Characterization of Pulmonary Dysfunction in Systemic Juvenile Idiopathic Arthritis Using Xenon and Proton MRI

Area of Science:

• Medical Imaging
• Pulmonology
• Rheumatology

Background:

• Systemic juvenile idiopathic arthritis-associated lung disease (SJIA-LD) is a serious complication requiring early detection.
• Diagnosis is challenging due to subtle or absent respiratory symptoms.
• CT imaging is often needed to identify early lung dysfunction.

Purpose of the Study:

• To evaluate the utility of xenon and proton lung MRI in identifying SJIA-LD.
• To assess structural changes and functional deficits in SJIA-LD using MRI.

Main Methods:

• Cross-sectional study of 31 participants (5-15 years old): 16 healthy, 7 SJIA without lung disease (SJIA-non-LD), and 8 SJIA-LD.
• Xenon ventilation MRI, xenon gas-exchange MRI, and proton ultrashort echo time (UTE) MRI were performed.
• Calculated ventilation defect percentage (VDP) and xenon signal ratios (RBC/Membrane/gas); compared with CT and PFTs where available.

Main Results:

• The RBC/Membrane ratio significantly differed between healthy individuals and SJIA-LD patients (p=0.014), correlating with DLCO.
• VDP did not significantly differ between groups but was high in 3/7 SJIA-LD patients.
• UTE MRI revealed SJIA-LD pattern findings in 4/7 SJIA-LD patients, but none in healthy or SJIA-non-LD participants (p<0.001).

Conclusions:

• Xenon and proton lung MRI can detect pulmonary abnormalities in SJIA-LD.
• RBC/Membrane ratio shows potential for characterizing diffusion limitation in SJIA-LD.
• Lung MRI may aid in SJIA-LD phenotyping and monitoring lung function changes.