MR imaging of the arthritic rabbit knee joint using albumin-(Gd-DTPA)30 with correlation to histopathology

Area of Science:

• Biomedical Imaging
• Rheumatology
• Vascular Biology

Background:

• Rheumatoid arthritis (RA) involves synovial inflammation and abnormal microvasculature.
• Assessing synovial microvascular changes non-invasively is crucial for RA management.
• Current methods for evaluating synovial vascularity are limited.

Purpose of the Study:

• To demonstrate a pilot technique for measuring abnormal capillary permeability in arthritic rabbit knees.
• To utilize dynamic MRI with a gadolinium-based blood pool agent for this measurement.
• To correlate MRI-derived microvascular parameters with histological findings.

Main Methods:

• Arthritis was induced in rabbit knees using carrageenan or ovalbumin.
• Dynamic, fat-presaturated T1-weighted spoiled gradient-recalled echo MRI was performed.
• Albumin-(Gd-DTPA)30 was administered intravenously, and synovial plasma volume (PV), fractional leak rate (FLR), and permeability-surface area product (PS) were computed.

Main Results:

• Dynamic MRI revealed albumin-(Gd-DTPA)30 extravasation into hypertrophic synovium in 6 of 8 arthritic knees.
• Histology confirmed marked synovial inflammation in these 6 knees.
• MRI-derived PV, FLR, and PS correlated strongly with histological findings (r² = 0.51, 0.97, 0.86).

Conclusions:

• Dynamic MRI with albumin-(Gd-DTPA)30 can non-invasively estimate synovial microvascular structural and functional characteristics.
• This technique shows promise for monitoring disease progression and treatment response in rheumatoid arthritis.
• The method accurately reflects synovial inflammation and vascular changes.