Fig. 11

Calculation of the linear growth rate (GR) of a lower third left kidney small renal mass (SRM) undergoing active surveillance (AS) in a 65-year-old patient (arrows). a Coronal contrast-enhanced CT of the renal mass showing an axial MTD of 2.5 cm (24.89 mm) at the beginning of the surveillance and (b) 3 which had only increased to 2.5 cm (25.44) 3 years later. With the use of the linear GR formula in centimeters, 2.5 cm − 2.5 cm = 0 cm divided by 36 months and multiplied by 12, the annual GR was shown to be 0 cm/year, indicating that the renal mass was stable. After 5 years of follow-up, the interval between imaging tests can be lengthened or even discontinued according to the decision of the multidisciplinary committee