A 4-point ranking scale is used to classify the affected vessels based on the wall thickness and mural contrast enhancement [20,21]. Although this can be acquired practically during body MRI/MRA studies, discussion of this modality is not in the scope of this manuscript. Noncerebral Vasculitis US and Color Doppler US US or color duplex US is a noninvasive imaging modality that has been used in the diagnosis of vasculitis. Particularly, in patients with suspected c-GCA, US/doppler US is recommended as the primary imaging modality [22]. Upper- and lower-extremity US can be added to increase diagnostic yield [23]. However, evaluation of the thoracic and abdominal vasculature is limited with US. Most of the literature on US is focused on its use in the temporal artery and, to a lesser extent, the extremity arteries. There is limited information regarding the use of chest, abdomen, and pelvis US or the diagnosis of LVV. CTA or CT with IV contrast can be combined with FDG-PET as a hybrid model for the early diagnosis of LVV [32-34]. In 1 study, the authors compared CTA with FDG-PET/CT and found that the sensitivity and specificity of CTA for diagnosing GCA were 73% and 78%, respectively, and that the negative predictive value (NPV) and positive predictive value (PPV) were 65% and 85%, respectively [35]. Other studies compared the diagnostic performance of CTA to FDG-PET/CT, and both procedures were similarly able to detect large-vessel involvement in GCA [34,36,37]. In the study by de Boysson et al [36] , CTA demonstrated high sensitivity of 95% and specificity of 100% when comparing the diagnosis per patient. However, when the diagnosis was compared per segments of the aorta and branches, FDG-PET/CT was more sensitive for the detection of inflammation, and CTA had lower sensitivity (61%) but still high specificity (98%). Two relatively small studies comparing contrast-enhanced CT and FDG-PET demonstrated comparable results, with a slightly superior diagnostic accuracy of FDG-PET [34,38].
Noncerebral Vasculitis. A 4-point ranking scale is used to classify the affected vessels based on the wall thickness and mural contrast enhancement [20,21]. Although this can be acquired practically during body MRI/MRA studies, discussion of this modality is not in the scope of this manuscript. Noncerebral Vasculitis US and Color Doppler US US or color duplex US is a noninvasive imaging modality that has been used in the diagnosis of vasculitis. Particularly, in patients with suspected c-GCA, US/doppler US is recommended as the primary imaging modality [22]. Upper- and lower-extremity US can be added to increase diagnostic yield [23]. However, evaluation of the thoracic and abdominal vasculature is limited with US. Most of the literature on US is focused on its use in the temporal artery and, to a lesser extent, the extremity arteries. There is limited information regarding the use of chest, abdomen, and pelvis US or the diagnosis of LVV. CTA or CT with IV contrast can be combined with FDG-PET as a hybrid model for the early diagnosis of LVV [32-34]. In 1 study, the authors compared CTA with FDG-PET/CT and found that the sensitivity and specificity of CTA for diagnosing GCA were 73% and 78%, respectively, and that the negative predictive value (NPV) and positive predictive value (PPV) were 65% and 85%, respectively [35]. Other studies compared the diagnostic performance of CTA to FDG-PET/CT, and both procedures were similarly able to detect large-vessel involvement in GCA [34,36,37]. In the study by de Boysson et al [36] , CTA demonstrated high sensitivity of 95% and specificity of 100% when comparing the diagnosis per patient. However, when the diagnosis was compared per segments of the aorta and branches, FDG-PET/CT was more sensitive for the detection of inflammation, and CTA had lower sensitivity (61%) but still high specificity (98%). Two relatively small studies comparing contrast-enhanced CT and FDG-PET demonstrated comparable results, with a slightly superior diagnostic accuracy of FDG-PET [34,38].