Contemporary imaging methods for the follow-up after endovascular abdominal aneurysm repair: a review

Low-profile versus standard-profile stent grafts in the treatment of abdominal aortic aneurysm: a case-matched study

Introduction

Endovascular aortic repair (EVAR) is nowadays a widespread method of managing abdominal aortic aneurysm (AAA). Low-profile stent grafts (LPSGs) enable treatment of patients with complex and anatomically challenging aneurysms, and facilitate a percutaneous and thus less invasive procedure.

Aim

To assess the outcomes of EVAR with low-profile versus standard-profile stent grafts (SPSGs).

Material and methods

Thirty-one patients with abdominal aortic aneurysms (AAA) were treated by endovascular aortic repair (EVAR) using LPSGs. The control group of patients treated with SPSGs was matched with MedCalc software. The clinical records and the preoperative and follow-up computed tomography angiography of patients who underwent endovascular treatment of AAA were included in this study.

Results

Patients in the LPSG group had significantly more often low access vessel diameter (< 6 mm) compared to the SPSG group (38.7% vs. 6.7%, p = 0.003). In 1-year follow-up, there was no rupture, no infection, no conversion to open repair and no aneurysm-related death. Five secondary interventions were necessary in the SPSG group and only 1 in the LPSG group (p = 0.09). Type of stent graft was not a risk factor of perioperative complications, presence of endoleak or reintervention (p > 0.05). Risk factors for perioperative complications were COPD and conical neck (OR = 6.3, 95% CI: 1.5-25, p = 0.01 and OR = 6.2, 95% CI: 1-39.76, p = 0.04). The risk factor for endoleak was lower maximal aneurysm diameter. The risk factor for reintervention was proximal neck diameter (OR = 0.77, 95% CI: 0.-0.97, p = 0.03).

Conclusions

Our study showed that use of LPSGs is a safe and viable method for patients with narrow access vessels who are not eligible for standard-profile systems.

Advantages of Photon-Counting Detector CT in Aortic Imaging

Photon-counting Computed Tomography (PCCT) is a promising imaging technique. Using detectors that count the number and energy of photons in multiple bins, PCCT offers several advantages over conventional CT, including a higher image quality, reduced contrast agent volume, radiation doses, and artifacts. Although PCCT is well established for cardiac imaging in assessing coronary artery disease, its application in aortic imaging remains limited. This review summarizes the available literature and provides an overview of the current use of PCCT for the diagnosis of aortic imaging, focusing mainly on endoleaks detection and characterization after endovascular aneurysm repair (EVAR), contrast dose volume, and radiation exposure reduction, particularly in patients with chronic kidney disease and in those requiring follow-up CT.

The value of metal artifact reduction and iterative algorithms in dual energy CT angiography in patients after complex endovascular aortic aneurysm repair

Rationale and objectives

Evaluation of the diagnostic value of linearly blended (LB) and virtual monoenergetic images (VMI) reconstruction techniques with and without metal artifacts reduction (MAR) and of adaptive statistical iterative reconstructions (ASIR) in the assessment of target vessels after branched/fenestrated endovascular aortic repair (f/brEVAR) procedures.

Materials and methods

CT scans of 28 patients were used in this study. Arterial phase of examination was obtained using a dual-energy fast-kVp switching scanner. CT numbers in the aorta, celiac trunk, superior mesenteric artery, and renal arteries were measured in the following reconstructions: LB, VMI 60 keV, VMI MAR 60 keV, VMI ASIR 60 % 60 keV. Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were calculated for each reconstruction. Luminal diameters (measurements at 2 levels of stent) and subjective image quality (5-point Likert scale) were assessed (2 readers, blinded to the type of reconstruction).

Results

The highest mean values of CNR and SNR in vascular structures were obtained in VMI MAR 60 keV (CNR 12.526 ± 2.46, SNR 17.398 ± 2.52), lower in VMI 60 keV (CNR 11.508 ± 2.01, SNR 16.524 ± 2.07) and VMI ASIR (CNR 11.086 ± 1.78, SNR 15.928 ± 1.82), and the lowest in LB (CNR 6.808 ± 0.79, SNR 11.492 ± 0.79) reconstructions. There were no statistically significant differences in the measurements of the stent width between reconstructions (p > 0.05). The highest subjective image quality was obtained in the ASIR VMI (4.25 ± 0.44) and the lowest in the MAR VMI (1.57 ± 0.5) reconstruction.

Conclusion

Despite obtaining the highest values of SNR and CNR in the MAR VMI reconstruction, the subjective diagnostic value was the lowest for this technique due to significant artifacts. The type of reconstruction did not significantly affect vessel diameter measurements (p > 0.05). Iterative reconstructions raised both objective and subjective image quality.

Clinical Evaluation of Non-Contrast-Enhanced Radial Quiescent-Interval Slice-Selective (QISS) Magnetic Resonance Angiography in Comparison to Contrast-Enhanced Computed Tomography Angiography for the Evaluation of Endoleaks after Abdominal Endovascular Aneurysm Repair

Purpose. Contrast-enhanced (CE) angiographic techniques, such as computed tomographic angiography (CE-CTA), are most commonly used for follow-up imaging after endovascular aneurysm repair. In this study, CE-CTA and non-CE QISS-MRA were compared for the first time for assessing endoleaks and aneurysms at follow-up after abdominal EVAR. Methods. Our study included 20 patients (17 male, median age 79.8 years) who underwent radial QISS-MRA and CE-CTA after EVAR at their first follow-up examination. Two interventional radiologists evaluated datasets from both techniques in each patient concerning presence of endoleaks, types of endoleaks, aneurysm diameter, and image quality. Interobserver and intermodal agreement were assessed with Cohen’s Kappa. Results. Image quality was rated as excellent or good for both modalities by both observers. Ferromagnetic embolization materials cause hyperdense artifacts in CE-CTA causing aneurysm sac diameter measurements to be inaccurate by up to 1 cm. Type 2 endoleaks with low-flow characteristics in CE-CTA were overlooked compared to radial QISS-MRA. Compared to CE-CTA, all endoleaks after abdominal EVAR were detected and classified correctly on QISS-MRA. The interobserver agreement between CE-CTA and QISS-MRA was almost perfect, except for type 2 endoleaks, where agreement was substantial. Intermodal aneurysm diameter correlate “very strongly” for both observers. Conclusions. Radial QISS-MRA is a contrast agent free technique for diagnosing and monitoring all types of endoleaks and aneurysms in patients after abdominal EVAR. It provides information about specific clinical questions concerning aneurysm diameter and presence and types of endoleaks without radiation exposure and the side effects associated with iodine-based contrast agents.

Contemporary follow-up imaging after endovascular repair of lower extremity atherosclerotic lesions

Atherosclerotic disease is currently one of the most important problems of modern medicine because it is a leading cause of increased morbidity, morbidity and mortality, and disability in the Western World. Atherosclerosis of the lower limbs (peripheral arterial disease - PAD) significantly affects the quality of life and in a considerable proportion of patients is a cause of disability. Radical treatment of PAD, both surgical and endovascular, aims at revascularisation of ischaemic tissues distal to obstructed arteries. Surveillance imaging is an important part of patient management after endovascular repair of PAD. Apart from availability and contraindications, challenges of imaging include calcifications, flow dynamics, and stent-related artefacts. The aim of this paper was to review the current literature on imaging methods for follow-up after endovascular repair of atherosclerotic lesions, with special attention paid to novel techniques. As a non-invasive modality, ultrasound is still the first-line examination, but computed tomography angiography remains a current state-of-the art technique for follow-up. However, since current imaging recommendations seem not to adhere to contemporary imaging possibilities, more attention should be paid to recent improvements in magnetic resonance angiography technology.