SAND 4 - Can we make single energy CT perform as good as dual energy CT in differentiating urinary acid stones from other urinary stones?

Many people form kidney stones, that sometimes pass to the ureter, where they can get stuck and cause renal colic, infections and damage the kidney function. Most of the stones, approximately 75-90%, pass to the urinary bladder, while others must be treated with laser, surgery or shock wave lithotripsy. Some of these stones are made of uric acid. This stone type constitutes a special case and can be treated by alkalization of the urine, after which the stone is dissolved and disappears. On conventional CT this stone type cannot be differentiated from other stones, but since a decade this is possible with so-called dual energy CT. Unfortunately, this is expensive high technology equipment not available at all hospitals and the patient normally has to undergo an additional examination when there is suspicion of a uric acid stone, leading to additional radiation exposure, delayed treatment and additional health care costs.

In a recently performed study at our institution a method to differentiate uric acid stones from other stone types was developed and showed promising results. The accuracy of this method remains to be tested on a larger group of patients to be able to be used in a clinical setting in the future. In the planned project we will test the accuracy of this method on approximately 300 patients, using dual energy CT as reference standard. It will also be compared to a method using only the density of the stones.