Evaluation of validity and reliability of novel rapid measurement for infundibulopelvic angle: a comparison with PACS system

For patients with lower pole renal calculi (LPC), preoperative evaluation of infundibulopelvic angles (IPA) is of great significance; however, conventional measuring method is often inconvenient in clinical setting. Here we introduce a rapid novel method using built-in inclinometer in smartphone which is often used in anatomical parameters evaluating to implement the measurement of IPA.The randomized, self-controlled study on evaluating inclinometer application measured IPA on urography films collected from enrolled LPC patients. Results of statistical analysis for its validity and reliability compared to conventional PACS system are reported. Predictive performance of postoperative stone-free rates by IPA measured with the novel method was also evaluated in this study.Bland-Altman plot result shows that there is favorable agreement between IPA values of these two methods. The time required to utilize the PACS was considerably greater than time required to take similar measure using smartphones. The precision-recall curve (PRC) indicates that the new method has similar predictive performance for postoperative clearance rates as PACS.In summary, measurement of IPA implemented by integrated inclinometer of smartphone is rapid, convenient, accurate and reliable in evaluating renal anatomy parameters of LPC patients.