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

Pitfalls and Possible Solutions. Aim: When using perfusion-weighted magneti c resonance imaging (MRI) in lesions with blood-brain barrier (BBB) disrupt ion two methods are normally applied to eliminate the influence of contrast material uptake on T-2 * dynamics: injection of contrast agent before star ting perfusion imaging (pre-injection) and simultaneous acquisition of T-1- and T-2*-dynamics using a dual echo (DE)-FLASH sequence. The purpose of th is study was to examine both methods with regard to their reliability. Mate rial and Methods: We performed four perfusion measurements in a patient wit h a primary cerebral lymphoma located in the corpus callosum: two measureme nts with a DE-FLASH sequence and two measurements with a gradient-echo echo -planar-imaging (GE-EPI) sequence, respectively. in both cases there was on e measurement with and one without pre-injection of contrast material. Resu lts: Pre-injection of contrast material reduced the influence of T-1 and al lowed us to monitor the transient signal drop when using the GE-EPI sequenc e. Analysis of the timecourse of DE-FLASH, however, showed that there was s till 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 pr e-injection nor DE-FLASH allow us to eliminate the effects of contrast agen t uptake completely. Both methods, however, increase the reliability of per fusion MRI. Their efficacy depends on the extent of the BBB disruption.