Quantitative contrast-enhanced magnetic resonance imaging to evaluate blood-brain barrier integrity in multiple sclerosis: a preliminary study

Gadolinium enhanced magnetic resonance imaging detects focal blood-brain ba rrier breakdown in new inflammatory multiple sclerosis lesions, but such le sions do not correlate with disease progression. To explore whether the lat ter might relate to subtle but widespread blood-brain barrier (BBB) breakdo wn with low grade inflammation mediating tissue damage, quantitative techni ques were used to detect subtle gadolinium enhancement within otherwise nor mal-appearing white matter and within lesions not showing visible enhanceme nt TI-weighted imaging was performed prior to and at 5, 20 and 40 min follo wing injection of 0.3 mmol/kg gadopentate dimeglumine in 33 patients with m ultiple sclerosis and five healthy control subjects. In healthy controls, a significant increase in white matter signal 5 min following contrast injec tion was observed (1.8%, P < 0.0005); the signal returned to baseline value s by 20 min. In multiple sclerosis patients, a non-significant trend was no ted for signal to remain elevated in normal-appearing white matter at the 2 0 and 40 min post-contrast time points; this was most apparent in primary p rogressive multiple sclerosis. Significant increases in signal intensity we re noted at all time points post contrast in apparent non-enhancing lesions . The transient post contrast signal increase in controls is likely due to intravascular gadopentate dimeglumine. The persistent increases in signal i ntensity in non-enhancing lesions suggest more widespread abnormalities in BBB than is visually apparent but substantiation of BBB leakage in normal a ppearing white matter will require further study using more sensitive metho ds.