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Abstract #0462

Consequences of Multi-Echo Fits in Perfusion MRI for the Determination of MTT in Presence of T1-Effects.

Matus Straka1, Heiko Schmiedeskamp1, Greg Zaharchuk1, Jalal B. Andre1, Jean-Marc Olivot2, Nancy J. Fischbein1, Maarten G. Lansberg2, Michael E. Moseley1, Gregory W. Albers2, Roland Bammer1

1Radiology, Stanford University, Stanford, CA, USA; 2Stanford Stroke Center, Stanford University, Stanford, CA, USA

Typical PWI exam employs single-echo acquisitions, but accuracy of perfusion parameters from such data can be severely flawed by T1 shortening. While CBV inaccuracies are widely understood, errors in MTT are not expected as temporal parameters are assumed to be immune to these effects. We give an explanation of the problem using simulations and exemplify it on a clinical scan. We conclude that MTT can be largely underestimated if T1-effects (e.g. due to tracer leakage) are not accounted for. As a solution we present an advanced imaging scheme based on multi-echo SAGE PWI sequence that can correct these problems.