Evaluation of CT as a predictor for kidney and renal artery mobility

Renal artery stent failure may result from excessive kidney mobility in some patients. We used computed tomography (CT) to determine the prevalence and magnitude of renal displacement due to postural changes.

A retrospective review of 100 consecutive CT colonography examinations was performed to measure renal artery location and displacement in both axial and coronal views using paired supine and prone non-contrast scans. Kidney displacement from the prone to supine position was correlated with a change in renal artery angular deviation. Statistical significance was determined using t-tests and Pearson correlations. Results were based on measurements made by a single observer.

Mobility and angular displacement between the prone and supine positions were significant bilaterally and in both planes (P < 0.01) except for the coronal plane kidney mobility on the left (P = 0.32). The axial plane correlation between kidney and artery mobility was significant bilaterally (left/right R=0.44/0.22, P < 0.01/0.03); the coronal plane correlation was only significant on the left (left/right R=0.26/0.18, P = 0.01/0.08). The mean axial plane mobility and angle change were greater on the left (left/right mobility 13 mm/7 mm; left/right angle change 18°/8°). In contrast, the mean coronal plane mobility and angle change were greater on the right (left/right mobility 4 mm/22 mm; left/right angle change 4°/8°). Fourteen patients had a mobility in excess of 32°.

During postural changes, the kidneys and renal arteries demonstrate significant correlated mobility. Renal artery movements can be identified using a low-radiation dose CT exam.