 2. evaluate whether there are treatment induced early changes in imaging metrics derived from 3D contrast enhanced ultrasound. This study will provide valuable insight as to the potential of baseline andor early post-treatment 3D ultrasound perfusion characteristics measurements of blood-flow of primary and metastatic liver tumors to predict tumor response to Stereotactic Ablative Radiotherapy. The investigators underlying goal is to assess whether early perfusion changes at 1-7 days after SABR initiation can be used as a non-invasive early biomarker for treatment response assessment. 