The feasibility of using arterial spin labeling for visualization of non perfused volumes after HIFU treatment in the kidney

Abstract

MR guidance of High Intensity Focused Ultrasound (MFgHIFU) ablation offers the possibility to determine if complete tumor ablation has been established based on imaging the non-perfused volume (NPV). For thermal therapy, contrast enhanced (CE) imaging with a gadolinium-based contrast agent is currently the golden standard to quantify the NPV. A drawback of this method is that gadolinium based intra-vascular contrast agents interfere with HIFU therapy in two ways. First, ablation can release toxic free gadolinium, by long-term decomposition of the encapsulating chelate. Second, it degrades the quality of MR-thermometry. Therefore, even if residual viable tumor tissue is observed with CE-MRI, the treatment cannot be continued. To address this problem for HIFU interventions on the kidney, this study explores other means of perfusion imaging, such as Arterial Spin Labeling (ASL). Petros Martirosan’s group at the University of Tubingen used Flow-sensitive Alternating Inversion Recovery (FAIR) to image perfusion in the kidneys without the use of contrast agents. This in vivo study on a porcine model investigates if ASL potentially allows to perform NPV measurements during therapy and to continue the intervention if incomplete ablation of the target volume is observed.