Evaluation of the accuracy of 3-dimensional ultrasonography of the kidney using an in vitro renal model.

OBJECTIVE Three-dimensional ultrasonography (3DUS) has recently become a reality because of advances in ultrasound probes and machine processing ability. We have developed an anthropomorphic phantom of the human loin to assess both the accuracy of 3DUS of the kidney and its potential usefulness for training in ultrasonographically guided percutaneous renal intervention. METHODS The model was built with easily available and inexpensive materials such as agar and latex with known ultrasonographic properties. The accuracy of 2-dimensional ultrasonography (2DUS) and 3DUS was assessed by measuring the dimensions of the pelvicalyceal system (PCS) ultrasonographically (pelvis width and calyx diameters) and then comparing these with measurements obtained at the time of construction. Radiology interventional trainees then punctured the PCS with 2DUS and 4-dimensional ultrasonographic (real-time/time-resolved 3DUS) guidance and reported the phantom's performance. RESULTS The 3-dimensional nature of the model's PCS could be clearly visualized on 2DUS and 3DUS, and the scan characteristics were very similar to those in real life. Measurements using 3DUS proved to be closer to the true dimensions of the model's PCS than those using 2DUS. The mean error percentage for 2DUS measurements was -10.2%, and that for 3DUS was -2.2% (P < 0.0001). Interventional trainees were satisfied with the "tissue feel" and level of difficulty posed on puncturing the phantom. CONCLUSIONS Three-dimensional ultrasonography proved to be more accurate than 2DUS for intrarenal measurements using this in vitro renal model. Three-dimensional ultrasonography has the potential to ease diagnostic renal scanning with the ability to further scrutinize and postprocess the scanned volumes. The model was realistic in its anthropomorphic properties and simulated human tissue during puncture.