Abstract
1584
Introduction: Childhood-onset large vessel vasculitides such as Takayasu arteritis are potentially devastating inflammatory diseases that predominately affect the aorta and its major branches. Diagnosis can often be delayed due to the nonspecific nature of symptoms and clinical heterogeneity of presentation. Lack of overt clinical symptoms and the absence of currently available reliable serologic biomarkers conceivably contribute to delay in diagnosis. F-18 fluorodeoxyglucose (FDG) positron-emission tomography (PET) in conjunction with magnetic resonance imaging (MRI) offer a promising approach in assessing inflammatory activity within the vasculature prior to the development of vessel damage (wall thickening, dilatation/aneurysm, stenosis, occlusion). Despite accumulating evidence supporting the role/utility of PET/MRI in characterizing disease activity, only few cases highlighting its use have been described in the pediatric literature to date.
Methods: Patients who presented to PET/MR with eventual diagnosis of large vessel vasculitis (LVV) from July 2019 to December 2019 were reviewed. Demographic information was collected. LVV anatomic region of involvement was documented, and visual grading was performed as follows: Grade 0: no vascular uptake (< mediastinum), Grade 1: vascular uptake < liver uptake, Grade 2: vascular uptake = liver uptake, Grade 3: vascular uptake > liver uptake. Arterial wall thickening was subjectively assessed by two independent radiologists and graded as follows: Grade 1: no visible wall thickening, Grade 2: perceptible wall thickening, Grade 3: marked wall thickening.
Results: Five patients (3F:2M) who presented to PET/MR with suspected large vessel vasculitis were identified (6 PET/MRI studies total). Median age at diagnosis was 15 years (range 12-16). In all but one patient PET/MRI was performed at diagnosis (n = 4), with one study performed at relapse (n =1). The most frequent pattern of vessel involvement was type V-generalized, diffuse (International TAK Conference in Tokyo 1994). One patient was noted to have involvement of the pulmonary arteries. All but one patient had evidence of disease damage (morphological vessel changes including wall thickening or luminal narrowing). One patient was a severe and refractory case: treated with two biologic agents and eventually cyclophosphamide (chemotherapy). One patient demonstrated diffuse CNS involvement.
Conclusions: FDG-PET/MR is able to identify and characterize vasculitis in the pediatric population. Longitudinal prospective studies are needed to further assess the potential applications of PET/MRI in monitoring therapeutic response and guiding treatment decisions in large vessel vasculitis in children.