one patient. CONCLUSION: Hematoma puncture and catheter placement for fibrinolytic therapy could be achieved with high accuracy and safety using frameless stereotaxy. This method allows unrestricted trajectory selection with catheter positioning along the main hematoma axis. Further studies are required to investigate if frameless stereotactic puncture and clot lysis could contribute to improve the outcome of patients with sICH.

Adult↗

PubMed1999

Accuracy of true frameless stereotaxy: in vivo measurement and laboratory phantom studies. Technical note.

The authors present the results of accuracy measurements, obtained in both laboratory phantom studies and an in vivo assessment, for a technique of frameless stereotaxy. An instrument holder was developed to facilitate stereotactic guidance and enable introduction of frameless methods to traditional frame-based procedures. The accuracy of frameless stereotaxy was assessed for images acquired using 0.5-tesla or 1.5-tesla magnetic resonance (MR) imaging or 2-mm axial, 3-mm axial, or 3-mm helical computerized tomography (CT) scanning. A clinical series is reported in which biopsy samples were obtained using a frameless stereotactic procedure, and the accuracy of these procedures was assessed using postoperative MR images and image fusion. The overall mean error of phantom frameless stereotaxy was found to be 1.3 mm (standard deviation [SD] 0.6 mm). The mean error for CT-directed frameless stereotaxy was 1.1 mm (SD 0.5 mm) and that for MR image-directed procedures was 1.4 mm (SD 0.7 mm). The CT-guided frameless stereotaxy was significantly more accurate than MR image-directed stereotaxy (p = 0.0001). In addition, 2-mm axial CT-guided stereotaxy was significantly more accurate than 3-mm axial CT-guided stereotaxy (p = 0.025). In the clinical series of 21 frameless stereotactically obtained biopsies, all specimens yielded the appropriate diagnosis and no complications ensued. Early postoperative MR images were obtained in 16 of these cases and displacement of the biopsy site from the intraoperative target was determined by fusion of pre- and postoperative image data sets. The mean in vivo linear error of frameless stereotactic biopsy sampling was 2.3 mm (SD 1.9 mm). The mean in vivo Euclidean error was 4.8 mm (SD 2 mm). The implications of these accuracy measurements and of error in stereotaxy are discussed.

Adult↗

PubMed2003

CyberKnife radiotherapy for localized prostate cancer: rationale and technical feasibility.

There is a clear dose response for localized prostate cancer radiotherapy and there probably is a radiobiological rationale for hypo-fractionation. Combining the two should maximize tumor control and increase the therapeutic ratio. This study examines the rationale and technical feasibility of CyberKnife radiotherapy (a robotic arm-driven linear accelerator) for localized prostate cancer. Its ability to deliver non-coplanar non-isocentric arcs can yield maximally conformal isodoses. It is the only integrated system capable of target position verification and real-time tracking during delivery of conformal stereotactic radiotherapy. Inverse planning with the CyberKnife is used to design a course of radiotherapy for localized prostate cancer. Fiducial markers within the gland are used to verify organ position and track organ motion via an orthogonal pair of electronic x-ray imaging devices and provide real-time feedback correction to the robotic arm during delivery. Conformal isodose curves and dose volume histograms (DVH) are used to compare with an optimized Intensity-Modulated Radiotherapy (IMRT) plan actually delivered to the study patient based upon CT scan-derived organ volumes. The CyberKnife can produce superior DVHs for sparing of rectum and bladder and excellent DVHs for target coverage compared with IMRT, and possesses dose heterogeneities to the same degree as IMRT plans. Because of the significantly longer delivery times required it would be best suited for hypo-fractionated regimens. Such dose regimens might allow for biologically equivalent dose escalation without increased normal tissue toxicity. Since the CyberKnife can verify organ position and motion and correct for this in real-time it is the ideal means of achieving such excellent DVHs without a compromise in doses to normal tissues. These capabilities are essential if one contemplates hypo-fractionated regimens with large dose-per-fraction sizes (>5Gy to 10Gy) and dose-escalation.

Equipment Design↗

PubMed2001

Surgical management of single and multiple brain metastases: results of a retrospective study.

BACKGROUND: Advancement in diagnosis and treatment of various cancer entities led to an increasing incidence of brain metastases in the last decades. Surgical excision of single and multiple brain metastases is one of the central treatment options beside radiotherapy, radiosurgery and chemotherapy. To evaluate the benefit of surgery with/without whole-brain radiation therapy (WBRT) in single brain metastases and the influence of image guidance for brain metastases resection, 104 patients were retrospectively evaluated for post-operative outcome. PATIENTS AND METHODS: Between January 1994 and December 1999 150 patients were surgically treated for brain metastases at the Department of Neurosurgery at the Technical University of Dresden. Outcome could be evaluated in 104 patients with respect to special treatment strategies and survival time (69 patients with single and 35 patients with multiple lesions). RESULTS: Most metastases originated from primary lung and breast tumours. Karnofsky performance score improved on average by 10 after surgery. The extent of the extracerebral tumour burden was the main influence on survival time. Patients' age below 70 years was combined with prolonged survival time (median survival time, MST: 4.5 months vs. 7 months). Patients with solitary cerebral metastasis had a MST of 16 months, whereas patients with singular lesions had a MST of 7 and 4 months, depending on the extent of the extracerebral tumour growth. Additional post-operative WBRT with 30 Gy was combined with an increase in MST in patients with single brain metastasis (surgery + WBRT: MST 13 months; surgery only: MST 8 months). In addition, the rate of recurrent cerebral tumour growth was distinctly higher in the non-WBRT group. Neuronavigation did not significantly improve post-operative survival time. In 80% of patients extracerebral tumour growth limited patients' survival. CONCLUSION: Surgery is an initial treatment option in patients with single and multiple brain metastases especially with large tumours (> 3 cm). Post-operative WBRT seems to prolong survival time in patients with single brain metastasis by decreasing local and distant tumour recurrence. Neuronavigational devices permit a targeted approach. Multiple processes can be extirpated in one session without prolonging the hospitalisation time for the patient. However, neuronavigational devices cannot assure complete tumour resection.

Aged↗

PubMed2006

Simultaneous image-guided and endoscopic navigation without rigid cranial fixation: application in infants: technical case report.

OBJECTIVE AND IMPORTANCE: Infants and young children demonstrate a variety of intraventricular and periventricular lesions. Endoscopy has proven useful in the treatment of many of these lesions, but its benefit is limited if it is applied to complex loculated cysts or if the disease is concealed by normal ependymal boundaries. In adults and older children, endoscopy can be augmented by the simultaneous use of frameless stereotaxy, but this combined modality has not been possible in infants and young children without rigid cranial fixation. We describe a method of achieving simultaneous stereotactic and endoscopic navigation in infants and young children by using a pinless, frameless stereotactic assembly. CLINICAL PRESENTATION: The first patient was a 6-week-old boy with macrocephaly and a bulging fontanelle. Computed tomographic and magnetic resonance imaging revealed a complex arachnoid cyst and obstructive hydrocephalus. The second patient was a 7-month-old, ex-premature (27-wk gestational age) boy who developed posthemorrhagic hydrocephalus. He underwent multiple shunt revisions, one of which was complicated by enterococcal ventriculitis. Despite bilateral ventriculoperitoneal shunts, he developed increasing head circumference, listlessness, and irritability. Imaging revealed an enlarged, multiloculated, and asymmetric ventricular system. INTERVENTION: Simultaneous image-guided and endoscopic neuronavigation was implemented in both patients. Before the procedure, a cranial reference arc was secured to the outer table of the cranium through a small incision adjacent to the operative field. After the stereotactic apparatus was registered, the software was used to plan a trajectory for the approach. A burr hole was then made, and a rigid 6-mm endoscope was inserted for direct visualization. Once advanced past the endoscopic port tip, the electromagnetic coil stylet was used to stereotactically track position and identify areas for fenestration, biopsy, and catheter insertion. CONCLUSION: Endoscopic views of complex hydrocephalus and arachnoid cysts alone are often difficult to interpret. Simultaneous image-guided and endoscopic neuronavigation may be advantageous in the management of complex cases that are anatomically related to the ventricular system in infants for whom rigid cranial fixation could lead to increased procedure-related morbidity.

Brain Diseases↗

PubMed1998

Stereotactic mechanical percutaneous renal access.

Obtaining accurate percutaneous renal access when treating intrarenal disease requires substantial skill. Robotic devices have been used in a variety of surgical applications and have been successful in facilitating percutaneous puncture while improving accuracy. Laboratory models of robotic devices for percutaneous renal access have also been developed. However, several technical hurdles need to be addressed. One relates to the device-patient interface. As a first step in creating a complete robotic system, a mechanical arm (PAKY) with active translational motion for percutaneous renal access has been developed and clinically assessed. The PAKY consists of a passive mechanical arm mounted on the operating table and a radiolucent needle driver that uses a novel active translational mechanism for needle advancement. The system utilizes real-time fluoroscopic images provided by a C-arm to align and monitor active needle placement. In vitro experiments to test needle placement accuracy were conducted using a porcine kidney suspended in agarose gel. Seven copper balls 3 to 12.5 mm diameter were placed in the collecting system as targets, and successful access was confirmed by electrical contact with the ball. The PAKY was then used clinically in nine patients. The number of attempts, target calix location, calix size, and time elapsed were evaluated. In the in vitro study, successful needle-ball contact occurred the first time in all 70 attempts, including 10 attempts at the 3-mm balls. Clinically, percutaneous access to the desired calix was attained on the first attempt in each case. The mean target calix diameter was 14.7 mm (range 7-40 mm). The mean time elapsed while attempting access was 8.2 minutes. No perioperative complications attributable to needle access occurred. Early experience indicates that the PAKY provides a steady needle holder and an effective and safe end-effector for percutaneous renal access. This device may provide the mechanical platform for the development of a complete robotic system capable of creating percutaneous renal access.

Adult↗

PubMed2000

Factors influencing the application accuracy of neuronavigation systems.

OBJECTIVE: The overall accuracy of neuronavigation systems may be influenced by (1) the technical accuracy, (2) the registration process, (3) voxel size and/or distortion of image data and (4) intraoperative events. The aim of this study was to test the influence of the registration and imaging modality on the accuracy. METHODS: A plexiglas phantom with 32 rods was taken for navigation targeting. Sixteen fiducials were attached to the surface of the phantom forming two different attachment patterns (clustered vs. diffusely scattered). This model was scanned by MRI and CT (1-mm slices). Registration was performed using different numbers and attachment patterns of the fiducials. Using CT or MRI, the localization error was measured in image space as the Euclidean distance between targets defined in image space and those detected in the physical space. Accuracy was measured with two commercial systems, the Zeiss MKM and the StealthStation. RESULTS: The mean localization error varied between 1.59 +/- 0.29 mm (MKM, 8 scattered fiducials, CT scanning) and 3.86 +/- 2.19 mm (MKM, 4 clustered fiducials, MRI). The worst localization error was 9.5 mm (MKM). In case of an optimal registration, the 95th percentile for the localization error was 2.2 (MKM) and 2.75 mm (StealthStation). The imaging modality has only minor influence on the localization error, with CT increasing accuracy minimally. Both the fiducial number and the attachment pattern critically influence the localization error: 8 fiducials and a generalized attachment pattern increase the accuracy significantly. No correlation between the calculated registration accuracy and the measured localization accuracy was found. CONCLUSION: The application accuracy of different neuronavigation systems critically depends on the registration. The calculated registration accuracy provided by the system does not correspond to the localization error found in reality. The accuracy of frameless neuronavigation systems is comparable to that of classical frame-based stereotactic devices.

Magnetic Resonance Imaging↗

PubMed1996

CT-target determination in postero-ventral pallidotomy: a universal method. Technical note.

Stereotactic targeting of the postero-ventral pallidum (PVP) presents special challenges to the surgeon 1) The target is in intimate relation to the optic tract and the internal capsule. 2) Proper angulation of the trajectory is crucial to achieve optimal effects given the long craniocaudal extension of the PVP. 3) The PVP is difficult to identify on computerized tomography (CT): the border between the internal capsule and the pallidum is usually not apparent. Potential sources of error in target determination include: - angulation of the scanning plane in relation to the intercommissural plane; - projection of the reference points (anterior commissure/posterior commissure [AC/PC]) results in the foreshortened intercommissural line, affecting the Y co-ordinate; - small tilts between the CT gantry and the stereotactic frame affect determination of the X and Z co-ordinates. Correction of these sources of error is done with basic trigonometric algorithms. The authors have developed a rapid method of stereotactic co-ordinate calculation which avoids the need to perform error-prone calculations under the pressure of operating room conditions. 1) The frame is applied with its basal plane corresponding roughly to the orbito-meatal line. 2) Thin CT slices (2 mm increments) are obtained through the area of interest and the slices are printed. 3) The major reference points (Foramen of Monro, AC, PC) are identified and marked. The PC point is projected onto the film containing AC (or viceversa if the PC slice is caudal to AC). 4) The intercommissural distance is measured, and the true length is obtained from a correction graph. The Y co-ordinate is then calculated as 1/2 ICL + 2 mm [towards AC]. 5) The slice corresponding to the target [Z co-ordinate] is obtained from a correction graph that takes into consideration the gap [number of slices] between AC and PC. 6) The X co-ordinate is placed 20 to 22 mm from midline. A graph that takes into consideration the coronal tilt of the stereotactic frame in relation to the CT gantry allows for final corrections of the X and Z co-ordinates. This step-by-step simple method of co-ordinate calculation can be used with any CT-compatible stereotactic frame.

Brain Mapping↗

PubMed1998

The safety and efficacy of stereotactic biopsy for intracranial lesions.

BACKGROUND: Stereotactic brain biopsy is considered by many physicians to have significant morbidity and mortality rates with a high risk of sampling error resulting in misdiagnosis. The technical aspects necessary to perform the procedure safely and effectively are unfamiliar to most physicians. METHODS: After reporting his initial results with stereotactic brain biopsy, several modifications were implemented by the author to improve the morbidity, mortality, and diagnostic yield rates, including complex surgical planning with regard to patient selection, biopsy trajectory, imaging technique, target choice, and intraoperative pathologic review. The results of implementing these modifications were examined retrospectively in 134 consecutive brain biopsies. RESULTS: One hundred and thirty-four stereotactic brain biopsies were performed in 122 patients. Computed tomography guidance was used in 85 patients (63%) and magnetic resonance imaging was used in 49 patients (37%). Sixty-four lesions (48%) were located in the right hemisphere, 61 (45%) in the left, and 9 (7%) in the midline. The most common diagnoses included 62 malignant brain tumors (46%), 24 benign brain tumors (18%), 23 neurologic disorders (17%), and 20 infections (15%). Five biopsies (4%) did not demonstrate a pathologic process for an overall diagnostic yield of 96%. Reasons for diagnostic failure included lesion location adjacent to the ventricular system, inaccurate targeting, and the inability to penetrate the tumor. One patient sustained a neurologic deficit after the biopsy for a morbidity rate of 0.7% and one sustained a fatal hemorrhage during the biopsy of a vascular tumor for a mortality rate of 0.7%. These results are comparable to those reported in 7471 biopsies (current series included) in which the morbidity rate was 3.5%, the mortality rate was 0.7%, and the diagnostic yield was 91%. CONCLUSIONS: Stereotactic brain biopsy is an extremely safe and effective procedure for evaluating intracranial lesions. Complex surgical planning can decrease the risk of potential complications and the use of intraoperative pathologic examination can improve the diagnostic yield for this procedure.

Adolescent↗

PubMed2003

[MR-guided stereotactic breast biopsy: technical aspects and preliminary results].

AIM: To assess the feasibility and accuracy of cytologic and microhistologic breast biopsy using a MR imaging-guided stereotactic system with MR-compatible non-magnetic needles. MATERIALS AND METHODS: Between December 2001 and September 2002, cytologic and microhistologic sampling of 14 lesions (12 patients) was performed in our radiology department using a commercially available MR-guided stereotactic device. MR-compatible non-magnetic needles or mixed kit (non-magnetic coaxial needle + conventional ferromagnetic needle) were used. Of the 12 patients examined, 2 were undergoing MR examination because of genetic/familial risk, 4 during post-operative follow-up and the remaining 6 for contradictory mammographic and sonographic findings. Ten of the 14 lesions were visible on MR alone. The mean lesion diameter was 12 mm (range 5-30 mm). RESULTS: The procedure was relatively simple and feasible. The procedure took 45 minutes on average. The cytologic samples were adequate in 4/14 cases (29%). The diagnosis was absence of malignant cells in one case, ductal carcinoma in one case and suspected carcinoma in two cases. The cytologic diagnosis was confirmed by core biopsy, and by post-operative histology in the malignant lesions. The remaining 10/14 (71%) cytologic samples were inadequate for diagnosis. All the microhistologic samples (100%) were considered sufficient for diagnosis and yielded diagnosis of benignity in 9/14 (60%) lesions and malignancy in 5/14 (40%). Two patients with benign diagnosis underwent surgery, which confirmed the diagnosis. The remaining seven patients were evaluated by follow-up MRI; the first follow-up at 3 months showed no significant changes. Post-operative histology of the 5 lesions with malignant microhistologic diagnosis confirmed the nature of the lesions. CONCLUSIONS: MR-guided stereotactic biopsy is a simple, fast and safe procedure comparable to the interventional breast procedures performed under mammography and ultrasound guidance. The stereotactic device used ensures correct positioning of the needle into the lesion. The new dedicated non-magnetic needles and the mixed kit provide quantitatively and qualitatively adequate tissue for the histologic analysis. On the basis of our initial experience, we conclude that the procedure is feasible and accurate and can therefore be recommended for routine clinical use.

Adult↗

PubMed2004

Frame-based and frameless stereotactic hematoma puncture and subsequent fibrinolytic therapy for the treatment of spontaneous intracerebral hemorrhage.

OBJECTIVES: Comparison of two minimally invasive procedures for the treatment of intracerebral hemorrhage and subsequent lysis with regard to technical implications and clinical outcome of the patients. METHODS: Retrospective analysis of 126 patients with spontaneous supratentorial intracerebral hemorrhage treated by frame-based (n=53) or frameless (n=75) hematoma aspiration and subsequent fibrinolysis with recombinant tissue plasminogen activator (rt-PA). Data were analysed for the whole group as well as for the two subsets of patients with regard to hematoma reduction, procedure-related complications, and the early and long term clinical outcome of the patients. Functional outcome was rated using the Glasgow Outcome Scale (GOS) and Barthel-Index (median follow-up 178 weeks). The prognostic impact of patient related covariates on the GOS was analysed using logistic regression analysis. RESULTS: 49 out of 126 patients (38.9 %) died, 25 of them in the early postoperative period. Only 22/126 (17.5 %) had a favorable long term outcome (GOS >3). Age > 65 years was significantly (p<0.03, OR 3.6) associated with a higher risk for an unfavorable long term outcome (GOS < or = 3). Treatment had no impact on outcome. Both techniques were highly effective in reducing the intracerebral blood volume by 75.8+/-21.4% of the initial hematoma volume in frame-based and 64.8+/-25.4 % in frameless stereotaxy within 2 days of rt-PA-therapy. Malpositioning of the catheter occurred more often in the frameless group (21.3% vs. 9.4 % in the frame-based procedure) without gaining statistical significance. CONCLUSIONS: Frame-based and frameless stereotactic hematoma aspirations with subsequent fibrinolysis are effective in volume reduction of intracerebral hemorrhage with comparable clinical outcome. The frameless procedure is associated with a higher risk for malpositioning of the catheter. Despite effective hematoma reduction with both techniques, the percentage of patients with a good clinical outcome remained limited especially in the elder subpopulation.

Aged↗