Clinical relevance of Positron Emission Tomography (PET) imaging following endovascular aneurysm repair using the Nellix endoprosthesis.

Abdominal aortic aneurysm (AAA) is a prevalent disorder affecting 4.3 to 8.8%
of men over the age of 60.1 Since the introduction of endovascular aneurysm
repair (EVAR) in the early 1990*s, EVAR is performed in the majority of
patients to prevent rupture.
One of the most devastating complications following EVAR is infection of the
used endograft. Because of the high mortality associated with endograft
infection, patients with a possible graft infection are treated with life-long
broadspectrum antibiotics. Unfortunately, the diagnosis is difficult and PET
imaging is often used as a tool to support diagnosis and to initiate life long
antibiotic treatment or even secondary surgery.
Following endograft placement, the aortic wall shows extensive inflammation and
increased metabolic activity. This is probably related to the insertion of the
prosthetic graft material itself and the mechanical manipulation and
deformation (strain) following endograft placement. The increased metabolic
activity in the aortic wall following EVAR might result in positive PET
findings. This could limit the use of PET imaging to identify endograft
infection and questions the use of life-long broadspectrum antibiotic treatment
in patients with a PET positive finding following EVAR.
The Nellix endoprosthesis is a relatively new device used for EVAR. The
difference with traditional endografts is that the entire aneurysm is filled by
two polymer-filled endobags, with two balloon expandable stents preserving flow
to the lower extremity. With this new device endoleaks, aneurismal flow outside
the stents, are less likely to occur and also migration is rare. In present
literature there is no data on the degree of physiologic inflammation following
implantation of a Nellix device and the value of postoperative FDG-PET imaging
to detect infection is not known. This makes the diagnosis of infection
following Nellix implantation extremely difficult.

To determine FDG uptake following uncomplicated EVAR using the Nellix
endoprosthesis. Does uncomplicated EVAR using the Nellix endoprosthesis result
in increased FDG uptake and false positive PET imaging? .

Observational case series (pilot).

Regular preoperative and follow-up imaging for EVAR planning and follow-up
using the Nellix endoprosthesis consists of Computed Tomography Angiography
preoperative and at six weeks, six months and one year after EVAR. In this
study the preoperative and first follow-up CTA (6 weeks after EVAR) will be
replaced by a PET/CTA. Regular blood samples are collected prior to CTA to
determine kidney function. For patients included in the study, additionally
several inflammation markers will be determined. (leukocyte count and CRP).