Imaging characteristics and diagnostic accuracy of FDG-PET/CT, contrast enhanced CT and combined imaging in patients with suspected mycotic or inflammatory abdominal aortic aneurysms

Histopathological evaluation of abdominal aortic aneurysms with deep learning

Computational analysis of histopathological specimens holds promise in identifying biomarkers, elucidating disease mechanisms, and streamlining clinical diagnosis. However, the application of deep learning techniques in vascular pathology remains underexplored. Here, we present a comprehensive evaluation of deep learning-based approaches to analyze digital whole-slide images of abdominal aortic aneurysm samples from 369 patients from three European centers. Deep learning demonstrated robust performance in predicting inflammatory characteristics, particularly in the adventitia, as well as fibrosis grade and remaining elastic fibers in the tunica media. Overall, this study represents the first comprehensive evaluation of computational pathology in vascular disease and has the potential to contribute to improved understanding of abdominal aortic aneurysm pathophysiology and personalization of treatment strategies, particularly when integrated with radiological phenotypes and clinical outcomes.

The Incidence of IgG4-Related and Inflammatory Abdominal Aortic Aneurysm Is Rare in a 101 Patient Cohort

Abdominal aortic aneurysms (AAA) are the most frequent aortic dilation, with considerable morbidity and mortality. Inflammatory (infl) and IgG4-positive AAAs represent specific subtypes of unclear incidence and clinical significance. Here, histologic and serologic analyses with retrospective clinical data acquisition are investigated via detailed histology, including morphologic (HE, EvG: inflammatory subtype, angiogenesis, and fibrosis) and immunhistochemic analyses (IgG and IgG4). In addition, complement factors C3/C4 and immunoglobulins IgG, IgG2, IgG4 and IgE were measured in serum samples and clinical data uses patients' metrics, as well as through semi-automated morphometric analysis (diameter, volume, angulation and vessel tortuosity). A total of 101 eligible patients showed five (5%) IgG4 positive (all scored 1) and seven (7%) inflammatory AAAs. An increased degree of inflammation was seen in IgG4 positive and inflAAA, respectively. However, serologic analysis revealed no increased levels of IgG or IgG4. The operative procedure time was not different for those cases and the short-term clinical outcomes were equal for the entire AAA cohort. Overall, the incidence of inflammatory and IgG4-positive AAA samples seems very low based on histologic and serum analyses. Both entities must be considered distinct disease phenotypes. Short-term operative outcomes were not different for both sub-cohorts.

Decisive diagnostic clue for infectious abdominal aortic aneurysm caused by Arthrobacter russicus in a diabetic elderly woman with renal dysfunction: A case report and literature review

Infectious aortic aneurysm (IAA) can be a rare but potentially fatal sequela of infectious inflammatory disease of the aortic wall with a high incidence of rupture. The definitive diagnosis is based on vascular imaging of the aneurysm using contrast-enhanced computed tomography (CE-CT) and identification of the causative microorganism from positive blood cultures (BCs). However, IAA remains extremely difficult to diagnose and treat in patients with prior antimicrobial treatment or with renal dysfunction. Here we describe a case of an 85-year-old woman with IAA caused by Arthrobacter russicus presenting with abdominal pain and fever that was initially diagnosed as a presumptive urinary tract infection and treated with empiric antimicrobial therapy. However, persistent abdominal pain with increased serological inflammation necessitated further evaluation. Unenhanced multimodality imaging considering the renal dysfunction revealed infectious aortitis of the infrarenal abdominal aorta, together with the initial culture results, leading to the tentative diagnosis of Klebsiella pneumoniae aortitis. Thereafter, serial monitoring with unenhanced magnetic resonance angiography (MRA) using thin-slab maximum intensity projection (TS-MIP) revealed acute aortic expansion strongly suggestive of a pseudoaneurysm that was successfully treated with early surgical repair under adequate infection control. Despite negative Gram staining and tissue culture results for the excised aortic wall, a definitive diagnosis of IAA secondary to A. russicus rather than K. pneumoniae was finally made by confirming the histologic findings consistent with IAA and the identification of A. russicus 16S rRNA on the resected aortic wall. The patient also developed a vascular graft infection during the postoperative course that required long-term systemic antimicrobial therapy. This case highlights the value of unenhanced MRA in the early detection of IAA in patients with renal dysfunction and the importance of a molecular diagnosis for identifying the causative microorganism in cases of culture- or tissue-negative IAA.