Near real-rime MRI of interstitial laser photocoagulation ofin vivo rat liver

Magnetic resonance imaging (MRI) is showing considerable promise as a monitor for interventional procedures. Laser surgery is “MRI compatible, ” and temperature-sensitive imaging techniques can be usefully applied to these procedures. We have been investigatingT1derived temperature-dependent imaging as a monitor for interstitial laser photocoagulation (ILP) in rat liver.In vitro experiments suggested that temperature calibration may be achieved. We have investigated ILPin vivo using short TR spin-echo imaging sequences taking one set of images every 30 s during and after the procedure. Our resultsin vivo suggest that this simple model may be inadequate for temperature mapping as the biological reaction to the ILP is on a similar time scale to that of the procedure. Nonetheless, MRI shows well-defined, repeatable signal changes that can be related to histological borders.