Type 2 Endoleaks: The Diagnostic Performance of Non-Specialized Readers on Arterial and Venous Phase Multi-Slice CT Angiography.

Richard Nolz,Ramona Woitek,Christian Loewe,Alexander Prusa,Maria Schoder,Sylvia Unterhumer,Julia Furtner,Asenbaum Ulrika,Andreas Wibmer,Carlos Zaragoza

doi:10.1371/journal.pone.0149725

Abstract

PurposeTo define the diagnostic precision of non-specialized readers in the detection of type 2 endoleaks (T2EL) in arterial versus venous phase acquisitions, and to evaluate an approach for radiation dose reduction.MethodsThe pre-discharge and final follow-up multi-slice CT angiographies of 167 patients were retrospectively analyzed. Image data were separated into an arterial and a venous phase reading set. Two radiology residents assessed the reading sets for the presence of a T2EL, feeding vessels, and aneurysm sac size. Findings were compared with a standard of reference established by two experts in interventional radiology. The effective dose was calculated.ResultsOverall, experts detected 131 T2ELs, and 331 feeding vessels in 334 examinations. Persistent T2ELs causing aneurysm sac growth > 5 mm were detected in 20 patients. Radiation in arterial and venous phases contributed to a mean of 58.6% and 39.0% of the total effective dose. Findings of reader 1 and 2 showed comparable sensitivities in arterial sets of 80.9 versus 85.5 (p = 0.09), and in venous sets of 73.3 versus 79.4 (p = 0.15), respectively. Reader 1 and 2 achieved a significant higher detection rate of feeding vessels with arterial compared to venous set (p = 0.04, p < 0.01). Both readers correctly identified T2ELs with growing aneurysm sac in all cases, independent of the acquisition phase.ConclusionArterial acquisitions enable non-specialized readers an accurate detection of T2ELs, and a significant better identification of feeding vessels. Based on our results, it seems reasonable to eliminate venous phase acquisitions.

Highlights

Successful endovascular aneurysm repair of infra-renal aortic aneurysms (EVAR) is defined by the absence of an endoleak, which prevents aneurysm sac enlargement and rupture
Persistent type 2 endoleaks (T2EL) causing aneurysm sac growth > 5 mm were detected in 20 patients
Twenty patients (12%) with a persistent T2EL met the criteria for reintervention

Summary

Introduction

Successful endovascular aneurysm repair of infra-renal aortic aneurysms (EVAR) is defined by the absence of an endoleak, which prevents aneurysm sac enlargement and rupture. Endoleaks are defined as persistent blood flow within the excluded aneurysm sac, and are classified based on the source of blood flow [1, 2]. Most endoleaks are type 2 endoleaks (T2EL), which are reported in up to 42% of patients with a rupture rate of 0.9% [3,4,5]. Multi-slice CT Angiography (MSCTA) is the imaging technique of choice for the diagnosis of endoleaks and aneurysm sac changes [7], and different imaging protocols have been suggested. Bi-phasic MSCTA could miss low-flow T2ELs [12]

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Conclusion