Created by Dr. Sharad Maheshwari, imagingsimplified@gmail.com. 10.01.2026

CT Stone Reporting & PCNL Assessment

Stone Size (mm)

AP dimension: Transverse dimension: Craniocaudal dimension:

Stone volume is calculated in mm³ using the ellipsoid formula.

Anatomical & Access Parameters

Posterior calyx: Infundibulopelvic angle (°): Infundibular width (mm): Infundibular length (mm): Skin-to-stone distance (mm): No retrorenal colon: Single access tract feasible:

Parameters & Normal Cut-offs

Parameter	Cut-off	Clinical Rationale
Stone size	≥ 20 mm	Threshold where PCNL is commonly preferred
Posterior calyx	Yes	Straighter, safer percutaneous access
Infundibulopelvic angle	> 45°	Improves access and fragment clearance
Infundibular width	≥ 5 mm	Facilitates instrument passage
Infundibular length	≤ 30 mm	Shorter tract reduces resistance
Skin-to-stone distance	≤ 100 mm	Acceptable access depth
Retrorenal colon	Absent	Reduces colonic injury risk
Access tracts	Single tract	Lower morbidity

How to Measure on CT

Infundibulopelvic Angle

Infundibular Length & Width

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Created by Dr. Sharad Maheshwari