Is perfusion-MRI feasible in lesions with disrupted blood-brain-barrier? Pitfalls and possible solutions.

Pitfalls and Possible Solutions. Aim: When using perfusion-weighted magnetic resonance imaging (MRI) in lesions with blood-brain barrier (BBB) disruption two methods are normally applied to eliminate the influence of contrast material uptake on T-2 * dynamics: injection of contrast agent before starting perfusion imaging (pre-injection) and simultaneous acquisition of T-1- and T-2*-dynamics using a dual echo (DE)-FLASH sequence. The purpose of this study was to examine both methods with regard to their reliability. Material and Methods: We performed four perfusion measurements in a patient with a primary cerebral lymphoma located in the corpus callosum: two measurements with a DE-FLASH sequence and two measurements with a gradient-echo echo-planar-imaging (GE-EPI) sequence, respectively. in both cases there was one measurement with and one without pre-injection of contrast material. Results: Pre-injection of contrast material reduced the influence of T-1 and allowed us to monitor the transient signal drop when using the GE-EPI sequence. Analysis of the timecourse of DE-FLASH, however, showed that there was still a T-1 decrease even after pre-injection. After the first pass the T-2*-dynamics showed a distinct long-term T-2*-decrease. Discussion: Neither pre-injection nor DE-FLASH allow us to eliminate the effects of contrast agent uptake completely. Both methods, however, increase the reliability of perfusion MRI. Their efficacy depends on the extent of the BBB disruption.