Sorry to hear about your husband's condition. Considering that he is suffering from metastatic renal cancer, the presence of hypodense lesions in the liver
can be suggestive of cancer. The only way to confirm this would be by doing a PET scan or a USG guided biopsy
(which is not required because he already has mets in the lungs).
I hope he is receiving treatment for the metastatic disease. Hoping for the best.