A 37-year-old miner has lifted significant loads and afterwards felt pain in the lumbar area irradiating to his left leg. He walks slowly and carefully. Lumbar lordosis is flattened. There is also left-sided scoliosis and tension of paravertebral muscles. Neri's and Dejerine's symptoms are positive, there is Lasegue's sign on the left from the angle of 350. What method will help to specify the diagnosis?