How Competent is Computed Tomography in Characterization and Grading of Renal Malignancies: Our Experience
Abstract
Objectives: Accurate diagnosis of renal tumors is critical for obtaining the best treatment and longest possible survival. The purpose of this study is to evaluate computed tomography (CT) parameters of renal masses in order to assess benign and malignant nature as well as accurate grading.
Materials and Methods: Fifty three cases with multiphasic abdominal CTs between 2006 and 2011 were included. Precontrast, corticomedullary, nephrographic postcontrast phase images were retrospectively examined for lesion characteristics, enhancement degrees with regard to the normal renal parenchyma and abdominal aorta, blinded to the surgical results. To compare independent groups for categorical variables chi-square, for metric variables Mann-Whitney U tests were used. Receiver operating characteristics curve analysis was performed to group renal tumor subtypes and when applicable the cut-off values were determined, “Youden” index was calculated. p<0.05 was considered as statistically significant.
Results: Forty six of 53 lesions were malignant, 32 (57.1%) of them clear cell renal cell carcinomas (CCRCC), 5 (9.4%) papillary and 1 (1.9% chromophobe cell RCC. Cystic changes, calcifications and larger size were more pronounced in CCRCC (p< 0.05). The mean sizes of Fuhrman grade I and grade 4 tumors were 31.2±10.9 mm and 63.8±29.8 mm respectively. Fuhrman grades were significantly correlated with the lesion size at diagnosis (p<0.05). To discriminate CCRCC from other masses and CCRCC from other RCC subtypes, 44.5 HU cut-off as the early wash-in showed 81.3%-76.2 % and 81.3%-87.5% sensitivity and specificity, respectively. To discriminate CCRCC among other subtypes the threshold levels calculated from early wash-in, tumor/aorta, tumor/renal parenchyma densities at corticomedullary and nephrographic phases showed equal sensitivity and specificity (83.5% and 75% respectively).
Conclusion: Large size at diagnosis, cystic changes and calcifications were useful parameters to discriminate CCRCC from other tumors and other RCC subtypes. A cut- off value of 44.5 HU for early wash-in could discriminate CCRCC with high sensitivity and specificity. Size and cystic changes showed significant correlation with RCC subtypes and Fuhrman grades.
Keywords
Kidney, Renal Cell Carcinoma, Multiphasic Computed Tomography, Clear Cell Variant
Ethical Statement
Ethics Committee Approval: Retrospective study. Informed Consent: Retrospective study.
Peer-review: Externally and internally peer-reviewed. Authorship Contributions
Concept: Z.A., C.Y.,
Design: Z.A., C.Y.,
Data Collection or
Processing: Z.A., C.Y.,
Analysis or Interpretation: Z.A., D.G.,
Literature Search: Z.A., E.P., A.G.Ç., Writing: Z.A.
Conflict of Interest: No conflict of interest was declared by the authors.
Financial Disclosure: The authors declared that this study received no financial support.
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