Predicting effectiveness of extracorporeal shockwave lithotripsy by stone attenuation value

Area of Science:

• Urology
• Nephrology
• Medical Imaging

Background:

• Extracorporeal shockwave lithotripsy (SWL) is a primary treatment for upper urinary tract stones.
• Stone characteristics, such as attenuation value, can influence SWL success rates.
• Computed tomography (CT) provides stone attenuation values in Hounsfield units (HU).

Purpose of the Study:

• To investigate the impact of pre-SWL stone attenuation value on treatment effectiveness.
• To compare SWL outcomes for stones with attenuation values below and above 1200 HU.

Main Methods:

• Prospective study of 99 patients with solitary upper urinary tract stones undergoing SWL.
• Pre-SWL CT scans determined stone attenuation values (mean 1213.3 HU).
• Patients grouped by stone attenuation (<1200 HU vs. >1200 HU); outcomes analyzed included shockwaves, intensity, retreatment, clearance, auxiliary procedures, and effectiveness quotient (EQ).

Main Results:

• Stones with lower attenuation (<1200 HU) required significantly fewer shocks (1317.1 vs. 1646.5) and lower intensity (p=0.03).
• Lower attenuation stones had a higher effectiveness quotient (80.4% vs. 66.2%, p=0.03) and no retreatment needed, unlike 14.03% in the higher attenuation group (p < 0.0001).
• Stone size, location, clearance rates, auxiliary procedure rates, and complication rates were similar between groups.

Conclusions:

• Lower stone attenuation values correlate with significantly better SWL effectiveness for upper urinary tract stones.
• Treating lower attenuation stones requires fewer shockwaves and lower intensity, improving treatment efficiency.
• Stone attenuation value is a critical factor in predicting SWL success and optimizing treatment planning.