Improved Carotid Stenosis Quantification on Novel 4D/3D-Doppler Ultrasonography Indexing to the Common Carotid Artery

Abstract

Purpose The accuracy of internal carotid artery stenosis (ICAS) quantification depends on the method of stenosis measurement, impacting therapeutic decisions and outcomes. The NASCET method references the stenotic to the distal ICAS lumen, the ECST method to the local outer and the common carotid artery (CC) method to the CC diameter. Direct morphometric stenosis measurement with four-dimensionally guided three-dimensional ultrasonography (4D/3DC-US) demonstrated good validity for the commonly used NASCET method. The NASCET definition has clinically relevant drawbacks. Our purpose was to investigate the validity of the ECST and CC methods.

Materials and Methods 4D/3DC-US percent-stenosis measures of 103 stenoses (80 patients) were compared to quantitative catheter angiography and duplex ultrasonography (DUS) in a blinded fashion.

Results The 4D/3DC-US versus angiography intermethod standard deviation of differences (SDD, n = 103) was lower for the CC method (5.7 %) compared to the NASCET (8.1 %, p < 0.001) and ECST methods (9.1 %, p < 0.001). Additionally, it was lower than the NASCET angiography interrater SDD of 52 stenoses (SDD 7.2 %, p = 0.047) and non-inferior for the ECST method (p = 0.065). Interobserver analysis of equivalent grading methods showed no differences for the SDDs between angiography and 4D/3DC-US observers (p > 0.076). Binary comparison to angiography showed equal Kappa values > 0.7 and an accuracy ≥ 85 % for the NASCET and CC methods, higher than for the ECST method. The binary accuracy of ICAS grading did not differ from DUS for all methods.

Conclusion The new 4D/3DC-US CC method is an accurate and well reproducible alternative to the NASCET and ECST methods and offers potential for clinical application.

Zusammenfassung

Ziele Die Genauigkeit des Stenosegrades einer Arteria carotis interna Stenose (ICAS) ist von der Messmethode abhängig und beeinflusst die Patientenstratifizierung sowie den neurologischen Verlauf. Die NASCET Messmethode bezieht das stenotische Restlumen auf das distale ICAS-Lumen, die ECST-Methode auf den lokalen Außendiameter und die Arteria carotis communis (CC) Methode auf den CC-Innendiameter. Die direkte morphometrische Stenosegradmessung mit vierdimensional orientiertem dreidimensionalem Farb-Doppler Ultraschall (4D/3DC-US) zeigte eine gute Validität für die etablierte NASCET-Messmethode. Die NASCET-Definition hat klinisch relevante Defizite. Unser Ziel war die Validität der ECST- und CC-Messmethoden zu untersuchen.

Material und Methoden Stenosegradmessungen von 103 Stenosen (80 Patienten) mittels 4D/3DC-US wurden verblindet mit der quantitativen Katheterangiografie und dem Duplex-Ultraschall (DUS) verglichen.

Ergebnisse Die Intermethoden-Standardabweichung der Differenzen (SDD) zwischen 4D/3DC-US und der Angiografie betrug für die CC-Methode 5,7 % im Vergleich zur NASCET- (8,1 %, p < 0,001) und ECST-Messmethode (9,1 %, p < 0,001) und war damit etwas geringer als die Interobserver-SDD der Angiografie in einer Subgruppe (52 Stenosen, SDD 7,2 %, p = 0,047) und äquivalent zur Interobserver-SDD der ECST-Messmethode (p = 0,065). Die Interobserveranalyse gleicher Graduierungsmethoden zeigte keine Differenzen für die SDD zwischen den angiografischen und den 4D/3DC-US Beobachtern (p > 0,076). Der binäre Vergleich zur Angiografie ergab gleiche Kappa-Werte von > 0,7 bei einer Genauigkeit von ≥ 85 % für die NASCET- und CC-Messmethode, höher als für die ECST-Methode. Die binäre Genauigkeit der ICAS-Graduierung unterschied sich in allen Messmethoden nicht von der Genauigkeit des DUS.

Schlussfolgerung Die neue 4D/3DC-US gestützte CC-Messmethode ist eine genaue und gut reproduzierbare Alternative zur NASCET- und ECST-Messmethode und bietet ein klinisches Applikationspotenzial

Key words

ultrasonography - three-dimensional - four-dimensional - angiography - carotid artery stenosis

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