Estadística

URI permanente para esta colección

https://hdl.handle.net/10669/292

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Examinando Estadística por Autor "Blandino, Alfredo"

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  • Miniatura
    Ítem
    Iodine Quantification to Distinguish Clear Cell from Papillary Renal Cell Carcinoma at Dual-Energy Multidetector CT: A Multireader Diagnostic Performance Study
    (2014-08) Mileto, Achille; Marin, Daniele; Alfaro Córdoba, Marcela; Ramirez Giraldo, Juan Carlos; Eusemann, Christian D.; Scribano, Emanuele; Blandino, Alfredo; Mazziotti, Silvio; Ascenti, Giorgio
    Purpose: to investigate whether dual-energy multidetector row computed tomographic (CT) imaging with iodine quantification is able to distinguish between clear cell and papillary renal cell carcinoma (RCC) subtypes. Materials and Methods: in this retrospective, HIPAA-compliant, institutional review board–approved study, 88 patients (57 men, 31 women) with diagnosis of either clear cell or papillary RCC at pathologic analysis, who underwent contrast material–enhanced dual-energy nephrographic phase study between December 2007 and June 2013, were included. Five readers, blinded to pathologic diagnosis, independently evaluated all cases by determining the lesion iodine concentration on color-coded iodine maps. The receiving operating characteristic curve analysis was adopted to estimate the optimal threshold for discriminating between clear cell and papillary RCC, and results were validated by using a leave-one-out cross-validation. Interobserver agreement was assessed by using an intraclass correlation coefficient. The correlation between tumor iodine concentration and tumor grade was investigated. Results: a tumor iodine concentration of 0.9 mg/mL represented the optimal threshold to discriminate between clear cell and papillary RCC, and it yielded the following: sensitivity, 98.2% (987 of 1005 [95% confidence interval: 97.7%, 98.7%]); specificity, 86.3% (272 of 315 [95% confidence interval: 85.0%, 87.7%]); positive predictive value, 95.8% (987 of 1030 [95% confidence interval: 95.0%, 96.6%]); negative predictive value, 93.7% (272 of 290 [95% confidence interval: 92.8%, 94.7%]); overall accuracy of 95.3% (1259 of 1320 [95% confidence interval: 94.6%, 96.2%]), with an area under the curve of 0.923 (95% confidence interval: 0.913, 0.933). An excellent agreement was found among the five readers in measured tumor iodine concentration (intraclass correlation coefficient, 0.9990 [95% confidence interval: 0. 9987, 0.9993). A significant correlation was found between tumor iodine concentration and tumor grade for both clear cell (τ = 0.85; P < .001) and papillary RCC (τ = 0.53; P < .001). Conclusion: dual-energy multidetector CT with iodine quantification can be used to distinguish between clear cell and papillary RCC, and it provides insights regarding the tumor grade.
  • Miniatura
    Ítem
    Nonlinear Image Blending for Dual-Energy MDCT of the Abdomen: Can Image Quality Be Preserved If the Contrast Medium Dose Is Reduced?
    (2014) Mileto, Achille; Ramirez Giraldo, Juan Carlos; Marin, Daniele; Alfaro Córdoba, Marcela; Eusemann, Christian D.; Scribano, Emanuele; Blandino, Alfredo; Mazziotti, Silvio; Ascenti, Giorgio
    OBJECTIVE. The objective of this study was to compare the image quality of a dual- energy nonlinear image blending technique at reduced load of contrast medium with a simulated 120-kVp linear blending technique at a full dose during portal venous phase MDCT of the abdomen. SUBJECTS AND METHODS. Forty-five patients (25 men, 20 women; mean age, 65.6 ± 9.7 [SD] years; mean body weight, 74.9 ± 12.4 kg) underwent contrast-enhanced single-phase dual-energy CT of the abdomen by a random assignment to one of three different contrast medium (iomeprol 400) dose injection protocols: 1.3, 1.0, or 0.65 mL/kg of body weight. The contrast-to-noise ratio (CNR) and noise at the portal vein, liver, aorta, and kidney were compared among the different datasets using the ANOVA. Three readers qualitatively assessed all datasets in a blinded and independent fashion. RESULTS. Nonlinear blended images at a 25% reduced dose allowed a significant improvement in CNR (p < 0.05 for all comparisons), compared with simulated 120-kVp linear blended images at a full dose. No statistically significant difference existed in CNR and noise between the nonlinear blended images at a 50% reduced dose and the simulated 120-kVp linear blended images at a full dose. Nonlinear blended images at a 50% reduced dose were considered in all cases to have acceptable image quality. CONCLUSION. The dual-energy nonlinear image blending technique allows reducing the dose of contrast medium up to 50% during portal venous phase imaging of the abdomen while preserving image quality.