Magnetic resonance spin-labeling perfusion imaging of synovitis in inflammatory arthritis at 3.0 T

The aim of this study was to test the feasibility of arterial spin labeling (ASL) perfusion imaging of synovitis in inflammatory joint diseases on a clinical 3.0 T whole-body scanner. Fifteen patients (geometric mean 47 years, range 8-69 years) with different types of inflammatory arthritis of the finger or wrist joints participated in the study. In addition to conventional spin-echo and dynamic contrast-enhanced FLASH3D sequences, a novel spin-labeling technique (FAIR-TrueFISP) for quantitative assessment of tissue perfusion was applied. Perfusion maps were calculated pixel-wise by means of the extended Bloch equations. Perfusion maps showed good image quality with clear visualization of hyperaemia in synovitis. The computed perfusion maps corresponded best to subtraction images of the dynamic series from 30 to 60 s after contrast-medium injection. The quantitative perfusion values of synovitis showed a good correlation with the disease activity. Perfusion values for inflamed synovium in phase of high activity were up to 230 ml/100 g tissue/min. The proposed modality allows for the assessment of disease activity in arthritis without the application of contrast-medium offering a new tool for therapy monitoring. As the technique provides quantitative information on hyperaemia, it potentially offers new insights in the pathophysiology of arthritic diseases.