error loading ultrasound .dcm and .vol files

Hello good afternoon, I have had problems loading different .dcm and .vol files, when loading the file it shows me the message //1: US [2] [Image sequence]: Image spacing may need to be calibrated for accurate size measurements. // I have tried different 3d ultrasound studies that were done on a Voluson GE equipment, does anyone know how I can solve this problem? Thank’s