Calcium stone fragility is predicted by helical CT attenuation values

K. C. Saw, J. A. McAteer, N. S. Fineberg, A. G. Monga, G. T. Chua, J. E. Lingeman, James Williams

Research output: Contribution to journalArticle

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Abstract

Background and Purpose: Helical CT has become the preferred method for imaging urinary calculi, and so it would be useful if data from helical CT could also be used to predict the number of shockwaves (SWs) needed to break a given stone. Methods and Materials: We measured the number of SWs required to comminute calcium stones in vitro. Results: The SW requirement correlated with stone size (volume, weight, diameter) and with helical CT attenuation values when the scans were performed at 3-mm collimation. When CT scans were performed at 1 mm collimation, the number of SWs needed for comminution did not correlate with helicul CT attenuation values. This result indicates that the correlation with 3-mm scans was attributable to volume-averaging effects, in which smaller stones yield smaller attenuation values. That is, attenuation values from helical CT at larger beam collimation widths contain information about stone size that can be exploited to predict the fragility of calcium stones. We observed that for calcium stones, the number of SWs to comminution was generally less than half the stone CT attenuation value in Hounsfield units. This 'half-attenuation rule' predicted the number of SWs needed to complete fragmentatlon for 95% of calcium stones (24/24 calcium oxalate monohydrate, 13/13 hydroxyapatite, 8/10 brushite stones). Conclusion: This in vitro study suggests that it may be possible to predict effective SW dose using helical CT prior to lithotripsy.

Original languageEnglish
Pages (from-to)471-474
Number of pages4
JournalJournal of Endourology
Volume14
Issue number6
StatePublished - 2000

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Spiral Computed Tomography
Calcium
Calcium Oxalate
Urinary Calculi
Lithotripsy
Durapatite
Weights and Measures
In Vitro Techniques

ASJC Scopus subject areas

  • Urology

Cite this

Saw, K. C., McAteer, J. A., Fineberg, N. S., Monga, A. G., Chua, G. T., Lingeman, J. E., & Williams, J. (2000). Calcium stone fragility is predicted by helical CT attenuation values. Journal of Endourology, 14(6), 471-474.

Calcium stone fragility is predicted by helical CT attenuation values. / Saw, K. C.; McAteer, J. A.; Fineberg, N. S.; Monga, A. G.; Chua, G. T.; Lingeman, J. E.; Williams, James.

In: Journal of Endourology, Vol. 14, No. 6, 2000, p. 471-474.

Research output: Contribution to journalArticle

Saw, KC, McAteer, JA, Fineberg, NS, Monga, AG, Chua, GT, Lingeman, JE & Williams, J 2000, 'Calcium stone fragility is predicted by helical CT attenuation values', Journal of Endourology, vol. 14, no. 6, pp. 471-474.
Saw KC, McAteer JA, Fineberg NS, Monga AG, Chua GT, Lingeman JE et al. Calcium stone fragility is predicted by helical CT attenuation values. Journal of Endourology. 2000;14(6):471-474.
Saw, K. C. ; McAteer, J. A. ; Fineberg, N. S. ; Monga, A. G. ; Chua, G. T. ; Lingeman, J. E. ; Williams, James. / Calcium stone fragility is predicted by helical CT attenuation values. In: Journal of Endourology. 2000 ; Vol. 14, No. 6. pp. 471-474.
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