Kidney Stone Volume Measurement using Ultra-Low Dose Computed Tomography and New Software Solutions
Ohad Kott, MD1, Thomas Yi, MD2, Jorge Pereira, MD3, David Grand, MD4, Adib Karam, MD4, Derek Merck, PhD4, Scott Collins, PhD4, Simone Thavaseelan, MD5, Gyan Pareek, MD6.
1Minimally Invasive Urology Institute, The Miriam Hospital, Providence, RI, 2The Warren Alpert Medical School of Brown University, Providence, RI, 3Mount Sinai Medical Center, Miami Beach, FL, 4Rhode Island Hospital, Providence, RI, 5Rhode Island Hospital; Warren Alpert Medical School of Brown University, Providence, RI, 6Minimally Invasive Urology Institute, The Miriam Hospital; The Warren Alpert Medical School of Brown University, Providence, RI.
BACKGROUND: Ultra-low dose computed tomography (UCT) is a promising alternative to standard dose CT (SCT) as imaging modality following nephrolithiasis treatment.Emerging software solutions allow easy stone size measurement including stone volume that provides clinically important information. This studyevaluated two software solutions using UCT and SCT: Ziostation and Synapse.
METHODS: 29 patients with nephrolithiasis who underwent nephrolithiasis treatment between October 2017-June 2019 were imaged using SCT immediately followed by UCT. Anonymized images were randomized to an Orthanc DICOM viewer prior to a blinded review by board-certified radiologist. Max stone diameters were measured in the axial and coronal planes, using standard electronic calipers. Radiologist stone volume was modeled as ellipsoids based on the max stone diameters. Stone volumes were compared to automated measurements by Ziostation and Synapse software and compared between doses. Stone location was recorded as upper/mid/lower pole or ureter. Site specific stone burden (SSB) was calculated as cumulative stone volume in each site.Radiation exposure was calculated from CT dose reports. SSB were considered concordant if < 30 mm^3. P-value of 0.05 was used as significance cutoff.
RESULTS: 74 unique stones were identified in 29 patients. Mean exposure of UCT was significantly lower than SCT with 2.6 and 10.2 (mSv, p < 0.01) respectively.Overall radiologist measurement concordance rate was 90% between UCT and SCT, with no significant difference between doses (p = 0.91). SSBconcordance rates within dose for Ziosoft and Synapse were 100% and 87% respectively.
No statistically significant difference was detected in SSB between UCT and SCT across all exams. UCT can be used for follow-up imaging postnephrolithiasis treatment exposing the patients to less radiation. Kidney stone volume measurement of post-operative SSB using Ziostation and Synapseis reproducible and operator-independent both in SCT and UCT. Adoption of such tools may benefit patients and surgeons. Dis-concordance rates in SSBbetween radiologist and software measurement warrant further research to determine the gold standard in SSB measurement.
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