Het interpreteren van de densiteit van nierstenen met de HU-waarde: weet wat je meet

In the current EAU guidelines one of the factors that determines treatment of urolithiasis is the estimated stone density, measured in Hounsfield Units (HU). It is unclear whether new CT reconstruction techniques affect the HU value of stones and how to measure it’s density.

In 107 patients, treated with PNL or URS, several HU measurements of the stone were performed in a retrospective manner on a plain CT-abdomen with different reconstruction techniques and coupe sizes. The differences between these HU measurements were calculated.

The maximum HU value (1,362) was measured on the iDose 0.9 mm reconstruction with measuring method M3. This is not significant different compared to the IMR 0.9 mm (1,238, p = 0.29). The maximum HU value on the IMR 0.9 mm was significantly higher than on the iDose 4 mm (1,038, p = 0.00026).

Coupe size, reconstruction technique and method of measurement greatly affect the measured HU value and thereby treatment of a kidney stone.