MRI temperature mapping during thermal balloon angioplasty

Knowledge on the thermal dose delivered during thermal balloon angioplasty (TBA) is desirable to understand why TBA's outcome varies widely among patients and why it is subject to high restenosis rates. In its conventional implementation, TBA involves injection of a heated medium into a balloon positioned within a stenotic blood vessel. The medium injection causes flow, motion and susceptibility-redistribution artefacts that are devastating to the proton resonance frequency shift (PRFS) technique of MRI temperature mapping. Here, we propose to separate in time medium injection and heating by first inflating a balloon with a medium at an initial temperature, and then by heating the medium up using laser light. The separation is shown to eliminate all the mentioned artefacts and to enable real-time MRI temperature mapping using the PRFS technique. Accurate and reliable temperature maps were acquired in a TBA balloon itself and in the surrounding phantom tissue during heat application.