Evaluation of chemical composition of urinary calculi by conventional radiography.
OBJECTIVE
The choice of the most efficient treatment modality for renal calculi could be facilitated by determining the precise chemical stone composition before treatment. We investigated the possibility of using conventional X-ray imaging to determine stone composition and to find a simple method of predicting stone fragility for treatment planning.


METHODS
The X-ray density of 92 stones with known infrared spectroscopy analyses (calcium oxalate monohydrate, calcium oxalate dihydrate, struvite, and calcium phosphate) was retrospectively investigated by scanning the films with a digital camera. The data analysis was done using a commercially available graphics program to compare the total gray-scale levels of the stones.


RESULTS
There was a significant difference in the mean gray-scale level of calcium phosphate and calcium oxalate stones (P < 0.01). The mean gray-scale difference between calcium oxalate dihydrate and calcium oxalate monohydrate was also significant (p < 0.02). All calcium oxalate, struvite, and calcium phosphate stones were correctly identified. Of the calcium oxalate monohydrate and calcium oxalate dihydrate stones, 98.4% and 66.6%, respectively, were correctly identified.


CONCLUSIONS
The method allows a reliable diagnosis of stone composition from radiographs, which can be useful in stone treatment planning.
Oehlschläger
Sven
S
Department of Urology, University Hospital Carl-Gustav-Carus, Technical University Dresden, Fetscherstrasse 74, D-01307 Dresden, Germany. sven.oehlschlaeger@mailbox.tu-dresden.de
Hakenberg
Oliver W
OW
Froehner
Michael
M
Manseck
Andreas
A
Wirth
Manfred P
MP
D002129:Calcium Oxalate / Q000032:analysis / Q000737:chemistry*; D002130:Calcium Phosphates / Q000032:analysis / Q000737:chemistry*; D005260:Female; D006801:Humans; D017616:Magnesium Compounds / Q000032:analysis / Q000737:chemistry*; D008297:Male; D010710:Phosphates / Q000032:analysis / Q000737:chemistry*; D011859:Radiography / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D000069877:Struvite; D014545:Urinary Calculi / Q000737:chemistry / Q000000981:diagnostic imaging
D002130:Calcium Phosphates; D017616:Magnesium Compounds; D010710:Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; D002129:Calcium Oxalate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; D000069877:Struvite; C485829:calcium phosphate, dibasic, anhydrous