Comparison of Xiralite with Clinical Examination and MRI SAT0101

BackgroundFluorescence optical imaging (FOI) with the Xiralite system is a point-of-care method for the assessment of inflammation in the hands [1]. We studied its diagnostic value in direct comparison to MRI with special respect to early arthritis. Objective20 patients with arthritis were included, 17 patients with early ar-thritis (disease duration at most 24 months).

MethodsXiralite images were acquired every second for 6 minutes, starting 10 seconds prior i.v. fluorophor injection (0.1mg/kg/BW of indocy-anine green). Image interpretation was done for 3 defined phases of increased signal intensities: Early (P1), intermediate (P2), and late phase (P3) and for an automatically generated sum image (SI). The results were compared with clinical examination (598 joints), and contrast enhanced MRI (fat saturated coronal proton-density (FS-PD-TSE), non-enhanced and enhanced T1-TSE with subtraction, coronal, and axial fat-saturated post i.v. Gadolinium (Dotarem, 0.2ml/kgBW) (FS-T1-TSE) sequences of the clinically leading, 251 joints). MRI was read according to the OMERACT cri-teria [2,3] and evaluated for synovitis (grade 0-3) and tenosyno-vitis for presence. MRI was used as the standard reference meth-od for calculation of sensitivity and specificity of FOI. Agreement rates between pairs of modalities were calculated along with 95% confidence intervals on all joints with a modified adjusted Chi2 test [4] to cover correlation of multiple joints within the same pa-tient. Intra- and interreader (2 experienced readers) variability was evaluated by means of Cohen´s kappa coefficients.

Table 1: Sensitivity and specificity of clinical exami-nation and FOI

Method Sensitivity SpecificityCE 58% 90%FOI 85% 65%FOI SI 55% 92% FOI P1 34% 95%FOI P2 83% 69% FOI P3 60% 92%

Stephanie Werner1, Peter Schott2, Malte Bahner3, Carsten Schwenke4, Bernward Kurtz2, Hans-Eckhard Langer1 (1) RHIO (Rheumatology, Immunology, Osteology) Düsseldorf and RHIO Research Institute, (2) Department of Radiology, Evangelisches Krankenhaus Düsseldorf, (3) mivenion GmbH, Berlin, (4) SCOSSIS, Statistical consulting, Berlin

ResultsSensitivity and specificity: With MRI as reference clinical ex-amination had a sensitivity of 58% and a specificity of 90%. FOI of all phases had a sensitivity of 85% and specificity of 65%. FOI phase 2 had a sensitivity of 83% and a specificity of 69%. Phase 1 had a lower sensitivity (34%) but very high specificity (95%). Agreement: 92% (53/57) of swollen joints and 85% (55/65) of joints with synovitis or tenosynovitis in MRI showed positive findings in FOI (Figure 1). Agreement rates (equal for negative and positive findings) were moderate to high, depending on the compared parameter, image and phase (Table 2). FOI did not de-tect MRI palmar tenosynovitis in 6 of 7 patients in projection of wrist or metacarpophalangeal joints (MCP), but detected dorsal tenosynovitis (all regions) and palmar tenosynovitis in projection of proximal interphalangeal joints (PIP). Intrareader and inter-reader agreement for FOI was found to be substantial [5] (both kappa 0.71).

ConclusionFOI detected clinical and MRI synovitis reliably, and agreed well with clinical examination and MRI. In early arthritis patients FOI recorded inflammatory changes more frequently than clinical ex-amination and MRI and might be of particular value for this indi-cation. FOI was more sensitive than clinical examination. The sen-sitivity and specificity differed for the phases, thus an adequate interpretation of a FOI sequence requires a specific evaluation of these. A limitation of the used FOI system was the low detection of palmar tenosynovitis, possibly caused by the tissue thickness and overlying bones.

References[1] Bremer C, Werner S, Langer HE. Assessing Activity of Rheumatic Arthritis with Fluorescence Optical Imaging. European Musculoskeletal Review 2009;4:96-100 [2] Conaghan P, Bird P, Ejbjerg B, et al. The EULAR-OMERACT rheuma-toid arthritis MRI reference image atlas: the metacarpophalangeal joints. Ann Rheum Dis 2005;64(1):i11-i21 [3] Ejbjerg B, McQueen F, Lassere M, et al. The EULAR-OMERACT rheumatoid arthritis reference image atlas: the wrist joint. Ann Rheum Dis 2005;64(1):i23-i47 [4] Schwenke C, Busse R. Analysis of dif-ferences in proportions from clustered data with multiple measurements in diagnostic studies. Methods Inf Med 2007;46(5):548-552 [5] Landis J, Koch G. The measurement of observer agreement for categorical data. Biometrics. 1977 Bd. 33, S. 159-174

Figure 1: Comparison of fluorescence optical imaging with MRIRight figure: contrast enhanced MRI with synovitis in wrist, MCP 4, interphalangeal joint (IP) and PIP 2 of the right hand. Left fig-ure: corresponding fluorescence optical imaging in phase 2. Increased signal intensities in wrist, MCP 4, IP and PIP 2 of the right hand.

Table 2: Agreement rates of fluorescence optical imaging, clinical examination and MRI for the sum image and the different phases

FOI CE s and t MRI S MRI S or T FOI SI 65% (95% CI 56-74%) 69% (95% CI 62-76%) 69% (95% CI 62-75%)FOI P1 87% (95% CI 81-94%) 81% (95% CI 72-91%) 79% (95% CI 69-89%)FOI P2 55% (95% CI 44-65%) 60% (95% CI 54-67%) 61% (95% CI 54-67%)FOI P3 81% (95% CI 73-89%) 82% (95% CI 76-88%) 80% (95% CI 74-86%)

Abbreviations: FOI: fluorescence optical imaging, SI: sum image, P1: phase 1, P2: phase 2, P3: phase 3, CE: clinical examina-tion, s: swollen, t: tender, S: synovitis, T: tenosynovitis, CI: confidence interval