Initial Experience and Evaluation of a Nomogram for Outcome Prediction in Management of Medium-sized (1-2 cm) Kidney Stones.

BACKGROUND: The gold standard treatment for solitary medium-sized (1-2 cm) renal stones is not defined by recent guidelines, since management modalities including shockwave lithotripsy (SWL), retrograde intrarenal surgery (RIRS), and percutaneous nephrolithotomy (PNL) are recommended. Improved ability to predict patient outcomes would aid in patients' counseling and decision-making. OBJECTIVE: To develop a nomogram predicting treatment failure, based on preoperative clinical variables, to be used in the preplanning setting. DESIGN, SETTING, AND PARTICIPANTS: We recruited 2605 patients from 14 centers and carried out a multicenter retrospective analysis of 699 SWL, 1290 RIRS, and 616 PN L procedures performed as first-line treatment for 1-2-cm kidney stones. The variables evaluated included age, gender, previous renal surgery, body mass index, stone size, location, stone density, skin-to-stone distance, presence of urinary tract infections (UTIs), and hydronephrosis. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Multivariate logistic regression was fitted to predict treatment failure, defined as the presence of residual fragments >4 mm. A nomogram was developed based on the coefficients of the logit function. RESULTS AND LIMITATIONS: A total of 2431 (93.3%) patients were stone free; 174 (6.7%) treatment failures were recorded and considered the event to be predicted. On univariate analysis, type of procedure, preoperative hydronephrosis, stone density, stone location, and laterality turned out to be statistically significant. Skin-to-stone distance, UTIs, and previous renal surgery were predictors of failure on multivariate analysis. Each variable was given a score based on statistical relevance. The main limitation of the current study is its retrospective nature. CONCLUSIONS: This nomogram provides a prediction of treatment failure and need of reintervention for medium-sized kidney stones. External validation is needed to determine its reproducibility and validity. PATIENT SUMMARY: We developed a preoperative model of treatment outcomes for 1-2-cm kidney stones. Its application may assist urologists to counsel patients with regard to stone management modality.

Value of triphasic MDCT in the differentiation of small renal cell carcinoma and oncocytoma.

INTRODUCTION: Although differentiation between benign and malignant small renal tumors (≤4 cm) is still difficult, it is a demand for decision making and determining the treatment strategy. Our aim is to evaluate the role of multidetector row computed tomography (MDCT) in the differentiation of small renal clear cell carcinoma (RCC) and renal oncocytoma (RO). METHODS: We reviewed triphasic computed tomographic (CT) scans performed in 43 patients diagnosed with RCC (n = 23) and RO (n = 21). After an unenhanced CT phase of the upper abdomen, triple-phase acquisition included a cortico-medullary phase (CMP), a nephrographic phase (NP), and a pyelographic phase (PP), and lesions were evaluated both qualitatively and quantitatively. RESULTS: RCCs were hypervascular in 13 cases and hypovascular in 10 cases, while ROs were hypervascular in nine cases and hypovascular in 12 cases. Mean attenuation values (MAVs) for hypervascular RCCs and hypervascular ROs on unenhanced examination were 34.0 ± 7.1 and 31.3 ± 8.1 HU, respectively. Enhancement in CMP was 173.1 ± 45.2 HU for RCCs and 151.1 ± 36.0 HU for ROs and a gradual wash-out in NP (148.8 ± 34.3 and 137.1 ± 33.9 HU for RCCs and ROs, respectively) and in PP (98.2 ± 36.0 HU for RCCs and 79.4 ± 21.5 HU for ROs) was observed. MAV for hypovascular RCCs and hypovascular ROs on unenhanced examination were 32.4 ± 12.0 and 28.9 ± 8.0 HU, respectively. Both hypovascular RCCs and ROs showed a statistically significant difference in each post contrastographic phase. CONCLUSIONS: Absolute attenuation and the quantitative amount of the enhancement were not strong predictors for RO and RCC differentiation.