A 65-year-old patient complains of pain in the lumbar spine, moderate disuria. He has been suffering from this condition for about half a year. Prostate volume is 45 cm3 (there are hypoechogenic nodes in both lobes, capsule invasion). Prostate-specific antigen is 60 ng/ml. Prostate biopsy revealed an adenocarcinoma. Which of the supplementary examination methods will allow to determine the stage of neoplastic process in this patient?