Split-Bolus Single-Phase Cardiac Multidetector Computed Tomography for Reliable Detection of Left Atrial Thrombus: Comparison to Transesophageal Echocardiography

Abstract

Purpose: Evaluation of a new cardiac MDCT protocol using a split-bolus contrast injection protocol and single MDCT scan for reliable diagnosis of LA/LAA thrombi in comparison to TEE, optimizing radiation exposure and use of contrast agent.

Materials and Methods: A total of 182 consecutive patients with drug refractory AF scheduled for PVI (62.6 % male, mean age: 64.1 ± 10.2 years) underwent routine diagnostic work including TEE and cardiac MDCT for the evaluation of LA/LAA anatomy and thrombus formation between November 2010 and March 2012. Contrast media injection was split into a pre-bolus of 30 ml and main bolus of 70 ml iodinated contrast agent separated by a short time delay.

Results: In this study, split-bolus cardiac MDCT identified 14 of 182 patients with filling defects of the LA/LAA. In all of these 14 patients, abnormalities were found in TEE. All 5 of the 14 patients with thrombus formation in cardiac MDCT were confirmed by TEE.

Conclusion: MDCT was 100 % accurate for thrombus, with strong but not perfect overall results for SEC equivalent on MDCT.

Key Points:

• Patients with no filling defect or thrombus in MDCT in the LA/LAA region are unlikely to have thrombus and may undergo PVI without TEE.

• Here, the role of an additional TEE in pre-procedural management prior to PVI in patients with AF has to be redefined.

• Using a split-bolus injection protocol increases the diagnostic accuracy of thrombus in the LA/LAA region.

Citation Format:

• Staab W, Sohns C, Zwaka PA et al. Split-Bolus Single-Phase Cardiac Multidetector Computed Tomography for Reliable Detection of Left Atrial Thrombus: Comparison to Transesophageal Echocardiography. Fortschr Röntgenstr 2014; 186: 1009 – 1015

Zusammenfassung

Ziel: Evaluierung eines neuen Kardio-MDCT-Protokoll mit Doppel-Bolus-Injektion zur Verbesserung der Detektion von LA- oder LAA-Thromben und Reduzierung falsch positiver Befunde im Vergleich zu den Ergebnissen der transösophagealen Echokardiografie (TEE).

Material und Methoden: Insgesamt wurden 182 konsekutive Patienten mit therapierefraktärem Vorhofflimmern (VHF) vor Pulmonalvenenisolation (PVI) eingeschlossen (62,6 % männlich, Alter 64,1 ± 10,2 Jahre). Zwischen November 2010 und März 2012 wurden Patienten mittels Kardio-MDCT und TEE vor PVI zur Evaluation der LA/LAA Anatomie und zum Thrombenausschluss untersucht. Es wurde ein Präbolus von 30 ml und ein Hauptbolus von 70 ml jodhaltigem Kontrastmittel appliziert, getrennt durch eine Pause von 20 Sekunden und abschließendem NaCl-Bolus von 40 ml. Die generierten CT-Datensätze wurden im 75 % RR-Intervall ausgewertet. Hier wurden Füllungsdefekte im LAA und LA analysiert. Die Ergebnisse wurden verglichen mit vorhandenem Spontankontrast (SEC) oder Thromben in der TEE. Klinische Risikostratifizierung für Thrombusbildung wurde für beide Verfahren mit dem CHADS2-Score durchgeführt. TEE und Kardio-MDCT wurden getrennt von den Ergebnissen der jeweils anderen Modalität ausgewertet.

Ergebnisse: Doppel-Bolus-Kardio-MDCT identifizierte 14 von 186 Patienten (7,7 %) mit Füllungsdefekten der LA-/LAA-Region. Bei diesen Patienten wurden ebenfalls Auffälligkeiten im TEE gefunden. Kardio-MDCT zeigte 2 falsch negative Befunde im Vergleich zur TEE, jedoch keine falsch positiven. Alle 5 der 14 Patienten (31,3 %) mit Thrombusnachweis im Kardio-MDCT wurden vom TEE bestätigt. Insgesamt betrug die Spezifität und Sensitivität der Kardio-MDCT 100 %, 88 %, 100 % PPW; NPW 99 %. Die multivariate Analyse identifizierte Bluthochdruck, Diabetes mellitus und ein CHADS2 ≥ 2 als unabhängige prognostische Faktoren für LA-/LAA-Thrombusbildung. Es wurde kein Thrombus bei Patienten mit VHF, Alter von ≤ 50 Jahren und einem CHADS2-Score von ≤ 1 nachgewiesen.

Schlussfolgerung: Mit dem Doppel-Bolus-Kardio-MDCT wird die Zuverlässigkeit für die Beurteilung von Thromben oder Füllungsdefekten (SEC- Äquivalent) der LA-/LAA-Region erhöht.

Kernaussagen:

• Bei Patienten ohne Füllungsdefekt oder Thrombus im MDCT, sollte diskutiert werden ob die PVI ohne vorheriges TEE durchgeführt werden kann.

• Im präprozeduralen Management vor PVI bei Patienten mit Vorhofflimmern sollte die Rolle des TEE neu definiert werden.

• Unter Verwendung des Doppel-Bolus-Injektionsprotokolls wird die diagnostische Genauigkeit zur Erfassung von Thromben in der LA-/LAA-Region erhöht.

Key words

cardiac - CT - ultrasound

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