Experimental feasibility of spectral photon-counting computed tomography with two contrast agents for the detection of endoleaks following endovascular aortic repair

Julia Dangelmaier,Loic Boussel,Melanie A Kimm,Heiner Daerr,Sebastian Ehn,Daniel Bar-Ness,Ewald Roessl,Daniela Muenzel,Franz Pfeiffer,Roland Proksa,Philippe Douek,Ernst J Rummeny,Salim Si-Mohamed,Peter B Noël,Felix K Kopp,Alexander A Fingerle

doi:10.1007/s00330-017-5252-7

Abstract

ObjectivesAfter endovascular aortic repair (EVAR), discrimination of endoleaks and intra-aneurysmatic calcifications within the aneurysm often requires multiphase computed tomography (CT). Spectral photon-counting CT (SPCCT) in combination with a two-contrast agent injection protocol may provide reliable detection of endoleaks with a single CT acquisition.MethodsTo evaluate the feasibility of SPCCT, the stent-lined compartment of an abdominal aortic aneurysm phantom was filled with a mixture of iodine and gadolinium mimicking enhanced blood. To represent endoleaks of different flow rates, the adjacent compartments contained either one of the contrast agents or calcium chloride to mimic intra-aneurysmatic calcifications. After data acquisition with a SPCCT prototype scanner with multi-energy bins, material decomposition was performed to generate iodine, gadolinium and calcium maps.ResultsIn a conventional CT slice, Hounsfield units (HU) of the compartments were similar ranging from 147 to 168 HU. Material-specific maps differentiate the distributions within the compartments filled with iodine, gadolinium or calcium.ConclusionSPCCT may replace multiphase CT to detect endoleaks without sacrificing diagnostic accuracy. It is a unique feature of our method to capture endoleak dynamics and allow reliable distinction from intra-aneurysmatic calcifications in a single scan, thereby enabling a significant reduction of radiation exposure.Key Points• SPCCT might enable advanced endoleak detection.• Material maps derived from SPCCT can differentiate iodine, gadolinium and calcium.• SPCCT may potentially reduce radiation burden for EVAR patients under post-interventional surveillance.

Highlights

An abdominal aortic diameter of 3 cm or more is considered as an abdominal aortic aneurysm (AAA)
Material maps derived from Spectral photon-counting CT (SPCCT) can differentiate iodine, gadolinium and calcium
We demonstrate in a phantom model that a single SPCCT scan could capture endoleak dynamics and discriminate endoleaks from intra-aneurysmatic calcifications

Summary

Introduction

An abdominal aortic diameter of 3 cm or more is considered as an abdominal aortic aneurysm (AAA). An endoleak is the most frequent complication (53% of all complications; incidence of 11.7%) following EVAR [7] and typically requires a secondary intervention [8], since it promotes further growing of the aneurysm (in 41% of patients), which can disastrously lead to aortic rupture (in 2.4%) [7]. The Society for Vascular Surgery recommends life-long follow-ups (1, 6 and 12 months after the intervention and annually thereafter) using contrast-enhanced computed tomography (CT) scans to detect possible complications related to EVAR [9]. A CT scan in the arterial phase enables the evaluation of the access vessels and an in-stent lumen visualization, whereby organ infarction—a potential adverse effect of vascular intervention—is usually reliably detectable in the delayed phase scan

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Results