A new stereotactic instrument for use with computerized tomography and magnetic resonance imaging

The new stereotactic instrument has the advantages of use with computerized tomography (CT) or magnetic resonance imaging (MRI) without special adaptations of instruments, brain targets transferred directly from CT or MRI to apparatus, and use with conventional stereotactic techniques. The apparatus is designed to meet present demands of neurosurgical facilities of good standards and capabilities, encompassing present and future developments towards more efficient and less invasive brain operations.     

X-ray and magnetic resonance stereotaxy for functional and nonfunctional neurosurgery

By means of new plastic stereotactic ring and head fixers, stereotactic procedures can be combined with MRI, with stereotactic coordinates obtained from the MRI images. The method was rechecked against CT stereotaxy and shows a good correspondence of the target coordinates. With MRI stereotaxy, structures near bony regions will be more accessible than with CT stereotaxy. Moreover, the MRI procedure seems to have advantages for functional therapy without the necessity of contrast ventriculography.     

Stereotactic neurosurgery and computerized tomographic scanning

The marriage of computerized tomographic (CT) scanning and stereotactic surgery opens up new technical possibilities, as it becomes feasible to introduce a probe into any lesion which is identified on a CT scan. The various CT stereotactic techniques are reviewed, and generally involve four variations. The head holder of a standard stereotactic apparatus can be adapted to the CT scanner to interdigitate the coordinates of both devices in a known relationship. Second, some types of CT scanners allow the visualization of the vertical coordinate. Third, a stereotactic microdrive can be incorporated into the scanner. Finally, a simple aiming device can be attached to the patient's head and repeated scans taken as the probe is advanced to the target. Various authors have reported the use of techniques for biopsy, aspiration of cysts or hematomas, insertion of radioisotopes, or as an adjunct to open surgery.     

Diagnosis and treatment of brainstem mass lesions by CT-guided stereotactic surgery

Current neuroradiographic techniques including computed tomographic scanning (CT) and magnetic resonance imaging (MRI) when added to the clinical neurologic examination can localize precisely even small lesions within the brainstem. While the clinical-radiographic diagnosis is accurate with respect to locale, it is often in error with respect to the pathologic nature of the solitary brainstem lesion. Therefore, empiric treatment without the benefit of a tissue diagnosis will often be inappropriate. CT-guided stereotactic surgery can safely and reliably provide a tissue diagnosis in such cases. Furthermore, in selected cases, therapeutic interventions can be of substantial and lasting benefit to the patient.     

Brown-Roberts-Wells stereotactic frame modifications to accomplish magnetic resonance imaging guidance in three planes

The Brown-Roberts-Wells (BRW) computer tomography (CT) stereotactic guidance system has been modified to accommodate magnetic resonance imaging (MRI). A smaller head ring, which fits in standard MRI head coils, is constructed of a non-ferromagnetic aluminum ring that is split to prevent eddy currents and anodized to prevent MRI image distortion and resolution degradation. A new localizing device has been designed in a box configuration, which allows BRW stereotactic coordinates to be calculated from coronal and sagittal MRI images, in addition to axial images. The system was tested utilizing a phantom and T1- and T2-weighted images. Using 5-mm MRI scan slices, targets were localized accurately to a 5-mm cube in three combined planes. Optimized calibration of both low field strength (0.3 T) and high field strength (1.5 T) MRI systems is necessary to obtain thin slice (5 mm) images with acceptable image resolution. To date, 10 patients have had MRI stereotactic localization of brain lesions that were better defined by MRI than CT.     

Animal research stereotactic instrument modified for computed tomographic guidance

While target localization for human stereotactic surgery has been refined by computed tomographic (CT) and magnetic resonance imaging (MRI), stereotaxis in experimental animals has remained dependent upon external cranial landmarks and standardized atlas coordinates. To overcome the limitations and inaccuracies of animal devices using the original Horsley-Clarke method, we modified a standard animal stereotactic instrument in order to make target localization and coordinate determination possible with CT imaging. Although the device can be adapted to any medium-sized animal species, we demonstrate its use with dogs here.     

Transposition of target information from the magnetic resonance and computed tomography scan images to conventional X-ray stereotactic space

A technique to apply reconstructed X-ray computed tomography (CT) and magnetic resonance imaging (MRI) for target determination in stereotactic Bragg peak proton beam therapy of intracranial lesions was developed. Twenty-one benign intracranial tumors and vascular abnormalities were managed using this technique. Clinical features of these lesions, as well as targeting problems associated with the MRI and CT image interpretation, are presented.     

CT引导下立体定向射频热凝三叉神经半月节对原发性三叉神经痛的疗效分析

目的：分析CT引导下立体定向射频热凝三叉神经半月节对原发性三叉神经痛的疗效,探讨其临床适用性。方法：选择从2011年5月至2012年12月于我院住院治疗原发性三叉神经痛的58例患者,在三维CT引导下采用通过BrainLAB手术计划系统经前入路卵圆孔穿刺三叉神经半月神经节,术中根据疼痛分布范围射频热凝三叉神经半月节。观察并比较治疗前后的VAS评分,临床疗效,术中和术后不良反应情况。结果：58例患者的穿刺手术均成功,术后1d、3d、6d的VAS评分均较治疗前显著降低（P〈0．01）;1周后58例患者中,有53例患者疼痛完全消失,l例患者偶然出现疼痛,但无需服用药物处理,共显效54例;4例患者疼痛有所减轻或疼痛发作频率降低,但仍需服用药物,或服用药物剂量较治疗前明显减少;疼痛无改善或者非用药不能缓解的持续痛仅1例。总有效例数为57例,总有效率达98．26％。术中发生不良反应6例,在术后均有所缓解。术后发生各种并发症共15例,均未明显影响手术效果。结论：CT引导可以较为准确的进入穿刺部位,使立体定向射频热凝三叉神经半月节手术更加顺利,达到治疗原发性三叉神经痛的理想效果,适合临床长期推广应用。     

MRI contribution to the stereotactic management of cerebral tumours

Of 67 patients with cerebral tumours studied by MRI, 60 underwent stereotactic biopsy for histological diagnosis. The data from MRI were compared with those obtained from the CT scan with regard to the pathological diagnosis. The tumoural nature and extent of a lesion were better revealed by MRI. The single or multiple localization of the process was also seen better by MRI. Moreover, the sagittal-plane views shown by MRI provide much more accurate target placement and probe guiding for an orthogonal stereotactic approach. Finally, a post-biopsy MRI can show the biopsy site in relation to the tumour better.     

Stereotactic interstitial brachytherapy--current concepts and concerns in twenty patients

Recent advances in imaging and stereotactic techniques have resulted in wider application of interstitial brachytherapy (IBT) for brain tumors. The advantages of brachytherapy alone or in combination with teletherapy have been detailed, and may be responsible for increasing survival time. We report the preliminary results of 20 patients who underwent CT stereotactic IBT for malignant brain tumors. Despite both old and recent evidence about the efficacy of IBT, concerns remain about the proper grade neoplasm, the target, the dose, and the timing for treatment. Current usage of IBT should be limited to centers with both stereotactic and radiotherapeutic expertise, and where the risks and benefits are being investigated.     

Non-invasive methods for the determination of body and carcass composition in livestock: dual-energy X-ray absorptiometry,computed tomography,magnetic resonance imaging and ultrasound: invited review

The ability to accurately measure body or carcass composition is important for performance testing, grading and finally selection or payment of meat-producing animals. Advances especially in non-invasive techniques are mainly based on the development of electronic and computer-driven methods in order to provide objective phenotypic data. The preference for a specific technique depends on the target animal species or carcass, combined with technical and practical aspects such as accuracy, reliability, cost, portability, speed, ease of use, safety and for in vivo measurements the need for fixation or sedation. The techniques rely on specific device-driven signals, which interact with tissues in the body or carcass at the atomic or molecular level, resulting in secondary or attenuated signals detected by the instruments and analyzed quantitatively. The electromagnetic signal produced by the instrument may originate from mechanical energy such as sound waves (ultrasound – US), ‘photon’ radiation (X-ray-computed tomography – CT, dual-energy X-ray absorptiometry – DXA) or radio frequency waves (magnetic resonance imaging – MRI). The signals detected by the corresponding instruments are processed to measure, for example, tissue depths, areas, volumes or distributions of fat, muscle (water, protein) and partly bone or bone mineral. Among the above techniques, CT is the most accurate one followed by MRI and DXA, whereas US can be used for all sizes of farm animal species even under field conditions. CT, MRI and US can provide volume data, whereas only DXA delivers immediate whole-body composition results without (2D) image manipulation. A combination of simple US and more expensive CT, MRI or DXA might be applied for farm animal selection programs in a stepwise approach.     

Computed tomography and magnetic resonance imaging in the diagnosis of accessory nasal sinuses, upper jaw and nasal cavity tumors

Radiation studies, including computed tomography (CT) and magnetic resonance imaging (MRI), revealed that these techniques can accurately determine the site of a tumor, the borders of its spread to the adjacent anatomic structures. They also revealed the features of CT in detecting osseous structural destruction and the advantage of MRI in visualizing the soft tissue component of a neoplasm and in distinguishing the degree of contrast of tumor tissue and concurrent secondary inflammation. The accuracy of CT and MRI for small tumors is 45-80 and 29% higher than that of X-ray study and traditional tomography, respectively. The potentialities of all radiation diagnostic techniques for over 3.0-cm tumors are equal.     

脑发育性静脉畸形9例临床影像特征分析及文献复习

目的:研究脑发育性静脉畸形(Cerebral Developmental Venous Anomalies,CDVA)临床及影像学特征及复习CDVA文献。方法:回顾性收集了自2011年11月至2014年3月我科确诊的9例CDVA的病人,对其临床特征、影像学检查方法包括电子计算机断层扫描(Computed Tomography,CT)、核磁共振成像(Magnetic Resonance Imaging,MRI)、数字减影血管造影(Digital Subtraction Angiography,DSA)及特征进行分析并对相关文献进行复习。结果:(1)临床症状:9例病人的临床症状包括头晕4例(4/9)、头痛4例(4/9)、恶心不适2例(2/9)、站立不稳1例((1/9)、小脑出血史1例(1/9)、眼部症状行眼科检查偶然发现小脑CDVA1例(1/9);(2)病变部位:病变位于幕上4例(4/9);幕下5例(5/9);(3)影像学检查:9例病人中,6例行CT平扫或增强扫描(3例平扫,3例平扫+增强);4例行MRI(1例平扫,3例平扫+增强);3例行DSA检查;(4)影像学特点:CT增强及重建、MRI的T1WI增强、SWI、MRA及DSA静脉期像均可显示出髓静脉及其形成的特征性"海蛇头"征象和其引流静脉。结论:CT、MRI、DSA影像学方法均可用于CDVA的诊断,在临床实践中需根据需要优化选择联合应用。     

Computer tomography-controlled stereotactic surgery

In computed tomography (CT)-controlled stereotactic surgery, the coordinate system of the CT scanner is applied to determine the target depth and direction as well as for readjustment of final probe direction. This method can be used for all types of stereotactic surgery for the brain.     

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.     

Combined use of digital subtraction angiography and MRI for radiosurgery and stereoencephalography

The authors report their experience with the combined use of digital subtraction angiography (DSA) and magnetic resonance imaging (MRI) for the stereotactic placement of intracerebral electrodes in epilepsy and for the radiosurgical treatment of otherwise inoperable arteriovenous malformations of the brain. Both imaging techniques, when used in conjunction, have been found most useful and complementary. For deep electrode placement, they permit optimal visualization of the cerebral structures to be reached by the electrode array while allowing the avoidance of vessels in the vicinity. For radiosurgery of arteriovenous malformations, DSA provides optimal visualization of the feeders and of the malformation itself, while the MRI reveals the cerebral structures to be spared by the photon beam of the linear accelerator. A discussion of their respective roles is presented, with the specific question as to whether MRI alone could be used for both procedures.     

Thalamic abscess: a stereotactically treatable lesion

A 69-year-old man developed abdominal pain, fever, shaking chills and acute hemiplegia. Computed tomography (CT) scanning demonstrated a hematoma within a thalamic space-occupying lesion having the radiological characteristics of a malignant glioma. Low-grade fever and leukocytosis persisted and follow-up CT scanning showed ring enhancement of the thalamic lesion and ependymitis suggesting a cerebral abscess. Stereotactic aspiration achieved drainage of the abscess and relief of mass effect and provided pus from which a causative organism was identified and treated with appropriate antibiotics. Contrast-enhanced CT scan should be obtained in cases of hemorrhage within mass lesions and tissue diagnosis should be achieved even in deep brain regions, as this can be accomplished safely using stereotactic techniques.     

Multiple sclerosis: the disease and its manifestations

Multiple sclerosis is an immune-mediated inflammatory demyelinating disease of the central nervous system clinically characterized by relapses and remissions of neurological disturbance. A typical relapse, exemplified by optic neuritis, increases in severity over a week or two and after approximately one month begins to remit. Resolution takes place over the course of two to three months. In the early stages, clinical recovery is virtually complete, though persistent abnormalities of conduction can usually be detected by evoked potential techniques and persistent structural abnormalities can be detected by magnetic resonance imaging (MRI). These techniques, together with cerebrospinal fluid examination for oligoclonal IgG, provide supporting evidence for the diagnosis which, in the absence of a specific test, nevertheless remains primarily clinical. The course of the disease is very variable, but after a number of years neurological deficit begins to accumulate after each relapse. In most patients, the relapsing and remitting phase of the disease is followed by a phase of continuous progression of disability. Cognitive disturbances can be detected in many patients even quite early in the course of the illness. Deficits in attention, memory and executive skills may be prominent and tend to become increasingly prominent as neurological deficit increases, although this is not always the case. There is some correlation between the extent of MRI abnormalities in the cerebral white matter and the severity of cognitive deficit. Depression and anxiety are commonly experienced but are poorly correlated to the lesion load seen on MRI. In contrast, the much rarer psychotic symptoms, euphoria and emotional lability are closely linked to the severity of white matter disease.     

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.     

Computed tomography and magnetic resonance imaging studies of Latimeria chalumnae

Synopsis Recent radiologic imaging techniques (CT[Computed Tomography] and MRI[Magnetic Resonance Imaging]) were used to investigate the cranial anatomy of the coelacanth Latimeria chalumnae. The non-invasive CT and MRI techniques were performed successfully on a 1.45 m female specimen. This specimen had been frozen a year earlier for future research; the CT was conducted on the frozen animal, whereas the MRI method was performed immediately after thawing. The CT technique provides information about differential density of the organism (especially informative with respect to hard tissues, bone and cartilage), whereas three different types of MRI (proton resonance T₁, T₂ and flash) distinguish cartilage, muscles, and different connective tissues. A total of 381 CT cross sections (2 mm thick with 1 mm of overlap) through the head region were used in a computerized three-dimensional reconstruction program to address questions concerning cranial morphology. The results obtained from these radiologic imaging techniques confirmed most of the basic anatomy known from traditional dissections. However, the morphology of complex structures. such as the cartilaginous processes of the neurocranium, and the integration of the branchial arches and palate can only now be described more accurately.