Background A systematic literature review was conducted to evaluate the value of Positron Emission Tomography (PET) scan in the diagnosis and management of large vessel vasculitis. Vasculitis is classified by American College of Rheumatology (ACR) criteria23-24. Though often based on ACR criteria, the clinical diagnosis of specific type of vasculitis by using ACR criteria only may be difficult20-25. The diagnosis of large vessel vasculitis can be challenging in difficult cases presenting with non-specific clinical features. The diagnosis of small vessel vasculitis is aided by antineutrophilic cytoplasmic antibodies. There are no specific serological markers for the diagnosis of large vessel vasculitis.
Objectives Doppler Ultrasound, Computed Tomography and Magnetic Resonance Imaging can identify the structural abnormalities (wall thickening, thrombus, calcifications and luminal stenoses) in vessels but do not provide an assessment of disease activity. These structural abnormalities develop later in course of vasculitis as a result of the inflammatory process and are irreversible. Biopsy of the affected vessel may not be possible in all cases. Moreover, in cases of GCA a negative temporal artery biopsy does not exclude the diagnosis. It is important to make a correct diagnosis as treatment with glucocorticoids and immunosuppressive therapy may lead to significant side effects.
PET is a relatively newer functional imaging investigation. It may be helpful in identifying areas of occult disease and excluding vascular inflammation.
Methods The earliest published literature about use of PET imaging in diagnosis of large vesselvasculitis was in 1999. Literature search was conducted using major online databases (see below) for articles published until March 2011. Articles published in languages other than English were excluded. Case reports were excluded from the review. Consecutive case series were included.
Studies using PET Imaging complemented with other modalities (Computed Tomography, Magnetic Resonance Imaging) were included. American College of Rheumatology Criteria was not mentioned in all studies.
The following search terms were used solely or in combination to search the literature
The following databases were used to conduct the search Pubmed, Medline, Embase, Cochrane. A total of 22 articles were selected for inclusion in the systematic review. These included 7 prospective studies, 7 Retrospective studies and 8 consecutive case series.
Results As a functional whole body imaging PET may be useful in evaluating diagnostically challenging cases of large vessel vasculitis. It may identify areas for obtaining biopsy and help in assessing the extent of disease. However, PET imaging is not widely available and there is of lack of standardization of imaging techniques.
Conclusions There is not enough evidence to include PET imaging in routine the work up of large vessel vasculitis. It may be useful in monitoring disease activity where inflammatory markers are not reliable.
Disclosure of Interest None Declared
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