Stone Heterogeneity Index and Shock Wave Lithotripsy Outcomes in Pediatrics (SHI/SWL)

Role of Stone Heterogeneity Index in Predicting Shock Wave Lithotripsy Outcomes for Urinary Calculi in Pediatrics

To assess the role of SHI in SWL outcomes for upper urinary tract calculi in pediatric population.

Study Overview

• Status: Active, not recruiting
• Conditions: Shock Wave Lithotripsy; Stone Heterogeneity Index

Detailed Description

Urolithiasis is a common health problem among children with an estimated incidence of approximately 5 to 36 per 100,000 children. The risk of recurrence of urolithiasis in children is high (up to 50% within 3 years of the first episode) and many have a predisposing metabolic risk factor, such as hypercalciuria (1). The recurrence of kidney stones in adults is very common, with up to 50% of adult incident stone formers experiencing a second occurrence within 5-10 years (2). However, the reported rates of recurrence among pediatric series are more variable, ranging from 16 to 67% at a median interval of 1-5 years between episodes (3-5).

Shock wave lithotripsy (SWL) is one of the first-line treatments in children for kidney stones smaller than 2 cm (6). There is wide disparity in the stone free rates documented in the literature for SWL in children ranging from 33 to 95%. The results are incomparable not just for lack of information but also because of variability of the confounding factors like patient-related factors including age, gender, patient tolerability, symptom severity, anatomy, and skin to stone distance and stone related factors including stone burden, location, composition, beside the type of lithotripter used, and the number of shockwaves in each session. All these factors impact SWL outcome in children. One such stone factor is stone density, diagnosed using non-contrast computer tomography (NCCT) scans (7, 8).

There are some factors that affect the success of SWL and stone composition is one of them. Hounsfield unit is known to be an independent predictor of ESWL success in adults (9). El-Assmy et al. showed that ≤ 600 HU is an independent predictor for ESWL success in children (10), McAdams et al. divided the patients into two groups (< 1000 and ≥ 1000 HU) and concluded that < 1000 HU is an important predictor of ESWL success (11).

Numerous studies have suggested an inverse association between stone density and SWL success with cut-offs are ranging from as low as 482 HU up to 1000 HU. However, these studies have shown variation in the assessment, HU markers, and utility of HU measurements. Researchers have also looked into adjunct factors to help maximize predictability of success (8) .

The majority specified the method of measuring mean stone density (MSD), creating single elliptical region of interest (ROI), a squared 10 × 10-pixel map, or a freehand ROI drawn along the stone edge to take into account abnormal shapes. These studies used 3 ROI within the image, either over-lapping or non-overlapping, and taking the mean of the three results or the peak HU (12-14), some measured the stones on a single axial plane that displayed the stone at its maximal diameter (15). A single study defined MSD as the average of the minimum and maximum HU readings (14).

Stone heterogeneity index (SHI) was identified to be a better indicator of success in patients with larger stones. SHI designated as the standard deviation of HU was found to be a truer reflection of SWL success in patients with larger stones, with higher heterogeneity likely to result in clearance. This new ratio was seen to have a higher negative predictive value than stone attenuation alone in predicting stone composition

• Study Type: Observational
• Enrollment (Estimated): 286

Contacts and Locations

Study Locations

• Egypt
  • Mansoura
    • Al Mansurah, Mansoura, Egypt
      • Mansoura University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The medical records of pediatric patients who underwent SWL at the Urologyy and Nephrology Center from January 2016 toDecember 2024 willl be retrospectively reviewed. Gender, age, history of SWL or stone surgery, and comorbidities will be recorded as patients' characteristics. Stone features on NCCT include the size, location, skin to stone distance (SSD), MSD, and SHI.

Hounsfield unit (HU): Multiple regions of interest (ROI), incorporating the stone but not the surrounding soft tissue. This will be done creating single elliptical ROI, a squared 10 × 10-pixel map, or a freehand ROI drawn along the stone edge to take into account abnormal shapes. We will used 3 ROI within the image, either over-lapping or non-overlapping, and taking the mean of the three results or the peak HU.

Stone heterogeneity index (SHI): SHI will be designated as the standard deviation of Hounsfield's units in the same specified region of interest.

Description

Inclusion Criteria:

• Age between 1year and 18 years.
• Both ureteric stone with size 5 mm-10 mm and renal stone with size 10 mm-20 mm.
• Only those patients who had NCCT available for review after at least 3 months from the last session of SWL will be included in the study.

Exclusion Criteria:

• Patients >18 years of age.
• Subjects suffering from active urinary tract infection.
• Multiple renal calculi.
• Presence of anatomical renal abnormalities that may affect stone clearance and renal insufficiency.

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
To assess the role of stone heterogeneity index (SHI) as an indicator of success of shock wave lithotripsy (SWL) in pediatric patients with upper urinary tract stones after three months	2 years

Secondary Outcome Measures

Outcome Measure	Time Frame
Assessment of independent factors affecting re-growth of residual fragments (RFs), spontaneous passage, and re-operation rates for clinically insignificant RFs after one year of follow up	2 years

Collaborators and Investigators

• Sponsor: Mansoura University
• Investigators: Principal Investigator: Marwan A Ismail, MSc, Mansoura University

Study record dates

Study Major Dates

• Study Start (Actual): March 4, 2025
• Primary Completion (Estimated): August 1, 2026
• Study Completion (Estimated): August 1, 2026

Study Registration Dates

• First Submitted: June 13, 2026
• First Submitted That Met QC Criteria: June 13, 2026
• First Posted (Actual): June 18, 2026

Study Record Updates

• Last Update Posted (Actual): June 18, 2026
• Last Update Submitted That Met QC Criteria: June 13, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: shock wave lithotripsy; stone heterogeneity index; Pediatric Calculi
• Other Study ID Numbers: MD.25.01.941

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No