Prediction of stone composition from plain radiographs: a prospective study

Prediction of stone composition from plain radiographs: a prospective study.
Ramakumar S, Patterson DE, LeRoy AJ, Bender CE, Erickson SB, Wilson DM, Segura JW.
J Endourol. 1999 Jul-Aug;13(6):397-401

Introduction

• Stone composition, as reflected in radiographic appearance, is important to help choose between ESWL and percutaneous/endoscopic procedures
• Predicting a stone's composition accurately from a plain radiograph would be a useful tool in clinical decision-making
• The ability of physicians to predict composition has not been adequately assessed
• This prospective study was designed to quantify the accuracy of a panel of physicians who routinely deal with stones in classifying stone composition solely from radiographs

Materials and Methods

• A panel of six members was created to review 100 plain-film radiographs from patients with renal stones of known composition
• The panel consisted of two urologists, two radiologists, and two nephrologists, all of whom have expertise in stone disease
• If the composition guessed was at least 40% of the total stone composition, the response was deemed correct

Results

• Overall, there was an average 39% correct response score among the six panelists When the stones were divided by size, 35% were <1 cm, and 65% were larger
• The accuracy of chemical composition determination did not improve with greater stone size, nor was there a difference in accuracy for pure and mixed stones
• The most frequently misclassified stone was calcium phosphate, with only 14% being correctly diagnosed

Conclusion

• With a random sampling of plain radiographs, a panel of physicians specializing in stone disease correctly diagnosed the composition of renal calculi less than half of the time without being given clinical information