Predictive value of dual-source stone energy spectrum CT for uric acid stones / 中华泌尿外科杂志

ABSTRACT

Objective:To investigate the predictive value of stone composition prediction method based on dual-source stone energy spectrum CT for uric acid stones.Methods:The clinical data of 204 patients with urinary stones, 159 males and 45 females, admitted to Shanghai Sixth People's Hospital from July 2020 to July 2022 were retrospectively analyzed. The average age was (50.7±14.3) years. There were 187 cases of upper urinary tract (kidney, ureter) stones and 17 cases of lower urinary tract (bladder, urethra) stones. All patients underwent preoperative dual-source stone energy spectroscopy CT, measuring CT values at 150 kV and 100 kV, respectively, and the calculated dual energy ratio (Ratio) was used to predict stone composition. Of the 204 cases in this group, 33 cases underwent percutaneous nephrolithotomy and 171 cases underwent ureteroscopic lithotripsy. Postoperative stone specimens were analyzed for stone composition by infrared spectroscopy. Subject work characteristic (ROC) curves were used to analyze the efficacy of preoperative dual-source stone energy spectrum CT to predict uric acid stones.Results:In 204 patients, preoperative CT predicted 28 cases of uric acid stones and 176 cases of non-uric acid stones, including 136 cases of calcium oxalate stones, 38 cases of hydroxyapatite, and 2 cases of cystine stones. Postoperative IR spectral analysis detected 26 cases of uric acid stones and 178 cases of non-uric acid stones, including 129 cases of calcium oxalate stones, 47 cases of hydroxyapatite, and 2 cases of cystine stones. Compared with the preoperative CT results, there were 2 false positives and no false negatives in the classification of uric acid stones. The ROC curve showed that the sensitivity of the CT value for predicting uric acid stones at 100 kV was 96.2%, the specificity was 99.5%, and the area under the ROC curve (AUC) was 0.995, with the best prediction value of 620 HU.The sensitivity of the CT value for predicting uric acid stones at 150 kV was 96.2%, specificity was 85.5%, AUC was 0.916, and the best predictive value was 597.5 HU. The sensitivity of using Ratio values for predicting uric acid stones was 100.0%, specificity was 97.9%, AUC was 0.996, and the best predictive value was 1.14. The CT values for uric acid stones at 100 kV and 150 kV were (558.58±77.07) HU and (521.12±83.54) HU, CT values for calcium oxalate stones were (1 335.26±301.82) HU and (878.21±200.21) HU, CT values for hydroxyapatite were (1 104.09±203.61) HU and (710.38±178.44) HU, respectively.The CT values of cystine stones were (684.5±67.18) HU and (573.5±67.10) HU, respectively, and the differences between uric acid stones and other components were statistically significant ( P<0.01). The Ratio values of uric acid stones, calcium oxalate stones, hydroxyapatite, and cystine stones were 1.08±0.06, 1.52±0.08, 1.62±0.40, and 1.19±0.02, respectively, and the differences were statistically significant ( P<0.01) when comparing uric acid stones with other components. Conclusion:The CT and Ratio values of dual-source stone energy spectrum CT can effectively distinguish uric acid stones from other types of stones, and the accuracy, sensitivity, and specificity of this method for predicting uric acid stones are high.