Aortitis: recent advances, current concepts and future possibilities

Infectious Aortitis on 18 F-FDG PET/CT

ABSTRACT

Infectious aortitis is a challenging radiographic diagnosis due to overlapping features with the noninfectious category. We present a case of a 58-year-old woman who tested positive for SARS-CoV-2 and Streptococcus pneumoniae bacteremia. 18 F-FDG PET/CT demonstrated large vessel vasculitis involving the thoracic, abdominal aorta, and the brachiocephalic branches of the aortic arch, and an incidental subcutaneous abscess in the right arm. Standard of care treatment was administered. Within a week, a drastic improvement of the wall thickening was noted, which can be, regardless of the biological markers, a surrogate marker of an infectious aortitis.

Thoracic aortic pseudoaneurysm: Inside its pathophysiology

OBJECTIVES

Our aim was to investigate pathophysiology of pseudoaneurysm of the thoracic aorta, an acute or chronic pathology, respectively, secondary to blunt thoracic trauma and aortitis, or complicating a deep penetrating aortic ulcer, intraparietal hematoma, aortic aneurysm, and even aortic graft, often with atherosclerosis as a common background.

METHODS

Given the relative rarity of this disease, an "inductive" retrospective method made it possible to retrieve clinical, radiological, and histopathological elements, which were mutually compared and validated through a "deductive" process of reinterpretation.

RESULTS

We have identified three main structural constituents of this disease: a cavity, a single blood entry port, communicating with the aortic lumen, and a pseudocapsule. It is often caused by a chronic degenerative pathology of the intima and medial layers of the aorta, typically involving elastic fibers and smooth muscle cells, with possible intermediate stages of deep aortic ulcer or intraparietal hematoma. Otherwise, the acute onset may be secondary to acute aortitis or aortic injury.

CONCLUSIONS

Today, thanks to the current angiographic tools represented by 3-D high resolution multidetector CT and MRI angiography, the diagnosis of thoracic aortic pseudoaneurysm is easier, as well as its surgical indications.

Outcome and prognosis of isolated carotid vasculitis

OBJECTIVE

To assess the prognosis and outcome of patients with isolated carotid vasculitis.

METHODS

We performed a retrospective multicenter study of 36 patients (median age at diagnosis was 37 [IQR 27-45] years and 11 [31 %] patients were men) with initial presentation as isolated carotid vasculitis. Study endpoints included vascular complications, relapses, and progression to large vessel vasculitis (i.e. Giant cell arteritis or Takayasu).

RESULTS

The most frequent involvement was the left internal carotid artery (39 %), and 81 % had stenosis. After a median follow-up of 32 months [IQR 12-96], 21 (58 %) patients had a vascular event, including 31 % of new onset vascular lesions and 25 % of stroke/transient ischemic attack. Patients with stroke had less carotidynia at diagnosis (33 % vs 74 %, p = 0.046), higher significant carotid stenosis (i.e. > 50 %) (89 % vs. 30 %, p = 0.026) and higher severe carotid stenosis (i.e. >70 %) (67 % vs 19 %, p = 0.012), compared to those without stroke. Twenty (52 %) patients experienced relapses. High CRP at diagnosis was associated with relapses (p = 0.022). At the end of follow-up, 21 (58 %) patients were classified as having Takayasu arteritis, 13 (36 %) as isolated carotid vasculitis, and two (6 %) as giant cell arteritis.

CONCLUSION

Carotid vasculitis may occur as a topographically limited lesion and is associated with significant rate of vascular complications.

Infectious aortitis and managing it at a community military hospital

Infectious aortitis is a rare disease process which can be of fungal, viral or bacterial aetiology. This disease process is often incidentally found during concomitant infectious processes, likely due to haematogenous spread. Common sources are from cardiac, genitourinary and gastroenterologic sources. CT imaging of the aorta is essential in identifying physiological changes-wall thickness changes, ectasia and stenosis. We present a case of a female in her early 60s with a medical history of cardiomyopathy with heart failure and reduced ejection fraction, who was initially admitted for acute cholecystitis complicated by the development of gallstone pancreatitis. Imaging evaluation incidentally noted findings consistent with aortitis with a penetrating ulcer, and blood cultures were positive for Staphylococcus aureus bacteraemia, confirming her diagnosis of infectious aortitis. She was started on intravenous antibiotics, required preoperative nutritional optimisation, and subsequently underwent an open aortic resection and aortoiliac reconstruction with rifampin-soaked Dacron graft.

Isolated Aortitis: Workup and Management

The finding of aortitis, often incidentally noted on surgical resection, should prompt evaluation for secondary causes including large-vessel vasculitis. In a large proportion of cases, no other inflammatory cause is identified and the diagnosis of clinically isolated aortitis is made. It is unknown whether this entity represents a more localized form of large-vessel vasculitis. The need for immunosuppressive therapy in patients with clinically isolated aortitis remains unclear. Patients with clinically isolated aortitis warrant imaging of the entire aorta at baseline and regular intervals because a significant proportion of patients have or develop abnormalities in other vascular beds.

An Automated Method for Artifical Intelligence Assisted Diagnosis of Active Aortitis Using Radiomic Analysis of FDG PET-CT Images

The aim of this study was to develop and validate an automated pipeline that could assist the diagnosis of active aortitis using radiomic imaging biomarkers derived from [18F]-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography (FDG PET-CT) images. The aorta was automatically segmented by convolutional neural network (CNN) on FDG PET-CT of aortitis and control patients. The FDG PET-CT dataset was split into training (43 aortitis:21 control), test (12 aortitis:5 control) and validation (24 aortitis:14 control) cohorts. Radiomic features (RF), including SUV metrics, were extracted from the segmented data and harmonized. Three radiomic fingerprints were constructed: A-RFs with high diagnostic utility removing highly correlated RFs; B used principal component analysis (PCA); C-Random Forest intrinsic feature selection. The diagnostic utility was evaluated with accuracy and area under the receiver operating characteristic curve (AUC). Several RFs and Fingerprints had high AUC values (AUC > 0.8), confirmed by balanced accuracy, across training, test and external validation datasets. Good diagnostic performance achieved across several multi-centre datasets suggests that a radiomic pipeline can be generalizable. These findings could be used to build an automated clinical decision tool to facilitate objective and standardized assessment regardless of observer experience.

Multidisciplinary diagnosis and management of inflammatory aortic aneurysms

BACKGROUND

Inflammatory abdominal aortic aneurysms (IAAAs) are a variant involving a distinct immunoinflammatory process, with nearly one half believed to be associated with IgG4-related disease (IgG4-RD).

METHODS

MEDLINE and Google Scholar searches were conducted for English-language publications relevant to inflammatory aortic aneurysms from January 1970 onward. The search terms included inflammatory aortic aneurysms, aortitis, periaortitis, IgG4-related disease, and retroperitoneal fibrosis. Relevant studies were selected for review based on their relevance.

RESULTS

Morphologically, IAAAs are characterized by a thickened aneurysm wall often displaying contrast enhancement and elevated metabolic activity on fluorine-18 fluorodeoxyglucose-positron emission tomography imaging. A strong association exists with perianeurysmal and retroperitoneal fibrosis. Although the rupture risk appears lower with IAAAs than with noninflammatory abdominal aortic aneurysms (AAAs), the currently recommended diameter threshold for operative management is the same. Open repair has been associated with increased morbidity compared with noninflammatory AAAs, and a retroperitoneal approach or minimal dissection transperitoneal approach has been recommended to avoid duodenal and retroperitoneal structural injuries. Endovascular aneurysm repair has been increasingly used, especially for patients unfit for open surgery. It is important to exclude an infectious etiology before the initiation of immunosuppressive therapy or operative repair. Multimodality imaging follow-up is critical to monitor disease activity and secondary involvement of retroperitoneal structures by the associated fibrotic process. Maintenance of immunosuppressive therapy will be needed postoperatively for most patients with active systemic disease, especially those with IgG4-RD and those with persistent symptoms. Additional interventions aimed at ureteral decompression could also be required, and lifelong follow-up is mandatory.

CONCLUSIONS

Preoperative multimodality imaging is a diagnostic cornerstone for assessment of the disease extent and activity. IgG4-RD is an increasingly recognized category of IAAAs, with implications for tailoring adjunctive medical therapy. Open surgical repair remains the procedure of choice, although endovascular aneurysm repair is increasingly being offered. Maintenance immunosuppressive therapy can be offered according to the disease activity as assessed by follow-up imaging studies.

Computed tomography for aortic assessment in children

Because the aorta is the major vessel of the body, basic knowledge of aortic pathology is essential to the pediatric imager. This review divides aortic pathology into anatomical (e.g., congenital abnormalities) and acquired (e.g., vasculitis, trauma) entities, providing a brief description of pathology, technical considerations in CT acquisition and processing, and some pearls and pitfalls of interpretation. The objective of this paper is to familiarize general pediatric imagers with imaging features of common as well as high-impact aortic pathology on CT and prepare them for acquisition and reporting.