Magnetic resonance imaging as a monitor of kidney enlargement and regression in experimental diabetes in rats.

The aim of the present study was to use magnetic resonance imaging as a non-invasive measure of renal enlargement and regression in experimental diabetes in rats. Rats were randomized into three groups: (1) non-diabetic control animals, (2) diabetic animals, untreated for 30 days after streptozotocin treatment and (3) diabetic animals treated with insulin from day 21 to day 30 after streptozotocin administration. Magnetic resonance images were obtained from anaesthetized rats and kidney, cortex, medulla and pelvis volumes were calculated throughout the experiment until day 30. In untreated diabetic animals, a marked increase in kidney volume was seen 4 days after the induction of diabetes (P < 0.05) and after 30 days this increase amounted to 73%, with similar increases in the cortex (63%) and medulla (69%). No change was seen in the pelvis volume. Insulin administration on day 21 to untreated diabetic rats abruptly reduced kidney volume by 21%, cortex volume by 27% and medulla volume by 18%, and after 4 days all three parameters were similar to those seen in non-diabetic controls. In conclusion, the present study has demonstrated the applicability of magnetic resonance imaging as a non-invasive measure of renal enlargement and regression in experimental diabetes in rats. In untreated hyperglycaemic diabetic rats, with manifest diabetic renal enlargement, acute regression in renal volume was observed concomitant with insulin-induced normoglycaemia.