Differentiating rheumatoid and psoriatic arthritis: a systematic analysis of high-resolution magnetic resonance imaging features-preliminary findings

Abstract

Background: Because of overlapping phenotypical presentations, the diagnostic differentiation of rheumatoid arthritis (RA) and psoriatic arthritis (PsA) remains challenging. Thus, this study aimed to examine the diagnostic value of distinct imaging features obtained by high-resolution 3-T MRI for the diagnostic differentiation.

Materials and methods: Seventeen patients with PsA and 28 patients with RA were imaged at high resolution using 3-T MRI scanners and a dedicated 16-channel hand coil. All images were analyzed according to the outcome measures in rheumatology clinical trials' (OMERACT) RAMRIS (Rheumatoid Arthritis Magnetic Resonance Imaging Score) and PsAMRIS (Psoriatic Arthritis Magnetic Resonance Imaging Score) for the presence and intensity of synovitis, flexor tenosynovitis, bone edema, bone erosion, periarticular inflammation, bone proliferation, and joint space narrowing. Next, odds ratios (OR) were calculated to determine the strength of the associations between these imaging features, demographic characteristics, and the outcome RA vs. PsA.

Results: PsA could be differentiated from RA by extracapsular inflammatory changes (PsAMRIS sub-score "periarticular inflammation"), with low odds for the presence of RA (OR of 0.06, p < 0.01) at all metacarpophalangeal (MCP) joints. A prediction model informed by the items that were strongest associated with the presence of RA or PsA demonstrated excellent differentiating capability with an area under the curve of 98.1%.

Conclusion: High-resolution imaging is beneficial for the identification of relevant imaging features that may assist the clinical differentiation of inflammatory conditions of the hand. At the MCP level, extracapsular inflammatory changes were strongly associated with PsA and may consequently allow the imaging differentiation of PsA and RA.

Keywords: MRI; Metacarpophalangeal joint; PsAMRIS; Psoriatic arthritis; RAMRIS; Rheumatoid arthritis.

Fig. 1

Overview of representative MRI findings in psoriatic arthritis (PsA) and rheumatoid arthritis (RA). Transversal T1w fat-saturated contrast-enhanced sequences of selected MCP joints of three patients each with PsA (a–c) and RA (d–f). a 39-year-old male. Severe periarticular inflammation (white arrow) with additional flexor tenosynovitis (arrowhead) and synovitis (open arrow). b 43-year-old male. Moderate periarticular inflammation (white arrow) with flexor tenosynovitis (open arrow). c 39-year-old female. Severe periarticular inflammation (white arrow) with corresponding flexor tenosynovitis (arrowhead). d 48-year-old female. Widespread synovitis (white arrow), bone erosions (open arrow), and severe flexor tenosynovitis (arrowhead). e 39-year-old male. Bone erosion (open arrow), synovitis (white arrow), and severe flexor tenosynovitis (arrowhead). f 43-year-old male. Multiple bone erosions (open arrow) and synovitis (white arrow). Note the absence of periarticular inflammation in d–f despite significant inflammatory joint changes at the joint level

Fig. 2

Detailed view of representative MRI findings in psoriatic arthritis (PsA) and rheumatoid arthritis (RA). Transversal T1w fat-saturated contrast-enhanced sequences of selected MCP joints of three patients each with PsA (a–c) and RA (d–f). a 29-year-old female. Severe periarticular inflammation (white arrow) with additional flexor tenosynovitis (arrowhead). b 47-year-old female. Severe periarticular inflammation (white arrow) with synovitis (open arrow) and flexor tenosynovitis (arrowhead). c 37-year-old male. Moderate periarticular inflammation (white arrow) with corresponding flexor tenosynovitis (arrowhead). d 55-year-old male. Widespread synovitis (white arrow) and multiple bone erosions (arrowhead). e 48-year-old female. Bone erosion (open arrow) and slight flexor tenosynovitis (arrowhead). f 39-year-old male. Bone erosion (open arrow) and synovitis (white arrow). Note the absence of periarticular inflammation in d–f despite significant inflammatory joint changes at the joint level

Fig. 3

Detailed view of representative MRI findings in PsA and RA. Transversal T1w fat-saturated contrast-enhanced sequences of selected MCP joints of three patients each with PsA (a–c) and RA (d–f). a 34-year-old male. Severe periarticular inflammation (white arrow) with additional mild synovitis (open arrow). b 42-year-old female. Severe dorsal periarticular inflammation (white arrow) with synovitis (open arrow). c 44-year-old female. Severe periarticular inflammation (white arrow) with corresponding mild flexor tenosynovitis (arrowhead). d 39-year-old male. Widespread synovitis (white arrow) with moderate flexor tenosynovitis (arrowhead) and large bone erosion (white arrow). e 41-year-old male. Multiple large bone erosions (white arrow) and severe synovitis (open arrow) with mild flexor tenosynovitis (arrowhead). f 56-year-old female. Bone erosion (white arrow) with moderate flexor tenosynovitis (arrowhead) and moderate synovitis (open arrow). Note the absence of periarticular inflammation in d–f despite significant inflammatory joint changes at the joint level

Fig. 4

Receiver operating characteristics (ROC) curve to illustrate the diagnostic ability of the calculated prediction model to determine the outcome RA. Given are different discrimination thresholds (circles with adjoined numbers). Area under the curve (AUC) = 98.1%