Systemic and vascular inflammation in patients with moderate to severe psoriasis as measured by [18F]-fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET/CT): a pilot study

Abstract

Objective: To evaluate the feasibility of using [18F]-fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET/CT) to detect and quantify systemic inflammation in patients with psoriasis.

Design: Case series with a nested case-control study.

Setting: Referral dermatology and preventive cardiology practices.

Participants: Six patients with psoriasis affecting more than 10% of their body surface area and 4 controls age and sex matched to 4 of the patients with psoriasis for a nested case-control study.

Main outcome measures: The FDG uptake in the liver, musculoskeletal structures, and aorta measured by mean standardized uptake value, a measure of FDG tracer uptake by macrophages and other inflammatory cells.

Results: FDG-PET/CT identified numerous foci of inflammation in 6 patients with psoriasis within the skin, liver, joints, tendons, and aorta. Inflammation in the joints was observed in a patient with psoriatic arthritis as well as in 1 patient with no history of joint disease or joint symptoms. In a nested case-control study, FDG-PET/CT imaging demonstrated increased vascular inflammation in multiple segments of the aorta compared with controls. These findings persisted after adjustment for traditional cardiovascular risk factors in multivariate analysis (mean β = 0.33; P < .001). Patients with psoriasis further demonstrated increased hepatic inflammation after adjusting for cardiovascular risk factors (β = 0.18; P < .001), but the association was no longer significant when adjusted for alcohol intake (β = -0.25; P = .07).

Conclusion: FDG-PET/CT is a sensitive tool for identifying inflammation and can be used to identify clinically observed inflammation in the skin and subclinical inflammation in the blood vessels, joints, and liver of patients with psoriasis.

Figures

Figure 1. FDG-PET/CT imaging of skin correlates with observed skin inflammation

(a) Photograph of patient with psoriasis showing extensive multifocal plaques. (b) Corresponding PET image from FDG-PET/CT study in same patient demonstrates skin inflammation in similar distribution.

Figure 2. FDG-PET/CT imaging Shows Multifocal Inflammation in Patient with Psoriasis Compared to Control

PET image from FDG-PET/CT study in patient with psoriasis is shown at left. FDG-PET image from control patient is shown at right for comparison (no abnormal FDG uptake). (A) FDG uptake in right knee joint (SUV 3.0) and distal right quadriceps tendon, left trochanteric bursa, and left ankle in asymptomatic psoriasis patient. (B) Moderate diffusely increased FDG uptake throughout liver (SUV 1.64) consistent with increased hepatic inflammation. (C) Diffuse FDG uptake in aortic wall (SUV 1.29–1.72) and in femoral arterial tree, consistent with vascular inflammation. (D) Focal areas of FDG uptake in skin consistent with inflammation in thick plaques in lower extremities.

Figure 2. FDG-PET/CT imaging Shows Multifocal Inflammation in Patient with Psoriasis Compared to Control

PET image from FDG-PET/CT study in patient with psoriasis is shown at left. FDG-PET image from control patient is shown at right for comparison (no abnormal FDG uptake). (A) FDG uptake in right knee joint (SUV 3.0) and distal right quadriceps tendon, left trochanteric bursa, and left ankle in asymptomatic psoriasis patient. (B) Moderate diffusely increased FDG uptake throughout liver (SUV 1.64) consistent with increased hepatic inflammation. (C) Diffuse FDG uptake in aortic wall (SUV 1.29–1.72) and in femoral arterial tree, consistent with vascular inflammation. (D) Focal areas of FDG uptake in skin consistent with inflammation in thick plaques in lower extremities.

Figure 2. FDG-PET/CT imaging Shows Multifocal Inflammation in Patient with Psoriasis Compared to Control

PET image from FDG-PET/CT study in patient with psoriasis is shown at left. FDG-PET image from control patient is shown at right for comparison (no abnormal FDG uptake). (A) FDG uptake in right knee joint (SUV 3.0) and distal right quadriceps tendon, left trochanteric bursa, and left ankle in asymptomatic psoriasis patient. (B) Moderate diffusely increased FDG uptake throughout liver (SUV 1.64) consistent with increased hepatic inflammation. (C) Diffuse FDG uptake in aortic wall (SUV 1.29–1.72) and in femoral arterial tree, consistent with vascular inflammation. (D) Focal areas of FDG uptake in skin consistent with inflammation in thick plaques in lower extremities.

Figure 2. FDG-PET/CT imaging Shows Multifocal Inflammation in Patient with Psoriasis Compared to Control

PET image from FDG-PET/CT study in patient with psoriasis is shown at left. FDG-PET image from control patient is shown at right for comparison (no abnormal FDG uptake). (A) FDG uptake in right knee joint (SUV 3.0) and distal right quadriceps tendon, left trochanteric bursa, and left ankle in asymptomatic psoriasis patient. (B) Moderate diffusely increased FDG uptake throughout liver (SUV 1.64) consistent with increased hepatic inflammation. (C) Diffuse FDG uptake in aortic wall (SUV 1.29–1.72) and in femoral arterial tree, consistent with vascular inflammation. (D) Focal areas of FDG uptake in skin consistent with inflammation in thick plaques in lower extremities.