Comparison of duplex sonography and high-resolution magnetic resonance imaging in the diagnosis of giant cell (temporal) arteritis

Other cerebrovascular occlusive disease

In this chapter we review the optimal imaging modalities for subacute and chronic stroke. We discuss the utility of computed tomography (CT) and multimodal CT imaging. Further, we analyze the importance of specific magnetic resonance imaging sequences, such as diffusion-weighted imaging for acute ischemic stroke, T2/fluid-attenuated inversion recovery for subacute and chronic stroke, and susceptibility imaging for detection of intracranial hemorrhages. Different ischemic stroke mechanisms are reviewed, and how these imaging modalities may aid in the determination of such. Further, we analyze how topographic patterns in ischemic stroke may provide important clues to the diagnosis, in addition to the temporal evolution of the stroke. Lastly, specific cerebrovascular occlusive diseases are reviewed, with emphasis on the optimal imaging modalities and their findings in each condition.

Giant Cell Arteritis and Polymyalgia Rheumatica: 2016 Update

Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are both more common among people of North European decent than among Mediterranean people. Women are 2-3 times more commonly affected. Giant cell arteritis and PMR are extremely rare before age 50 years. Polymyalgia rheumatica may be "isolated" or associated with GCA. There is increased expression of inflammatory cytokines in temporal arteries of PMR patients, without overt histological evidence of arteritis. One-third of "isolated" PMR patients have vascular uptake in positron emission tomography (PET) scans, suggesting clinically unrecognized, "hidden" GCA. Typical manifestations of GCA are headache, tenderness over temporal arteries, jaw claudication, PMR, acute vision loss, and low-grade fever. Bilateral aching of the shoulders with morning stiffness is typical for PMR. In both conditions sedimentation rate and C-reactive protein are elevated, and anemia and thrombocytosis may occur. Color duplex ultrasonography of the temporal arteries may aid in GCA diagnosis. Temporal artery biopsy showing vasculitis, often with giant cells, confirms GCA diagnosis. In cases with negative biopsy one must rely on the clinical presentation and laboratory abnormalities. The diagnosis of PMR is made primarily on clinical grounds. Other conditions that may mimic GCA or PMR must be excluded. Glucocorticoids are the treatment of choice for both conditions. Prompt treatment is crucial in GCA, to prevent irreversible complications of acute vision loss and stroke. Addition of low-dose aspirin may further prevent these complications. The average duration of treatment is 2-3 years, but some patients require a prolonged course of treatment, and some may develop disease-related or treatment-related complications. No steroid-sparing agent has been proven to be widely effective thus far, but some promising therapeutic agents are currently being studied.

The Expanding Role of Imaging in Systemic Vasculitis

Various imaging modalities, including color duplex ultrasonography, CT angiography, magnetic resonance angiography, and PET, are emerging as important aids to the diagnosis, staging, evaluation of disease activity and response to treatment in systemic vasculitis. Although large-vessel vasculitis is the main target of imaging, refinement and increasing accuracy of imaging modalities are also providing useful information in the evaluation of medium-vessel and small-vessel vasculitis.

Association between specimen length and diagnostic yield of temporal artery biopsy

OBJECTIVES

Temporal artery biopsy (TAB) is performed in patients suspected of giant cell arteritis (GCA). Inadequate TAB specimen length is considered a possible explanation for a negative biopsy in patients with GCA. We investigated the association between specimen length and diagnostic yield of TAB.

METHOD

We conducted a retrospective analysis of 240 patients who underwent TAB in a single hospital between 2000 and 2015. Patients were diagnosed with GCA based on positive TAB or, when TAB was negative, on clinical grounds that fulfilled the American College of Rheumatology (ACR) 1990 criteria. Baseline clinical and laboratory features and TAB length were obtained from medical records. Among patients diagnosed with GCA, the rate of TAB positivity was calculated according to biopsy length (< 5, 5-9, 10-14, and ≥ 20 mm).

RESULTS

Out of 240 patients, 88 were diagnosed with GCA: 62 had a positive TAB and 26 were diagnosed based on clinical grounds despite a negative TAB. Among those who were diagnosed with GCA, the length of the TAB specimen was similar in those with a positive and a negative TAB (1.13 ± 1.68 mm vs. 1.15 ± 0.61 mm, respectively, p = 0.928). The TAB positivity rate was similar among all ranges of biopsy length [< 5 mm: 7/10 (70%); 5-9 mm: 22/31 (71%); 10-14 mm: 11/16 (69%); 15-19 mm: 11/16 (69%); ≥ 20 mm: 11/15 (73%, p = ns] and was similar to the overall biopsy positivity rate.

CONCLUSIONS

Specimen length is not associated with diagnostic yield of TAB.

Gut and Liver in Vasculitic Disorders

BACKGROUND

Although the gastrointestinal (GI) tract including its related organs is not generally regarded as one of the primary organ systems of primary and secondary vasculitic disorders, there are numerous mechanisms of these diseases operative in or around the different structures and compartments of the GI tract.

KEY MESSAGES

A majority of the respective clinical symptoms and problems are linked to an alteration of (peri)vascular homeostasis. Alteration of perivascular matrix metabolism can also affect the functional integrity and motility of the GI tract. Apart from the specific GI phenomena of the individual diseases as outlined in detail in this review, the epidemiology of GI involvement follows in general the characteristics of the respective underlying systemic disease. In addition, gender and age do neither influence the occurrence nor the severity of the GI manifestations significantly. With respect to clinical symptoms, vasculitides may result in abdominal pain, bleeding, ileus, intestinal necrosis and hematochezia because of reduced blood flow and hyper-acute occlusion in the antiphospholipid syndrome. Small-bowel involvement in vasculitic entities can cause pseudoobstruction, obstruction, malabsorption and bacterial overgrowth. Laboratory parameters can point to specific diseases but are frequently nonspecific. Thus, if biopsy fails or in unclear endoscopic situations, a variety of imaging techniques including Doppler ultrasound, abdominal CT, MRI and angiography are used and required for identification and localization of the underlying disease. Therapeutic strategies in vasculitides usually include corticosteroids and immunosuppressants, for example, cyclophosphamide in granulomatosis with polyangiitis and in panarteriitis nodosa but also biologics such as rituximab in ANCA-associated vasculitides. Virostatic drugs including interferon-α and ribavirin can be used in hepatitis B- and C-triggered vasculitides such as panarteriitis nodosa and hepatitis C-associated cryoglobulinemia.

CONCLUSIONS

Immediate diagnostic and therapeutic steps of action need to be performed if vasculitis of the GI tract is suspected in order to avoid irreversible damage to organs and to improve the well-being and life of the affected patient.

Why a standard contrast-enhanced MRI might be useful in intracranial internal carotid artery stenosis

In patients with ischemic stroke of unknown cause cerebral vasculitis is a rare but relevant differential diagnosis, especially when signs of intracranial artery stenosis are found and laboratory findings show systemic inflammation. In such cases, high-resolution T1w vessel wall magnetic resonance imaging (MRI; 'black blood' technique) at 3 T is preferentially performed, but may not be available in every hospital. We report a case of an 84-year-old man with right hemispheric transient ischemic attack and signs of distal occlusion in the right internal carotid artery (ICA) in duplex sonography. Standard MRI with contrast agent pointed the way to the correct diagnosis since it showed an intramural contrast uptake in the right ICA and both vertebral arteries. Temporal artery biopsy confirmed the suspected diagnosis of a giant cell arteritis and dedicated vessel wall MRI performed later supported the suspected intracranial large artery inflammation. Our case also shows that early diagnosis and immunosuppressive therapy may not always prevent disease progression, as our patient suffered several infarcts in the left middle cerebral artery (MCA) territory with consecutive high-grade hemiparesis of the right side within the following four months.

Imaging in Giant Cell Arteritis

Much progress has been made in the use of imaging as a diagnostic tool in giant cell arteritis (GCA), which assists in the management of patients where the initial diagnosis is unclear. This includes patients with atypical cranial symptoms, or with predominantly systemic, constitutional or limb symptoms. Ultrasound and magnetic resonance imaging are capable of visualising both the cranial and extracranial large vessel circulation, with vessel wall thickening and stenotic lesions being visualised. Computed tomographic angiography is helpful in visualising the aorta for aneurysm complicating GCA but can also detect vessel wall thickening in established large vessel vasculitis. PET-CT is a very sensitive test for early vascular inflammation in extracranial large vessel vasculitis, before aneurysmal or stenotic lesions have developed, of use in the patient with unexplained constitutional symptoms. The place of imaging in the follow-up of GCA is being investigated, and repeated imaging may be useful in select cases. Generally, vascular abnormalities become less defined once glucocorticoid treatment has been started, and therefore, imaging studies must be conducted early as part of a GCA fast-track assessment.

Description and Validation of Histological Patterns and Proposal of a Dynamic Model of Inflammatory Infiltration in Giant-cell Arteritis

The extent of inflammatory infiltrates in arteries from patients with giant-cell arteritis (GCA) have been described using different terms and definitions. Studies investigating the relationship between GCA histological features and clinical manifestations have produced controversial results. The aims of this study were to characterize and validate histological patterns in temporal artery biopsies (TABs) from GCA patients, to explore additional histological features, including the coexistence of different patterns, and also to investigate the relationship of the inflammatory patterns with clinical and laboratory features.We performed histological examination of TAB from patients with GCA consecutively diagnosed between 1992 and 2012. Patterns of inflammation were defined according to the extent and distribution of inflammatory infiltrates within the artery. Clinical and laboratory variables were recorded. Two external investigators underwent a focused, one-day training session and then independently scored 77 cases. Quadratic-weighted kappa was calculated.TAB from 285 patients (200 female/85 male) were evaluated. Four histological inflammatory patterns were distinguished: 1 - adventitial (n = 16); 2 - adventitial invasive: adventitial involvement with some extension to the muscular layer (n = 21); 3 - concentric bilayer: adventitial and intimal involvement with media layer preservation (n = 52); and 4 - panarteritic (n = 196). Skip lesions were observed in 10% and coexistence of various patterns in 43%. Raw agreement of each external scorer with the gold-standard was 82% and 77% (55% and 46% agreement expected from chance); kappa = 0.82 (95% confidence interval [CI] 0.70-0.95) and 0.79 (95% CI 0.68-0.91). Although abnormalities on temporal artery palpation and the presence of jaw claudication and scalp tenderness tended to occur more frequently in patients with arteries depicting more extensive inflammation, no statistically significant correlations were found between histological patterns and clinical features or laboratory findings.In conclusion, we have described and validated 4 histological patterns. The presence of different coexisting patterns likely reflects sequential steps in the progression of inflammation and injury. No clear relationship was found between these patterns and clinical or laboratory findings. However, several cranial manifestations tended to occur more often in patients with temporal arteries exhibiting panarteritic inflammation. This validated score system may be useful to standardize stratification of histological severity for immunopathology biomarker studies or correlation with imaging.

Imaging in systemic vasculitis

PURPOSE OF REVIEW

Imaging is becoming a relevant tool for the assessment of patients with systemic vasculitis. This review focuses on recently generated data with potential clinical impact in the diagnosis, evaluation of disease extent and management of systemic vasculitis.

RECENT FINDINGS

Temporal artery examination by color duplex ultrasonography (CDUS) is a valuable approach to the diagnosis of giant-cell arteritis. Evaluation of additional arteries may increase its diagnostic performance. However, CDUS-specific findings may not be detected in arteries with early inflammation and CDUS-guidance of temporal artery biopsy does not seem to significantly increase its diagnostic yield. Large-vessel involvement detected by computed tomography angiography occurs in two out of three of patients with giant-cell arteritis at diagnosis. Furthermore, significant ascending aortic dilatation can be observed in one out of three of patients after long-term follow-up. Objective cut-offs for detecting large-vessel inflammation by positron emission tomography (PET) are trying to be established through prospective studies. PET may also contribute to the assessment of disease extent in patients with ANCA-associated vasculitis or Behçet's disease.

SUMMARY

Data generated by existing and emerging imaging techniques are expected to have a major impact in the diagnosis, appraisal of disease extent, evaluation of disease activity and response to treatment in patients with systemic vasculitis.

Advances in the diagnosis of large vessel vasculitis

The diagnosis of large-vessel vasculitis has experienced substantial improvement in recent years. While Takayasu arteritis diagnosis relies on imaging, the involvement of epicranial arteries by giant-cell arteritis facilitates histopathological confirmation. When appropriately performed temporal artery biopsy has high sensitivity and specificity. However, an optimal biopsy is not always achievable and, occasionally, the superficial temporal artery may not be involved. Imaging in its various modalities including colour-duplex ultrasonography, computed tomography angiography, magnetic resonance angiography and positron emission tomography, are emerging as important procedures for the diagnosis and assessment of disease extent in large-vessel vasculitis. Recent contributions to the better performance and interpretation of temporal artery biopsies as well as advances in imaging are the focus of the present review.

3T MRI reveals extra- and intracranial involvement in giant cell arteritis

BACKGROUND AND PURPOSE

The frequency and amount of intracranial, intradural inflammatory vessel wall enhancement in giant cell arteritis remain unclear. The purpose of this work was to prospectively assess the intracranial extent of vasculitic changes in patients with giant cell arteritis using a dedicated MR imaging protocol optimized for assessment of mural changes of intracranial arteries.

MATERIALS AND METHODS

Twenty-eight patients with suspected giant cell arteritis underwent 3T MR imaging. Imaging included a fat-saturated T1WI pre- and postcontrast application optimized for assessment of intradural vessel wall enhancement and high-resolution fat-saturated T1WI to evaluate superficial extracranial vessels. Temporal artery biopsies were available in 11 cases. Vessel wall enhancement of intradural and extracranial vessels was evaluated by 2 observers independently.

RESULTS

Twenty patients had giant cell arteritis; 9 cases were biopsy-proved. Clear vessel wall enhancement of superficial extracranial and intradural internal carotid arteries was detected in 16 and 10 patients, respectively. Slight vessel wall enhancement of the vertebral arteries was seen. Of 9 patients with giant cell arteritis with vessel occlusion or stenosis, 2 presented with cerebral ischemic infarcts. Vessel occlusion or stenosis site coincided with the location of vessel wall enhancement of the vertebral arteries in 4 patients and of the intradural ICA in 1 patient.

CONCLUSIONS

Vessel wall enhancement of intradural arteries, mainly the ICA, can be regularly found in patients with giant cell arteritis. Mural inflammatory changes of the intradural ICA detected on MR imaging may identify a subgroup of patients with giant cell arteritis and should be further evaluated in clinical studies.

Role of ultrasound in the understanding and management of vasculitis

Vasculitis is characterized by a circumferential vessel-wall thickening ('halo'), which can be visualized by modern imaging techniques. In particular, the resolution of ultrasound has increased to 0.1 mm. Ultrasound detects abnormalities that are pathognomonic even in arteries with a diameter below 1 mm. It is particularly helpful in the diagnosis of large-vessel vasculitides, such as classic temporal arteritis, large-vessel giant-cell arteritis (GCA), Takayasu arteritis and idiopathic aortitis. Echocardiography is important for determining cardiac involvement in Takayasu arteritis and also for examining the coronary arteries of children with suspected Kawasaki disease, which is a medium-vessel vasculitis. In small vessel vasculitides ultrasound has only a role for determining the distribution or organ involvement. Fast-track clinics for the diagnosis of GCA help to initiate treatment before complications such as blindness occur; patients receive appointments within 24 h in these clinics. Clinical examination and ultrasound of temporal and axillary arteries are performed by an experienced rheumatologist. In most cases this is able to determine if GCA is present. Temporal artery biopsy can be still carried out in ambivalent cases. The wall swelling of temporal arteries disappears after 2-3 weeks of glucocorticoid treatment. After 3 days of treatment, diagnosis becomes more difficult with ultrasound in some cases. In larger arteries, such as the axillary arteries, wall thickening disappears within months. It tends to be darker (more hypoechoic) in acute disease because of oedema.

ACR Appropriateness Criteria Headache

Most patients presenting with uncomplicated, nontraumatic, primary headache do not require imaging. When history, physical, or neurologic examination elicits "red flags" or critical features of the headache, then further investigation with imaging may be warranted to exclude a secondary cause. Imaging procedures may be diagnostically useful for patients with headaches that are: associated with trauma; new, worse, or abrupt onset; thunderclap; radiating to the neck; due to trigeminal autonomic cephalgia; persistent and positional; and temporal in older individuals. Pregnant patients, immunocompromised individuals, cancer patients, and patients with papilledema or systemic illnesses, including hypercoagulable disorders may benefit from imaging. Unlike most headaches, those associated with cough, exertion, or sexual activity usually require neuroimaging with MRI of the brain with and without contrast to exclude potentially underlying pathology before a primary headache syndrome is diagnosed. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

The diagnosis and classification of giant cell arteritis

Giant-cell arteritis (GCA) involves the major branches of the aorta with predilection for the extracranial branches of the carotid artery. It occurs in individuals older than 50 years and the incidence increases with age. The signs and symptoms of giant cell arteritis can be classified into four subsets: cranial arteritis, extracranial arteritis, systemic symptoms and polymyalgia rheumatica. Patients may develop any combination of these manifestations, associated with laboratory evidence of an acute-phase reaction. The only test that confirms GCA diagnosis is a temporal artery biopsy, showing vasculitis with mononuclear cell inflammatory infiltrates, often with giant cells. Due to the focal and segmental nature of the infiltrates, areas of inflammation may be missed by the biopsy and the histological examination is normal in about 15% of the cases. Some imaging modalities may aid in the diagnosis of GCA. Among those, color duplex ultrasonography of the temporal arteries is more commonly used. There are no independent validating criteria to determine whether giant cell arteritis is present when a temporal artery biopsy is negative. The American College of Rheumatology criteria for the classification of giant cell arteritis may assist in the diagnosis. However, meeting classification criteria is not equivalent to making the diagnosis in individual patients, and the final diagnosis should be based on all clinical, laboratory, imaging and histological findings. Glucocorticoids are the treatment of choice for GCA. The initial dose is 40-60 mg/day for most uncomplicated cases. Addition of low-dose aspirin (100 mg/d) has been shown to significantly decrease the rate of vision loss and stroke during the course of the disease.

Imaging in vasculitis

Vasculitides may involve small, medium-sized or large arteries. In small-vessel vasculitides imaging studies of lungs, nasal sinuses, cerebrum, heart and other organs are important for determining disease extension and disease activity. Aneurysms are a hallmark of medium-sized artery vasculitides. In large-vessel vasculitis, imaging studies depict homogeneous, circumferential wall swelling and smoothly tapered luminal narrowing. Ultrasound and high-resolution magnetic resonance imaging (MRI) show characteristic wall abnormalities in temporal and occipital arteries whereas ultrasound, MRI, MR angiography, computed tomography (CT), CT angiography and positron emission tomography delineate characteristic features in extra-cranial arteries that are affected in large-vessel giant cell arteritis, Takayasu arteritis and idiopathic aortitis. Conventional angiography has still its place for therapeutic interventions. Imaging has led to a better understanding of the nature and distribution of vasculitides. It significantly facilitates diagnosis of patients with suspected vasculitis.

Headache and temporal arteritis: when to suspect and how to manage

Temporal arteritis, also termed giant cell arteritis, is one of the vasculitides affecting large and medium sized cranial arteries, particularly of the carotid tree. Clinical manifestations may vary from the classic constellation of temporal headache in the elderly accompanied by constitutional signs, jaw claudication, and visual symptoms; therefore, a high index of clinical suspicion may be necessary to identify the disorder. Once suspected, immediate treatment is crucial while exploring any number of diagnostic tools to confirm or refute the diagnosis, since morbidity from untreated temporal arteritis can be devastating. At the same time, achieving a definitive diagnosis is paramount, as treatment can be toxic with significant morbidity of its own. Temporal artery biopsy remains the gold standard, but noninvasive diagnostic approaches are being refined. Corticosteroids remain the cornerstone of treatment, but are ineffective for, not tolerated by, or contraindicated in some individuals, necessitating the exploration of alternatives.

Effects of early corticosteroid treatment on magnetic resonance imaging and ultrasonography findings in giant cell arteritis

OBJECTIVE

To compare the impact of initial corticosteroid treatment on high-resolution MRI and colour-coded duplex sonography (CCDS) findings in patients with GCA (temporal).

METHODS

Sensitivity and specificity of CCDS and high-resolution contrast-enhanced MRI studies of 59 patients with suspected GCA were retrospectively analysed. Patients were grouped according to the duration of steroid treatment before imaging: 0-1 day, 2-4 days and >4 days. In 41 patients, imaging results were compared with findings of temporal artery biopsy (TAB).

RESULTS

Sixty-one per cent (36/59) of patients were diagnosed with GCA. TAB findings were positive in 59% (24/41). The compared results of TAB sensitivity of CCDS and MRI under steroid treatment of 0-1 day were 92% and 90%, 2-4 days 80% and 78% and >4 days 50% and 80%, respectively. The compared results of the final clinical diagnosis sensitivity of CCDS and MRI under steroid treatment of 0-1 day was 88% and 85%, 2-4 days 50% and 64% and >4 days 50% and 56%, respectively.

CONCLUSION

Sensitivity of a first-time CCDS or an MRI for detection of GCA rapidly decreases under corticosteroid treatment. Therefore imaging of patients with suspected GCA should be performed as soon as possible, preferably within the first days of treatment.

Carotidynia: revisiting an unfamiliar entity

Carotidynia (unilateral neck pain reproducible with light pressure on the carotid artery) is a controversial and poorly understood vascular condition. This review provides important historical information, several representative case reports, and a comprehensive summary of the literature. The authors also propose an algorithm for the care of these patients.

Giant cell arteritis: epidemiology, diagnosis, and management

Giant cell arteritis (GCA), also called temporal arteritis, is a vasculitis that affects large and middle-sized blood vessels--with predisposition to the involvement of cranial arteries derived from the carotid artery--in individuals older than 50 years of age. Familial aggregation of GCA has been observed. Incidence of GCA is higher in white individuals than those of other ethnicities, particularly those of Scandinavian background. A temporal artery biopsy is the gold standard test for the diagnosis of GCA. Several imaging modalities, in particular ultrasonography, are useful in the diagnosis of GCA. Corticosteroids are the cornerstone of treatment in GCA. Alternative, steroid-sparing drugs, particularly methotrexate, should be considered in GCA patients with severe corticosteroid-related side effects and/or in those who require prolonged corticosteroid therapy due to relapses of the disease.

Role of ultrasonography in the diagnosis of temporal arteritis

Background

Temporal artery (TA) biopsy is the current standard for diagnosing temporal arteritis, but has limited sensitivity. Colour duplex ultrasonography is a newer, non-invasive method of diagnosing temporal arteritis.

Methods

A systematic review was performed of trials comparing TA biopsy with duplex ultrasonography. Duplex results (halo sign, stenosis or vessel occlusion) were compared with either TA biospy findings or the American College of Rheumatology research criteria for diagnosing temporal arteritis. Trials were identified from MEDLINE, Embase and the Cochrane Library trials register. The performance of duplex ultrasonography was assessed with weighted independent sensitivity and specificity values, and summary receiver operating characteristic curve analysis.

Results

There were 17 eligible studies containing 998 patients. When the halo sign on duplex imaging was compared with TA biopsy, the sensitivity was 75 (95 per cent confidence interval 67 to 82) per cent and the specificity was 83 (78 to 88) per cent. There was no heterogeneity across the eligible studies.

Conclusion

Duplex ultrasonography was relatively accurate for diagnosing temporal arteritis. It should become the first-line investigation, with biopsy reserved for patients with a negative scan.

[Classification and therapy of vasculitis according to recommendations of the European League Against Rheumatism (EULAR)]

Vasculitis is still being classified according the criteria of the American College of Rheumatology and the Chapel Hill Consensus Conference Definitions. Diagnostic criteria are currently being established. The classification criteria are based on the size of the inflamed blood vessel (e.g. large vessel vasculitis with inflammation of the aorta and its branches), clinical symptoms and findings (such as cephalalgia in giant cell arteritis) and histological findings. In recent years a definition of disease stages and activity has been established and a number of controlled trials have been carried out in order to provide evidence-based stage and activity adapted therapy regimens. Recommendations for the management of vasculitis have been published in 2009 by EULAR (European League Against Rheumatism). This article gives a review of the classification of vasculitis and summarizes the current European guidelines on management.

[Vasculitis assessment with [18F]FDG positron emission tomography]

[18F]fluorodeoxyglucose positron emission tomography (PET) is a noninvasive metabolic imaging modality that is well-suited to the assessment of activity and extent of large vessel vasculitis. PET imaging has demonstrated its usefulness in diagnosing giant cell arteritis (notably in its silent form), Takayasu's arteritis, and unclassified aortitis. PET imaging could be more effective than magnetic resonance imaging in detecting the earliest stages of vascular wall inflammation. The visual grading of vascular [18F]FDG uptake makes it possible to discriminate arteritis from active atherosclerosis, providing therefore high specificity. High sensitivity can also be achieved provided scanning is performed during active inflammatory phase, preferably before starting corticosteroid treatment. Prospective studies are needed to determine the exact value of PET imaging in assessing other vasculitis subsets, infectious aortitis, and large vessel vasculitis outcome and response to immunosuppressive treatment.

Diagnostic value of T2-weighted imaging for the detection of superficial cranial artery inflammation in giant cell arteritis

PURPOSE

To evaluate the diagnostic value of T2-weighted radial MR imaging for the detection of superficial cranial arteries' inflammatory involvement in patients with giant cell arteritis (GCA).

MATERIALS AND METHODS

Forty-three patients with suspected giant cell arteritis underwent 3 Tesla (T) high-field MRI. T2-weighted inversion recovery (IR) fast spin echo images with radial sampling (BLADE-technique) were acquired and compared with postcontrast T1-weighted spin echo images.

RESULTS

T2-weighted images revealed mural edema in the superficial cranial arteries in 11 patients in concordance with severe inflammatory contrast enhancement in T1-weighted images (grade 4 in a 4-point ranking scale). Excellent correlation (r = 0.82; P < 0.001) of measured wall thickness in T1- and T2-weighted images was achieved.

CONCLUSION

The results of this study indicate the potential of radial T2 weighted imaging for a first detection of inflammatory changes in the small superficial cranial arteries without the need for contrast medium. Future studies are needed to evaluate the influence of spatial resolution of the T2 images and to improve the detection of moderate GCA related changes in vessel inflammation.

[Imaging techniques for giant cell arteritis. Ultrasound and MRI]

This article summarizes the examination technique, typical findings, interpretation and limitations of ultrasound diagnosis in patients with giant cell arteritis. Colour-coded sonography of the temporal artery has gained increasing attention. If experienced ultrasound examiners are available, diagnosis of giant cell arteritis in patients with a typical clinical constellation can be made based solely on sonographic findings, in particular by a hypoechogenic halo. The hitherto probably under-diagnosed large vessel variant of giant cell arteritis shows characteristic findings with a simple and quick ultrasound examination of the proximal arm arteries. High resolution MRI has been shown to be a promising technique for non-invasive imaging of giant cell arteritis. Mural inflammatory changes of the superficial temporal arteries can be depicted and the cranial involvement pattern can be readily assessed and in combination with MR angiography extracranial involvement can be determined within the same investigation. Aortitis is a feared complication of giant cell arteritis but can be detected and inflammatory stenoses of the aortic branch vessels can also be revealed. In the hands of an experienced operator ultrasonography can be regarded as the non-invasive imaging modality of first choice whereas MRI is more expensive and may not be as widely available. However, its imaging acquisition is standardized and is more observer-independent. Reading of the images is a routine task for a vascular radiologist and larger areas of the vasculature can be simultaneously assessed.

The spectrum of vascular involvement in giant-cell arteritis: clinical consequences of detrimental vascular remodelling at different sites

Although repeatedly reported in the literature, the extracranial involvement by giant-cell arteritis has been considered anecdotal until recent years. The emergence of new or improved imaging techniques along with a closer follow-up of these patients and their increase in life expectancy are beginning to underline that the clinical impact of extracranial involvement by GCA may be more relevant than previously thought. This review focuses on the extent of vascular involvement in GCA as reported by pathology and imaging studies as well as the clinical consequences of imperfect vascular remodelling in various vascular territories.

[Large-vessel vasculitis. Imaging and interventional therapy]

Giant cell arteritis and Takayasu's arteritis are classified as primary large-vessel vasculitides. Inflammatory cell infiltrates and cytokines induce destruction and hyperplasia of the vessel wall, leading to stenoses or aneurysms. When extracranial large arteries are involved, there is often a similar clinical and radiologic disease pattern of an inflammatory aortic arch syndrome. Rare causes of large-vessel vasculitis include Behçet's disease, association with other autoimmune diseases, and infection. Depending on the localization, imaging is usually performed by means of duplex ultrasound, magnetic resonance imaging, computed tomography, or positron emission tomography. These imaging modalities are used not only to establish the diagnosis but also to determine the disease extent and activity and to perform follow-up in the course of medical therapy. Angiography offers the option to perform interventional therapy for vascular stenoses and occlusions.

Imaging for large-vessel vasculitis

PURPOSE OF REVIEW

Ultrasonography, MRI, and PET are increasingly studied in large-vessel vasculitis. They have broadened our knowledge on these disorders and have a place in the diagnostic approach of these patients.

RECENT FINDINGS

Temporal artery ultrasonography can be used to guide the surgeon to that artery segment with the clearest 'halo' sign to perform a biopsy, or in experienced hands can even replace biopsy. The distal subclavian, axillary, and brachial arteries can also be examined. High-resolution MRI depicts superficial cranial and extracranial involvement patterns in giant cell arteritis (GCA). Contrast enhancement is prominent in active inflammation and decreases under successful steroid therapy. Presence of aortic complications such as aneurysm or dissection can be ruled out within the same investigation. Large thoracic vessel FDG-uptake is seen in the majority of patients with GCA, especially at the subclavian arteries and the aorta. FDG-PET cannot predict which patients are bound to relapse, and once steroids are started, interpretation is hazardous, which makes its role in follow-up uncertain. Increased thoracic aortic FDG-uptake at diagnosis of GCA may be a bad prognostic factor for later aortic dilatation. In patients with isolated polymyalgia rheumatica - who have less intense vascular FDG uptake - symptoms are caused by inflammation around the shoulders, hips, and spine.

SUMMARY

Ultrasonography, MRI, and PET remain promising techniques in the scientific and clinical approach of large-vessel vasculitis.