Dual-Energy CTA in Patients with Symptomatic Peripheral Arterial Occlusive Disease: Study of Diagnostic Accuracy and Impeding Factors

Abstract

Purpose The purpose of this study was to assess the diagnostic performance of dual-energy CT angiography (DE-CTA) in patients with symptomatic peripheral artery occlusive disease (PAOD) and to identify factors that impede its diagnostic accuracy.

Materials and Methods Dual-source DE-CTA scans of the lower extremities of 94 patients were retrospectively compared to the diagnostic reference standard, digital subtraction angiography (DSA). Two independent observers assessed PAOD incidence, image quality, artifacts, and diagnostic accuracy of DE-CTA in 1014 arterial segments on axial, combined 80/140 kVp reconstructions and on 3 D maximum intensity projections (MIP) after automated bone and plaque removal. The impact of calcifications, image quality, and image artifacts on the diagnostic accuracy was evaluated using Fisher’s exact test. Furthermore, interobserver agreement was analyzed.

Results Two observers achieved sensitivities of 98.0 % and 93.9 %, respectively, and specificities of 75.0 % and 66.7 %, respectively, for detecting stenoses of > 50 % of the lower extremity arteries. Calcifications impeded specificity, e. g. from 81.2 % to 46.2 % for reader 1 (p < 0.001). Specificity increased with higher image quality, e. g. from 70.0 % to 76.4 % for reader 1 (p < 0.001). Artifacts decreased the specificity of reader 2 (p < 0.001). The overall interobserver agreement ranged between moderate and substantial for stenosis detection and calcified plaques.

Conclusion DE-CTA is accurate in the detection of arterial stenoses of > 50 % in symptomatic PAOD patients. Calcified atherosclerotic plaques, image quality, and artifacts may impede specificity.

Key Points: 

• Sensitivities of DE-CTA were 98.0 and 93.9 %, specificities 75.0 % and 66.7 %.

• Interobserver agreement was moderate to substantial for stenosis and plaque detection.

• Calcified atherosclerotic plaques, image quality, and artifacts may impede specificity.

Citation Format

• Klink T, Wilhelm T, Roth C et al. Dual-Energy CTA in Patients with Symptomatic Peripheral Arterial Occlusive Disease: Study of Diagnostic Accuracy and Impeding Factors. Fortschr Röntgenstr 2017; 189: 441 – 452

Zusammenfassung

Zielsetzung Das Ziel dieser Studie war, die diagnostische Genauigkeit der Dual-energy CT Angiographie (DE-CTA) bei Patienten mit symptomatischer peripherer arterieller Verschlusskrankheit (pAVK) zu erfassen, und Faktoren zu identifizieren, die die diagnostische Genauigkeit negativ beeinflussen.

Material und Methoden Dual-source DE-CTA Untersuchungen der unteren Extremitäten von 94 Patienten wurden retrospektiv mit dem diagnostischen Referenzstandard digitale Subtraktionsangiografie (DSA) verglichen. Zwei unabhängige Auswerter haben die Inzidenz der pAVK, die Bildqualität, Artefakte und die diagnostische Genauigkeit der DE-CTA in 1014 arteriellen Segmenten anhand axialer, kombinierter 80/140kVp Rekonstruktionen und 3 D Maximum-Intensitäts-Projektionen (MIP) nach automatischer Knochen- und Plaqueentfernung ausgewertet. Der Einfluss von Verkalkungen, der Bildqualität und von -artefakten auf die diagnostische Genauigkeit wurde mittels Fisher Tests evaluiert. Darüber hinaus wurde die Übereinstimmung der Auswerter analysiert.

Ergebnisse Die zwei Auswerter erzielten Sensitivitätswerte von 98,0 % und 93,9 %, und Spezifitätswerte von 75,0 % und 66,7 % bei der Detektion von Stenosen > 50 %. Verkalkungen beeinflussten die Spezifität negativ, z. B. von 81,2 % auf 46,2 % bei Auswerter 1 (p < 0,001). Die Spezifität nahm bei besserer Bildqualität signifikant zu, z. B. von 70,0 % auf 76,4 % bei Auswerter 1 (p < 0,001). Artefakte reduzierten die Spezifität von Auswerter 2 signifikant (p < 0,001). Die Übereinstimmung der Auswerter war moderat bis substanziell bei der Stenosedetektion und Kalkplaqueauswertung.

Schlussfolgerungen Die DE-CTA ermöglicht eine zuverlässige Detektion von > 50 %igen Stenosen bei Patienten mit symptomatischer pAVK. Kalzifizierte atherosklerotischen Plaques, die Bildqualität, -artefakte können die Spezifität negative beeinflussen.

Kernaussagen: 

• Die Sensitivitätswerte (DE-CTA) waren 98,0 und 93.9 %, die Spezifitätswerte 75,0 % und 66,7 %.

• Die Auswerterübereinstimmg war moderat bis substanziell für die Stenose- und Plaquedetektion.

• Kalkplaques, Bildqualität und Artefakte können die Spezifität beeinträchtigen.

Key words

vascular - CT angiography - dual-energy computed tomography angiography - peripheral artery occlusive disease - critical limb ischemia

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