Positron emission tomography and computed tomography angiography for the diagnosis of giant cell arteritis: A real-life prospective study

Abstract

The use of 18F-fluoro-deoxyglucose positron emission tomography scan (FDG-PET) and computed tomography angiography (CTA) to improve accuracy of diagnosis of giant cell arteritis (GCA) is a very important clinical need. We aimed to compare the diagnostic performance of FDG-PET and CTA in patients with GCA.FDG-PET and CTA were acquired in all consecutive patients suspected for GCA. Results of FDG-PET and CTA were compared with the final diagnosis based on clinical judgment, temporal artery biopsy (TAB) findings, and ACR criteria. Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were calculated for each method.Twenty-four patients suspected for GCA were included. Fifteen (62.5%) were ultimately diagnosed as having GCA. Among them, all fulfilled ACR criteria and 6 had biopsy-proven GCA. Strong FDG uptake in large vessels was found in 10 patients who all had GCA. Mean maximal standard uptake values (SUVmax) per patient measured at all the arterial territories were of 3.7 (range: 2.8-4.7). FDG uptake was negative in 14 patients including 9 and 5 patients without and with GCA, respectively. Mural thickening suggestive of aortitis or branch vessel arteritis was observed on CTA in 11 patients with and 2 patients without GCA. No mural thickening was observed in 11 patients including 7 patients without and 4 patients with GCA. Overall, sensitivity was 66.7% and 73.3%, specificity was 100% and 84.6%, NPV was 64.3% and 64.6%, and PPV was 100% and 84.6% of FDG-PET and CTA, respectively.Both FDG-PET and CTA have a strong diagnostic yield for the diagnosis of GCA. FDG-PET appeared to have a higher PPV as compared to CTA and may be the preferred noninvasive technique to explore patients with suspected GCA.

Figure 1

Studied patients. PET+ referred to FDG-PET showing strong FDG uptake in large vessels. PET− referred to FDG-PET with no FDG uptake in large vessels. CTA+ referred to CTA showing mural thickening suggestive of large vessels arteritis. CTA− referred to CTA showing no mural thickening. GCA+ referred to patients with confirmed GCA diagnosis. GCA− referred to patient with infirmed GCA diagnosis. CTA = computed tomography angiography, GCA = giant cell arteritis, PET = positron emission tomography combined with computed tomography, TAB = temporal artery biopsy.

Figure 2

SUVmax and serum CRP level in patients with GCA. Mean SUV max referred to the mean SUVmax per patient measured at all the arterial territories in patients with GCA (GCA+, black circles). CRP referred to the maximum CRP value measured in serum per patient. CRP = C-reactive protein, GCA = giant cell arteritis, SUVmax = maximal standard uptake values.