Simultaneous assessment of cerebral hemodynamics and contrast agent uptakein lesions with disrupted blood-brain-barrier

The purpose of this study was to develop a method that eliminates the influ ence of the TI relaxation time upon the signal-time course in perfusion-wei ghted imaging of cerebral lesions with blood-brain-barrier (BBB) disruption . On a 1.5 T whole body clinical magnetic resonance (MR) imager, we impleme nted a dual-echo RP-spoiled FLASH sequence (TE = 6/23.6 ms). We developed a postprocessing routine that allowed to calculate a signal-time course repr esenting only the change in T2* and another one representing only the chang e in T1. Using this method, we examined 7 patients with various brain lesio ns showing evidence of BBB disruption. In the signal-time-curves obtained f rom the early echo we found a distinct signal drop due to the T2* effect. T hese effects could be eliminated by the correction algorithm yielding a 67% higher signal increase. Correction of the signal-time curve of the late ec ho yielded a more pronounced maximum signal drop and a decrease in postcont rast signal intensity. We found that without this correction the relative r egional cerebral blood volume and the first moment of the concentration-tim e curve were underestimated by 72% and 22%, respectively. The dual echo-seq uence combined with the postprocessing algorithm separates T1 and T2* effec ts and thus allows to assess cerebral hemodynamics and contrast agent kinet ics simultaneously, This method may be a useful tool for characterizing, st aging, and therapy monitoring of brain tumors. (C) 1998 Elsevier Science In c.