Animal study of renal volume measurement on abdominal CT using digital image processing; Preliminary report

On abdominal computed tomography (CT) scans of two anesthetized Landrace pigs with 3-mm slice interval, kidneys were extracted by two steps of digital image processing: automatic segmentation in a single slice using the character of pixel distribution of the kidney, and removal of residual noise using batch processing with folding method. The measured renal volume by this method was compared with the actual renal volume obtained by means of three consecutive water displacement measurements on surgically removed kidneys. The mean percentage error was 2.9% between mean renal volume measured by our image processing (78.3 and 67.4 cm3 for right and left, respectively) and mean actual renal volume (80 and 70 cm3, respectively). Renal volume measurement on abdominal CT in pigs using this digital image processing was feasible and reliable with negligible error rate in comparison with actual renal volume.