Figure 8.1

Color-coded Duplex sonography finding of superficial temporal artery in a normal person (A,B) and in a patient with giant cell arteritis (C,D). (A) and (C) longitudinal view; (B) and (D) axial view. White arrows in (C) and (D) indicate hypoechogenic vessel wall thickening, the so-called halo sign. (Reprinted with permission from: Diagnose und Therapie der Riesenzellarteriitis. Ness Th. et al. Deutsches Ärzteblatt 2013;21:376.)

The halo sign in the temporal artery correlated well with the clinically defined pretest probability of GCA (cranial/temporal arteritis subtype; ACR criteria plus diplopia or jaw claudication) [16]. A unilateral superficial temporal artery halo sign had a specificity of 91% whereas a bilateral halo sign had a specificity of 100% for the diagnosis of GCA [17]. In the case of concordant clinical and sonographic results, TA biopsy seems not justified.

Both imaging methods (MRI and CCDS) have been shown to have comparable sensitivity and specificity in a retrospective analysis [18]. CDDS is more investigator dependent and MRI is more expensive but more reproducible. Since histology (TA biopsy) is the gold standard for establishing GCA diagnosis, diagnostic accuracy of ultrasound and MRI can be verified in temporal arteries accessible for biopsy but not in LVs. In these, the specificity of imaging findings remains uncertain. On the other hand, it has been shown that only 58% of LV-GCA patients had positive temporal artery biopsies (TABs) for the presence of GCA [19], which indicates that this procedure cannot be the gold standard for establishing the diagnosis in this setting. Overall, TAB has been found negative in 9–44% of established clinical diagnoses mostly due to the segmental nature of the histologic lesion [15]. MRI and PET probably have a higher sensitivity regarding aortic involvement and of course involvement of vessel segments difficult or not accessible to ultrasound examination [6].

CDDS results showed a sensitivity of 88% and a specificity of 96% with regard to the clinical diagnosis (ACR criteria) and a sensitivity of 95% with regard to positive TAB histology. The specificity for the presence of a hypoechoic temporal artery wall swelling (“halo”) was 99.5% [6]. Patients with suspected or diagnosed temporal arteritis, polymyalgia rheumatica, pyrexia or inflammation of unknown origin and/or arm claudication should have CDDS examination of proximal arteries.

A meta-analysis of 23 studies that investigated the diagnostic accuracy of Doppler, color Doppler and Duplex ultrasound for the presence of temporal arteritis showed that several centers reached similar results, while others arrived at less sensitive or less specific results. Sensitivities and specificities were higher in centers that used higher-quality equipment and duplex ultrasound [15].

Since GCA affects almost exclusively patients above the age of 50 years, differential diagnosis with arteriosclerosis is important. Arteriosclerotic wall changes/thickening usually appear less homogeneous, less circumferential, with calcified arteriosclerotic plaques, ulcers; stenoses extend over shorter segments, they are not concentric, not tapering and location of lesions is different (e.g., mainly at bifurcations).

Furthermore, differential diagnosis with the other LVV, namely TA, has to be considered: TA usually affects women below the age of 40 years, symptoms like tender scalp or polymyalgia syndrome are exceptional; involvement of temporal artery in TA is not known but involvement of CCA is more frequent; ultrasound image of wall thickening (“halo”) is brighter in TA than in GCA probably due to a larger mural edema in GCA which is a more acute disease than TA [20].

Sensitivity of CCDS as well as MRI for detection of GCA affecting the superficial temporal artery rapidly decreases under corticosteroid treatment and imaging therefore should be performed within the first 4 days of treatment [14,17,21]. This is probably because the “halo” mainly reflects edema. Sensitivity of arterial biopsy persists longer under corticosteroids and is not altered with the first week(s) of treatment [22].

In larger affected vessels, echogenic residual ultrasound changes remain detectable in the majority of patients for months, even after normalization of systemic inflammatory parameters [6,9]. Such changes might be missed in the smaller temporal artery, where image resolution is lower. On the other hand, it is difficult to confidently discriminate between active inflammatory and chronic fibrotic lesions on the basis of vessel wall thickness alone. Vessel stenosis may be due to active vasculitis, but also to scarring after inflammation has abated. PET may be a more reliable procedure in the evaluation of disease activity [23].

The high sensitivity of CCDS and MRI offer the potential to detect relapses under steroid treatment. Indeed anecdotal cases with recurring halo sign have been reported [17]. It seems plausible that imaging-guided performance of arterial biopsy would increase the number of positive findings [17]; this, however, has not been systematically studied.

Takayasu arteritis

TA, also known as pulseless disease, is a rare idiopathic chronic granulomatous inflammatory vasculitis characterized by wall thickening, fibrosis, stenosis, thrombosis or obliteration and aneurysm formation of the aorta and its major branches and of the pulmonary arteries. Involvement of the aortic arch and its major branches usually occurs at the origin from the aorta [24,25]. The incidence in Europe and in the United States varies from 1.2 to 2.6/million per year, but it is probably higher in Japan. It is generally considered a disease of young adults with a peak onset in the second and third decades of life and a striking predilection for females. It is the most common LVV in childhood [26]. Clinical manifestations are quite variable. Constitutional symptoms may include fatigue, night sweats, malaise, anorexia, weight loss, low-grade fever, arthralgia and myalgia.

Neurological manifestations include headache, transient ischemic attack, cerebral infarction and hemorrhage, hypertensive encephalopathy, confusion, vertigo, dementia and bilateral blindness.

Vascular disease may range from no symptoms to catastrophic disease related to vascular occlusion. The disease is classified into five types on the basis of the pattern of anatomical involvement: type I, aortic arch and its branches; type II, descending thoracic and abdominal aorta; type III, aortic arch and thoraco-abdominal aorta; type IV, pulmonary artery in addition to the aforementioned types; and type V, coronary artery in addition to the other types. The most frequently affected arteries are the subclavian (90%), carotid (45%), vertebral (25%) and renal (20%) which are all accessible for ultrasound imaging [27]. Renal artery involvement with stenosis and secondary renovascular hypertension is more frequent in Asian countries [28].

Sonography is often the first modality used to evaluate a patient with suspected TA. CCDS findings include uniform concentric thickening of the arterial wall (long segments of diffuse, homogeneous, moderately echoic circumferential vessel wall thickening). An increase in wall thickness is usually associated with secondary signs such as decreased pulsatility and loss of a normal triphasic flow pattern, with a monophasic or biphasic parvus tardus type of spectral flow pattern. Wall thickening leads to decreased luminal diameter/stenosis usually over a long segment of arterial wall, in contrast to atherosclerosis and fibromuscular dysplasia, where stenoses are commonly short segment, not concentric with different lesion location. In TA, plaque formation and calcifications are rare. Dilatation and aneurysm formation is usually confined to the aorta, whereas occlusions usually affect subclavian, carotid or vertebral arteries. Due to the slow evolution, there is usually associated collateral flow. Carotid ultrasound can best demonstrate diffuse, homogeneous wall thickening of the bilateral common carotid arteries (CCAs) known as the “macaroni sign” [29]. Especially in the “prestenotic or prepulseless stage” such findings may establish diagnosis in the setting of constitutional symptoms if the primary extracranial branches of the aortic arch are examined and angiography may fail because of not yet present significant narrowing of the vessel lumen [20,30]. CCDS is definitively much more sensitive to detect inflammatory wall thickening of carotid and subclavian arteries [30,31]. With respect to parameters for disease activity, there is edema and contrast enhancement at MRI; CCDS has a higher resolution for vessel wall imaging and may be repeatedly applied allowing for assessment of subtle changes in vessel wall thickness. FDG-PET seems to offer best measures of disease activity. Compared to angiography, there was high agreement of CCDS with respect to stenoses of CCA, brachiocephalic trunk and vertebral arteries. Not unexpectedly Doppler studies also showed increased arterial stiffness in CCA. There are only few data regarding ultrasound follow-up findings and response to treatment, thus the value of CCDS for treatment monitoring is unclear.

Cervical vein inflammation

Behçet disease

Small vessel vasculitis accounts for much of the pathologic process in Behçet disease. Only the rare instances of large venous thrombosis, which may typically also involve the cerebral venous sinuses, are accessible to ultrasound and the findings are not specific for the disease.

Lemierre syndrome

This eponym denotes a septic thrombophlebitis of the internal jugular vein, in most instances caused by Fusobacterium necrophorum and usually representing a complication of tonsillitis or pharyngitis [32].

Medium and small vessel vasculitis

The vessels involved in medium vessel vasculitis like polyarteritis nodosa or Kawasaki disease and in small vessel vasculitides like the ANCA-associated vasculitides or the immune complex vasculitides as well as the vasculitides in the setting of systemic inflammatory diseases like systemic lupus erythematosus or other connective tissue diseases usually are not a domain of ultrasound diagnostics.

Small (to medium) vessel vasculitis

PACNS (primary angiitis of the central nervous system, CNS), PCNSV (primary CNS vasculitis) and GACNS (granulomatous angiitis of the CNS)

It is a rare vasculitic syndrome confined to cerebral vasculature, difficult to recognize and primarily a diagnosis of exclusion [33]. Small vessels are mainly involved and although basal (proximal) cerebral arteries may be affected there are no data on the role of ultrasound in this entity where angiography also has a low sensitivity and specificity. This is mainly due to the fact that the vessels affected are distal and small, even beyond the current resolution of angiography. There are many PACNS mimics to be considered, mainly the reversible cerebral vasoconstriction syndrome (RCVS) (also called postpartum angiopathy, benign angiopathy of the CNS, etc.) [34]. In both cases TCD may show, as an aspecific sign, increased blood flow velocities in the basal cerebral arteries.

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