A medical instrument for enhancing diagnosis and treatment comprising a handle, an ablation probe extending from the handle, a catheter extending from the handle. The catheter defines a lumen and the ablation probe is located within the lumen of the catheter. A port in fluid communication with the lumen of the catheter is configured for connection to a vacuum or fluid source, and application of a vacuum or an injection of fluid creates a consistent zone of permittivity around the ablation probe.