Abstract
The purpose of our study was to assess the role of a 64-slice multidetector CT (MDCT) scanner in the characterization of different solid renal masses, using a simplified approach to correct the postenhancement attenuation values. The study included 96 consecutive adults (58 men, 38 women) with renal masses; 93 with unilateral and three with bilateral masses. All of our patients underwent multiphasic CT study including pre- and postcontrast corticomedullary (CM) and nephrographic phases. We analyzed the images and corrected the postcontrast attenuation values at the CM phase. The postbiopsy or -surgical data were used as reference standard. There were 53 masses at the right kidney, 40 at the left kidney, and three bilateral. The final diagnosis of the 96 solid parenchymal masses were 28 clear-type renal cell carcinoma (RCC), 22 papillary-type RCC, 21 chromophobe-type RCC, six XP 11.2 chromosomal translocation–type RCC, 15 angiomyolipoma (AML), and seven oncocytoma. All the AML had fat, with attenuation values less than -40 HU at the nonenhanced scan. There is no difference in the precontrast attenuation values for the different types other than AML. At the postcontrast CM phase after the correction of the attenuation values, the clear cell type could be separated easily, with attenuation values >20 with specificity, sensitivity, and overall accuracy of 92, 84, and 93%, respectively. The 64-slice MDCT scanner with application of enhancement values correction allows diagnosis of clear cell carcinoma. Also, AML could be identified easily with fat inside at the precontrast scan.
Highlights
The great majority of renal masses are found incidentally as a result of the wide use of computed tomography (CT), ultrasonography (US), and magnetic resonance (MR) imaging
In a study by Kim et al.[15], the authors found that the degree of enhancement is the most useful parameter in differentiating subtypes of renal cell carcinoma (RCC), especially conventional renal carcinoma vs. nonconventional renal carcinomas with high validity (p value < 0.05 in both the CM phase and the excretory phase)
Conventional renal carcinoma showed stronger enhancement than nonconventional renal carcinomas in both the CM and excretory phases, and the tumors that enhanced more than approximately 84 Histologies/Attenuation Values Precontrast (HU) in the CM phase and 44 HU in the excretory phase were likely to be conventional renal carcinoma
Summary
The great majority of renal masses are found incidentally as a result of the wide use of computed tomography (CT), ultrasonography (US), and magnetic resonance (MR) imaging. Most of these are simple renal cysts that can be diagnosed and do not require treatment. Solid and complex cystic renal masses are discovered, many of which are clearly malignant and need to be surgically removed, while others may not require surgical intervention[1]. There was a time when renal cancer was just a solid enhancing mass in the kidney that required no further description and was removed with radical nephrectomy. One manifestation of the evolution of our knowledge of renal cancer is the discovery of an increasingly complex array of tumor subtypes; these tumor subtypes range from the common to almost unheard of[2]
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