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were several frames later than the projections used to construct the set of gram-
matical rules, and these later frames were used for the analysis. Due to the differ-
ent types of topologies of coronary vascularisation, the set of analyzed images was
as follows:
Table 2
Number of images with particular coronary arteries topologies
Balanced artery
distribution
Right artery
dominant
Left artery
dominant
9
6
5
Structure of the coronary vascularisation was determined by a diagnostician at
the stage of acquisition of image data. This distinction was intended to obtain ad-
ditional information about the importance of providing health risks of the patient
depending on the place where pathology occurs and the type of coronary vascu-
larisation (e.g. stenosis occurring in the left coronary artery will constitute a
greater threat to the health of patients having a left artery dominant structure in
comparison to the patients having a right artery dominant structure). The above set
of image data was used to determine the percentage efficiency of correct recogni-
tions of the stenoses present, using the methodology proposed here. The recogni-
tion consists in identifying the locations of stenoses, their number, extent and type
(concentric or eccentric). For the research data included in the experiment, 85% of
recognitions were correct. This value is the percentage proportion of the number
of images in which the occurring stenoses were correctly located, measured and
properly interpreted to the number of all analysed images included in the experi-
mental data set. No indication of major differences in the effectiveness evaluation,
depending on the structure of the coronary vascularisation are noticed. The follow-
ing figure 12 shows the image of CT coronary vascularisation, together with a re-
cord describing the pathological changes occurring in the right and left coronary
arteries.
In order to assess whether the size of the stenosis was correctly measured, we
used comparative values from the syngo Vessel View software forming part of the
HeartView CI suite [4]. This programme is used in everyday clinical practice
where examinations are made with the SOMATOM Sensation Cardiac 64 tomo-
graph [4]. In order to confirm or reject the regularity of the stenosis type determi-
nation (concentric or eccentric) shown in the examined image, we decided to use a
visual assessment, because the aforementioned programs did not have this func-
tionality implemented. As the set of test data was small - a dozen or so elements -
the results obtained are very promising, and this effectiveness is due, among other
things, to the strong generalising properties of the algorithms applied. Further re-
search on improving the presented analysis techniques of lesions occurring in the
morphology of coronary vessels might bring about a further improvement in the
effectiveness and the future standardisation of these methods, obviously after they
have first been tested on a much more numerous image data set.
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