Absolute Hounsfield unit measurement on noncontrast computed tomography cannot accurately predict struvite stone...

Area of Science:

• Nephrology
• Radiology
• Urology

Background:

• Struvite stones are a common type of urinary calculus.
• Accurate preoperative identification of stone composition is crucial for effective treatment planning.

Purpose of the Study:

• To evaluate the efficacy of single-energy noncontrast computed tomography (NCCT) in predicting the presence and percentage of struvite stone composition in vivo.
• To determine if NCCT parameters can differentiate between pure and mixed struvite stones.

Main Methods:

• Retrospective analysis of patients with struvite components on stone analysis (January 2008-March 2012).
• Inclusion criteria: NCCT prior to stone analysis and stone size ≥4 mm.
• Urologist blinded to stone composition reviewed NCCT for stone location, dimensions, and Hounsfield units (HU); HU density (HUD) calculated. Statistical analysis included t-tests, ANOVA, and Spearman's correlation.

Main Results:

• Forty-four patients met inclusion criteria; struvite was the most prevalent component (mean 50.1%).
• No significant correlation found between struvite percentage and HU or HUD.
• Pure struvite stones (n=5) had significantly lower HUD than mixed struvite stones (n=39) (27.9±23.6 vs 72.5±55.9, p=0.006), despite significant overlap.

Conclusions:

• While overlap exists, a lower HUD on NCCT may suggest a higher likelihood of pure struvite stone composition.
• NCCT can provide valuable information for differentiating stone types, aiding in clinical decision-making.
• Further research may refine the role of CT imaging in predicting urinary stone composition.