T he establishment of a percutaneous tract into the renal collecting system is important and requires imaging supervision during percutaneous nephrolithotomy (PCNL) (1, 2). Unlike percutaneous nephrostomy for patients with hydronephrosis, if percutaneous stone removal is planned, the puncture should be performed in a calyx with possible access to the stone. Montvilas et al. (3) demonstrated that ultrasonography (US)-guided techniques yield lower technical success in patients with non-dilated than in those with dilated collecting systems (82% vs. 98.2%). Furthermore, renal anomalies and scoliosis make needle access more challenging and necessitate puncture planning and control. The syngo iGuide navigation system (Siemens Healthcare) is a three-dimensional (3D) virtual needle tracking system which helps predict and observe the needle trajectory, facilitating real-time puncture to the target (4-7). We report our experience of percutaneous tract establishment for patients with non-dilated renal collecting systems after failed US-guided attempts. Methods Patient selectionThis retrospective study was approved by our Institutional Review Board and informed consent was waived. Between May 2014 and May 2015, of 442 patients with non-dilated renal collecting systems who required PCNL access in two urology surgery departments at our hospital, routine US-guided nephrostomy attempts failed in 33 patients. Those 33 patients (19 males, 14 females; mean age, 60.1±11.8 years) with non-dilated renal collecting systems underwent C-arm computed tomography (CT) with 3D virtual navigation system-guided establishment of PCNL access. A collecting system was identified as non-dilated if no calyceal dilatation was observed on US. All cases had previously failed under US-guidance. The mean body mass index (BMI) was 24.7±4.5 kg/m 2 (range, 17. I N T E R V E N T I O N A L R A D I O LO G Y O R I G I N A L A R T I C L E PURPOSEWe aimed to evaluate the clinical superiority of using C-arm computed tomography (CT) to establish percutaneous nephrolithotripsy (PCNL) access for patients with non-dilated renal collecting systems. METHODSFrom May 2014 to May 2015, 33 patients underwent C-arm CT-guided puncture to establish PCNL access after failed attempts of ultrasonography-guided nephrostomy. Technical success, procedure details, radiation exposure, complications, and stone-free rate were recorded. RESULTSThe technical success rate was 97% (32/33) with a mean puncture score of 4.5/5. Mean puncture, dilation, and fragmentation times were 17.9±6.0, 12.6±3.9, and 33.1±8.8 minutes, respectively. Mean radiation exposure was 4.8±2.1 mSv without serious complications. Stone-free rate was 93.8%. CONCLUSIONC-arm CT is a useful tool to establish PCNL access, particularly in cases of upper pole access or complicated anatomy.You may cite this article as: Jiao D, Zhang Z, Sun Z, Wang Y, Han X. Percutaneous nephrolithotripsy: C-arm CT with 3D virtual navigation in non-dilated renal collecting systems. Diagn Interv Radiol 2018; 24: 17-22.