Abdominal Computed Tomography-A New Tool for Predicting Recurrent Stone Disease

Purpose: To evaluate whether CT-identified Randall plaques can be used to foresee the recurrence of stone disease (SD); to define a cut point that could identify a high-risk population. Materials and Methods: A retrospective study of patients attended for SD from January 2004 to December 2009 was conducted. Study population was patients with a first episode of calcium SD that was diagnosed by abdominal CT. Papillae tip attenuation was measured in Hounsfield units (HU) on unenhanced abdominal CT images. Patients with recurrent SD were identified; t test, Pearson correlation, and receiver operating characteristic (ROC) curve analysis were used. Results: A total of 543 patients were evaluated; 187 fulfilled the criteria and were included, and 49 (26.2%) had recurrent SD. Mean follow-up: 5 years (3-7 years). Papillae tip attenuation was significantly higher in the recurrent group (46.2 HU vs 40.1 HU, P = 0.01) and correlated well with the possibility of developing SD (R = 0.83). Attenuation >43 HU showed a ROC curve area under the curve = 0.87 with sensitivity = 77% and specificity = 84% separating patients with a RR = 8.7 of development of recurrent SD. The number of papillae >43 HU correlated with recurrent SD (RR = 11.2 for >= 3 papillae vs <3 papillae with density >43 HU). Conclusions: The presence of the Randall plaques can be used as a marker for predicting SD recurrence. A cut point of 43HU could be used to identify a high-risk population.