Takayasu arteritis: Utility and limitations of magnetic resonance imaging in diagnosis and treatment

Abstract

Objective. Previous studies have confirmed the poor correlation of symptoms, signs, and levels of acute-phase reactants with disease activity in ϳ50% of all patients with Takayasu arteritis (TA). Invasive angiographic studies demonstrate vessel lumen anatomy, but do not provide qualitative information about the vessel wall. Moreover, sequential invasive angiographic studies expose patients to high-dose ionizing radiation and catheter/procedure-related morbidity. The aim of the present study was to determine the utility of new developments in vascular magnetic resonance (MR) technology in patients with TA.Methods. Electrocardiogram-gated "edemaweighted" MR was used to evaluate the aorta and its primary branches with regard to the vascular lumen, vessel wall anatomy, and vessel wall edema in 24 TA patients (77 studies). Inclusion criteria were age <50 years and features of TA on both clinical examination and invasive angiographic studies. Patients were stratified based on clinical and laboratory indications of having either unequivocally active disease, inactive disease, or uncertain disease status.Results. MR revealed vessel wall edema in 94% (17 of 18), 81% (13 of 16), and 56% (24 of 43) of studies obtained during periods of unequivocally active disease, uncertain disease activity, and apparent clinical remission, respectively. Westergren erythrocyte sedimentation rate and C-reactive protein values did not correlate with either the clinical assessment of disease activity or MR evidence of vascular edema. The frequency of presumed vascular inflammation (edema), as assessed by MR, in patients who appeared to be in remission was similar to the reported frequency of new angiographic lesions and histopathologic evidence of active disease in surgical specimens from patients thought to be in remission. However, the presence of edema within vessel walls did not consistently correlate with the occurrence of new anatomic changes found on subsequent studies.Conclusion. Inconsistencies in the presence or absence of vessel edema and subsequent anatomic changes have cast doubt on the utility of edemaweighted MR imaging as a sole guide to disease activity and treatment in TA. In this study, the greatest utility of MR was in providing a safe, noninvasive means of assessing changes in vascular anatomy.

Is 18F‐fluorodeoxyglucose positron emission tomography scanning a reliable way to assess disease activity in takayasu arteritis?

“…We have shown that the ESR and CRP values as well as the proportion of patients with elevated ESR or CRP values did not correlate with abnormal vascular uptake on FDG-PET scans. We found no correlation between positive findings of PET scanning and radiologic activity as assessed by gadolinium uptake, wall edema, or wall thickening, while previous studies have underlined the potential value of these criteria in evaluating TA patients (4,11,16).…”

“…Assessing disease activity in TA patients is challenging because clinical, biologic, and radiologic data do not always correlate (1)(2)(3)(4). In the present study, we found a lack of correlation between FDG uptake and biologic or radiologic assessment of disease activity and a trend toward an association between FDG uptake and clinical activity.…”

“…We believe that this minimized the risk of misevaluation of clinical activity that would have resulted from knowledge of the biologic data. Increased vessel wall thickness and mural contrast enhancement on T1 sequences as well as vessel wall edema on STIR T2 sequences have been proposed as markers of disease activity, but are also recognized as nonspecific (4). Because there are no validated MRI criteria for disease activity in TA, we chose to define radiologically active cases as patients in whom any of the 3 MRI criteria was present.…”

“…Other imaging modalities, such as MRI (4,11), CT scan (12), and Doppler (13), have recently emerged as alternative radiologic procedures and are now used routinely. Because of its capacity to detect areas of increased glucose metabolism, some authors have claimed that PET scanning could play a role in the management of large-vessel vasculitis.…”

“…Evaluation of disease activity in patients with TA is challenging because clinical features do not correlate with acute-phase reactants in ϳ50% of cases (1)(2)(3), and imaging modalities do not always correlate with clinical and laboratory parameters (4). The complexity of evaluating disease activity in TA is further underlined by the fact that up to 45% of patients in clinical remission have histologic evidence of active disease (1,5).…”