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The aims of this study are to verify non-inferiority of magnetic resonance (MR) without contrast agent associated to color-Doppler ultrasound for the diagnosis of endoleaks after endovascular aortic repair (EVAR), to evaluate both the economical and biological cost-effectiveness of such diagnostic algorithm as an alternative to computed tomography (CT) with contrast agent, and to analyze its impact on both patients work-flow and infrastructure logistics
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In this prospective observational study, 250 patients who underwent EVAR will be studied. They will be enrolled after referral for a CT with contrast agent at IRCCS Policlinico San Donato or at ASST Santi Paolo e Carlo. Those with absolute contraindications to RM will be excluded.
All enrolled subjects will undergo MR with contrast agent and color-Doppler ultrasound after CT. Before and after each examination, they will be submitted a questionnaire to evaluate their perception towards the former, and both costs and exposure deriving from such examinations will be evaluated along with patients' responses. Moreover, both CT and MR along with color-Doppler ultrasound will be analyzed with regards to human resources management, operational management, patients' clinical workflow and organization.
All CT examinations will be independently evaluated by two radiologists with 4- and 8-year expertise in thoracic or abdominal CT. Results obtained from CT examinations will be used as a reference standard using the "worst case scenario" method: if either reader reported endoleak, the CT will be considered positive. The more experienced reader will anonymously and randomly repeat CT evaluation after 1 month.
For CMR examinations, a 15-minute protocol will be used on a 1.5-T device. The following sequences will be performed:
steady state free-precession (true-FISP) half-Fourier single shot spin-echo (HASTE) All examinations will be independently and blindly evaluated by the same two radiologists as CT examinations, and they will be considered positive if areas (even smaller than 5 mm) of alterate signal in comparison to surrounding muscle in the same slice are present inside the aneurismatic sac. The more experienced reader will anonymously and randomly repeat CT evaluation after 1 month.
Color-Doppler ultrasound will be performed with a 1-5 MHz probe, by a radiologist with 7-year expertise in aortic ultrasound, blinded to MR and CT results. Ultrasound images will be evaluated both directly and through spectral flow study.
The sample size was calculated assuming an alpha error of 5%, 90% power and 10% endoleak prevalence. In order to prove a negative predictive value of MR without contrast agent and color-Doppler ultrasound not inferior to 90%, 250 patients should be enrolled.
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250 participants in 1 patient group
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Data sourced from clinicaltrials.gov
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