Hounsfield units (HU) and stone size as determined using non-contrast computed tomography (NCCT) can be used to predict the success of shock wave lithotripsy (SWL), researchers reported online in International Urology and Nephrology.
Serdar Celik, MD, and colleagues at Dokuz Eylul Unversity in Izmir, Turkey, studied 254 patients: 113 with kidney stones and 141 with ureteral stones. All had undergone NCCT prior to SWL. Subjects had a mean age of 51 years and a mean stone size of 10.9 mm. After serial measurements of the highest HU value (HUmax) and lowest HU value (HUmin), the researchers calculated an HU value that was the average of these 2 values (HUave).
Patients who underwent successful SWL (the stone-free group) had significantly smaller stone diameter and lower HUmax, lower HUmin, and lower HUave values compared with patients who had residual fragments. Dr. Celik’s group also found that skin-to-stone distance predicted SWL success.