Diagnostic performance of ¹⁸F-fluorodeoxyglucose positron emission tomography in giant cell arteritis: a systematic review and meta-analysis

A Case of Large Vessel Giant Cell Arteritis Presenting With Cough and Diagnosed Using an FDG-PET Scan

Giant-cell arteritis (GCA) is a type of vasculitis characterised by the presence of granulomas. It is the predominant form of systemic vasculitis in adults and primarily affects the larger arteries in individuals aged ≥ 50 years. GCA affects the major arteries, such as the aorta and its branches, particularly the outer branches of the external carotid artery. Signs and symptoms can be categorised into cranial, extracranial, and systemic manifestations. Patients with headaches, jaw claudication, and vision disturbances usually have extracranial branches of the external carotid artery. Aside from being the prevailing manifestation of GCA, our primary concern regarding this variant is the potential for irreversible vision loss if not properly identified and addressed. Conversely, the GCA can also affect other major blood vessels such as the aorta. Here, we present the case of a 70-year-old Caucasian female patient with cranial GCA who had experienced a temporal headache three years prior. The patient was successfully treated with prednisolone, which was gradually reduced to a very low level with the assistance of methotrexate. Recently, the patient presented with a dry cough that lasted for two months and elevated inflammatory markers. After thorough research, it was determined that there was no evidence of infection, including atypical infections, and that no abnormalities were found in the lungs. Ultimately, via an 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) scan, the patient was diagnosed with large vessel giant cell arteritis (LV-GCA). This impacted the aorta, carotid arteries, and subclavian arteries. The patient experienced notable improvement in her cough and a reduction in inflammatory markers after receiving a high dosage of oral prednisolone. This case exemplifies the unusual manifestation of LV-GCA and verifies that recurring symptoms may differ from the original presentation. While dry cough is not commonly listed as a symptom of LV-GCA, it can be present as a manifestation or the sole presentation in certain patients, particularly when inflammatory markers are consistently high and there is no pulmonary disease.

PET/CT in Inflammatory and Auto-immune Disorders: Focus on Several Key Molecular Concepts, FDG, and Radiolabeled Probe Perspectives

Chronic immune diseases mainly include autoimmune and inflammatory diseases. Managing chronic inflammatory and autoimmune diseases has become a significant public health concern, and therapeutic advancements over the past 50 years have been substantial. As therapeutic tools continue to multiply, the challenge now lies in providing each patient with personalized care tailored to the specifics of their condition, ushering in the era of personalized medicine. Precise and holistic imaging is essential in this context to comprehensively map the inflammatory processes in each patient, identify prognostic factors, and monitor treatment responses and complications. Imaging of patients with inflammatory and autoimmune diseases must provide a comprehensive view of the body, enabling the whole-body mapping of systemic involvement. It should identify key cellular players in the pathology, involving both innate immunity (dendritic cells, macrophages), adaptive immunity (lymphocytes), and microenvironmental cells (stromal cells, tissue cells). As a highly sensitive imaging tool with vectorized molecular probe capabilities, PET/CT can be of high relevance in the management of numerous inflammatory and autoimmune diseases. Relying on key molecular concepts of immunity, the clinical usefulness of FDG-PET/CT in several relevant inflammatory and immune-inflammatory conditions, validated or emerging, will be discussed in this review, together with radiolabeled probe perspectives.

Limb arteries involvement assessed by FDG/PET CT at diagnosis of giant cell arteritis and risk of relapse: An observational study

INTRODUCTION

Steroids and anti-IL6 biotherapy are highly effective in obtaining remission in patients with giant cell arteritis (GCA) but the risk of relapses remains high. We aimed to identify predictors of relapse in GCA.

METHODS

All consecutive patients admitted with a new diagnosis of GCA - according to the 2022 American College of Rheumatology/EULAR (ACR/EULAR) classification criteria - between May 2011 and May 2022 were eligible for this study. The primary outcome was the GCA relapse rate over the 36-months follow up. Factors associated with the primary outcome and time to first relapse were analyzed.

RESULTS

One hundred and eight patients (74 [69-81] years, 64.8% women) with a new diagnosis of GCA were studied. GCA was biopsy-proven in 65 (60.2%) cases. Ninety-eight (90.7%) FDG/PET CT scans performed at diagnosis were available for review. All patients received steroids given for 21.0 [18.0-28.5] months, associated with methotrexate (n=1, 0.9%) or tocilizumab (n=2, 1.9%). During a median follow-up of 27.5 [11.4-35.0] months, relapse occurred in 40 (37%) patients. Multivariable Cox regression model, including general signs, gender, aortic wall thickness, FDG uptake in arterial wall and IV steroid pulse as covariates, showed that both general signs (HR 2.0 [1.0-4.0, P<0.05) and FDG uptake in limb arteries (HR 2.7 [1.3-5.5], P<0.01) at diagnosis were associated with GCA relapse.

CONCLUSION

FDG uptake in limb arteries at diagnosis is a predictor of relapse in newly diagnosed GCA.

The additional value of 18F-FDG PET/CT imaging in guiding the treatment strategy of non-tuberculous mycobacterial patients

OBJECTIVES

Non-tuberculous mycobacteria (NTM) infection is an increasing health problem due to delaying an effective treatment. However, there are few data on 18F-FDG PET/CT for evaluating the status of NTM patients. The aim of this study was to investigate the potential value of 18F-FDG PET/CT in guiding the treatment strategy of NTM patients.

METHODS

We retrospectively analyzed the cases of 23 NTM patients who underwent 18F-FDG PET/CT. The clinical data, including immune status and severity of NTM pulmonary disease (NTM-PD), were reviewed. The metabolic parameters of 18F-FDG included maximum standardized uptake value (SUVmax), SUVmax of the most FDG-avid lesion (SUVTop), SUVTop/SUVmax of the liver (SURLiver), SUVTop/SUVmax of the blood (SURBlood), metabolic lesion volume (MLV), and total lesion glycolysis (TLG). The optimal cut-off values of these parameters were determined using receiver operating characteristic curves.

RESULTS

There were 6 patients (26.09%) with localized pulmonary diseases and 17 patients (73.91%) with disseminated diseases. The NTM lesions had high or moderate 18F-FDG uptake (median SUVTop: 8.2 ± 5.7). As for immune status, the median SUVTop in immunocompromised and immunocompetent patients were 5.2 ± 2.5 and 10.0 ± 6.4, respectively, with a significant difference (P = 0.038). As for extent of lesion involvement, SURLiver and SURBlood in localized pulmonary and disseminated diseases were 1.9 ± 1.1 vs. 3.8 ± 1.6, and 2.7 ± 1.8 vs. 5.5 ± 2.6, respectively, with a significant difference (P = 0.016 and 0.026). Moreover, for disease severity, SUVmax of the lung lesion (SUVI-lung) and SUVmax of the marrow (SUVMarrow) in the severe group were 7.7 ± 4.3 and 4.4 ± 2.7, respectively, significantly higher than those in the non-severe group (4.4 ± 2.0 and 2.4 ± 0.8, respectively) (P = 0.027 and 0.036). The ROC curves showed that SUVTop, SURLiver, SURBlood, SUVI-lung, and SUVMarrow had a high sensitivity and specificity for the identification of immune status, lesion extent, and severity of disease in NTM patients.

CONCLUSION

18F-FDG PET/CT is a useful tool in the diagnosis, evaluation of disease activity, immune status, and extent of lesion involvement in NTM patients, and can contribute to planning the appropriate treatment for NTM.

Usefulness of 18F-FDG PET-CT for assessing large-vessel involvement in patients with suspected giant cell arteritis and negative temporal artery biopsy

OBJECTIVE

To investigate the usefulness of 18F-FDG PET-CT for assessing large-vessel (LV) involvement in patients with suspected giant cell arteritis (GCA) and a negative temporal artery biopsy (TAB).

METHODS

A retrospective review of our hospital databases was conducted to identify patients with suspected GCA and negative TAB who underwent an 18F-FDG PET-CT in an attempt to confirm the diagnosis. The gold standard for GCA diagnosis was clinical confirmation after a follow-up period of at least 12 months.

RESULTS

Out of the 127 patients included in the study, 73 were diagnosed with GCA after a detailed review of their medical records. Of the 73 patients finally diagnosed with GCA, 18F-FDG PET-CT was considered positive in 61 cases (83.5%). Among the 54 patients without GCA, 18F-FDG PET-CT was considered positive in only eight cases (14.8%), which included 1 case of Erdheim-Chester disease, 3 cases of IgG4-related disease, 1 case of sarcoidosis, and 3 cases of isolated aortitis. Overall, the diagnostic performance of 18F-FDG PET-CT for assessing LV involvement in patients finally diagnosed with GCA and negative TAB yielded a sensitivity of 83.5%, specificity of 85.1%, and a diagnostic accuracy of 84% with an area under the ROC curve of 0.844 (95% CI: 0.752 to 0.936). The sensitivity was 89% in occult systemic GCA and 100% in extracranial LV-GCA.

CONCLUSION

Our study confirms the utility of 18F-FDG PET-CT in patients presenting with suspected GCA and a negative TAB by demonstrating the presence of LV involvement across different subsets of the disease.

Positron Emission Computed Tomography Spectrum of Large Vessel Vasculitis in a Tertiary Center: Differences in 18F-fluorodeoxyglucose Uptake between Large Vessel Vasculitis with Predominant Cranial and Extracranial Giant Cell Arteritis Phenotypes

(1) Objective:To assess the spectrum of PET-CT-related large vessel vasculitis (LVV) in a Spanish tertiary center and to determine whether FDG uptake by PET-CT differs between giant cell arteritis (GCA) with predominant cranial or extracranial phenotypes. (2) Methods: The spectrum of patients diagnosed with LVV by PET-CT in a tertiary referral hospital that cares for 450,000 people over a period of two years was reviewed. Moreover, differences in FDG uptake between LVV-GCA with predominantly cranial and extracranial phenotype were analyzed. (3) Results: Eighty patients were diagnosed with LVV by PET-CT. Most were due to systemic vasculitis (n = 64; 80%), especially GCA (n = 54; 67.5%). Other conditions included the presence of rheumatic diseases (n = 4; 3.2%), tumors (n = 9; 7.2%) and infections (n = 3; 2.4%). LVV-GCA patients with predominant extracranial GCA phenotype were younger (mean ± SD: 68.07 ± 9.91 vs. 75.46 ± 7.64 years; p = 0.017) and had a longer delay to the diagnosis (median [interquartile range] 12 [4-18] vs. 4 [3-8]; p = 0.006), but had polymyalgia rheumatica symptoms more frequently than those with predominantly cranial GCA phenotype (46.3% vs. 15.4%, p = 0.057). When FDG uptake was compared according to the two different disease patterns, no statistically significant differences were observed. However, patients with extracranial LVV-GCA showed a non-significantly higher frequency of vasculitic involvement of lower-extremity arteries. (4) Conclusions: Regardless of the predominant phenotype, LVV identified by PET-CT is more commonly due to GCA in the Spanish population. In these GCA patients, younger age, PMR, and a higher frequency of lower-extremity artery vasculitis suggest the presence of LVV.

Imaging in diagnosis, monitoring and outcome prediction of large vessel vasculitis: a systematic literature review and meta-analysis informing the 2023 update of the EULAR recommendations

OBJECTIVES

To update the evidence on imaging for diagnosis, monitoring and outcome prediction in large vessel vasculitis (LVV) to inform the 2023 update of the European Alliance of Associations for Rheumatology recommendations on imaging in LVV.

METHODS

Systematic literature review (SLR) (2017-2022) including prospective cohort and cross-sectional studies (>20 participants) on diagnostic, monitoring, outcome prediction and technical aspects of LVV imaging. Diagnostic accuracy data were meta-analysed in combination with data from an earlier (2017) SLR.

RESULTS

The update retrieved 38 studies, giving a total of 81 studies when combined with the 2017 SLR. For giant cell arteritis (GCA), and taking clinical diagnosis as a reference standard, low risk of bias (RoB) studies yielded pooled sensitivities and specificities (95% CI) of 88% (82% to 92%) and 96% (95% CI 86% to 99%) for ultrasound (n=8 studies), 81% (95% CI 71% to 89%) and 98% (95% CI 89% to 100%) for MRI (n=3) and 76% (95% CI 67% to 83%) and 95% (95% CI 71% to 99%) for fluorodeoxyglucose positron emission tomography (FDG-PET, n=4), respectively. Compared with studies assessing cranial arteries only, low RoB studies with ultrasound assessing both cranial and extracranial arteries revealed a higher sensitivity (93% (95% CI 88% to 96%) vs 80% (95% CI 71% to 87%)) with comparable specificity (94% (95% CI 83% to 98%) vs 97% (95% CI 71% to 100%)). No new studies on diagnostic imaging for Takayasu arteritis (TAK) were found. Some monitoring studies in GCA or TAK reported associations of imaging with clinical signs of inflammation. No evidence was found to determine whether imaging severity might predict worse clinical outcomes.

CONCLUSION

Ultrasound, MRI and FDG-PET revealed a good performance for the diagnosis of GCA. Cranial and extracranial vascular ultrasound had a higher pooled sensitivity with similar specificity compared with limited cranial ultrasound.

Diagnostic yield of combined cranial and large vessel PET/CT, ultrasound and MRI in giant cell arteritis: A systematic review and meta-analysis

OBJECTIVES

To estimate the diagnostic accuracy of combined cranial and large vessel imaging by PET/CT, ultrasound and MRI for giant cell arteritis (GCA).

METHODS

PubMed, Embase, Cochrane and Web of Science databases were searched from inception till August, 312,022. Studies were included if they involved patients with suspected GCA and assessed the diagnostic accuracy of combined cranial and large vessel imaging by PET/CT, ultrasound or MRI with the final clinical diagnosis as reference standard.

RESULTS

Eleven (1578 patients), 3 (149 patients) and 0 studies were included for the diagnostic accuracy of ultrasound, PET/CT and MRI, respectively. Combined cranial and large vessel ultrasound had a sensitivity of 86% (76-92%) and specificity of 96% (92-98%). PET/CT of both cranial and large vessels yielded a sensitivity of 82% (61-93%) and specificity of 79% (60-90%). No studies assessed both PET/CT and ultrasound, which precluded head-to-head comparison. Addition of large vessel ultrasound to ultrasound of the temporal arteries (7 studies) significantly increased sensitivity (91% versus 80%, p < 0.001) without decrease in specificity (96% versus 95%, p = 0.57). Evaluating cranial arteries in addition to large vessels on PET/CT (3 studies) tended to increase the sensitivity (82% versus 68%, p = 0.07) without decrease in specificity (81% versus 79%, p = 0.70).

CONCLUSION

Combined cranial and large vessel ultrasound and PET/CT provided excellent accuracy for the diagnosis of GCA. Either PET/CT or ultrasound may be preferred depending on setting, expertise and clinical presentation. The diagnostic accuracy of combined cranial and large vessel MRI needs to be determined in future studies.

Role of 18F-FDG PET/CT in Large Vessel Vasculitis and Polymyalgia Rheumatica

Systemic vasculitides comprise a group of autoimmune diseases affecting blood vessels, including large vessel vasculitis (LVV) and medium-sized vessel vasculitis such as giant cell arteritis (GCA) and Takayasu arteritis (TAK). GCA frequently overlaps with polymyalgia rheumatica (PMR), a rheumatic inflammatory condition affecting bursae, tendons or tendon sheaths, and joints. ¹⁸F-FDG PET/CT plays an important role in the diagnostic work-up of GCA, PMR, and TAK and is increasingly used to monitor treatment response. This continuing education article provides up-to-date guidance on the role of ¹⁸F-FDG PET/CT in patients with LVV, medium-sized vessel vasculitis, and PMR. It provides a general introduction on the clinical presentation and challenges in the diagnostic work-up of LVV and medium-sized vessel vasculitis, with a focus on the 2 major LVV subtypes: GCA, including PMR, and TAK. Next, practice points to perform and interpret the results of ¹⁸F-FDG PET/CT are described in line with the published procedure recommendations. Furthermore, the diagnostic performance and its role for treatment monitoring are discussed, taking into account recent international recommendations for the use of imaging in LVV and medium-sized vessel vasculitis in clinical practice. This is illustrated by several clinically representative PET/CT scan examples. Lastly, knowledge of limitations and pitfalls is essential to understand the role of ¹⁸F-FDG PET/CT in LVV, medium-sized vessel vasculitis, and PMR. Challenges and opportunities, as well as future research and conclusions, are highlighted. Learning objectives provide up-to-date guidance for the role of ¹⁸F-FDG PET/CT in patients with suspected LVV, medium-sized vessel vasculitis, and PMR.

Update on Imaging of Inflammatory Arthritis and Related Disorders

Arthritis and other rheumatic disorders are very frequent in the general population and responsible for a huge physical and disability burden to affected patients as well as a major cost to the society. Precise evaluation often relies on clinical data only but additional imaging may be required i) for a more objective assessment of the disease status, such as in rheumatoid arthritis (RA) or ankylosing spondyloarthritis (AS), ii) for providing prognostic information and evaluating response to treatment or iii) for establishing diagnosis, in patients with unclear clinical picture, such as polymyalgia rheumatica (PMR) and large-vessel vasculitis (LVV). Besides radiological techniques (x-rays, ultrasound, and MRI), functional and molecular imaging has emerged as a valid tool for this purpose in several disorders. Bone scanning has long been a method of choice but is now more used as a triage tool in patients with unclear complaints, including degenerative disorders (eg osteoarthritis). ¹⁸F-FDG-PET/CT (FDG) proved efficient in assessing the extent of the disease and response to treatment in RA and related disorders, and to provide accurate diagnosis in some systemic disorders, including PMR and LVV. Based on glucose metabolism, FDG-PET/CT is able to show increased metabolism in peripheral cells involved in inflammation (eg neutrophils, lymphocytes or monocytes/macrophages) but also in fibroblasts that proliferate in the pannus. The lack of specificity of FDG is a limitation and many alternative tracers were developed at the preclinical stage or applied in the clinics, especially within clinical trials. They include imaging of macrophages using translocator protein (TSPO), folate-receptors or other targets on activated cells. These new tools will undoubtedly become more and more available in the everyday clinical workup of patients with rheumatisms. Finally, it should be kept in mind that a very simple tracer, ¹⁸F-fluoride is widely more performant in AS than FDG.

Positron Emission Tomography Imaging in Vasculitis

Systemic vasculitides comprise a group of autoimmune diseases affecting blood vessels. [18F]-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (FDG-PET/CT) plays an important role in the diagnosis and therapeutic monitoring of vasculitides affecting large-sized and medium-sized vessels. FDG-PET/CT also provides complementary information to other vascular imaging tools. The resolution and sensitivity of newer generation scanners continues to increase, hereby improving the ability of FDG-PET/CT to accurately assess the full disease extent in patients with vasculitis. Novel tracers targeting specific immune cells will allow for more detailed detection of vascular infiltrates.

18-Fluorodeoxyglucose positron emission tomography/computed tomography for large vessel vasculitis in clinical practice

Diagnosis, prognostic assessment, and monitoring disease activity in patients with large vessel vasculitis (LVV) can be challenging. Early recognition of LVV and treatment adaptation is essential because vascular complications (aneurysm, dilatations, ischemic complications) or treatment related side effects can occur frequently in these patients. 18-fluorodeoxyglucose positron emission tomography/computed tomography (2-[18F]FDG-PET/CT) is increasingly used to diagnose, follow, and evaluate treatment response in LVV. In this review, we aimed to summarize the current evidence on the value of 2-[18F]FDG-PET/CT for diagnosis, follow, and treatment monitoring in LVV.

Performance of Deauville Criteria in [18F]FDG-PET/CT Diagnostics of Giant Cell Arteritis

In this retrospective study, PET/CT data from 59 patients with suspected giant cell arteritis (GCA) were reviewed using the Deauville criteria to determine an optimal cut-off between PET positivity and negativity. Seventeen standardised vascular regions were analysed per patient by three investigators blinded to clinical information. Statistical analysis included ROC curves with areas under the curve (AUC), Cohen's and Fleiss' kappa (κ) to calculate sensitivity, specificity, accuracy, and agreement. According to final clinician's diagnosis and the revised 2017 ACR criteria GCA was confirmed in 29 of 59 (49.2 %) patients. With a diagnostic cut-off ≥ 4 (highest tracer uptake of a vessel wall exceeds liver uptake) for PET positivity, all investigators achieved high accuracy (range, 89.8-93.2%) and AUC (range, 0.94-0.97). Sensitivity and specificity ranged from 89.7-96.6% and 83.3-96.7%, respectively. Agreement between the three investigators suggested 'almost perfect agreement' (Fleiss' κ = 0.84) A Deauville score of ≥4 as threshold for PET positivity yielded excellent results with high accuracy and almost perfect inter-rater agreement, suggesting a standardized, reproducible, and reliable score in diagnosing GCA. However, the small sample size and reference standard could lead to biases. Therefore, verification in a multicentre study with a larger patient cohort and prospective setting is needed.

Advances in Radiopharmaceutical Sciences for Vascular Inflammation Imaging: Focus on Clinical Applications

Biomedical imaging technologies offer identification of several anatomic and molecular features of disease pathogenesis. Molecular imaging techniques to assess cellular processes in vivo have been useful in advancing our understanding of several vascular inflammatory diseases. For the non-invasive molecular imaging of vascular inflammation, nuclear medicine constitutes one of the best imaging modalities, thanks to its high sensitivity for the detection of probes in tissues. 2-[¹⁸F]fluoro-2-deoxy-d-glucose ([¹⁸F]FDG) is currently the most widely used radiopharmaceutical for molecular imaging of vascular inflammatory diseases such as atherosclerosis and large-vessel vasculitis. The combination of [¹⁸F]FDG and positron emission tomography (PET) imaging has become a powerful tool to identify and monitor non-invasively inflammatory activities over time but suffers from several limitations including a lack of specificity and avid background in different localizations. The use of novel radiotracers may help to better understand the underlying pathophysiological processes and overcome some limitations of [¹⁸F]FDG PET for the imaging of vascular inflammation. This review examines how [¹⁸F]FDG PET has given us deeper insight into the role of inflammation in different vascular pathologies progression and discusses perspectives for alternative radiopharmaceuticals that could provide a more specific and simple identification of pathologies where vascular inflammation is implicated. Use of these novel PET tracers could lead to a better understanding of underlying disease mechanisms and help inform the identification and stratification of patients for newly emerging immune-modulatory therapies. Future research is needed to realize the true clinical translational value of PET imaging in vascular inflammatory diseases.

18F-FDG PET/CT in cardiovascular infection and inflammation

The diagnosis of cardiovascular infection and inflammation by [¹⁸F]FDG PET/CT in Nuclear Cardiology is of growing interest, because with respect to echocardiography this technique has improved the certainty in the diagnosis of infective endocarditis in patients with prosthetic valves, the increasing number of patients with implantable cardiac devices because of the progressive ageing of the population, as well as in patients with suspected large vessel vasculitis. All are serious clinical situations which require correct diagnosis and appropriate treatment as soon as possible, because they can cause severe complications, high mortality and also increased health care costs. We review the use of [¹⁸F]FDG PET/CT in cardiovascular infection and inflammation, including the clinical point of view and the contribution of other image modalities. We focus on the appropriate methodology for this exploration, patient preparation, image acquisition and correct interpretation and the quantification possibilities, defining the specific characteristics of the diagnosis in patients with prosthetic valves, implantable cardiac devices and large vessel vasculitis in the initial diagnosis as well as during follow-up to assess treatment response. We analyze the possible causes of false positive and false negative results and emphasize the special value of a multidisciplinary team for optimal management of these patients.

Contextualizing temporal arterial magnetic resonance angiography in the diagnosis of giant cell arteritis: a retrospective cohort study

OBJECTIVES

Imaging modalities have become common in evaluating patients for a possible diagnosis of GCA. This study seeks to contextualize how temporal arterial magnetic resonance angiography (TA-MRA) can be used in facilitating the diagnosis of GCA.

METHODS

A retrospective cohort study was performed on patients who had been previously referred to a rheumatologist for evaluation of possible GCA in Hamilton, Ontario, Canada. Data including clinical features, inflammatory markers, imaging, and biopsy results were extracted. Multivariable logistic regression model to predict the diagnosis of GCA. Using these models, the utility of TA-MRA in series with or in parallel to clinical evaluation was demonstrated across the cohort as well as in subgroups defined by biopsy and imaging status.

RESULTS

In total 268 patients had complete data. Those diagnosed with biopsy- and/or imaging-positive GCA were more likely to demonstrate classic features including jaw claudication and vision loss. Clinical multivariable modelling allowed for fair discriminability [receiver operating characteristic (ROC) 0.759, 95% CI: 0.703, 0.815] for diagnosing GCA; there was excellent discriminability in facilitating the diagnosis of biopsy-positive GCA (ROC 0.949, 0.898-1.000). When used in those with a pre-test probability of 50% or higher, TA-MRA had a positive predictive value of 93.0%; in those with a pre-test probability of 25% or less TA-MRA had a negative predictive value of 89.5%.

CONCLUSION

In those with high disease probability, TA-MRA can effectively rule in disease (and replace temporal artery biopsy). In those with low to medium probability, TA-MRA can help rule out the disease, but this continues to be a challenging diagnostic population.

Diagnostic Role of 18F-Fluorodeoxyglucose Positron Emission Tomography for the Evaluation of Patients With Inflammation of Unknown Origin

BACKGROUND

Sometimes, the underlying causes of inflammation cannot be established despite meticulous investigation, including medical history, physical examination, laboratory tests, and radiologic procedures. Rheumatologists are often faced with patients whose condition is known as inflammation of unknown origin (IUO). Differential diagnosis of IUO is diverse, and investigation of these cases is challenging and time-consuming.

OBJECTIVE

The study aimed to assess the diagnostic role of positron emission tomography/computed tomography (PET/CT) in the evaluation of patients with IUO.

METHODS

The study sample consisted of 97 adult patients with IUO who have not been previously diagnosed with an infectious, inflammatory, or malignant disease. The necessary data were collected from January 2015 to June 2018 with a 6-month follow-up period. The patients were screened using PET/CT after a specific diagnosis could not be established with detailed laboratory and radiologic evaluations.

RESULTS

A final diagnosis was established at follow-up, and 47 (54%) of the 97 patients had inflammatory diseases, 30 (34.4%) had malignancies, and 10 (11.4%) had infections. Despite meticulous investigation, 10 patients were left undiagnosed in the follow-up. PET/CT aided diagnosis in 59 patients (60.8%), but it was not helpful in 38 patients (39.2%). PET/CT was positive in 30 (63%) of the 47 patients with inflammatory diseases, whose final diagnosis was inflammatory rheumatic disease, as follows: large-vessel vasculitis in 19 patients, polymyalgia rheumatica in 7 patients, and seronegative arthritis or other rare miscellaneous diseases in 4 patients. The sensitivity of PET/CT was 67% with a specificity and diagnostic accuracy of 100% and 71%, respectively.

CONCLUSIONS

Investigation of the underlying etiology of IUO is time-consuming and challenging. PET/CT may help identify the final diagnosis more quickly by locating an obscure inflammatory site; thus, it may reduce the number of unnecessary biopsies, diagnostic time, anxiety, work loss, morbidity, and mortality.

Imaging Tests in the Early Diagnosis of Giant Cell Arteritis

Early recognition of giant cell arteritis (GCA) is crucial to avoid the development of ischemic vascular complications, such as blindness. The classic approach to making the diagnosis of GCA is based on a positive temporal artery biopsy, which is among the criteria proposed by the American College of Rheumatology (ACR) in 1990 to classify a patient as having GCA. However, imaging techniques, particularly ultrasound (US) of the temporal arteries, are increasingly being considered as an alternative for the diagnosis of GCA. Recent recommendations from the European League Against Rheumatism (EULAR) for the use of imaging techniques for large vessel vasculitis (LVV) included US as the first imaging option for the diagnosis of GCA. Furthermore, although the ACR classification criteria are useful in identifying patients with the classic cranial pattern of GCA, they are often inadequate in identifying GCA patients who have the extracranial phenotype of LVV. In this sense, the advent of other imaging techniques, such as magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET)/CT, has made it possible to detect the presence of extracranial involvement of the LVV in patients with GCA presenting as refractory rheumatic polymyalgia without cranial ischemic manifestations. Imaging techniques have been the key elements in redefining the diagnostic work-up of GCA. US is currently considered the main imaging modality to improve the early diagnosis of GCA.

Aortitis - An Interdisciplinary Challenge

The term 'aortitis' comprises a heterogeneous spectrum of diseases, with varied etiology and clinical presentations, whose common characteristic is the inflammation of the aortic wall. Since aortitis can mimic almost all common cardiovascular disorders, its clinical recognition remains a challenge. Some cases of aortitis remain undetected for a long time and may be diagnosed after severe life-threatening complications have already arisen. The diagnosis of aortitis is based on the presence of homogeneous circumferential thickening of the aortic wall detected on aortic imaging, or typical histological features in combination with clinical findings and laboratory parameters. Management of aortitis is usually conservative (immunosuppressive drugs in noninfectious aortitis; antimicrobial drugs in infectious). However, if vascular complications such as aortic aneurysm, rupture, or steno-occlusive events appear, aortic surgery or endovascular therapy may be required. This review article summarizes the current knowledge regarding the etiology, clinical presentation, diagnosis, and treatment of inflammatory diseases of the aorta to promote better clinical management of these entities.

The Utility of 18F-FDG PET/CT in Patients With Clinical Suspicion of Polymyalgia Rheumatica and Giant Cell Arteritis: A Prospective, Observational, and Cross-sectional Study

Objective

To define the proportions of agreement between fluorine‐18‐fluorodeoxyglucose (18F‐FDG) positron emission tomography/computed tomography (PET/CT), clinical diagnosis, and temporal artery biopsy (TAB) in patients with polymyalgia rheumatica (PMR) and giant cell arteritis (GCA). Furthermore, the association of 18F‐FDG PET/CT uptake patterns and clinical presentation of newly diagnosed PMR and GCA was investigated.

Methods

Eighty patients newly suspected of having PMR, GCA, or concomitant PMR and GCA were included and followed for 40 weeks. Every patient underwent an 18F‐FDG PET/CT scan before or within 3 days of initiation of steroids in case of GCA. FDG uptakes in 8 paired articular/periarticular sites and 14 arterial segments were evaluated based on a 4‐point visual grading scale.

Results

Of the 80 patients (female: 50 [62.5%]; mean age ± SD: 72.0 ± 7.9), 64 (80.0%) patients were diagnosed with pure PMR, 3 (3.7%) with pure GCA, and 10 (12.5%) with concomitant PMR and GCA. Additionally, three (3.7%) patients were diagnosed with seronegative rheumatoid arthritis during the follow‐up period. For the diagnosis of PMR, 18F‐FDG PET/CT had a proportion of agreement of 75.3 (64.2‐84.4), compared with clinical diagnosis. When comparing findings of 18F‐FDG PET/CT with TAB, 18F‐FDG PET/CT had a proportion of agreement of 93.0 (84.3‐97.7) in all included patients and 69.2 (38.6‐90.9) in the subgroup of patients with vasculitis. C‐reactive protein was significantly higher in patients with PMR activity on 18F‐FDG PET/CT compared with those without 18F‐FDG PET/CT activity (P value = 0.006).

Conclusions

18F‐FDG PET/CT is a powerful imaging technique in PMR and GCA that was in good agreement with clinical diagnosis and TAB.

An update on the general management approach to common vasculitides

Primary systemic vasculitides (PSV) are multisystem diseases associated with high morbidity and mortality, particularly if not treated in a timely manner. In recent decades, clinical trials have delivered considerable evidence to underpin optimal diagnostic and therapeutic approaches. This article provides a brief overview of PSV in adults, focusing on the latest updates and recommendations for the management of antineutrophil cytoplasmic antibody-associated vasculitis and giant cell arteritis.

18F-fluorodeoxyglucose positron emission tomography/computed tomography of giant cell arteritis with lower extremity involvement in association with polymyalgia rheumatica

An 80-year-old man presented with new-onset pain in the shoulders and lower extremities and elevated serum inflammatory markers. A clinical diagnosis of polymyalgia rheumatica (PMR) was made, but there was a suboptimal response to glucocorticoid therapy, prompting further evaluation. ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) revealed intense FDG uptake in the arteries of the bilateral lower extremities, head, and neck, but sparing the aorta, suggestive of an uncommon pattern of giant cell arteritis (GCA). There were also imaging signs consistent with PMR, including FDG uptake in the synovium of large joints. This case highlights the uncommon manifestation of GCA with lower extremity involvement and sparing of the aorta. The combination of FDG PET imaging features and elevated serum markers obviated the need for invasive biopsy. One might also conclude that standard FDG PET/CT imaging protocols covering orbits/vertex to thighs incompletely evaluate the extent of arterial distribution of GCA.

[The current place of non-invasive large-vessel imaging in the diagnosis and follow-up of giant cell arteritis]

Large vessel involvement in giant cell arteritis has long been described, although its right frequency and potential prognostic value have only been highlighted for two decades. Large vessel involvement not only is associated with a high incidence of late aortic aneurysms, but also might cause greater resistance to glucocorticoids and longer treatment duration, as well as worse late cardiovascular outcomes. These data were brought to our attention, thanks to substantial progress recently made in large vessel imaging. This relies on four single, often complementary, approaches of varying availability: colour Doppler ultrasound, contrast-enhanced computed tomography with angiography and, magnetic resonance imaging, which all demonstrate homogeneous circumferential wall thickening and describe structural changes; 18F-fluorodeoxyglucose positron emission tomography-computed tomography (PET/CT), which depicts wall inflammation and assesses many vascular territories in the same examination. In addition, integrated head-and-neck PET/CT can accurately and reliably diagnose cranial arteritis. All four procedures exhibit high diagnostic performance for a large vessel arteritis diagnosis so that the choice is left to the physician, depending on local practices and accessibility; the most important is to carry out the chosen modality without delay to avoid false or equivocal results, due to early vascular oedema changes as a result of high dose glucocorticoid treatment. Yet, ultrasound study of the superficial cranial and subclavian/axillary arteries remains a first line assessment aimed at strengthening and expediting the clinical diagnosis as well as raising suspicion of large-vessel involvement. In treated patients, vascular imaging results are poorly correlated with clinical-biological controlled disease so that it is strongly recommended not to renew imaging studies unless a large vessel relapse or complication is suspected. On the other hand, a structural monitoring of aorta following giant cell arteritis is mandatory, but uncertainties remain regarding the best procedural approach, timing of first control and spacing between controls. Individuals at greater risk of developing aortic complication, e.g. those with classic risk factors for aneurysm and/or visualised aortitis, should be monitored more closely.

Steroid refractory giant cell arteritis with bilateral vertebral artery occlusion and middle cerebellar peduncle infarction

Giant cell arteritis is the most common primary systemic vasculitis in adults aged ≥50 years and peaks in the eighth decade of life. Common symptoms include headache, scalp tenderness and jaw claudication. Elevated acute phase reactants (erythrocyte sedimentation rate and C-reactive protein) are present in >90% of patients. Visual loss is a well-recognised complication, but approximately 2-4% of giant cell arteritis patients experience stroke, most frequently in the vertebrobasilar territory. We describe a 72-year-old male who developed bilateral vertebral artery occlusion and middle cerebellar peduncle infarction secondary to giant cell arteritis in spite of high-dose steroids.

Giant cell arteritis manifested by chronic dry cough

A 77-year-old man visited the hospital with a chronic cough persisting for 2.5 months accompanied with night sweats, weight loss (3.5 kg) and elevated C-reactive protein level. Chest CT of the lung field was normal, but aortic wall thickening accompanied by a contrast effect was noted. Positron emission tomography-CT (PET-CT) showed that the aorta and subclavian artery were inflamed, suggesting large-vessel vasculitis. Ultrasonography showed thickening of the superficial temporal artery wall (macaroni sign). Biopsy revealed lymphocytic infiltration in the tunica media and foreign-body giant cell reaction with the elastic lamina, resulting in a diagnosis of giant cell arteritis (GCA). The cough was considered a symptom of GCA as it resolved following prednisolone administration. Cough may rarely be an initial GCA symptom. However, for chronic cough accompanied with elevated inflammatory findings but with a normal lung field, imaging studies such as PET-CT are useful for the differential diagnosis.

Imaging in Vasculitis

Purpose of Review

Vasculitides are characterized by mostly autoimmunologically induced inflammatory processes of vascular structures. They have various clinical and radiologic appearances. Early diagnosis and reliable monitoring are indispensable for adequate therapy to prevent potentially serious complications. Imaging, in addition to laboratory tests and physical examination, constitutes a key component in assessing disease extent and activity. This review presents current standards and some typical findings in the context of imaging in vasculitis with particular attention to large vessel vasculitides.

Recent Findings

Recently, imaging has gained importance in the management of vasculitis, especially regarding large vessel vasculitides (LVV). Recently, EULAR (European League Against Rheumatism) has launched its recommendations concerning the diagnosis of LVVs. Imaging is recommended as the preferred complement to clinical examination. Color-coded duplex sonography is considered the first choice imaging test in suspected giant cell arteritis, and magnetic resonance imaging is considered the first choice in suspected Takayasu’s arteritis.

Summary

Due to diversity of clinical and radiologic presentations, diagnosis and therapy monitoring of vasculitides may constitute a challenge. As a result of ongoing technological progress, a variety of non-invasive imaging modalities now play an elemental role in the interdisciplinary management of vasculitic diseases.

The role of cardiac imaging in the management of non-ischemic cardiovascular diseases in human immunodeficiency virus infection

Infection with human immunodeficiency virus (HIV) has become the pandemic of the new century. About 36.9 million people are living with HIV worldwide. The introduction of antiretroviral therapy in 1996 has dramatically changed the global landscape of HIV care, resulting in significantly improved survival and changing HIV to a chronic disease. With near-normal life expectancy, contemporary cardiac care faces multiple challenges of cardiovascular diseases, disorders specific to HIV/AIDS, and those related to aging and higher prevalence of traditional risk factors. Non-ischemic cardiovascular diseases are major components of cardiovascular morbidity and mortality in HIV/AIDS. Non-invasive cardiac imaging plays a pivotal role in the management of these diseases. This review summarizes the non-ischemic presentation of the HIV cardiovascular spectrum focusing on the role of cardiac imaging in the management of these disorders.

Diagnosis of giant cell arteritis

GCA is the most common form of primary systemic vasculitis affecting older people. It is considered a clinical emergency because it can lead to irreversible blindness in around 20% of untreated cases. High doses of glucocorticoids should be initiated promptly to prevent disease-related complications; however, glucocorticoids therapy usually results in significant toxicity. Therefore, correct diagnosis is crucial. For many years, temporal artery biopsy has been considered the diagnostic ‘gold standard’ for GCA, but it has many limitations (including low sensitivity). US has proven to be effective for diagnosing GCA and can reliably replace temporal artery biopsy in particular clinical settings. In cases of suspected GCA with large-vessel involvement, other imaging modalities can be used for diagnosis (e.g. CT and PET). Here we review the current evidence for each diagnostic modality and propose an algorithm to diagnose cranial-GCA in a setting with rapid access to high quality US.

18F-Fluorodeoxyglucose PET/Computed Tomography in the Diagnosis and Monitoring of Giant Cell Arteritis

18F-Fluorodeoxyglucose (FDG) PET/computed tomography (CT) is a highly accurate diagnostic tool for large vessel vasculitis (LVV) and is one of the recommended imaging modalities for confirmation of the diagnosis. This article focuses on the role of FDG-PET/CT in LVV diagnosis and disease monitoring, mainly focusing on giant cell arteritis; in particular, the diagnostic accuracy, diagnostic criteria, the potential pitfalls in the interpretation of large vessel FDG uptake, and the clinical indication compared with other imaging modalities are discussed.

Giant Cell Arteritis (GCA): Pathogenesis, Clinical Aspects and Treatment Approaches

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Giant Cell Arteritis (GCA), or Horton’s Arteritis, is a chronic form of vasculitis of the large and medium vessels, especially involving the extracranial branches of the carotid arteries, in particular, the temporal artery, with the involvement of the axillary, femoral and iliac arteries too. Arterial wall inflammation leads to luminal occlusion and tissue ischemia, which is responsible for the clinical manifestations of the disease.

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A substantial number of patients affected by GCA present head and neck symptoms, including ocular, neurological and otorhinolaryngological manifestations.

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The aim of this article is to present pathogenesis, clinical aspects and treatment approaches of GCA manifestations.

Fully integrated 18F-FDG PET/MR in large vessel vasculitis

BACKGROUND

To evaluate the usefulness of [18F] fluorodeoxyglucose (FDG) positron emission tomography (PET)/magnetic resonance (MR) in large vessels vasculitis (LVV) patients.

METHODS

We performed an observational retrospective study based on our records. Images were acquired on a PET/MR scanner using 18F-FDG-PET whole body imaging. For each PET scan, a qualitative analysis and a semi-quantitative measure using the maximum of the standardized uptake value (SUVMax) were performed. SUVMax measurements normalized to the liver uptake were categorized using a grading scale. Vessel's wall thickness (WT) was measured at five fixed points (inferior margin of T5, T9, T12, L3, thickest area-max WT).

RESULTS

23 LVV patients were included, 56.5% giant cells arteritis, 34.8% Takayasu's arteritis and 8.7% isolated aortitis, all Caucasian, mostly females (82%). We considered 32 PET scans for the LVV group (from min. 1 to max. 3 scans/patient) mainly during follow-up (29/32 scans), and 23 PET scans from a control group of non-metastatic malignancies patients. We found higher SUVMax compared to controls, in all sites, irrespective of clinical disease activity. Mean WT resulted higher in patients than in controls but was not correlated to SUVMax. Mean WT positively correlated with age in both cohorts, inversely correlated to disease duration, while no correlation with SUVMax was observed. The concordance between clinically active disease and PET hypermetabolism was poor (K Cohen 0.33).

CONCLUSIONS

PET/MR is a safe imaging technique capable of detecting inflammation in aortic wall. Low radiological exposure of PET/MR should be considered especially in young women receiving follow-up studies.

The Clinical Impact of Using 18F-FDG-PET/CT in the Diagnosis of Suspected Vasculitis: The Effect of Dose and Timing of Glucocorticoid Treatment

¹⁸F-Fluorodeoxyglucose positron-emission tomography (¹⁸F-FDG-PET) with computed tomography (CT) is effective for diagnosing large vessel vasculitis, but its usefulness in accurately diagnosing suspected, unselected vasculitis remains unknown. We evaluated the feasibility of ¹⁸F-FDG-PET/CT in real-life cohort of patients with suspicion of vasculitis. The effect of the dose and the timing of glucocorticoid (GC) medication on imaging findings were in special interest. 82 patients with suspected vasculitis were evaluated by whole-body ¹⁸F-FDG-PET/CT. GC treatment as prednisolone equivalent doses at the scanning moment and before imaging was evaluated. 38/82 patients were diagnosed with vasculitis. Twenty-one out of 38 patients had increased ¹⁸F-FDG accumulation in blood vessel walls indicating vasculitis in various sized vessels. Vasculitis patients with a positive vasculitis finding in ¹⁸F-FDG-PET/CT had a significantly shorter duration of GC use (median = 4.0 vs 7.0 days, P=0.034), and they used lower GC dose during the PET scan (median dose = 15.0 mg/day vs 40.0 mg/day, p=0.004) compared to ¹⁸F-FDG-PET/CT-negative patients. Vasculitis patients with a positive ¹⁸F-FDG-PET/CT result had significantly higher C-reactive protein (CRP) than patients with a negative ¹⁸F-FDG-PET/CT finding (mean value = 154.5 vs 90.4 mg/L, p=0.018). We found that ¹⁸F-FDG-PET/CT positivity was significantly associated with a lower dose and shorter duration of GC medication and higher CRP level in vasculitis patients. ¹⁸F-FDG-PET/CT revealed clinically significant information in over half of the patients and was effective in confirming the final diagnosis.

Diagnostic Performance of 18F-FDG PET/CT in Infectious and Inflammatory Diseases according to Published Meta-Analyses

Purpose

To date, several meta-analyses have reported data about the diagnostic performance of ¹⁸F-FDG PET/CT in infectious and inflammatory diseases. This article aims to summarize the published evidence-based data about the diagnostic performance of ¹⁸F-FDG PET/CT in this setting.

Methods

A comprehensive computer literature search of meta-analyses published in PubMed/MEDLINE and Cochrane library database from January 2009 through December 2018 and regarding the diagnostic performance of ¹⁸F-FDG PET/CT in infectious and inflammatory diseases was carried out. This combination of key words was used: (i) “PET” OR “positron emission tomography” OR “FDG” OR “fluorodeoxyglucose” AND (ii) meta-analysis. Only records on inflammatory or infectious diseases were selected.

Results

The diagnostic performance of ¹⁸F-FDG PET/CT in detecting inflammatory and infectious diseases has been summarized taking into account 36 meta-analyses published in the literature. Evidence-based data demonstrated good diagnostic performance of ¹⁸F-FDG PET/CT for several inflammatory and infectious diseases, in particular cardiovascular infectious and inflammatory diseases and some musculoskeletal infections.

Conclusions

Evidence-based data about the diagnostic performance of ¹⁸F-FDG PET/CT in infectious and inflammatory diseases are increasing, with good diagnostic performance of this imaging method for some indications. More prospective multicenter studies and cost-effective analyses are warranted.

[Positron emission tomography/computed tomography in rheumatology]

Combined positron emission tomography/computed tomography (PET/CT) is a whole-body imaging procedure, which enables sensitive detection of inflammatory changes. It may be used to simultaneously obtain both precise anatomical and molecular information in order to comprehensively characterize diseases. The glucose analogue ¹⁸F-fluorodeoxyglucose (FDG) represents a universally applicable radiotracer for imaging of inflammatory processes. Its accumulation in tissues can be semiquantitatively characterized by use of standardized uptake values (SUV). In principle, a broad spectrum of infectious and non-infectious inflammatory and malignant diseases can be imaged. ¹⁸F-FDG PET/CT has become a valuable modality and is increasingly being used for evaluation of large vessel vasculitis and for evaluation of elevated systemic inflammatory markers without known cause. Beside the radiotracer ¹⁸F-FDG, other radiopharmaceuticals enable a non-invasive analysis of additional parameters of inflammatory disorders, such as other metabolic pathways or the expression of surface receptors.

Imaging the Vasculitides

"Neuroimaging plays a vital role in the diagnosis of primary and secondary vasculitic disorders. There multiple neuroimaging options available to accurately describe the underlying clinical deficits of involved cases. Noninvasive neuroimaging modalities provide less risk and when interdigitated, form the basis for a more conclusive understanding of the disease process. There are instances in which invasive cerebral angiography may be needed to image the intricate and at times, small involved vessels. Neuroradiologists should be included in the multidisciplinary team of physicians caring for patients with vasculitides and in research to provide more sensitive and safe modalities for accurate diagnosis."

F-18 FDG PET for assessment of disease activity of large vessel vasculitis: A systematic review and meta-analysis

BACKGROUND

The aim of this study is to investigate the performance of F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) or positron emission tomography/computed tomography (PET/CT) for the assessment of disease activity in patients with large vessel vasculitis (LVV) through a meta-analysis.

METHODS

The MEDLINE via PubMed and EMBASE were searched for the studies evaluating the performance of F-18 FDG PET or PET/CT in the assessment of disease activity in patients with LVV. Pooled sensitivity, specificity, diagnostic odds ratios (DORs), and summary receiver-operating characteristic (sROC) curve were estimated across the included studies. Possible publication bias was assessed by Deek's funnel plot asymmetry tests.

RESULTS

A total of 439 PET images from 298 patients pooled from nine studies showed that the pooled sensitivity was 0.88 [95% confidence interval (CI) 0.79-0.93] without heterogeneity (χ2 = 14.42, P = .07) and the pooled specificity was 0.81 (95% CI 0.64-0.91) with heterogeneity (χ2 = 63.72, P = .00) for the detection of active LVV. The pooled DOR was 30 (95% CI 8-107). Hierarchical sROC curve indicates that the area under the curve was 0.91 (95% CI 0.89-0.94). There was no significant publication bias (P = .42), and meta-regression analysis revealed that none of the variables was the source of the study heterogeneity.

CONCLUSIONS

F-18 FDG PET has a good performance for the detection of active disease status in patients with LVV. Revised criteria for the assessment of disease activity incorporated with F-18 FDG PET or PET/CT should be introduced and validated. Further studies are warranted to determine if PET-based treatment of LVV can improve outcomes.

Imaging modalities in the management of aortitis

Aortitis is a pathological term that refers to the inflammation of one or more layers of the aortic wall. It is associated with a wide spectrum of inflammatory diseases of infectious and non-infectious origins, and often present with vague clinical findings and non-specific laboratory results that can model other entities. As a result, aortitis may not form part of the initial workup and appropriate treatment can be delayed or missed. Therefore, imaging modalities are required to assess for inflammation and structural changes in the aorta to support or exclude the diagnosis of aortitis. This review presents current literature on the imaging modalities utilized in the diagnosis and management of aortitis, which surgeons and physicians should be familiar with for providing optimal patient care.