A study showed lower sensitivity MRA Chest, Abdomen, and Pelvis Although MRA is considered an ideal imaging modality for vessel wall evaluation with its high tissue resolution ability, the literature on LVV diagnosis is limited. In a recent study involving 75 patients, when the authors used the temporal artery biopsy as the reference test, the sensitivity and specificity of MRA to diagnose LVV was 79% and 96%, respectively [73]. In the same study, PPV and NPV were 92% and 88%, respectively [73]. However, in a meta-analysis to diagnose TAK only, the pooled sensitivities and specificities were as high as 92% [29]. In addition, another study found that the use of whole-body contrast-enhanced MRA in patients with TAK was useful to diagnose active versus inactive TAK [74]. Similar to CTA, wall thickening and enhancement of the vessel wall on MRA were considered good markers of disease activity [29]. Per EULAR recommendations, MRA was considered as a first imaging modality for patients with TAK, considering the age of this population [22]. Interestingly, a prospective study by Quinn et al [53], demonstrated that MRA identified a greater extent of vascular involvement than PET because MRA can detect both arterial wall abnormalities (wall thickness and edema) and luminal abnormalities (aneurysm, stenosis, and occlusion). However, when investigators assessed disease activity, the interrater agreement was greater for PET scan reads than for MRA reads (kappa = 0.84 versus 0.58), indicating that assessment of disease activity by PET is more reliable than MRA. In that study, the authors found that vascular thickness and vascular edema on short-tau inversion recovery sequences were independently associated with the global FDG-PET/CT study interpretation on disease activity [53]. In another study, Einspieler et al [54] demonstrated consistent results between the use of FDG-PET/MRI and FDG- PET/CT.
Noncerebral Vasculitis. A study showed lower sensitivity MRA Chest, Abdomen, and Pelvis Although MRA is considered an ideal imaging modality for vessel wall evaluation with its high tissue resolution ability, the literature on LVV diagnosis is limited. In a recent study involving 75 patients, when the authors used the temporal artery biopsy as the reference test, the sensitivity and specificity of MRA to diagnose LVV was 79% and 96%, respectively [73]. In the same study, PPV and NPV were 92% and 88%, respectively [73]. However, in a meta-analysis to diagnose TAK only, the pooled sensitivities and specificities were as high as 92% [29]. In addition, another study found that the use of whole-body contrast-enhanced MRA in patients with TAK was useful to diagnose active versus inactive TAK [74]. Similar to CTA, wall thickening and enhancement of the vessel wall on MRA were considered good markers of disease activity [29]. Per EULAR recommendations, MRA was considered as a first imaging modality for patients with TAK, considering the age of this population [22]. Interestingly, a prospective study by Quinn et al [53], demonstrated that MRA identified a greater extent of vascular involvement than PET because MRA can detect both arterial wall abnormalities (wall thickness and edema) and luminal abnormalities (aneurysm, stenosis, and occlusion). However, when investigators assessed disease activity, the interrater agreement was greater for PET scan reads than for MRA reads (kappa = 0.84 versus 0.58), indicating that assessment of disease activity by PET is more reliable than MRA. In that study, the authors found that vascular thickness and vascular edema on short-tau inversion recovery sequences were independently associated with the global FDG-PET/CT study interpretation on disease activity [53]. In another study, Einspieler et al [54] demonstrated consistent results between the use of FDG-PET/MRI and FDG- PET/CT.