Biomedical subjects

H Schiffbauer

Publications and source records attributed to H Schiffbauer.

5 recordsLinked to original sources

PubMed2003

Anatomy of the cerebral ventricular system for endoscopic neurosurgery: a magnetic resonance study.

BACKGROUND: Endoscopy has developed into an integral part of minimally invasive neurosurgery. For further technological innovations, detailed knowledge about the pathological anatomy is essential. The gross anatomy of the cerebral ventricular system has been meticulously investigated with ventriculography and casts. Extensive volumetric measurements based on neuroradiological images have been performed, but only little is known about the surgically relevant linear distances in patients with hydrocephalus. METHOD: Thirty healthy volunteers and thirty patients suffering from hydrocephalus were scanned with high-resolution 3-D magnetic resonance imaging sequences. The image volumes were sliced identically with the help of Siemens Prominence software. Individual anatomical measurements of the ventricular system were carried out, mean values and standard deviations were calculated, and different endoscopic approaches were investigated. FINDINGS: In healthy volunteers the measurements confirmed the results obtained from ventriculography and anatomic casts. In hydrocephalic patients the ventricular system was found to be enlarged asymmetrically. The optimal neuroendoscopic approach showed considerable, interindividual variation. INTERPRETATION: This 3-D magnetic resonance imaging study revealed surgically and clinically relevant aspects of the pathologic anatomy of hydrocephalic patients, in comparison to healthy volunteers. Individualized planning of the endoscopic approach appears to be warranted. Finally, the data provided a sound basis for the further development of neuroendoscopes.

Adult↗

PubMed2002

Versatile intraoperative MRI in neurosurgery and radiology.

BACKGROUND: Several models for the application of intra-operative magnetic resonance imaging (IMRI) have recently been reported, most of them unique. Two fundamental issues need to be addressed: optimal use of the scanner to ensure a wide base for research, development and clinical application, and an organisational model that facilitates such use. METHOD: While in our setting the IMRI project was initiated by the neurosurgeons, the need for wider use of the facilities was recognised since the beginning of the planning phase in 1996. An organisational model was developed that allowed for development of neurosurgical applications, radiological imaging, and radiological interventions and for the research and development work of the vendor. A resistive 0.23 T MR scanner was installed in a dedicated operating room environment. Unique to this scanner is the ability to turn off the magnet, allowing for normal OR activities and devices, and to turn on the magnet as needed with a relatively short six-minute ramp up time. A staged surgical technique was perfected, allowing for transfer of data to the neuronavigator outside the scanner during surgery. In neurosurgery, IMRI was used as one part of a neuronavigational system that included ultrasound imaging, intra-operative cortical stimulation during awake procedures, electrocorticography and two neuronavigators. FINDINGS: 34 neurosurgical cases included 27 brain tumour resections, 5 brain tumour biopsies, 1 extirpation of an arterio-venous malformation, and 1 haematoma evacuation. The scanner could also be used for normal clinical imaging where obese patients, children, claustophobic patients and postoperative control examinations were the major groups. The radiologists performed 110 interventions, including bone and abdominal biopsies, nerve root infiltrations and local pain therapies, with the optical needle tracking system under continuous MRI guidance. The organisational model allowed frequent use of the facilities for both neurosurgery and radiology and continuous development of the facilities. Intra-operative ultrasound was used in 20 tumour resections and in two open brain biopsies. This resulted in reduction of the number of MR imaging sessions during surgery. Five of the 27 resections were performed as awake craniotomies with cortical stimulation. For two of the resections, electrocorticography and depth electrode registrations were used. Furthermore, various non-MRI-compatible instruments and devices were used. INTERPRETATION: Intra-operative MRI is an imaging tool that can be useful especially in the context of neuronavigation. A scanner that can be turned off during surgery is particularly appropriate for neurosurgery. The concept of joint use of such facilities with other clinicians is mutually worthwhile.

Adult↗

PubMed2002

Relevance of image fusion for target point determination in functional neurosurgery.

BACKGROUND: For the treatment of medically refractory movement disorders such as Parkinson's disease, essential tremor and primary dystonia, deep brain stimulation (DBS) has become one of the main treatment options. The targets for implantation of the stimulation electrodes are various nuclei within the basal ganglia or the thalamic and subthalamic area. Accurate target localisation is of major importance for outcome and patient safety. The goal of this study was to evaluate the role of image fusion in the determination of target co-ordinates. METHOD: We conducted a retrospective study on 10 patients in whom 17 DBS electrodes had been implanted. Coordinates of the anterior and posterior commissures and of the DBS targets were compared on pre- and postoperative computerised tomography (CT) and fused CT/magnetic resonance scans. The targets as defined on the images were further compared with the targets derived intra-operatively with microelectrode recordings (MER) and macrostimulation. FINDINGS: The achievable mean target accuracy was of the order of the diameter of the DBS electrode and of the accuracy of the image fusion algorithm, i.e. about 1 mm. However, the maximal differences were between 1.8 mm and 3.2 mm. INTERPRETATION: Image fusion is a helpful tool for accurate determination of target point co-ordinates in DBS. In combination with intraoperative, electrophysiological recordings and stimulation which are still considered to be the most reliable localisation methods, image fusion may help to discern the anatomical and functional three-dimensionality of the target nuclei. Image fusion may reduce the number of trajectories needed for intraoperative electrophysiological determination of the optimal electrode localisation and thus lower the risk of complications.

Aged↗

PubMed2001

Registration in interventional procedures with optical navigator.

Performing interventional procedures in the close proximity to an MR scanner widens the range of operations available for an optical tracking system. In order to gain the full benefits from both unrestricted use of surgical instruments outside the magnet and intraoperative imaging, a method for transferring the registration data of the optical navigator between two locations is required. An optical tracking system, which provides such a transfer method and tracks patient position during a surgical procedure, has been developed, tested, and demonstrated with two patient cases. J. Magn. Reson. Imaging 2001;13:93-98.

Adult↗

PubMed2001

Functional activity within brain tumors: a magnetic source imaging study.

OBJECTIVE: To determine whether low-grade gliomas contain functional cortical activity more often than high-grade gliomas within radiologically defined abnormal tissue. METHODS: Patients with intra-axial cerebral lesions located in the vicinity of eloquent brain cortex preoperatively underwent magnetic source imaging. A dual 37-channel biomagnetometer was used to perform the imaging. Evoked magnetic fields were analyzed using the single-equivalent dipole representation to ascertain the neuronal source. Stimuli included painless tactile somatosensory stimulation of fingers, toes, and lips and auditory presentation of pure sinusoidal tones. RESULTS: A retrospective analysis of 106 nonconsecutively treated patients, who had undergone preoperative magnetic source imaging between February 1996 and December 1999, revealed that 24.5% of the patients had been at risk for neurological deficits, because functionally active tissue was located within or at the border of the tumor. Functional activity was found within the radiologically defined lesion in 18% of Grade 2 tumors, in 17% of Grade 3 tumors, and in 8% of Grade 4 tumors. CONCLUSION: The results confirm that, regardless of tumor grade, intra-axial brain tumors may involve or directly border on functional cortex. The degree of involvement of functionally viable cortex appeared greater for low-grade tumors than for high-grade lesions. On the other hand, high-grade lesions were more likely to be associated with functional cortex at their margins or within peritumoral edema. To safely maximize tumor resection, preoperative functional imaging and intraoperative electrophysiological mapping of the cerebral cortex and the white matter tracts are deemed necessary.

Brain Mapping↗