Optimizing imaging quality in endourology with the Uro Dyna-CT: contrast agent dilution matters

The implementation of the Uro Dyna-CT (Siemens Healthcare Solutions, Erlangen, Germany) with interventional 3D- and cross-sectional imaging necessitates the development of new standards for endourologic procedures such as the customized use of diluted contrast agent. Our aim was to find the ideal contrast agent dilution (CAD) for the interventional use of the Uro Dyna-CT in a standardized setting and prove the experimental findings in a clinical case.

Retrograde pyelographies were performed with 10 different CADs of Imeron 300 (Bracco, Konstanz, Germany) in 10 different pig's urinary tracts. Fluoroscopy, X-ray, 3D- and slice-image reconstruction was performed with the Uro Dyna-CT. Image quality was evaluated, blinded and randomized by 5 observers. Small plastic jars were filled with the CADs and 2 artificial stones (Plaster of paris). Images were evaluated by two observers. The ex vivo findings were transferred to a clinical setting in a complex percutaneous lithotomy procedure. Unweighted and weighted kappa coefficients were calculated to indicate the degree of observers' agreement.

Twenty percent diluted contrast agent provides the best image quality and stone detection when interventional cross-sectional imaging is considered without limitations in fluoroscopy or X-ray quality. This was proved in a percutaneous lithotomy of an obese patient.

Image quality of the Uro Dyna-CT can be optimized by the use of 20 % diluted contrast agent. This knowledge helps to provide high-quality 3D imaging in the endourological operation room.