This paper presents the preliminary results of applying multi image photogrammetric techniques for the three-dimensional monitoring of the intraoperative brainshift. The "brainshift" is the motion of cerebral structures occurring in neurosurgery after the craniotomy (opening of the skull in order to access the brain for surgical repair). The causes of this effect are mainly the changes of pressure and loss of cerebrospinal liquid. The phenomenon of brainshift can influence negatively the planning and execution of neurosurgical intervention. A research project at the Clinic of Neuroradiology and Neurosurgery of the Medical University of Innsbruck (Austria) aims at the quantification of the intraoperative brainshift by means of photogrammetry. The goals of the project are: (i) the development of a multi-image photogrammetric system for the quantitative monitoring of intraoperative brainshift by means of 3D measurements performed on the surface of the brain during neurosurgery after craniotomy, (ii) transformation of the pre-operative performed MR and CT datasets in function of the quantified intra-operative brainshift. This paper presents the proposed multi-image photogrammetric system, as well as, the first results achieved, in collaboration with Hometrica Consulting, for the automatic 3D measurement and tracking of selected points on the surface of the brain.
Content of this study is the verification whether the direct cortical stimulation agrees with the results of fMRI
and to determine of what size the deviations are. It is primary to say that neuron populations, which lead to
an involuntary movement with the anesthetized and awake patient over synapses, are excited during an
electric direct cortical stimulation. With fMRI (similarly like in positron emission tomography), the circulation
alteration after an activation of brain areas by arbitrary, active movement or spontaneous cerebral activation
by sensory stimulation is represented in sectional images. With intraoperative electrophysiology individual
muscles or muscle groups can be activated directly. The exact correlation of these two methods has the goal
to replace ICS in future by preoperative fMRI. Numerous authors pointed out that fMRI can play an important
part in preoperative functional mapping . Indeed these studies don't comprise any direct comparison with
intraoperative cortical stimulation, the gold standard of intraoperative functional localisation.
Aim of this study therefore was the development of a three-dimensional registration system for the transfer of
preoperative functional MR-data on intraoperative electro-physiological stimulation points with high precision
and to install in the neuro-surgical operating room. The preoperative neuro-functional diagnostics should be
integrated directly in the neuro-surgical operation planning and the correlation of the functional localisation
should be examined.
This study investigates the instationary flow field in human femoarl arteries. The flow fiel is measured before and after the implantaion of five different metal stent implants in elastic and scaled silicone models of femoral arteries. The pulsating flow field is investigated under physiological conditions within the silicone vessel. For the simulation of the physilogical hemodynamics a computer controlled pump for the reproducible generation of flow patterns and a fluid with flow properties similar to human blood is used. At significant positions distal, proximal and inside the stent dopplersonographic measurements are performed with stationary and pulsatile flow. Via fast fourier analysis the sampled doppler audio signal, gained from the ultrasound stereo output, is converted into velocity profiles and displayed as color coded 3D spectrograms. By subtracting the spectra of the unstented model of the stented models differential spectra are obtained and compared. These differential spectra are used for a semiquantitative analysis of the flow field change caused by stents and are easy to interpret for the examining physician.