Comparison between 3D TOF magnetic resonance angiography and intra-arterial digital subtraction angiography in imaging the circle of willis
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Date
2002
Authors
Mohd Ghazali, Rozita
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The purpose of this study is to compare the accuracy of 3D time of flight magnetic
resonance angiography (3D TOF MRA) with intraarterial digital subtraction angiography
(IADSA) in depicting the arterial segments of the circle of Willis.
38 patients who had underwent both 3D TOF MRA
and IADSA examinations in Hospital Universiti Sains Malaysia from November 1998 to
December 2000 were included in this study giving a total of 398 arterial segments
compared and analysed. Two observers performed blinded retrospective analysis of the
IADSA images and MIP display of the 3D TOF MRA of the circle of Willis on separate
sessions. The AI, A2, Ml and PI segments were depicted as normal calibre, small or
absent while the ACOM and PCOM segments were depicted as functional, patent or not visualised.
The 3D TOF MRA was good in depiction of the Al, A2, Ml, Pl and
ACOM segments of the circle of Willis with a sensitivity of 100%, 94.5%, 100%, 96.8%
and 100% respectively. There were no false positive results for the Al, A2, Ml and PI
segments with a positive predictive values of 100%. However, the positive predictive
value for the ACOM segment was 89.5% (2 false positive results out of 19 segments).
The specificity was excellent for the AI, A2 and PI segments at IOO% and acceptable for
the ACOM segment at 90.5%. There were no false negative results for the AI and
ACOM segments. However, the negative predictive value for the A2 and PI segments
were low at 25% (3 out of 4 false negative results) and 60% (2 out of 5 false negative
results) respectively. The 3D TOF MRA method was however a poor method for
depiction of the PCOM segments with a sensitivity of 21.4%. The negative predictive
value was very low at 5.2% with 53 out of 58 false negative results.
Observer agreement between IADSA and 3D TOF MRA range from kappa "perfect" to
''slight" but inter-observer agreement for the 3D TOF MRA technique was excellent with
the kappa values within the "perfect" range.
MIP display of the 3D TOF MRA is sensitive for depicting the
anatomy of the circle of Willis except for the PCOM segment. It is thus a reliable method
for screening of this arterial circle.
Description
Keywords
3D TOF magnetic resonance angiography (MRA)