Dual-energy CT angiography in imaging surveillance of endovascular aneurysm repair – Preliminary study results. Issue 148 (March 2022)

• Record Type: Journal Article
• Authors: Charalambous, Stavros; Perisinakis, Kostas; Kontopodis, Nikolaos; Papadakis, Antonios E.; Maris, Thomas G.; Ioannou, Christos V.; Karantanas, Apostolos; Tsetis, Dimitrios
• Is Part Of: European journal of radiology. Issue 148(2022)
• Publication Date: 2022-03
• Subjects: Computed tomography -- Dual energy CT -- Aortic aneurysm -- Endovascular aneurysm repair -- Endoleak; AAA abdominal aortic aneurysm -- ASG aneurysm sac growth -- AUC area under curve -- CNR contrast-to-noise ratio -- CTA computed tomography angiography -- CTDIvol volume CT dose index -- DECT dual-energy CT -- DECTA dual-energy CT angiography -- DEI dual energy index -- DLP dose-length product -- EI endoleak index -- EVAR endovascular aneurysm repair -- GSI gemstone spectral imaging -- IC iodine concentration -- Zeff effective atomic number -- NIC normalized iodine concentration -- NZeff normalized effective atomic number -- ROI region of interest -- S slope -- SECT single-energy CT -- TNC true non-contrast -- T2EL type II endoleak -- VMI virtual monochromatic images -- VUI virtual unenhanced images; Medical radiology -- Periodicals; Radiology -- Periodicals; Radiologie médicale -- Périodiques; Medical radiology; Periodicals; 616.075705
• DOI: 10.1016/j.ejrad.2022.110165
• Languages: English
• ISSNs: 0720-048X

Abstract

Highlights: CT angiography is the imaging modality of choice after endovascular aneurysm repair. Endoleak development is the drawback of endovascular aneurysm repair. Dual-energy CT imaging may efficiently identify suspicious type II endoleak lesions for aneurysm expansion. Low-keV monochromatic images improve the conspicuity for the detection of type II endoleaks. Abstract: Purpose: To investigate the value of dual-energy CT imaging to discriminate low- from high- risk type II endoleaks (T2EL) after endovascular aneurysm repair (EVAR). Method: Study participants were consecutive patients referred for CT at 1-month post-EVAR. CT imaging acquisition included a dual-energy CT angiography (DECTA) and a delayed single-energy CT (SECT) imaging. Patients diagnosed with T2EL were re-examined at 6-months post-EVAR to assess the aneurysm sac growth (ASG). Upon ASG recorded, patients were categorized as having low- (group A) or high- risk (group B) T2EL. DECTA image data were employed to calculate the normalized effective atomic number (NZeff ), the normalized iodine concentration, the slope of HUendoleak /HUaorta against monochromatic energy, the dual-energy index and an improvised endoleak index (EI) for each T2EL. Statistical analysis was employed to compare all above parameters regarding their ability to differentiate low- from high- risk T2EL. Results: Among 40 patients examined at 1-month post-EVAR, 14 patients were diagnosed with T2EL. NZeff and EI were found to be significantly lower in group A. NZeff was found to have the highest power to discriminate high-risk T2EL with an area-under-curve of 86.7%, showing100% specificity and 60% sensitivity. The optimal contrast-to-noise ratio for T2EL demonstrated a median peak conspicuity level at 54-keV. The mean effective dose from DECTA and SECT scans was 27.8% lower compared to the sum of three SECT acquisitions. Conclusions: NZeff and EI were found to have a significant power in predicting the aggressiveness of T2EL lesions. Virtual monochromatic images at 54-keV may enhance T2EL detection efficiency.