Assessment of kidney volumes in polycystic kidney disease from coronal and axial MR images

Total renal volume (TRV) and individual renal cysts are important quantitative indicators of the progression of autosomal dominant polycystic kidney disease (ADPKD). TRV has been assessed by manually tracing renal contours from CT or MR scans, often employing contrast media (CM). We developed a fast and nearly automated technique based on the analysis of MR axial images acquired without CM injection for TRV quantification. Twenty ADPKD patients underwent MRI. Automatic extraction of kidney contours was performed on each acquired slice; the segmentation procedure was based on region growing and on the application of morphological operators and curvature-based motion. The area inside each contour was calculated and TRV was derived. Volume measurements were compared between axial and coronal acquisitions. TRV estimated in patients from axial acquisition was 1931±1117ml (range: 428÷4622ml) and from coronal acquisition volumes resulted in 1943±1135ml (range: 393÷4604ml) (p>0.05). These automatic measurements were in excellent correlation (r=0.99, y=1.01×-13.9) with a small bias and narrow limits of agreement in both absolute (-12±93ml) and percentage (-0.2±4.6%) terms. This preliminary study showed TRV from axial and coronal MRI acquisitions can be assessed automatically and with comparable and accurate results without requiring the use of potentially nephrotoxic contrast medium.