[Horton's disease and extra-temporal vessel locations: role of 18FDG PET scan. Report of 3 cases and review of the literature]

Positron Emission Tomography/Computerized Tomography in Newly Diagnosed Patients with Giant Cell Arteritis Who Are Taking Glucocorticoids

OBJECTIVE

Large vessel uptake on positron emission tomography/computerized tomography (PET/CT) supports the diagnosis of giant cell arteritis (GCA). Its value, however, in patients without arteritis on temporal artery biopsy and in those receiving glucocorticoids remains unknown. We compared PET/CT results in GCA patients with positive (TAB+) and negative temporal artery biopsies (TAB-), and controls.

METHODS

Patients with new clinically diagnosed GCA starting treatment with glucocorticoids underwent temporal artery biopsy and PET/CT. Using a visual semiquantitative approach, 18F-fluorodeoxyglucose (FDG) uptake was scored in 8 vascular territories and summed overall to give a total score in patients and matched controls.

RESULTS

Twenty-eight patients with GCA and 28 controls were enrolled. Eighteen patients with GCA were TAB+. Mean PET/CT scores after an average of 11.9 days of prednisone were higher in patients with GCA compared to controls, for both total uptake (10.34 ± 2.72 vs 7.73 ± 2.56; p = 0.001), and in 6 of 8 specific vascular territories. PET/CT scores were similar between TAB+ and TAB- patients with GCA. The optimal cutoff for distinguishing GCA cases from controls was a total PET/CT score of ≥ 9, with an area under the receiver-operating characteristic curve of 0.75, sensitivity 71.4%, and specificity 64.3%. Among patients with GCA, these measures correlated with greater total PET/CT scores: systemic symptoms (p = 0.015), lower hemoglobin (p = 0.009), and higher platelet count (p = 0.008).

CONCLUSION

Vascular FDG uptake scores were increased in most patients with GCA despite exposure to prednisone; however, the sensitivity and specificity of PET/CT in this setting were lower than those previously reported.

[Giant cell arteritis-related upper/lower limb vasculitis]

Upper/lower limb vasculitis has been considered an uncommon manifestation of giant cell arteritis, occurring in 3 to 16% of patients. Upper/lower limb vasculitis is still associated with significant morbidity, leading to limb/toe amputation in 5.6 to 15.8% of patients. Yearly clinical vascular examination should be performed systematically to screen upper/lower limb vasculitis at an early stage in patients with giant cell arteritis. Duplex ultrasound has proved to be a reliable non-invasive imaging method for detecting arterial stenoses of the upper/lower limbs in patients with giant cell arteritis. Patients with giant cell arteritis-related upper/lower limb vasculitis should undergo routine investigations to detect underlying aortic complications, concomitant aortic localizations being encountered in more than 50% of cases. Prednisone is the first-line therapy at an initial dose of 0.7-1 mg/kg daily. Prevention of platelet aggregation with low-dose aspirin is potentially effective in preventing ischemic complications of GCA. The indication of surgical therapy should be based on the severity of giant cell arteritis-related upper/lower limb clinical symptoms to avoid unnecessary morbidity in the course of interventional therapy.

[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.

Giant cell arteritis: heterogeneity in clinical presentation and imaging results

OBJECTIVE

Giant cell arteritis (GCA) is commonly known for its clinical presentation of temporal arteritis. However, GCA affects large arteries, predominantly the aorta and its proximal branches, in up to 75% of cases. We describe the clinical presentation and diagnostic test results of patients with large-vessel GCA.

METHODS

Case description of 11 patients with large-vessel GCA diagnosed consecutively in our hospital.

RESULTS

The clinical presentation of large-vessel GCA is highly variable, from systemic inflammation to aortic rupture. Imaging shows variable abnormalities, but 18-fluorodeoxyglucose positron-emission-tomography (18-FDG PET) seems to be a sensitive and reasonably specific diagnostic test for large-vessel GCA.

CONCLUSION

Large-vessel GCA is a clinically heterogeneous condition. 18-FDG PET should be considered in the diagnostic work-up of suspected cases. Since this disorder has a high complication rate, and is responsive to treatment with corticosteroids, a high level of clinical suspicion is warranted.

[18F]Fluorodeoxyglucose PET in Large Vessel Vasculitis

[(18)F]fluorodeoxyglucose (FDG) PET is a noninvasive metabolic imaging modality based on the regional distribution of [18F]FDG that is highly effective in assessing the activity and extent of giant cell arteritis and Takayasu's arteritis, respectively. Metabolic imaging using [18F]FDG-PET has been shown to identify more affected vascular regions than morphologic imaging with MRI in both diseases. The visual grading of vascular [18F]FDG uptake helps to discriminate arteritis from atherosclerosis and therefore provides high specificity. High sensitivity is attained by scanning during the active inflammatory phase. Thus, [18F]FDG-PET has the potential to develop into a valuable tool in the diagnostic workup of giant cell arteritis and Takayasu's arteritis.

La tomographie d'émission de positons en médecine interne : applications actuelles et perspectives d'avenir

PURPOSE

Fluorodeoxyglucose positron emission tomography (FDG-PET) is a promising imaging technique that has already proven effective in modifying patient care in oncology. Fluorodeoxyglucose still remains the main radiopharmaceutical agent routinely used for PET imaging. A growing interest has recently lead to broaden PET research on benign disorders. The field of inflammatory or immune diseases and globally the field of internal medicine could also be impacted by FDG-PET.

MAIN POINTS

Great vessels vasculitides and fever of unknown origin have both been studied by several teams and could become indications for PET. In addition, current indications now extend to paraneoplastic syndromes. It is thus possible to foresee that the clinical applications for PET will continue to expand in these patients.

PERSPECTIVES AND PROJECTS

In the future, inflammatory arthritis, chronic inflammatory bowel diseases, systemic erythematous lupus, histiocytosis, or pulmonary and retroperitoneal fibrosis might benefit from PET even if, available data remains scarce to this day. Although PET will probably alter the landscape of patient management in internal medicine in the near future, additional clinical research is still needed to ascertain the exact role of PET.

Aortite inflammatoire et maladie de Horton. À propos du suivi évolutif scanographique prospectif d'une série de 11 patients

PURPOSE

To determine clinical and radiological features, using computed tomography (CT-scan) in patients with aortic involvement related to giant cell arteritis (GCA), and to assess both clinical and CT-scan outcome after therapy institution.

METHODS

Aortic involvement due to GCA was investigated in all patients, using CT-scan at diagnosis, and at 3, 6 and 12 months follow-up after therapy institution.

RESULTS

The 11 consecutive patients consisted of 4 men and 7 women with mean age of 64.5 years. Patients exhibited: constitutional symptoms (N=9; 82%), dorsalgia (N=3; 27%), clinical signs of GCA (N=3; 27%) and of upper limb large vessel impairment (N=6; 55%). CT-scan showed aortitis involving both thoracic and abdominal aorta (N=6; 55%), abdominal (N=2; 18%) or thoracic aorta (N=2; 18%) and thoracic aortic aneurysm (N=1; 9%). At one-year follow-up, CT-scan revealed: complete resolution (N=7; 64%) and improvement (N=3; 27%) of aortic damage; the patient, who had thoracic aortic aneurysm, underwent surgical treatment, as aortic lesion remained unchanged on CT-scan.

CONCLUSION

Our study underlines that CT-scan is a helpful test in diagnosis and follow-up of aortic involvement in patients with GCA.

Use of ultrasonography and positron emission tomography in the diagnosis and assessment of large-vessel vasculitis

PURPOSE OF REVIEW

Ultrasonography and positron emission tomography have been increasingly studied and, in part, introduced in clinical practice to diagnose large-vessel vasculitides, such as temporal arteritis, Takayasu arteritis, large-vessel giant cell arteritis, and isolated aortitis.

RECENT FINDINGS

Ultrasonography reveals characteristic homogenous, concentric wall thickening in vasculitis, often combined with stenoses and, less frequently, with acute occlusions. Thirteen studies describe sensitivities of 40 to 100% (median, 86%) for temporal artery vessel wall edema compared with histology, and of 35 to 86% (median, 70%) compared with clinical diagnosis. If wall edema, stenoses, and occlusions are included, sensitivities increase to 91 to 100% (median, 95%) compared with histology, and to 83 to 100% (median, 88%) compared with clinical diagnosis. Specificities for wall edema are 68 to 100% (median, 93%) compared with histology, and 78 to 100% (median, 97%) compared with clinical diagnosis. One should be aware of large-vessel giant cell arteritis in all patients with temporal arteritis and polymyalgia rheumatica. Ultrasonography reveals characteristic wall thickening, particularly of the distal subclavian, axillary, and proximal brachial arteries. Findings in Takayasu arteritis are similar, but the vessel wall swelling is usually brighter. Positron emission tomography reveals vasculitis in arteries with a diameter of more than 4 mm. Ultrasonography and positron emission tomography agreed completely in the anatomic distribution of changes in patients with large-vessel giant cell arteritis. It reveals asymptomatic large-vessel vasculitis in giant cell arteritis and Takayasu arteritis. Positron emission tomography is not suitable for the assessment of temporal arteries.

SUMMARY

Ultrasonography and positron emission tomography are new, promising techniques to assess large-vessel vasculitides.