Stereotactic CT scanning for the biopsy of intracranial lesions and functional neurosurgery

This report describes a system for incorporation of stereotactic CT scanning data, stereotactic arteriographic data and a computer-generated stereotactic atlas into a three-dimensional matrix utilizing an operating room computer. 86 patients have undergone computer-assisted stereotactic biopsies of intracranial lesions without mortality or neurologic morbidity. Neuroablative and neuroaugmentative procedures have been performed on 5 patients using the CT stereotactic atlas with good correlation with target points determined by ventriculography and microelectrode recording.     

Present and future developments of stereotactic technology

Incorporation of a surgical computer system into stereotactic methodology provides the facility for efficient utilization of the multiple data bases at the disposal of the modern stereotactician. Computed tomography, magnetic resonance imaging, and digital fluoroscopy data gathered in stereotactic conditions are digitized into a stereotactic surgical matrix for surgical planning and interactive surgical procedures. The advantages of this system are illustrated in stereotactic biopsy, interstitial irradiation, and laser resections of intracranial tumors.     

Pulmonary vein isolation with a multielectrode basket catheter

Pulmonary vein (PV) isolation (PVI) techniques have evolved as a curative treatment of atrial fibrillation (AF) since PVI guided by circumferential mapping with a circular catheter was initially proposed. A multielectrode basket catheter (MBC) is also useful for PVI because of some advantages; (1) an MBC provides some information about the PV anatomy on the fluoroscopic image, (2) an MBC can utilize the non-fluoroscopic navigation system, (3) an MBC enables the direct three-dimensional mapping around the PV ostium and antrum, (4) the distal electrodes of the MBC can be used to monitor some activation changes within the PV in real time and thereby indicate the effects of ablation at the ostium and antrum as radiofrequency lesions are created. PVI with an MBC is an effective and safe procedure to cure AF by integrating the PV anatomy and electrophysiology in combination with a non-fluoroscopic three-dimensional navigation system for the ablation catheter.     

An unexpected evolution of symptomatic mild middle cerebral artery (MCA) stenosis: asymptomatic occlusion

Background  

The intracranial localization of large artery disease is recognized as the main cause of ischemic stroke in the world, considering all countries, although its global burden is widely underestimated. Indeed it has been reported more frequently in Asians and African-American people, but the finding of intracranial stenosis as a cause of ischemic stroke is relatively common also in Caucasians. The prognosis of patients with stroke due to intracranial steno-occlusion is strictly dependent on the time of recanalization. Moreover, the course of the vessel involvement is highly dynamic in both directions, improvement or worsening, although several data are derived from the atherosclerotic subtype, compared to other causes.     

烟雾病5例临床分析

目的：研究烟雾病（moyamoya disease,MMD）的临床及影像学特征。方法：回顾性分析5例烟雾病患者,分析其临床及影像学特点。结果：本组病例既往均无阳性病史,中、青年起病,男性居多,均以缺血性脑血管病起病,肢体瘫痪不重,经颅多普勒（TCD）及头颅核磁改变明显,数字减影血管造影（DSA）检查均存在血管闭塞及侧支开放,烟雾血管网形成,1例MRA证实烟雾血管网形成。结论：对于无既往史的中、青年脑卒中患者,要考虑MMD的可能,需完善TCD、头核磁检寻找证据,最后完善数字减影血管造影确诊。     

烟雾病5 例临床分析

目的:研究烟雾病(moyamoya disease,MMD)的临床及影像学特征。方法:回顾性分析5例烟雾病患者,分析其临床及影像学特点。结果:本组病例既往均无阳性病史,中、青年起病,男性居多,均以缺血性脑血管病起病,肢体瘫痪不重,经颅多普勒(TCD)及头颅核磁改变明显,数字减影血管造影(DSA)检查均存在血管闭塞及侧支开放,烟雾血管网形成,1例MRA证实烟雾血管网形成。结论:对于无既往史的中、青年脑卒中患者,要考虑MMD的可能,需完善TCD、头核磁检寻找证据,最后完善数字减影血管造影确诊。     

Computer-assisted stereotactic biopsy of intracranial lesions

The use of a computer program that allows the integration of stereotactically gathered CT, MRI and digital angiographic data in the planning of a biopsy trajectory is described. This system has been used to perform 447 stereotactic biopsies in 439 patients. Intracranial hemorrhages occurred in three patients; combined morbidity and mortality was less than 1%. Incorporation of angiographic data and visualization of the surgical trajectory enhances the safety and accuracy of stereotactic biopsy of intracranial lesions.     

Use of the Brown-Roberts-Wells stereotactic frame for functional neurosurgery

The Brown-Roberts-Wells (BRW) stereotactic unit has proven itself to be a highly accurate instrument for biopsying or locating pathologic intracranial lesions based on CT scan information. We utilized the BRW frame to select 18 target sites in 12 patients undergoing functional stereotactic procedures. Two patients had bilateral cingulumotomies, 5 had thalamotomies for movement disorders, and 5 underwent electrode implantations for the treatment of chronic pain. Stereotactic frame settings were determined using a positive contrast ventriculogram, orthogonal radiographs, and a computer program provided with the BRW system. In addition, attempts were made to select targets based on CT scan landmarks alone, and these were compared to those derived using ventriculography. We found the BRW frame to be a satisfactory device for performing functional neurosurgical procedures based on ventriculographic landmarks. Coordinates derived from CT scans were similar to those obtained with ventriculography, but were not accurate enough to permit the use of CT scanning as the sole means of target identification. Although future improvements in imaging techniques and computer software are likely to occur, our experience supports ventriculography as the current method of choice for the precise localization of functional targets with the BRW stereotactic system.     

A case report of stereotactic radiosurgery in a patient with Ehlers–Danlos syndrome

In this report, we outline the case of a patient who has Ehlers–Danlos Syndrome (EDS) who received two courses of CyberKnife stereotactic radiosurgery (SRS) for metastatic non-small cell lung cancer. Patients with EDS have increased blood vessel fragility, and therefore are subject to increased risk of bleeding. There are no published data regarding the risks of hemorrhage associated with SRS for intracranial metastases in this patient population. The patient described in this case report had two courses of SRS for two sites of brain metastases. She tolerated treatment well, with no acute toxicity and good local control to date. We have also included a discussion of published literature regarding toxicity of intracranial radiation in patients with EDS.     

Estimation of neural noise. Functional anatomy of the human thalamus.

In the course of stereotactic thalamotomy, the neural noise level of subcortical structures was estimated quantitatively with the aid of two semimicro-electrodes. The neural noise showed several characteristic features in terms of its amplitude and discharge pattern so that it was correlated with the possible anatomical substrate, thus providing the functional anatomy of the subcortical structures. The study on saggital plane revealed a systematic difference of the noise level between VL and Vim-Vc that could be explained by the different cell size in respective nucleus. Several exceptional cases were also presented, emphasizing the neural noise study in stereotactic surgery.     

Magnetic resonance imaging stereotaxy: recognition and utilization of the commissures

Magnetic Resonance Imaging (MRI) offers a non-invasive method to visualize the intracerebral structures. Coupled to a compatible stereotactic frame and software, MRI can be used to determine the coordinates of intracranial targets. Coordinates of the anterior commissure, posterior commissure, targets and intercommissural distance were obtained from positive contrast ventriculography and by MRI in 6 patients undergoing stereotactic localization prior to the implantation of stimulating thalamic electrodes for pain control. The correlation of coordinates and measurements obtained with ventriculography and MRI is +/- 1 mm in most measurements, but up to 3 mm in 2 cases. Magnetic resonance stereotaxy allows non-invasive and precise localization of intracerebral targets, but does not yet allow its routine use with confidence. Further understanding of distortion and artifacts and corrections of these is mandatory.     

Evaluation of Flow Velocity in Unilateral Middle Cerebral Artery Stenosis by Transcranial Doppler

To determine the optimal velocity values in diagnosing unilateral middle cerebral artery (MCA) stenosis by Transcranial Doppler (TCD), and improve the diagnostic accuracy using magnetic resonance angiography (MRA), a total of 302 unilateral MCA stenosis patients undergoing TCD also consented to a MRA of the intracranial arteries. The peak systolic velocity (PSV) and each MCA spectrum for each patient were recorded. Using the MRA to confirm, the degree of middle cerebral artery stenosis was categorized into four groups: normal (normal caliber and signal), mild (<50 %), moderate (50–69 %), severe (70–99 %, or no flow detected). The velocity difference among these four groups was significant (P < 0.001). The optimal PSV values for normal and stenosis were 160 cm/s. For mild and moderate were 200 cm/s, for moderate and severe were 280 cm/s. Using PSV as the diagnostic criteria, the Kappa number was >0.668. The optimal PSV differential value for mild and moderate was 70 cm/s, for moderate and severe at 120 cm/s. Optimal combined criteria for moderate stenosis were PSV >200 cm/s and PSV differential value >70 cm/s (specificity 87.2 %), for severe stenosis were PSV >280 cm/s and PSV differential value >120 cm/s (sensibility 81.6 %). Transcranial Doppler distinguishes normal and MCA stenosis with a reduced lumen diameter of less than 50 %. Using the PSV criteria, TCD has a high coincidence rate with MRA in the diagnosis of MCA stenosis. Combined PSV differential value and the abnormal spectrum may improve the accuracy of TCD in diagnosing moderate or severe stenosis.     

Postnatal alterations in elastic fiber organization precede resistance artery narrowing in SHR

Resistance artery narrowing and stiffening are key elements in the pathogenesis of essential hypertension, but their origin is not completely understood. In mesenteric resistance arteries (MRA) from spontaneously hypertensive rats (SHR), we have shown that inward remodeling is associated with abnormal elastic fiber organization, leading to smaller fenestrae in the internal elastic lamina. Our current aim is to determine whether this alteration is an early event that precedes vessel narrowing, or if elastic fiber reorganization in SHR arteries occurs because of the remodeling process itself. Using MRA from 10-day-old, 30-day-old, and 6-mo-old SHR and normotensive Wistar Kyoto rats, we investigated the time course of the development of structural and mechanical alterations (pressure myography), elastic fiber organization (confocal microscopy), and amount of elastin (radioimmunoassay for desmosine) and collagen (picrosirius red). SHR MRA had an impairment of fenestrae enlargement during the first month of life. In 30-day-old SHR, smaller fenestrae and more packed elastic fibers in the internal elastic lamina were paralleled by increased wall stiffness. Collagen and elastin levels were unaltered at this age. MRA from 6-mo-old SHR also had smaller fenestrae and a denser network of adventitial elastic fibers, accompanied by increased collagen content and vessel narrowing. At this age, elastase digestion was less effective in SHR MRA, suggesting a lower susceptibility of elastic fibers to enzymatic degradation. These data suggest that abnormal elastic fiber deposition in SHR increases resistance artery stiffness at an early age, which might participate in vessel narrowing later in life.     

Volume navigation with contrast enhanced ultrasound and image fusion for percutaneous interventions: first results

Objective

Assessing the feasibility and efficiency of interventions using ultrasound (US) volume navigation (V Nav) with real time needle tracking and image fusion with contrast enhanced (ce) CT, MRI or US.

Methods

First an in vitro study on a liver phantom with CT data image fusion was performed, involving the puncture of a 10 mm lesion in a depth of 5 cm performed by 15 examiners with US guided freehand technique vs. V Nav for the purpose of time optimization. Then 23 patients underwent ultrasound-navigated biopsies or interventions using V Nav image fusion of live ultrasound with ceCT, ceMRI or CEUS, which were acquired before the intervention. A CEUS data set was acquired in all patients. Image fusion was established for CEUS and CT or CEUS and MRI using anatomical landmarks in the area of the targeted lesion. The definition of a virtual biopsy line with navigational axes targeting the lesion was achieved by the usage of sterile trocar with a magnetic sensor embedded in its distal tip employing a dedicated navigation software for real time needle tracking.

Results

The in vitro study showed significantly less time needed for the simulated interventions in all examiners when V Nav was used (p<0.05). In the study involving patients, in all 10 biopsies of suspect lesions of the liver a histological confirmation was achieved. We also used V Nav for a breast biopsy (intraductal carcinoma), for a biopsy of the abdominal wall (metastasis of ovarial carcinoma) and for radiofrequency ablations (4 ablations). In 8 cases of inflammatory abdominal lesions 9 percutaneous drainages were successfully inserted.

Conclusion

Percutaneous biopsies and drainages, even of small lesions involving complex access pathways, can be accomplished with a high success rate by using 3D real time image fusion together with real time needle tracking.     

A method for stereotactic laser microsurgery in the treatment of deep-seated CNS neoplasms

Intracranial tumors are reconstructed in stereotactic space by means of computerized axial tomographic data. The intracranial tumor is operated on with the patient in the stereotactic frame using a carbon dioxide laser to approach the lesion and vaporize it. Ultimately, a gas-filled cavity results which can be monitored on AP and lateral radiographs. Vaporization continues until the cavity produced is superimposable on the coronal and sagittal CT reconstruction. 2 cases treated by this method are presented.     

Use of navigation bronchoscopy for biopsy and endobronchial fiducial placement

Electromagnetic navigation bronchoscopy (ENB) is a technique that can be used to biopsy pulmonary lesions beyond areas that are traditionally accessible by bronchoscopy. It can also guide biopsies of peribronchial lymph nodes and guide the placement of fiducial markers for stereotactic radiosurgery. With ENB, the patient is placed in a magnetic field and their anatomy is merged with a 3D reconstructed chest cat scan (CCT). A locatable, steerable probe is used to guide a working channel to the target, usually a peripheral tumor. Biopsies can be taken, and markers can be placed. The accuracy of this system depends largely on a small bronchus leading toward to target. The diagnostic yield is similar to CT-guided biopsies, with a false-negative rate of about 30%, although results may be improved with combined ENB and radial endoscopic ultrasound (EUS). The incidence of pneumothorax is 5% to 8% with ENB-directed biopsies compared with approximately 30% with CT-guided transthoracic biopsy.     

Experience using two CT-guided stereotactic biopsy methods

15 patients had intracranial CT-guided stereotactic biopsies. Biopsies were performed either with a Riechert-Mundinger stereotactic frame modified for use in the CT or by using the CT scan to establish the relationship of the intracranial lesion to identifiable bony landmarks, and subsequently performing the biopsy in a standard stereotactic frame. Both systems provided safe and accurate methods for obtaining intracranial tissue.     

Shining light on signaling and metabolic networks by genetically encoded biosensors

Fluorescent labels have revolutionized cell biology. Signaling intermediates and metabolites can be measured in real time with subcellular spatial resolution. Most of these sensors are based on fluorescent proteins, and many report fluorescence resonance energy transfer. Because the biosensors are genetically encoded, a toolbox for addressing cell biological questions at the systems level is now available. Fluorescent biosensors are able to determine the localization of proteins and their dynamics, to reveal the cellular and subcellular localization of the respective interactions and activities, and to provide complementary data on the steady state levels of ions, metabolites, and signaling intermediates with high temporal and spatial resolution. They represent the basis for cell-based high-throughput assays that are necessary for a systems perspective on plant cell function.     

Non-Enhanced MR Imaging of Cerebral Aneurysms: 7 Tesla versus 1.5 Tesla

Purpose

To prospectively evaluate 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) in comparison to 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of unruptured intracranial aneurysms (UIA).

Material and Methods

Sixteen neurosurgical patients (male n = 5, female n = 11) with single or multiple UIA were enrolled in this trial. All patients were accordingly examined at 7 Tesla and 1.5 Tesla MRI utilizing dedicated head coils. The following sequences were obtained: 7 Tesla TOF MRA, 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced MPRAGE. Image analysis was performed by two radiologists with regard to delineation of aneurysm features (dome, neck, parent vessel), presence of artifacts, vessel-tissue-contrast and overall image quality. Interobserver accordance and intermethod comparisons were calculated by kappa coefficient and Lin''s concordance correlation coefficient.

Results

A total of 20 intracranial aneurysms were detected in 16 patients, with two patients showing multiple aneurysms (n = 2, n = 4). Out of 20 intracranial aneurysms, 14 aneurysms were located in the anterior circulation and 6 aneurysms in the posterior circulation. 7 Tesla MPRAGE imaging was superior over 1.5 and 7 Tesla TOF MRA in the assessment of all considered aneurysm and image quality features (e.g. image quality: mean MPRAGE7T: 5.0; mean TOF7T: 4.3; mean TOF1.5T: 4.3). Ratings for 7 Tesla TOF MRA were equal or higher over 1.5 Tesla TOF MRA for all assessed features except for artifact delineation (mean TOF7T: 4.3; mean TOF1.5T 4.4). Interobserver accordance was good to excellent for most ratings.

Conclusion

7 Tesla MPRAGE imaging demonstrated its superiority in the detection and assessment of UIA as well as overall imaging features, offering excellent interobserver accordance and highest scores for all ratings. Hence, it may bear the potential to serve as a high-quality diagnostic tool for pretherapeutic assessment and follow-up of untreated UIA.     

Imaging opportunities for treatment planning in intraoperative electron beam radiotherapy (IOERT): Developments in the context of RADIANCE system

AimThe purpose of this report is to store the information of the pre-planning and compare this data with the actual data of the procedure.BackgroundCurrently, intraoperative electron beam radiotherapy clinical practice lacks a treatment planning system.Materials and methodsThe RADIANCE concept approaches treatment planning by providing the user with a navigation platform based on a three-dimensional imaging system in which the radiation oncologist can target the tumor and risk areas in different sections (axial, coronal, sagittal), while a volume rendering engine displays a 3D image that is automatically updated as we make any changes of the space. Finally, the user may select the parameters of the applicator, energy and dose of treatment to optimize the procedure. Six cases are clinically described and illustrated.ResultsRADIANCE is a useful tool in planning IOERT. Tumor segmentation and risk areas with minimal guide in the selection of parameters for the applicator. Complex locations are challenging, where the experience and skill of the radiation oncologist is necessary to optimize the process. New developments include imaging innovated uses. Intraoperative imaging will approach reality and allow real time, dosimetry estimations, stereotactic recognition of patient and tumor bed position, will guide automatization of radiation beam recognition and pre-robotic arrangements with linear accelerator movements.ConclusionsRADIANCE offers a new imaging expansion for IOERT, in the context of a multidisciplinary approach to optimize and define the treatment parameters to approximate the actual treatment radiotherapy procedure.