Low-Field MRI vs. Ultrasound-Which Is More Sensitive In Detecting Inflammation And Bone Damage In MCP And MTP Joints In Mild Or Moderate Rheumatoid Arthritis?

M. Walther1, B. Schicke2, A. Krause1, W.A. Schmidt1 1Department of Rheumatology and Clinical Immunology, Immanuel Krankenhaus Berlin; 2Tumor-Zentrum Berlin e. V., Berlin, Germany

Background: Ultrasound (US) and low-field magnetic resonance imaging (MRI) are both more sensitive in detecting synovitis, tenosynovitis and erosions as compared to conventional radiography. This makes these newer imaging modalities particularly useful in the diagnosis of early and mild or moderately active rheumatoid arthritis (RA)

Objectives: It has been shown that low-field MRI is more sensitive than US in particular to detect erosions. However, in clinical practice its use is usually limited to one hand or foot whereas ultrasound can easily be performed at both hands and feet. Therefore, this study aimed at evaluating how low-field MRI of the dominant hand or foot compared to US of both hands and feet to detect erosions, synovial thickening, tenosynovitis and inflammatory activity documented by bone-marrow oedema (MRI) or synovial vascularity (US) of MCP and MTP joints?

Methods: Twenty-six patients (14 female), mean age 48 (21-73) years, with mild or moderate RA at baseline and a mean disease duration of 13 months (1-66) were examined clinically, by ultrasound and by low-field MRI at baseline, after 6 and 12 months. Radiographs from hands and forefeet were taken at baseline and after 12 months. Gadolinium-enhanced low-field MRI (0.2 Tesla; Esaote C-Scan, Genua, Italy) was performed at the dominant (clinically most active) hand or forefoot including MCP joints 2-5 or MTP joints 1-5. B-mode and Power Doppler US (linear probe, 4-12 MHz, Esaote Technos MPX, Genua, Italy) was performed at the same joints that had been examined by MRI. In addition, MCP joints 2 and 5 and MTP joints 5 joints of both hands and feet were also examined by US. MRI and US examiners were blinded for other study results.

Results: Mean DAS28 was 3.9 and 2.7, CRP was 12.6 and 5.4 mg/dl and ESR was 22 and 11 mm/h at baseline and after 12 months, respectively. Rheumatoid factor and anti-CCP antibodies were positive in 46% and 42%, respectively.
There was a high concordance of US and MRI results. However, MRI detected significantly more erosions while ultrasound detected significant more tenosynovitis.

Table 1. Pathologic findings at any timepoint as detected by ultrasound and MRI, respectively (78 examinations)
	US+ / MRI+	US+ / MRI–	US– / MRI+
Erosions*	49	7	18
Synovial thickening	56	8	10
Tenosynovitis*	12	18	3
Power Doppler signals/bone marrow oedema	23	15	14

* US vs. MRI p<0,05.

Table 2. Patients with positive findings in at least one joint at baseline and after 12 month
	Baseline/12 month
	US	MRI	X-ray
Erosions	17/20	23/24	4/4
Synovial thickening	22/21	26/18	NA
Tenosynovitis	12/8	9/2	NA
Power Doppler signals/bone marrow oedema	14/10	15/13	NA

NA= Non applicable.

Conclusion: When low-field MRI is performed at the dominant hand or foot only and US is performed at both hands and feet, MRI is superior to US in detecting erosions, while US detects more tenosynovitis than MRI. US and low-field MRI are comparably sensitive to detect synovial thickening and inflammatory activity in MCP and MTP joints in RA.

Disclosure of Interest: None declared

Citation: Ann Rheum Dis 2010;69(Suppl3):466

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