Characterization of small solid renal lesions: can benign and malignant tumors be differentiated with CT?

Abstract

Conclusion: In general, ADC values are not useful in differentiating adrenal lesions. However, when ADC values are applied to lesions that are indeterminate on signal intensity index, they may help in differentiating a subset of benign and malignant lesions. Editorial CommentAdrenal incidentalomas are found in about 6% of patients submitted to abdominal computed tomography. Based on distinct radiologic criteria classified as morphologic (size, shape, rate of growing), histologic (lipid content of the mass on CT without contrast or on chemical-shift imaging on MRI without contrast) and physiologic (absolute washout of contrast on CT), the vast majority of adrenal incidentalomas are adequately characterized as a benign or malignant. Lipid rich adrenal adenoma loses signal intensity when protons from water and fat are on opposed-phase in comparison with imaging when these protons are inphase. Signal intensity index higher than 16.5% is usually found in benign adenomas. Indeterminate adrenal lesion represents a lesion with signal intensity index below 16.5%. In such situation, the authors showed that use of ADC values obtained with diffusion-weighted imaging (DWI) might be useful in differentiating benign from malignant adrenal lesions.Although in our protocol for DWI of adrenal masses we use a different "b-value" (b-factor of 1000), we have found no utility of DWI even in this selected group of patients with indeterminate lesion on CSI. Actually we have seen two out of 13 adrenal adenomas showing the lowest ADC values. As pointed out by the authors, the different proportion of lipid-poor adenomas and fat-containing adrenal metastases may explain distinct results with DWI. Roentgenol. 2011; 197: 887-96 Objective: The purpose of this study was to evaluate the diagnostic performance of CT in determining whether a small solid renal enhancing mass is benign or malignant. Materials and Methods: Ninety-nine biopsies of enhancing solid renal masses 4 cm or smaller without fat on CT scans were performed under CT fluoroscopic guidance. The growth pattern, interface with parenchyma, presence of a scar and segmental inversion enhancement, unenhanced CT histogram, and pattern and degree of enhancement on triphasic MDCT images were independently evaluated by two radiologists. Biopsy and pathology reports were used as the reference standard, and imaging follow-up of benign lesions was performed for at least 1 year. Statistical analysis was performed to determine the significance of CT criteria in differentiating malignant from benign lesions. Results: Of the 99 lesions, 74 (75%) were malignant at biopsy, and 25 (25%) were benign. Lesions with gradual enhancement were more likely to be benign. No significant correlation was found between other CT Dr. Adilson Prando

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Can Renal Biopsy Accurately Predict Histological Subtype and Fuhrman Grade of Renal Cell Carcinoma?

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