Three-dimensional CT-scan reconstruction of renal calculi. A new tool for mapping-out staghorn calculi and follow-up of radiolucent stones.

OBJECTIVES: The development of CT scanners (CT scan) with continuous rapid spiral acquisition now allows three-dimensional reconstructions of mobile organs such as kidneys. The aim of this study was to appreciate the merits of this new technique in the field of renal lithiasis.
METHOD: This non-invasive technique was applied in 27 renal calculi (23 staghorn and 4 radiolucent stones). The acquisition does not require any injection of contrast material. Reconstruction was carried out by three-dimensional (3D) shaded surface display.
RESULTS: 3D reconstruction of calculi permits a precise study of the shape of the stone, and of the number, size and direction of its branches. Therefore, it allows for better planning of the PCNL (number of ports, per-operative pelvi-caliceal exploration ...). Large radiolucent calculi are clearly defined with 3DS, facilitating the follow-up under medical treatment.
CONCLUSION: 3D CT scan reconstruction is a noninvasive, cost-effective method which offers high quality 3D images of renal calculi. These results should spur the more widespread use of this technique.