Fluorescence Optical Imaging for Treatment Monitoring in Patients With Early and Active Rheumatoid Arthritis in a 1-Year Follow-Up Period

Anne-Marie Glimm; Lisa Ines Sprenger; Ida Kristin Haugen; Ulrich Mansmann; Sandra Hermann; Thomas Häupl; Paula Hoff; Gerd-Rüdiger Burmester; Marina Backhaus; Lien Le; Sarah Ohrndorf

Disclosures

Arthritis Res Ther. 2019;21(209) 

In This Article

Background

To monitor therapeutic response in patients with rheumatoid arthritis (RA), clinical disease activity scores such as DAS28 are applied.[1] Besides, more sensitive and objective imaging modalities are recommended in the clinical management of RA.[2] Magnetic resonance imaging (MRI) and musculoskeletal ultrasound (US) are both widely used in clinical practice and research within the field of RA.[3–8] MRI-detected pathologies such as synovitis and tenosynovitis are highly responsive to antirheumatic treatment.[9–11] However, MRI has the disadvantage of high costs, time exposure, and occasional contraindications (e.g., pacemaker and claustrophobia).[12] In several studies, US-detected synovitis and tenosynovitis have also been shown to be sensitive to change under therapy, especially in Power Doppler mode (PDUS)[13–16] reflecting disease activity. US is a cost-effective, widespread method that is risk-free for patients, is indefinitely repeatable, and involves less inconvenience than MRI. Drawbacks may be the dependency on the examiner[17] and the inability to pairwise compare baseline and follow-up images immediately while investigating unless all images are saved for analysis later on; however, US images are usually saved as "still images" (lost of dynamic approach).

In search of an imaging method for the optimal detection of disease activity, new procedures are developed and investigated. Since 2009, the fluorescence optical imaging (FOI) "Xiralite" (Xiralite GmbH, Berlin, Germany) has been shown to detect inflammation in preclinical studies[18,19] as well as in humans[20–26] in the joint regions of both hands. The basis of the Xiralite method is the demonstration of an impaired microcirculation caused by the inflammatory process of arthritis. Here, the enhancement of an intravenously applied dye indocyanine green (ICG) is evaluated. FOI is a non-ionizing technique that examines both hands in one session of 6 min. Besides, the examination itself can be performed by clinical assistants. Impediments in the sense of resulting contraindications are an impaired liver function, since the applied dye is primarily excreted biliarily.[27] Furthermore, an allergic reaction to the ICG solution can occur.[28] However, the overall risk of ICG to the patient is low.[29]

Previous studies have demonstrated good agreements between FOI, clinical assessment, MRI, and US[21] as well as a moderate und substantial reliability for the scoring of FOI images[22] Additionally, FOI may also detect subclinical inflammation.[25] Only one study has evaluated the responsiveness of FOI, so far. Meier et al. found a reduction in the signal intensity during therapy response in a group of patients with forms of different arthritis who were examined by a computer-based evaluation of FOI and MRI; however, the observed group was heterogeneous and only investigated over a time period of 6 months.[30]

The aim of the present study was the investigation of FOI's ability to reflect treatment response in a homogenous cohort of patients with early and active RA over a period of 12 months. Besides, we aimed for exploration of its correlations with clinical outcomes such as DAS28. The correlation with US as a common imaging modality in daily rheumatological practice was set as a secondary outcome.

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