A simplified fluid-sensitive MRI protocol for the hands to detect inflammation without contrast administration: a large study of symptom-free subjects from the general population as a reference for normality

Objective: MRI of the hands is valuable for risk-stratification in patients with arthralgia at-risk for developing rheumatoid arthritis (RA). Contrast-enhanced MRI is considered standard for assessment of RA, but has practical disadvantages. It also shows inflammation-like features in the general population, especially at older age, which should be considered in image interpretation. The modified-Dixon (mDixon) technique is reliable compared to contrast-enhanced sequences. Moreover, this short protocol without contrast-enhancement is patient-friendly. Whether it also shows inflammation-like features in the general population is unknown. We studied this to support accurate use in the clinic. Methods: Two hundred twenty symptom-free volunteers from different age-categories were recruited from the general population and underwent mDixon MRI of both hands. Two readers independently scored MRIs for synovitis, tenosynovitis, and bone marrow edema (BME) in the metacarpophalangeal-joints (MCP) and wrists according to the RAMRIS. Features were considered present if scored by both readers; frequencies > 5% were considered relevant in terms of specificity and determined per age-category (< 40/40- < 60/ ≥ 60-years). Results: Higher age correlated with higher BME-scores (p-value < 0.005), but not with synovitis and tenosynovitis-scores. BME (grade 1) occurred in some bones in people aged ≥ 60, 14% had BME in the lunate, 7% in metacarpal-1, and 6% in the trapezium. Synovitis and tenosynovitis did not occur in > 5%, except for grade-1 synovitis in the right distal radio-ulnar-joint in people aged ≥ 60 (11%). Conclusion: On mDixon MRI, inflammatory features in the hands of the general population are rare. This facilitates image interpretation. To prevent overinterpretation, only several locations should be considered when evaluating people aged ≥ 60-years.