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Predicting the stone composition of children preoperatively by Hounsfield unit detection on non-contrast computed
Mesut Altan1, Burak Çitamak1, Ali Cansu Bozaci1
1Hacettepe University School of Medicine, Department of Urology, Ankara, Turkey.
Insights
This study shows that Hounsfield unit (HU) values from non-contrast computed tomography (NCCT) can help predict kidney stone composition in children. Combining HU values with urine pH can accurately differentiate between calcium oxalate, cystine, and struvite stones.
Area of Science:
- Pediatric Nephrology
- Medical Imaging
- Urology
Background:
- Limited research exists on predicting pediatric kidney stone composition using imaging.
- Hounsfield unit (HU) values correlate with stone composition in adults.
Purpose of the Study:
- To predict kidney stone composition in children using pre-intervention non-contrast computed tomography (NCCT) Hounsfield unit (HU) properties.
- To guide more effective interventions for pediatric kidney stones.
Main Methods:
- Retrospective analysis of 94 children with available NCCT and stone analysis.
- Categorization of stones into calcium oxalate (CaOx), cystine, and struvite groups.
- Measurement of core HU, periphery HU, Hounsfield density (HUD), and spot urine pH for statistical comparison.
Main Results:
- Calcium oxalate (CaOx) stones showed significantly higher core, periphery, and mean HU values compared to cystine and struvite stones.
- Hounsfield density (HUD) differed significantly between CaOx and cystine stones, but not between cystine and struvite stones.
- Urine pH was higher in the struvite group than in the cystine group, aiding differentiation.
Conclusions:
- Non-contrast computed tomography (NCCT) provides valuable information for determining pediatric kidney stone composition.
- Hounsfield unit (HU) parameters can distinguish CaOx stones from cystine and struvite stones.
- Integrating spot urine pH assessment is crucial for differentiating cystine from struvite stones.
Introduction:
Many studies have been performed on adult patients to reveal the relationship between Hounsfield unit (HU) value and composition of stone, but none have focused on childhood.
Objective:
We aimed to predict stone composition by HU properties in pre-intervention non-contrast computed tomography (NCCT) in children. This could help to orient patients towards more successful interventions.
Materials And Methods:
Data of 94 children, whose pre-intervention NCCT and post-interventional stone analysis were available were included. Stones were grouped into three groups: calcium oxalate (CaOx), cystine, and struvite. Besides spot urine PH value, core HU, periphery HU, and Hounsfield density (HUD) values were measured and groups were compared statistically.
Results:
The mean age of patients was 7 ± 4 (2-17) years and the female/male ratio was 51/43. The mean stone size was 11.7 ± 5 (4-24) mm. There were 50, 38, and 6 patients in the CaOx, cystine, and struvite groups, respectively. The median values for core HU, periphery HU, and mean HU in the CaOx group were significantly higher than the corresponding median values in the cystine and struvite groups. Significant median HUD difference was seen only between the CaOx and cystine groups. No difference was seen between the cystine and struvite groups in terms of HU parameters. To distinguish these groups, mean spot urine PH values were compared and were found to be higher in the struvite group than the cystine group (Table).
Discussion:
The retrospective nature and small number of patients in some groups are limitations of this study, which also does not include all stone compositions. Our cystine stone rate was higher than childhood stone composition distribution in the literature. This is because our center is a reference center in a region with high recurrence rates of cystine stones. In fact, high numbers of cystine stones helped us to compare them with calcium stones more accurately and became an advantage for this study.
Conclusions:
NCCT at diagnosis can provide some information for determination of stone composition. While CaOx stones can be discriminated from cystine and struvite stones using HU parameters, a simple spot urine pH assessment must be added to distinguish cystine stones from struvite stones.
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