Lithiasis size estimation variability depending on image technical methodology

Area of Science:

• Urology
• Medical Imaging
• Nephrology

Background:

• Accurate lithiasic size determination is vital for selecting appropriate surgical or medical treatments.
• Current methods for measuring lithiasic size lack standardization, impacting treatment decisions.

Purpose of the Study:

• To compare estimated lithiasic sizes from plain radiography and computerized axial tomography (CT) scans (using different techniques) against actual sizes.
• To identify the optimal imaging modality for reliable lithiasic size assessment.

Main Methods:

• An in vitro model using 245 lithiases was employed, with measurements taken using a calibrator, plain X-ray, and CT scans (bone and soft tissue windows).
• Surface area (cm²) for radiography and surface area/volume (cm³) for CT were determined.
• Measurements were performed by three independent researchers unaware of each other's results; statistical analysis used the Wilcoxon sign test.

Main Results:

• CT scans in bone window slightly overestimated lithiasic volume (0.12 vs. 0.17 cm³), while soft tissue window significantly overestimated it (0.12 vs. 0.21 cm³).
• No significant difference was found between actual surface size and bone window CT scan surface size (0.39 vs. 0.36/0.37 cm²).
• Plain radiography underestimated surface size (0.39 vs. 0.37 cm²), and soft tissue window CT slightly overestimated it (0.42/0.44 cm²).

Conclusions:

• Computerized axial tomography (CT) using a bone window provides the most accurate in vitro estimation of lithiasic size, despite potential overestimation of the craniocaudal diameter.
• Soft tissue window CT scans tend to overestimate lithiasic size.
• Plain radiography underestimates lithiasic size.