[en] The new imaging techniques modify the diagnostic, or even sometimes therapeutic, decision lines. Their efficiency is much greater than that of the old techniques, while pretium doloris and side-effects are considerably reduced. Such advances are not without a major disadvantage: the ever increasing cost of imaging explorations. Radiological guidance (with conventional radiology, ultrasounds and computerized tomography) facilitates percutaneous procedures for diagnostic (biopsy) or therapeutic purposes (emptying of abscesses, chemonucleolysis of herniated lumbar disc, etc.)