Molecular Imaging of Aortic Aneurysm and Its Translational Power for Clinical Risk Assessment

Impact of frailty on adverse outcomes in patients with abdominal aortic aneurysm undergoing surgery: a systematic review and meta-analysis

OBJECTIVE

To explore the prognostic role of frailty in patients with abdominal aortic aneurysm (AAA) by conducting this systematic review and meta-analysis METHODS: We conducted an extensive literature search on PubMed, Web of Sciences, and Embase databases to identify studies that reported the association of frailty with postoperative complications, reintervention, or all-cause mortality in patients with AAA after surgery. Short-term mortality was defined by a combination of in-hospital and 30-day death.

RESULTS

Seven cohort studies reporting on 9 articles with 323,788 AAA patients were included. The reported prevalence of frailty in AAA patients ranged between 2.3% and 34.6%. Pooling the results revealed that frailty was significantly associated with a higher risk of short-term all-cause mortality (adjusted risk ratios [RR] 3.20; 95% confidence intervals [CI] 1.95-5.26), long-term all-cause mortality (adjusted RR 2.86; 95% CI 2.57-3.17), and postoperative complications (adjusted RR 2.19; 95% CI 1.50-3.20) compared to non-frail individuals. However, there was no clear association between frailty and reintervention (HR 1.44; 95% CI 0.97-2.16).

CONCLUSIONS

Frailty independently predicts the short and long-term survival as well as postoperative complications in patients with AAA undergoing surgery. Assessing frail status may potentially enhance surgical decision-making for these patients.

Mapping microarchitectural degeneration in the dilated ascending aorta with ex vivo diffusion tensor imaging

Aims

Thoracic aortic aneurysms (TAAs) carry a risk of catastrophic dissection. Current strategies to evaluate this risk entail measuring aortic diameter but do not image medial degeneration, the cause of TAAs. We sought to determine if the advanced magnetic resonance imaging (MRI) acquisition strategy, diffusion tensor imaging (DTI), could delineate medial degeneration in the ascending thoracic aorta.

Methods and results

Porcine ascending aortas were subjected to enzyme microinjection, which yielded local aortic medial degeneration. These lesions were detected by DTI, using a 9.4 T MRI scanner, based on tensor disorientation, disrupted diffusion tracts, and altered DTI metrics. High-resolution spatial analysis revealed that fractional anisotropy positively correlated, and mean and radial diffusivity inversely correlated, with smooth muscle cell (SMC) and elastin content (P < 0.001 for all). Ten operatively harvested human ascending aorta samples (mean subject age 61.6 ± 13.3 years, diameter range 29-64 mm) showed medial pathology that was more diffuse and more complex. Nonetheless, DTI metrics within an aorta spatially correlated with SMC, elastin, and, especially, glycosaminoglycan (GAG) content. Moreover, there were inter-individual differences in slice-averaged DTI metrics. Glycosaminoglycan accumulation and elastin degradation were captured by reduced fractional anisotropy (R2 = 0.47, P = 0.043; R2 = 0.76, P = 0.002), with GAG accumulation also captured by increased mean diffusivity (R2 = 0.46, P = 0.045) and increased radial diffusivity (R2 = 0.60, P = 0.015).

Conclusion

Ex vivo high-field DTI can detect ascending aorta medial degeneration and can differentiate TAAs in accordance with their histopathology, especially elastin and GAG changes. This non-destructive window into aortic medial microstructure raises prospects for probing the risks of TAAs beyond lumen dimensions.

A role of FDG PET/CT for Response Assessment in Large Vessel Disease?

Currently, a large amount of evidence-based data clearly demonstrates the usefulness of [¹⁸F]FDG PET/CT in the diagnosis of several infectious and inflammatory diseases, including those related to the large vessels. The aim of this article is to clarify whether, beyond initial diagnosis, [¹⁸F]FDG PET/CT may have a role in treatment response assessment in inflammatory or infectious diseases of the large vessels, including large vessel vasculitis, vascular graft infection, retroperitoneal fibrosis/chronic periaortitis and infective native aortic aneurysms. Rapidly accumulating data suggest that [¹⁸F]FDG PET/CT could be a valuable imaging method for therapy monitoring in some infectious and inflammatory diseases of large vessels. The available data, albeit preliminary, indicate that [¹⁸F]FDG PET/CT could even play a pivotal role in the management of these diseases, leading to better drug dosage, confirmation of the usefulness of the treatment, and early modification of the therapeutic strategy. However, to date, the role of [¹⁸F]FDG PET/CT for treatment assessment in large vessel diseases, in particular large vessel vasculitis, is not clearly defined and well-designed prospective studies are needed to confirm its possible role in treatment monitoring and treatment guidance.