Evaluation des diagnostischen Stellenwertes der kontrastmittelverstärkten dynamischen MR-Angiographie des Unterschenkels
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Philipps-Universität Marburg
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Abstract
The peripheral arterial occlusive disease (PAOD) belongs to the spectrum of
cardiovascular disorders, which is the most common reason of death in Germany. The
prevalence of PAOD rises significantly with increasing age. About 20 % of men older
than 65 years are affected.
Therefore an early and correct diagnosis is vital for therapy and further outcome of the
patient. Diagnostic methods are assessing medical history, physical examination,
especially the evaluation of the ABI, and advanced medical imaging.
Until today conventional digital subtraction angiography (DSA) is considered to be the
gold standard among the imaging diagnostic methods. Because of different risks
(radiation exposure, contrast media reactions, nephrotoxicity) and the complications
associated with invasive methods (bleeding, infection) an alternative imaging
technique is desired. Because of the technological progress 3D CE-MRA has shown to
be one of the most promising choices.
Aim of the study was to compare time-resolved 4D CE-MRA-sequences (TWIST) with
high spatial resolution 3D CE-MRA-sequences (MIP) to the gold standard DSA by
detecting clinical relevant stenosis in the calf. The evaluated vessel segments were the
tibiofibular trunk, the anterior and posterior tibial artery and the fibular artery.
Sensitivity and specificity were evaluated. Also, the reader agreement and the
agreement between the two sequences (MIP, TWIST) of the corresponding reader has
been evaluated. Furthermore image quality was recorded and evaluated.
In this study, 100 cases from a 17 months time period were taken into account. The
gender ratio was 60 % men and 40 % women, while the average age was 72.2 years.
Evaluating the degree of stenosis by DSA, about 65 % of the cases showed clinical
relevant stenosis, which means a stenosis of more than 51 %. 30 % of the cases did
not show any stenosis in DSA and about 5 % showed no clinical relevant stenosis
(stenosis less than 50 %).
Concerning the evaluation of image quality it became apparent that image quality of
MIP has been lower than the ones of DSA and TWIST.
Analysing the statistics, it became apparent that high spatial resolution MIP-sequences
showed inferior results than time-resolved TWIST sequences. The average sensitivity
of MIP was 62.5 % and the average specificity was 48 %. In comparison, the average
sensitivity of TWIST was 82 % and the average specificity was 59.5 %.
The investigator comparison it became noticeable that the less experienced
investigator surveyed a lower quality of MIP results.
To verify the impact of image quality on statistical results, the data was overhauled.
Only cases with very good and good image quality were included and were reevaluated.
This led to overall better indices, increasing the average sensitivity of MIP
to 84.5 % and of TWIST to 91 %. The average specificity of MIP and TWIST increased
to 71.5 %.
The reader agreement for MIP sequences was moderate (ĸ = 0.49) while it was
substantial (ĸ = 0.65) for TWIST sequences. After overhauling the data reader
agreement improved also. For MIP it became substantial (ĸ = 0.78) and for TWIST it
was almost perfect (ĸ = 0.81).
Investigator-independent method can be assumed because of the improved reader
agreement. This was noticeable at both MRA sequences, whereat time-resolved
TWIST showed a higher investigator independence than high spatial resolution MIP.
The sequence agreement showed a significant better evaluation (p < 0.05) for clinical
relevant diseased cases in DSA for TWIST sequences compared to MIP sequences.
There was no significant difference in evaluation for healthy cases in DSA for MIP and
TWIST.
After overhauling the data there was no difference in evaluation for both healthy and
diseased cases in DSA for MIP and TWIST.
In conclusion the already used 3D CE-MRA is a potential alternative for DSA for
diagnostics and therapy planning. Especially the additional acquisition of time-resolved
TWIST sequences yields useful image material. If images of good quality are available
MIP reconstructions are sufficient for evaluation.
Because of the mixed image quality, in clinical routine a two step approach is
suggested. First, a 3D CE-MRA of the complete lower extremity should be performed.
This should be followed by an immediate analysis of image quality of the calf region. If
image quality is considered suboptimal, an additional time-resolved TWIST sequence
has to be acquired.
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Dates
Created: 2012Issued: 2012-10-05Updated: 2012-10-09
Faculty
Medizin
Publisher
Philipps-Universität Marburg
Language
ger
Data types
DoctoralThesis
Keywords
Dynamische MR-AngiographieTWISTFLASHDynamic-MR-Angiography, FLASHTWIST
DFG-subjects
UnterschenkelDigitale SubtraktionsangiographieMagnetresonanzangiographiePeriphere arterielle Verschlusskrankheit
DDC-Numbers
610
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Clefisch, Susanne: Evaluation des diagnostischen Stellenwertes der kontrastmittelverstärkten dynamischen MR-Angiographie des Unterschenkels. : Philipps-Universität Marburg 2012-10-05. DOI: https://doi.org/10.17192/z2012.0546.
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This item has been published with the following license: In Copyright