Integrated head-thoracic vascular MRI at 3 T: Assessment of cranial, cervical and thoracic involvement of giant cell arteritis

Diagnosing Giant Cell Arteritis: A Comprehensive Practical Guide for the Practicing Rheumatologist

Giant cell arteritis (GCA) is the most common large vessel vasculitis in the elderly population. In recent years, advanced imaging has changed the way GCA can be diagnosed in many locations. The GCA fast-track clinic (FTC) approach combined with ultrasound (US) examination allows prompt treatment and diagnosis with high certainty. FTCs have been shown to improve prognosis while being cost effective. However, all diagnostic modalities are highly operator dependent, and in many locations expertise in advanced imaging may not be available. In this paper, we review the current evidence on GCA diagnostics and propose a simple algorithm for diagnosing GCA for use by rheumatologists not working in specialist centres.

Vessel wall MR imaging of central nervous system vasculitis: a systematic review

PURPOSE

Beyond vessel wall enhancement, little is understood about vessel wall MR imaging (VW-MRI) features of vasculitis affecting the central nervous system (CNS). We reviewed vessel wall MR imaging patterns of inflammatory versus infectious vasculitis and also compared imaging patterns for intracranial versus extracranial arteries of the head and neck.

METHODS

Studies reporting vasculitis of the CNS/head and neck and included MR imaging descriptions of vessel wall features were identified by searching PubMed, Scopus, Cochrane, Web of Science, and EMBASE up to June 10, 2020. From 6065 publications, 115 met the inclusion criteria. Data on study characteristics, vasculitis type, MR details, and VW-MRI descriptions were extracted.

RESULTS

Studies used VW-MRI for inflammatory (64%), infectious (17%), or both inflammatory and infectious vasculitides (19%). Vasculitis affecting intracranial versus extracranial arteries were reported in 58% and 39% of studies, respectively. Commonly reported VW-MRI features were vessel wall enhancement (89%), thickening (72%), edema (10%), and perivascular enhancement (16%). Inflammatory vasculitides affecting the intracranial arteries were less frequently reported to have vessel wall thickening (p = 0.006) and perivascular enhancement (p = 0.001) than extracranial arteries. Varicella zoster/herpes simplex vasculitis (VZV/HSV, 45%) and primary angiitis of the CNS (PACNS, 22%) were the most commonly reported CNS infectious and inflammatory vasculitides, respectively. Patients with VZV/HSV vasculitis more frequently showed decreased or resolution of vessel wall enhancement after therapy compared to PACNS (89% versus 59%).

CONCLUSIONS

To establish imaging biomarkers of vessel wall inflammation in the CNS, VW-MRI features of vasculitis accounting for disease mechanism and anatomy should be better understood.

Clinical value of [18F]FDG-PET/CT and 3D-black-blood 3T-MRI for the diagnosis of large vessel vasculitis and single-organ vasculitis of the aorta

BACKGROUND

We aimed to investigate the clinical value of a 3D-T1w turbo-spin-echo (TSE) sequence and [18F]fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) for the diagnosis of active large vessel vasculitis (LVV) and single-organ vasculitis (SOV) of the aorta.

METHODS

Twenty-four patients with suspected vasculitis who underwent MRI and PET/CT were retrospectively evaluated. MRI was analyzed for concentric contrast enhancement and wall thickening, and flow artifact intensity (4-point-scales). PET/CT analysis comprised qualitative, quantitative and semiquantitative methods. Imaging findings were correlated with final diagnosis derived from the clinical follow-up data.

RESULTS

Fifteen of 24 patients had a clinically confirmed active vasculitis, two had inactive vasculitis and 7 no vasculitis. [18F]FDG-PET/CT and 3D-T1w TSE-MRI revealed both a high diagnostic accuracy of 88% and 83%, respectively. In patients in whom both PET/CT and MRI showed concordant findings (19 patients), the accuracy increased to 95% with a high positive predictive value (92%) and negative predictive value (100%); thus, a correct diagnosis was obtained in 18 of 19 patients. Among the five patients with discordant findings PET/CT correctly identified the two patients without active vasculitis while rated false positive on MRI. Of the three remaining patients with active vasculitis, two were correctly identified by MRI and one by PET/CT.

CONCLUSIONS

3D-T1w TSE-MRI and [18F]FDG-PET/CT are both useful in the diagnosis of active vasculitis with high diagnostic accuracies. The diagnostic accuracy was even optimized by combining the two analysis methods. Therefore, there might be substantial potential for the application of whole-body hybrid PET/MRI in the evaluation of vasculitis in future studies.

3D-black-blood 3T-MRI for the diagnosis of thoracic large vessel vasculitis: A feasibility study

OBJECTIVES

To evaluate the feasibility of T1w-3D black-blood turbo spin echo (TSE) sequence with variable flip angles for the diagnosis of thoracic large vessel vasculitis (LVV).

METHODS

Thirty-five patients with LVV, diagnosed according to the current standard of reference, and 35 controls were imaged at 3.0T using 1.2 × 1.3 × 2.0 mm³ fat-suppressed, T1w-3D, modified Volumetric Isotropic TSE Acquisition (mVISTA) pre- and post-contrast. Applying a navigator and peripheral pulse unit triggering (PPU), the total scan time was 10-12 min. Thoracic aorta and subclavian and pulmonary arteries were evaluated for image quality (IQ), flow artefact intensity, diagnostic confidence, concentric wall thickening and contrast enhancement (CWT, CCE) using a 4-point scale.

RESULTS

IQ was good in all examinations (3.25 ± 0.72) and good to excellent in 342 of 408 evaluated segments (83.8 %), while 84.1 % showed no or minor flow artefacts. The interobserver reproducibility for the identification of CCE and CWT was 0.969 and 0.971 (p < 0.001) with an average diagnostic confidence of 3.47 ± 0.64. CCE and CWT were strongly correlated (Cohen's k = 0.87; P < 0.001) and significantly more frequent in the LVV-group (52.8 % vs. 1.0 %; 59.8 % vs. 2.4 %; P < 0.001).

CONCLUSIONS

Navigated fat-suppressed T1w-3D black-blood MRI with PPU-triggering allows diagnosis of thoracic LVV.

KEY POINTS

• Cross-sectional imaging is frequently applied in the diagnosis of LVV. • Navigated, PPU-triggered, T1w-3D mVISTA pre- and post contrast takes 10-12 min. • In this prospective, single-centre study, T1w-3D mVISTA accurately depicted large thoracic vessels. • T1w-3D mVISTA visualized CWT/CCW as correlates of mural inflammation in LVV. • T1w-3D mVISTA might be an alternative diagnostic tool without ionizing radiation.

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.

18F-fluorodeoxyglucose positron emission tomography in elderly patients with an elevated erythrocyte sedimentation rate of unknown origin

Patients with an elevated erythrocyte sedimentation rate (ESR) and non-specific symptoms often pose a diagnostic dilemma. PET/CT visualises infection, inflammation and malignancy, all of which may cause elevated ESR. The objective of this study was to determine the contribution of 18F-fluorodeoxglucose positron emission tomography (PET/CT) in the diagnostic work-up of referred patients with an elevated ESR, in whom initial routine evaluation did not reveal a diagnosis. We conducted a combined retrospective (A) and prospective (B) study in elderly (>50 years) patients with a significantly elevated ESR of≥50 mm/h and non-specific complaints. In study A, 30 patients were included. Malignancy (8 patients), auto-inflammatory disease (8 patients, including 5 with large-vessel vasculitis) and infection (3 patients) were suggested by PET/CT. Two scans showed non-specific abnormalities and 9 scans were normal. Of the 21 abnormal PET/CT results, 12 diagnoses were independently confirmed and two alternative diagnosis were made. Two diagnoses were established in patients with a normal scan. In study B, 58 patients in whom a prior protocolised work-up was non-diagnostic, were included. Of these, 25 PET/CT-scans showed suspected auto-inflammatory disease, particularly large-vessel vasculitis (14 cases). Infection and malignancy was suspected in 5 and 3 cases, respectively. Seven scans demonstrated non-specific abnormalities, 20 were normal. Of the 40 abnormal PET/CT results, 22 diagnoses were confirmed, 3 alternative diagnoses were established. Only one diagnosis was established in the 20 patients with a normal scan. In both studies, the final diagnosis was based on histology, clinical follow-up, response to therapy or additional imaging. In conclusion, PET/CT may be of potential value in the diagnostic work-up of patients with elevated ESR if routine evaluation reveals no diagnosis. In particular, large-vessel vasculitis appears to be a common finding. A normal PET/CT scan in these patients suggests that it is safe to follow a wait-and-see policy.

Temporal artery biopsy for giant cell arteritis: retrospective audit

Objectives

Temporal artery biopsy (TAB) is performed in suspected cases of sight-threatening giant cell arteritis (GCA). We aimed to determine the feasibility of TAB in patients who are suspected of having GCA.

Design, setting and participants

A retrospective audit of all patients undergoing TAB at a single teaching hospital between 2005 and 2011, identified from the histopathology database.

Main outcome measures

(1) Clinical profile and biochemical criteria associated with positive histology. (2) Proportion of negative histology patients who were commenced on steroid therapy.

Results

One hundred and fifty-three TAB were performed (mean age 70.8 years, men:women = 3:2, 110 Caucasian: 43 Asian). Thirty-two biopsies were positive for GCA and 121 were negative. In total, 68 (61%) of 112 negative TAB patients were clinically diagnosed with GCA despite histological findings (P < 0.001). Nine out of 153 biopsies were non-arterial. Histologically positive TAB patients were of higher mean age (77.1 [95% CI 74.5–79.7] versus 69.1 [95% CI 66.7–71.6]; P < 0.001) and had a higher erythrocyte sedimentation rate (ESR) (60 [95% CI 46.1–73.9] versus 39.8 [95% CI 34.2–45.3]; P < 0.01)] than those with negative histology.

Conclusions

Raised ESR and higher age may be the most useful indicators of GCA. Many histologically negative individuals were nevertheless clinically diagnosed and managed as GCA.

[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.

Long-term follow-up of aortic involvement in giant cell arteritis: a series of 48 patients

To date, only a few series have analyzed the long-term outcome of giant cell arteritis (GCA) patients with aortic involvement, which prompted us to conduct the current retrospective study. Our aims were to 1) determine the prevalence of GCA in patients exhibiting nonatherosclerotic aortic involvement (that is, aortitis, aortic ectasia, and/or aneurysm); and 2) evaluate clinical features and long-term outcome of GCA patients exhibiting aortitis, aortic ectasia, and/or aortic aneurysm.From January 1997 to March 2008, 66 consecutive patients in the Department of Internal Medicine at the University of Rouen medical center received a diagnosis of nonatheromatous aortic complications (aortitis, aortic ectasia, and/or aneurysm). In these 66 patients, aortic involvement was related to GCA (n = 48), Takayasu arteritis (n = 6), relapsing polychondritis (n = 1), and infection (n = 11).Of the 48 patients with GCA, aortic involvement preceded the initial GCA diagnosis in 1 patient. Aortic involvement was identified in association with GCA in 40 patients (83.3%), and developed after the onset of GCA in the 7 remaining patients (14.6%). Aortic involvement was more often asymptomatic (77.1%). The aortic helical computed tomography (CT)-scan procedure principally showed isolated aortitis (circumferential thickening of the aortic wall >3 mm) in 41 patients (85.4%). In the remaining 7 patients with GCA (14.6%), aortic helical CT scan demonstrated aortic thoracic ectasia and aortitis (n = 3), aortic thoracic aneurysm and both thoracic and abdominal aortitis (n = 3), and both aortic abdominal aneurysm and aortitis (n = 1). All patients were given steroid therapy at a median daily dose of 1 mg/kg initially.At 6-month follow-up, 34 of 48 patients systematically underwent both thoracic and abdominal CT scan. Aortic helical CT scan demonstrated complete disappearance of aortitis in 8.8% of patients, improvement of aortitis in 47.1%, unchanged pattern of aortitis and/or aortic thoracic ectasia/aneurysm in 41.2%, and deterioration of aortic thoracic aneurysm in 1 patient (2.9%). At 18-month follow-up, 11 patients systematically underwent both thoracic and abdominal CT scan. Aortic helical CT scan showed complete disappearance of aortitis (n = 1), improvement of aortitis (n = 1), unchanged pattern of aortic thoracic ectasia/aneurysm (n = 2), and deterioration of aortic thoracic aneurysm (n = 1). At patients' last follow-up, the median daily dose of prednisone was 7 mg. Steroid therapy could be discontinued in 17 patients (35.4%).The current retrospective study suggests that aortic impairment may be more prevalent than previously reported. Our findings suggest that specific inflammatory thickening of the aortic wall is common at the time of GCA diagnosis, and that aortitis may be the first manifestation of GCA-associated aortic complications. Whether isolated aortitis leads to vascular wall injury responsible for late-onset aneurysmal disease remains to be determined. At this time, we recommend long-term monitoring for aortic aneurysms, especially in high-risk subjects, although the optimal frequency and imaging modality have not yet been determined. A yearly screening strategy for thoracic/abdominal aortic aneurysms has been proposed for patients with GCA, including physical examination, 2-view chest radiograph, and abdominal ultrasound.

[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.

Role of imaging in vasculitis and connective tissue diseases

Imaging techniques play a pivotal role in securing the diagnosis of large vessel vasculitis, and in demonstrating internal organ involvement in connective tissue diseases. In large vessel vasculitis, angiography is useful in demonstrating vessel stenoses or aneurysms. However, angiography is unable to reveal initial lesions such as vessel wall oedema and thickening, and is thus not useful to make an early diagnosis. In contrast, colour Doppler ultrasonography, computerized tomography angiography, and magnetic resonance imaging/angiography are able to delineate both the vessel wall and the lumen. Therefore, they may show vessel wall alterations when the lumen is still unaffected on angiography. 18fluorodeoxyglucose positron emission tomography does not visualize the vessel wall, but is very sensitive in revealing inflamed vessels. All of these investigations have also been used to follow up patients over time and to monitor response to treatment. In connective tissue diseases, imaging techniques are particularly useful to study internal organs, especially the brain and lung. Magnetic resonance imaging is the investigation of choice to detect and monitor brain disease, while computerized tomography is the best procedure for lung disease. However, since most imaging findings are not entirely specific for any given condition, it is important to interpret the results of imaging in the broader clinical context.

Giant cell arteritis: an updated review

Giant cell arteritis (GCA) is the most common primary vasculitis of adults. The incidence of this disease is practically nil in the population under the age of 50 years, then rises dramatically with each passing decade. The median age of onset of the disease is about 75 years. As the ageing population expands, it is increasingly important for ophthalmologists to be familiar with GCA and its various manifestations, ophthalmic and non-ophthalmic. A heightened awareness of this condition can avoid delays in diagnosis and treatment. It is well known that prompt initiation of steroids remains the most effective means for preventing potentially devastating ischaemic complications. This review summarizes the current concepts regarding the immunopathogenetic pathways that lead to arteritis and the major phenotypic subtypes of GCA with emphasis on large vessel vasculitis, novel modalities for disease detection and investigative trials using alternative, non-steroid therapies.

1H MR spectroscopic imaging with short and long echo time to discriminate glycine in glial tumours

OBJECT

To investigate glycine (Gly) concentrations in low- and high-grade gliomas based on (1)H MR spectroscopic imaging (MRSI) with short and long echo time (TE). Myoinositol (MI) and Gly appear at the same resonance frequency of 3.56 ppm, but due to strong coupling the MI signal dephases more rapidly. Therefore, their contribution to the 3.56 ppm signal should be distinguishable comparing MRSI data acquired at short and long TE.

MATERIALS AND METHODS

(1)H MRSI (TE = 30 and 144 ms) was performed at 3 T in 29 patients with histopathological confirmed World Health Organization (WHO) grade II-IV gliomas and in FIVE healthy subjects. All spectra from the gliomas revealed increase of the 3.56 ppm resonance in the short TE spectra. Signal intensities of Gly and MI were differentiated either by analysing the short to long TE ratio of the resonance or by performing a weighted difference. Gly concentrations were compared between high-grade (WHO III-IV) and low-grade gliomas.

RESULTS

High-grade gliomas showed significantly higher Gly concentrations compared to low-grade gliomas.

CONCLUSION

Appropriate data processing of short and long TE (1)H MRSI provides a tool to distinguish and to quantify Gly and MI concentrations in gliomas. As Gly seems to be a marker of malignancy, more dedicated spectroscopic methods to differentiate these metabolites are justified.

Spontaneous bilateral necrosis of the tongue: a manifestation of giant cell arteritis?

Giant cell arteritis is a chronic vasculitis, which involves large- and medium-sized branches of the arteries originating from the aortic arch. This disease is a diagnostic challenge with a wide range of clinical symptoms and findings due to different affected vessels. Classic symptoms are temporally located headache, thickened temporal artery and jaw claudication. Furthermore, visual symptoms like diplopia or loss of vision can occur. The tongue has an excellent blood supply and ischemic ulceration due to giant cell vasculitis is usually unilateral and rarely described in literature. We present a patient with a spontaneous bilateral tongue necrosis and are convinced that this extraordinary case must be deemed to be a manifestation of giant cell arteritis, although it does not completly satisfy the usually used diagnostic criteria formulated by the American College of Rheumatology.

Influence of corticosteroid treatment on MRI findings in giant cell arteritis

Giant cell arteritis (GCA) remains a diagnostic challenge. With the use of a high-resolution MRI protocol, visualization of the superficial cranial arteries is feasible and mural inflammation can be assessed noninvasively. Until today, it is not known how soon inflammatory signals in diagnostic MR imaging vanish after initiation of treatment. Here, we report sequential MR imaging findings during the initial weeks of corticosteroid treatment in a 79-year-old female patient with histologically proven GCA. Mural inflammatory changes decreased within the first 2 weeks and have almost entirely vanished after 2 1/2 months of continued treatment. Moreover, MR angiography revealed sequential stenoses of the subclavian artery, which improved in variable extent with some residuals despite high dose steroid medication. This report underlines the value of high-resolution MRI in diagnosis and follow-up of GCA and illustrates the potential of MRI to detect and monitor intra- and extra-cranial involvement patterns of GCA in high detail.

High resolution 3T MRI for the assessment of cervical and superficial cranial arteries in giant cell arteritis

A new high-resolution MR protocol for the combined assessment of neurovascular arterial anatomy and subsequent evaluation of inflammatory disease in cranial vessels walls has been investigated. First-pass contrast-enhanced MR angiography (CE-MRA) in combination with parallel imaging at high field permits the depiction of the neurovascular geometry with large coverage, including the aortic arch, supraaortic vessels, and almost the entire head, with high, submillimeter detail. Utilizing the remaining contrast agent, postcontrast T(1)-weighted turbo spin-echo (TSE) imaging was used to generate late enhancement images of the vessel walls to assess the morphology and potential inflammatory changes in cranial arteries with high in-plane (195 x 260 microm(2)) spatial resolution. As a result, a combined analysis of neurovascular arterial anatomy as well as cranial vessel wall inflammations could be achieved in less than 45 minutes in all studies. The feasibility and clinical value for the diagnosis of rheumatologic diseases and simultaneous arteriosclerotic involvement was demonstrated in seven patients with suspected giant cell arteritis (GCA). Excellent CE-MRA image quality could be achieved and even vascular geometry of small superficial cranial arteries could be successfully visualized using single dose (0.1 mmol/kg) contrast agent administration and a dedicated phased-array head and neck coil at 3T.

3-T MRI reveals cranial and thoracic inflammatory changes in giant cell arteritis

Giant cell arteritis (GCA) is a diagnostic challenge. The correct diagnosis is needed for immediate initiation of corticosteroid treatment since blindness is a dreaded complication. Typically, the superficial cranial arteries are affected by this granulomatous vasculitis of large- and medium-sized arteries. However, GCA is not limited to the cranial arteries. Involvement of various arteries such as the cervical and thoracic arteries can also occur. Here, we report a case of histologically proven GCA with cranial and extracranial involvement. We illustrate the usefulness of a comprehensive vascular high-resolution magnetic resonance imaging examination that combines assessment of mural inflammatory changes of the small temporal and occipital arteries with the evaluation of extracranial vasculature to assist in the difficult non-invasive diagnosis and to determine the extent of this inflammatory disease.

Analysis of the changes in the 1H NMR spectral pattern of perchloric acid extracts of C6 cells with growth

The aim of this work was to identify spectral markers of cell proliferation that could be of use in clinical MRS. Cultured C6 ATCC rat glioma cells were used as models for this purpose and metabolites were extracted with perchloric acid at three different growth curve stages: log, confluence and post-confluence. 1D and 2D in vitro(1)H NMR spectra were recorded at 9.4 T. Statistically significant changes in myo-inositol and glutamine concentrations between log phase and post-confluence were found when normalized to the creatine ratio. The myo-inositol/creatine ratio was 2.76 +/- 0.82 at log phase increasing to 7.43 +/- 1.34 at post-confluence, while the glutamine/creatine ratio decreased from 0.22 +/- 0.03 to 0.10 +/- 0.02. No significant differences were recorded for other metabolites investigated. The fact that both myo-inositol and glutamine are detectable by in vivo MRS at clinical fields makes their changes relevant as potential astrocytic tumour proliferation rate markers in clinical MRS.

Bildgebende Verfahren bei Riesenzellarteriitis (M. Horton)

This review article highlights several diagnostic imaging modalities in giant cell arteritis. Color-coded Duplex sonography is a relatively cost-efficient but strongly observer-dependent imaging modality. It may be difficult to distinguish inflammatory from atherosclerotic mural changes. Positron emission tomography with (18)F-fluoro-2-deoxy-D-glucose is very sensitive in detecting extracranial involvement of large vessel vasculitis. However, it provides no information on inflammatory changes of the superficial cranial arteries. High-resolution MRI is a new observer-independent method that allows visualizing and assessing the superficial cranial arteries in high detail. Extracranial large artery involvement can be evaluated during the same investigation. At present, only single-center experiences with this promising but rather complex procedure exist. A comparative multicenter trial is about to be initiated.