Imaging modalities in the management of aortitis

Hybrid PET/MRI of large vessel vasculitis : Radiation dose compared to PET/CT with view on cumulative effective dose

BACKGROUND

The diagnosis of large vessel vasculitis (LVV) is often challenging due to the various clinical appearances and the low prevalence. Hybrid imaging by positron emission tomography and computed tomography (PET/CT) is a highly relevant imaging modality for diagnostics and disease surveillance but may be associated with a significant amount of radiation dose especially in patients with complications.

OBJECTIVE

The aim of this retrospective analysis was to compare the image quality and impact of hybrid imaging methods PET/CT and PET/MRI on the potential for dose reduction.

METHODS

This retrospective single-center study included a cohort of 32 patients who were referred to PET/MRI for the evaluation of LVV, including graft infections and fever of unknown origin. This cohort was compared to a similar cohort of 37 patients who were examined with PET/CT in the same period. Mean radiation dose as well as image quality to establish a diagnosis were compared between the groups.

RESULTS

The mean radiation dose applied in PET/MRI was significantly lower when compared to PET/CT (mean 6.6 mSV vs. 31.7 mSV; p < 0.001). This effect was based on the partially multiphasic CT protocols. At the same time, diagnostic image quality using a 4-point scale showed similar results for both imaging modalities in the work-up of LVV.

CONCLUSION

With PET/MRI, the radiation exposure can be significantly reduced with similar image quality and diagnostic impact. Patients with LVV have a higher risk of receiving a clinically relevant cumulative effective dose (CED) and PET/MRI should be made available to them.

A review on the deeper understanding of inflammation and infection of the thoracic aorta

OBJECTIVE

To review the current literature regarding infection and inflammation of the thoracic aorta and to summarise its aetiologies, pathogenesis and clinical presentation. Additionally, the authors sought to compare diagnostic methods and to analyse the different management options.

METHOD

A comprehensive electronic search using PubMed, MEDLINE, Scopus and Google Scholar was conducted to find relevant journal articles with key search terms including: 'aortitis', 'thoracic aortic infection' and 'surgical management of infected thoracic aortic aneurysms'. Prominent publications from 1995 till present (2021) were analysed to achieve a deeper understanding of thoracic aorta infection and inflammation, and the information was then collated to form this review.

RESULTS

The literature review revealed that infectious causes are more prominent than non-infectious causes, with Gram positive bacteria such as Staphylococcus, Enterococcus and Streptococcus accounting for approximately 60% of the infections. The authors also noted that Staphylococcus Aureus was associated with poorer outcomes. Key diagnostic tools include MRI and multi-slice CT imaging, which are useful imaging modalities in defining the extent of the disease thus allowing for planning surgical intervention. Surgical intervention itself is extremely multifaceted and the rarity of the condition means no large-scale comparative research between all the management options exists. Until more large-scale comparative data becomes available to guide treatment, the optimal approach must be decided on a case-by-case basis, considering the benefits and drawback of each treatment option.

CONCLUSION

A high index of suspicion and a comprehensive history is required to effectively diagnose and manage infection and inflammation of the thoracic aorta. Differentiating between infectious and inflammatory cases is crucial for management planning, as infectious causes typically require antibiotics and surgical intervention. Over the years, the post treatment results have shown significant improvement due to earlier diagnosis, advancement in surgical options and increasingly specific microbial therapy.

Aortitis masquerading as intramural hematoma: When to observe, when to operate? A case report

Radiologic evidence of aortic disease is not always consistent with the diagnosis. With a lack of accompanying symptoms or with an atypical presentation, diagnosis, and management of aortic pathology rely greatly on imaging techniques. We report the case of a 58-year-old female who presented with incidental radiographic findings consistent with a type A aortic intramural hematoma and a vague left-sided chest discomfort. After follow-up, imaging was consistent with disease progression and hematoma expansion; the affected segment was resected and pathology reported lymphoplasmacytic aortitis as the underlying etiology of the imaging findings rather than an intramural hematoma. The patient lacked symptoms or serology consistent with the rheumatologic disease, and the postoperative course was uneventful. The management of a suspected ascending intramural hematoma is controversial, especially when the patient presents with atypical signs and symptoms. Features of disease progression may warrant urgent surgical intervention.