The appearance of analytical stereoplotters with large possibili-
ties of application software further development should allow to combine
easiness of use and great accuracy in measurements, both conditions being
necessary to provide a good knowledge of intracranial vasculature.
B) COMPLEMENTARITY OF THE 3 SOURCES OF INFORMATION
It has been widely pointed out in literature ; but it is necessa-
ry to develop a coherent system to analyse these data : a referential devi-
ce should lead to this coherence.
A multitude of systems have been described [ 1,2,3,4,7] .
Whatever the method, the purpose is always the same one : it is
the transfer of topographic co-ordinates x,y,z from scanner to the stereo-
tactic system, as accurately as possible.
Once you have got over this problem of coherence between the dif-
ferent sources of information available (Scanner, Stereotaxis, Stereosco-
Py), the interchanging of these information has to be studied.
It can be carried out by dedicated software on the computer of
the stereoplotter L5] - This software allows to plot and check correspon-
ding points on C.T. slices and radiograms. Thus with this methodology, each
point of the cerebral space can be replaced into its C.T. Scanner, stereo-
tactic and stereoscopic contexts. (fig.6).
II - COHERENCE OF THE 3-D INFORMATION ANALYSIS SYSTEM - REFERENTIAL DEVICE
Thanks to the device that we have constructed* we may deter-
mine the C.T. Scanner cross-sectional plane in relation to the stereotactic
frame, taken as a reference (fig. 3-4).
We can distinguish two parts :
Fig.3 (left) : Referential device
and fixation system.
Fig.4 (right) : Referential device
on the patient's head in the ste-
reotactic frame.
* A. QUEQUINER INSA RENNES
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