Improved contrast agent bolus tracking using T1 FARM.

Current MRI bolus tracking techniques, such as saturation recovery Turbo-FLASH (srTFL), suffer from signal saturation at high contrast concentrations. In this study T1 Fast Acquisition Relaxation Mapping (T1 FARM) was compared to srTFL. In phantoms, T1 FARM maps were linear with [Gd-DTPA] up to 7.0 mmol/L while srTFL images saturated above 2.0 mmol/L. In the canine left ventricle, blood concentration curves determined from T1 FARM saturated with bolus injections exceeding 0.075 mmol/kg, while srTFL curves saturated above 0.025 mmol/kg of Gd-DTPA. Also, T1 FARM improved contrast-to-noise ratio in tissue concentration curves since higher contrast concentrations could be measured without saturating.