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Abstract #1576

The Influence of Holmium-166 Loaded Microspheres on ADC Measurements Using DWI

Gerrit Hendrik van de Maat1, Peter R. Seevinck1, Chris J.G Bakker2

1Image Sciences Institute, Utrecht, Netherlands; 2Department of Radiology, University Medical Center, Utrecht, Netherlands

It was shown that the presence of HoMS attenuates the signal of diffusion weighted images leading to a ADC reduction of 0.1mm2/ms per mg/ml HoMS. The reduction of the ADC is caused by the additional gradients induced by the microspheres resulting in a additional weighting factor for calculation of the ADC which is not taken into account. The dependency of the ADC on concentration HoMS is an effect that should be considered when using DWI for evaluating tumor viability after radioembolization. Since the local concentration can range up to 15mg/ml, a potential underestimation of the ADC of 1.5mm2/ms can occur which may lead to wrong diagnostic conclusions.