404 Can MRI Non-Invasively Measure Blood-Brain-Barrier Permeability?

Abstract Aim Blood brain barrier (BBB) integrity in neurological disease is tested with gadolinium-enhanced Magnetic Resonance Imaging (MRI). Pathology studies have shown gadolinium deposits brains intact BBBs, thus raising concern. We propose a novel use of Arterial Spin Labelling (ASL) –a MRI technique which ‘tags’ blood-water making it tracer– as safer alternative assessing BBB permeability. ASL’s ability to capture T2 (transverse relaxation time) changes tagged water blood vs. tissue (post-exchange across the BBB) supports its feasibility. Method developed an ASL protocol and collected data from healthy volunteers (n=5) on 3T Achieva Scanner parameters: echo times (TEs) 30, 40, 50, 60, 70ms; repetition time 4200ms; field view 240x240x47mm post label delays (PLDs) 1,000ms 1,500ms. calculated mean signal (arb units) images at each TE, then extracted T2(ms) values for volunteer PLD. The primary outcome was change PLDs. Results Calculated T2s demonstrated majority increasing longer PLDs (n=3) 55.3+5.3ms PLD 62.1+10.8ms However, results are inconclusive sample size precluded statistical testing. Conclusions that passage, indicating exchange through BBB. This permeability, but more wide-scale need be performed.