Kidney volume quantification using contrast-enhanced in vivo X-ray micro-CT in mice

The present study sought to establish a standard in vivo imaging procedure for mouse kidney anatomy evaluation using contrast-enhanced high-resolution X-ray microtomography (micro-CT). Micro-CT estimation of kidney volume was compared with ex vivo measurement by micro-CT and water displacement. Control values were obtained in four strains (BALB/c, C3H/HeN, 129/Sv and C57BL/6J) of healthy male and female mice aged 22 +/- 2 weeks. An excellent correlation was found between in vivo and ex vivo kidney volumes (n = 26 mice; 52 kidneys; r = 0.96). In vivo measurement systematically overestimated ex vivo kidney volume by 28 +/- 4%, while there was no significant difference between the ex vivo micro-CT value and the true kidney volume on water displacement (2.3 +/- 2.1%). In vivo kidney volume also correlated strongly with kidney weight and in vivo kidney length (n = 52 mice; 104 kidneys; r = 0.84, r = 0.92 respectively). Differences between strains were observed for kidney volume when comparing either kidney volume or kidney weight to body weight. In conclusion, this study demonstrated that contrast-enhanced micro-CT enables accurate in vivo measurement of kidney volume, length and thickness in mice. Reference parameters are reported for four strains. The technique provides a useful follow-up research tool for mouse phenotyping and renal disease studies.