Renal surface area normalisation: preliminary results

Full text: The Renal Surface Area (RSA) was investigated as a measurement of renal size. This was done from the posterior view of DMSA renal images, using an ROI drawn closely around each kidney and knowledge of the pixel size for each camera. The results from 59 patients with two normal kidneys were used to create normograms relative to Age, Body Surface Area (BSA), weight (WT) and Height (HT). Those normograms were then tested firstly for 'tightness' of the normal range, and then to determine how well each was able to separate normal and abnormal kidneys (either damaged or hypertrophied). The kidneys were classified according to their visual appearances and relative function: -N2 two normal kidneys; D1 and N1 = minimal damage on one side with function still within the range 45 - 55%; D2 and H1 = significantly damaged kidney with compensatory hypertrophy on the other side; D3 and H2 absent or severely damaged kidney on one side. 13 patients with significant or severe damage to one or both kidneys were studied. 11 patients were excluded as they had the D1 and N1 pattern. RSA normalised to BSA, produced the tightest normal range, and was the best discriminator between normal and abnormal kidneys. When one kidney is damaged, RSA measurements are better able to detect hypertrophy of the normal kidney than a size reduction in the damaged kidney. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc