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 Table of Contents  
IMAGES IN RHEUMATOLOGY
Year : 2017  |  Volume : 12  |  Issue : 3  |  Page : 179-183

Fluorodeoxyglucose positron emission tomography–Computed tomography in diagnosis of large vessel vasculitis in cases of pyrexia of unknown origin


1 Department of Nuclear Medicine and PET CT, Army Hospital Research and Referral, New Delhi, India
2 Department of Rheumatology, Army Hospital Research and Referral, New Delhi, India

Date of Web Publication19-Jun-2017

Correspondence Address:
Anurag Jain
Department of Nuclear Medicine, Army Hospital R and R, New Delhi - 110 010
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/injr.injr_22_17

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  Abstract 


Keywords: 18 F-flourodeoxyglucose(FDG), Large vessel vasculitis, PET/CT,pyrexia of unknown origin


How to cite this article:
Jain A, Solanki KP, Hegde A, John AR, Kumar N. Fluorodeoxyglucose positron emission tomography–Computed tomography in diagnosis of large vessel vasculitis in cases of pyrexia of unknown origin. Indian J Rheumatol 2017;12:179-83

How to cite this URL:
Jain A, Solanki KP, Hegde A, John AR, Kumar N. Fluorodeoxyglucose positron emission tomography–Computed tomography in diagnosis of large vessel vasculitis in cases of pyrexia of unknown origin. Indian J Rheumatol [serial online] 2017 [cited 2019 Nov 20];12:179-83. Available from: http://www.indianjrheumatol.com/text.asp?2017/12/3/179/208292

There is a growing body of evidence, which demonstrates the role of 18 F-fluorodeoxyglucose (FDG) positron emission tomography–computed tomography (PET/CT) in the diagnosis of large-vessel vasculitis.[1] We herein report two cases who presented with pyrexia of unknown origin and were evaluated by FDG-PET/CT, that then lead to the confirmation of diagnosis of large-vessel vasculitis. The patients were then managed with steroid therapy with good response.

Large vessel vasculitis is a chronic inflammatory condition of the large blood vessels. The first case of Takayasu's arteritis (a type of large vessel vasculitis) was described in 1908 by Japanese ophthalmologist Dr. Mikito Takayasu at the annual meeting of Japanese ophthalmology society. Dr Takayasu described a peculiar “wreath like” appearance of a blood vessel in the retina.[2] Another form of large vessel vasculitis is Giant-cell arteritis or temporal arteritis, which mostly involve large arteries of the head.

Case 1

A 72-year-old male, presented with low-grade intermittent fever of 2 months duration, associated with prodromal symptoms of body ache, malaise, and episodic diffuse headache. General and systemic examination were normal. He was evaluated exhaustively. Hematological investigations revealed a rising erythrocyte sedimentation rate (ESR) and progressively decreasing hemoglobin (Hb) values [Table 1]. Routine biochemical tests, infectious disease and workup for connective tissue disease, blood and urine cultures, and ultrasonography of abdomen were unremarkable.
Table 1: Blood investigation of case 1

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He was treated empirically for enteric fever and malaria, however, the fever persisted. Empirical ATT was started without any relief. At this point, the treating physician thought of occult malignancy presenting as fever of unknown origin (FUO) and referred the patient for PET/CT scan. FDG-PET/CT imaging demonstrated increased uptake in a linear fashion along the aorta and its branches [Figure 1].
Figure 1: Axial section showing diffusely increased FDG in both femoral arteries uptake in bilateral femoral artery

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Positron emission tomography–computed tomography findings

There is symmetric homogeneous moderately increased FDG uptake (SUV max 3.6) diffusely in the following large arteries: bilateral subclavian, aorta, aortic root bifurcation, common iliac, bilateral external and internal iliac, bilateral femoral arteries-suggestive of large vessel vasculitis [Figure 1], [Figure 2], [Figure 3], [Figure 4].
Figure 2: Comparative axial section showing physiological uptake in normal person

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Figure 3: Coronal section showing diffusely increased FDG uptake in abdominal aorta, aortic bifurcation and bilateral axillary artery

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Figure 4: Comparative coronal section showing physiological FDG uptake in normal person

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The patient was finally managed as a case of large vessel vasculitis with steroids with good symptomatic improvement.

Case 2

A 78-year-old male presented with low-to-moderate grade fever for 4 months associated with generalized weakness and easy fatigability. There was no other significant positive history. General examination revealed normal peripheral pulses. Systemic examination was essentially normal. He was evaluated exhaustively. All the hematological investigations were within normal limits, except rising ESR (115 mm in 1st hour → 140 mm in 1st h) and low Hb values (7.3 g → 6.4 g%) [Table 2]. Routine biochemical tests were normal. Infectious disease work, sputum acid–fast bacilli, antinuclear antibodies, and antineutrophil cytoplasmic antibody were negative. Serum protein electrophoresis revealed hypergammaglobulinemia. Urine for Bence Jones protein was negative. Contrast-enhanced CT (CECT) chest was suggestive of fibrotic opacities in both lungs while CECT abdomen was normal. The patient was advised FDG PET/CT to investigate the cause of FUO.
Table 2: Blood investigation of case 2

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Positron emission tomography–computed tomography findings

FDG-PET/CT imaging was performed. The images show mildly increased FDG uptake in the wall of descending thoracic and abdominal aorta (SUV max-1.6 w.r.t SUV max-1.3 of liver along with irregular wall thickening [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]. Corroborative CT angiography was performed which was suggestive of diffuse concentric mural thickening involving thoracic and abdominal aorta, bilateral subclavian, and left axillary artery with luminal narrowing.
Figure 5: Whole body PET image coronal section showing increased FDG uptake in descending thoracic aorta

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Figure 6: Comparative whole body FDG PET/CT image at the same coronal section of a normal person showing and physiological uptake

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Figure 7: Axial section of Thorax showing circumferentially increased FDG uptake in descending thoracic aorta

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Figure 8: Comparative axial section of a normal person showing physiological FDG uptake

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Figure 9: Maximum intensity projection image coronal section showing increased FOG uptake in descending thoracic aorta

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Figure 10: Whole body PET image coronal section showing increased FOG uptake in descending thoracic aorta

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Figure 11: Axial section of Thorax showing circumferentially increased FOG uptake in descending thoracic aorta

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The patient was diagnosed as a case of aortoarteritis and managed with steroids and methotrexate.


  Discussion Top


Striking images of large-vessel involvement in large vessel vasculitis have been generated through FDG PET scans.[3] These images indicate the potential of this technique for studying large-vessel vasculitis and imply that PET scan is useful for the diagnosis of vasculitis. Because of high uptake of FDG in the brain, the small diameter of the temporal artery, and the relatively high background activity of the skin, direct evaluation of the temporal arteries is not possible with the current whole-body PET techniques. In the evaluation of the great vessels, however, it is a valuable tool.

Linear, contiguous, FDG uptake similar to or greater than liver within the great vessel is typical for large vessel vasculitis. Giant-cell arteritis and Takayasu's arteritis can both involve the large vessels. Takayasu's arteritis typically affects younger patients (<40 years) whereas Giant-cell arteritis affects patients over the age of 50 years. In patients with large vessel vasculitis, FDG uptake has been found to correlate with ESR and C-reactive protein levels. Anemia and elevated ESR often accompany active disease. FDG PET/CT has been shown to be useful in determining the degree and extent of large vessel vasculitis. FDG uptake can also be seen with atherosclerotic disease; however, this is typically less intense and is noncontiguous.[4]

There is a limited number of studies on role of FDG PET/CT in the diagnosis of large-vessel vasculitis as a cause for pyrexia of unknown origin. In a study of 25 patients with Giant-cell arteritis and 13 patients with Polymyalgia rheumatica, thoracic vascular FDG uptake had a sensitivity of 56% for the diagnoses of Giant-cell arteritis or polymyalgia rheumatica, a specificity of 98%, and a positive predictive value of 93%.[3] In an ongoing follow-up study, Blockmans studied total 40 patients, out of which 20 were of Giant cell arteritis and 20 with polymyalgia rheumatica. In polymyalgia rheumatica, FDG uptake localizing in vascular region was noted in only 3(15%) and 18 out of 20 showed FDG uptake in bilateral shoulder and hip joint. Among patients with Giant cell arteritis, 16(80%) shows intense FDG uptake in large vessels. Of all the 40 patients, follow up studies for 14 patients were done, at 3 months. FDG uptake had disappeared in the seven patients (5O%) undergoing follow-up studies and persisted (albeit with lower uptake) in the other 7. At 6 months, there was no further decrease in FDG uptake in the 6 patients reevaluated at that time.[5]


  Conclusion Top


Making the diagnosis of large-vessel vasculitis can be extremely difficult. Unfortunately, it is very common for the disease to smolder in the walls of large blood vessels for years, causing only nonspecific symptoms associated with the systemic phase of the illness (or no symptoms), until a major complication results. These major complications may include dilation of the aorta with “stretching” of the aortic valve in the heart; critically reduced blood flow to an arm or leg; a stroke caused by high blood pressure in vessels of the brain, among others.[6] FDG PET CT scan is valuable in cases where suspicion of large vessel vasculitis is made for cases with pyrexia of unknown origin. It also helps in knowing the extent of disease.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgment

We would like to acknowledge the Department of Rheumatology, Army Hospital R and R-Delhi Cantt 110010.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Akin E, Coen A, Momeni M. PET-CT findings in large vessel vasculitis presenting as FUO, a case report. Clin Rheumatol 2009;28:737-8.  Back to cited text no. 1
[PUBMED]    
2.
Takayasu M. A case with peculiar changes of the central retinal vessels. Acta Soc Ophthalmol Jpn Tokyo 1908;12:554.  Back to cited text no. 2
    
3.
Blockmans D, Stroobants S, Maes A, Mortelmans L. Positron emission tomography in giant cell arteritis and polymyalgia rheumatica: Evidence for inflammation of the aortic arch. Am J Med 2000;108:246-9.  Back to cited text no. 3
[PUBMED]    
4.
Watter M. F 18-FDG PET in large vessel vasculitis. North America: Radiology Clinics; 2007. p. 735-44.  Back to cited text no. 4
    
5.
Blockmans D. Utility of imaging studies in assessment of vascular inflammation. Cleve Clin J Med 2002;69 Suppl 2:SII95-9.  Back to cited text no. 5
[PUBMED]    
6.
Available from: http://www.hopkinsvasculitis.org/types-vasculitis/takayasus-arteritis/#treatment. [Last accessed on 2017 Feb 28].  Back to cited text no. 6
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]
 
 
    Tables

  [Table 1], [Table 2]



 

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