Three-dimensional ultrasound reconstruction of the pelvicaliceal system: an in-vitro study

Three-dimensional (3D) reconstruction of the pelvicaliceal system (PCS) can be helpful for percutaneous renal procedures. 3D reconstruction of the PCS using ultrasound (US) has not been studied. We determined the feasibility and accuracy of 3DUS reconstruction of the PCS in an in vitro model.

Ten pig kidneys were scanned in vitro using freehand 3DUS (Logiq 9, GE medical systems). Multi-planar reformatted (MPR) and volume rendered (VR) reconstructions of the PCS were processed on a workstation. Using resin casts of the PCS as the reference standard, MPR reconstructions were compared for maximal polar and antero-posterior (AP) PCS length, lower pole infundibular (LPInf) diameter and number of calices. VR movies were compared for number of calices. Three blinded reviewers matched VR movies to casts and given an "anatomical representation" score using a five-point scale.

There were no significant differences in maximal AP length, LPInf diameter or number of calices between MPR reconstructions and casts. Maximal polar length between MPR reconstructions and casts were different (t = 6.44, P = 0.0001). VR movie reconstructions underestimated the number of calices visualised (t = 3.23, P = 0.01). A total of 22 out of 30 (73%) 3D VR videos were accurately matched to their casts. The 3D VR median score for anatomical representation was 3 (fair representation).

Three-dimensional ultrasound reconstruction of the porcine PCS is quantitatively comparable to corresponding casts of the PCS. 3D VR movies of the PCS were a fair representation of the PCS anatomy. 3DUS is a potential tool in the planning and execution of percutaneous renal procedures.