Abdominal Radiography With Digital Tomosynthesis: An Alternative to Computed Tomography for Identification of Urinary Calculi?

Abstract Objective To compare the accuracy of plain abdominal radiography (kidneys, ureter, and bladder [KUB]) with digital tomosynthesis (DT) to noncontrast computed tomography (NCCT), the gold standard imaging modality for urinary stones. Due to radiation and cost concerns, KUB is often used for diagnosis and follow-up of nephrolithiasis. DT, a novel technique that produces high-quality radiographs with less radiation and/or cost than low-dose NCCT, has not been assessed in this situation. Materials and Methods Seven fresh tissue cadavers were implanted with stones of known size and/or composition and imaged with KUB, DT, and NCCT. Four blinded readers (2 urologists, 2 radiologists) evaluated KUBs for presence and/or location of calculi. They then re-evaluated with addition of tomograms to assess additional value. After a memory extinction period, readers evaluated NCCT images. Accuracy of detection was determined using nearest-neighbor match with generalized linear mixed modeling. Results Total of 59 stones were identified on reference read. Overall, NCCT and DT were both superior to KUB alone ( P P = .06). When evaluating uric acid stones, NCCT and DT outperformed KUB ( P P P  = .16). Intrarenal stones were better evaluated on DT and NCCT ( P P  = 1.00). Accuracy was lower than anticipated across modalities due to use of the cadaver model. Conclusion Our study demonstrates DT is superior to KUB for identification of intrarenal calculi and could replace routine use of KUB or NCCT for detecting renal stones, even those composed of uric acid.