Korean J Urol.  2012 Mar;53(3):159-164.

Characterization of Small Renal Masses Less than 4 cm with Quadriphasic Multidetector Helical Computed Tomography: Differentiation of Benign and Malignant Lesions

• Choi SK
• Jeon SH
• Chang SG

Abstract

PURPOSE
To identify the characteristic quadriphasic (unenhanced, corticomedullary, nephrographic, and excretory phase) helical multidetector computed tomography (MDCT) features of renal masses less than 4 cm to distinguish benign from malignant renal masses.
MATERIALS AND METHODS
In total, 84 patients were retrospectively analyzed to determine the characteristic features for the prediction of subtypes of small renal masses. The patients' age, gender, and tumor size and CT features, including the presence of intra-tumor degenerative changes, septation, calcification, and wall irregularity, were evaluated. In addition, the degree and pattern of enhancement obtained during four phases were analyzed. The relationship between the subtype of the small renal masses and the gender, morphological features, and pattern of contrast enhancement on the CT was analyzed by using the chi-square test. Tumor size and degree of contrast enhancement were compared by the Mann-Whitney U test. The predictive value of each of the CT features was determined by multivariate logistic regression analysis.
RESULTS
Of the 84 small renal masses, 17 (20%) were benign and 67 (80%) were malignant. Univariate analysis revealed that renal cell carcinoma lesions showed heterogeneous enhancement (p=0.002) and higher mean attenuation value on the corticomedullary and nephrographic phases (135.1+/-53.9, p=0.000, and 132.4+/-43.6, p=0.006). The multivariate analysis with logistic regression model showed that only the mean attenuation value on the corticomedullary phase had a statistically significant correlation (p=0.021).
CONCLUSIONS
For the characterization of small renal masses, the degree of enhancement on the corticomedullary phase is a valuable parameter. Furthermore, the heterogeneous enhancement pattern and degree of enhancement on the nephrographic phase can provide information for differentiating small renal masses.

Keyword

Benign neoplasm; Computed tomography; Renal cell carcinoma

MeSH Terms

Carcinoma, Renal Cell
Humans
Logistic Models
Multidetector Computed Tomography
Multivariate Analysis
Retrospective Studies

Figure

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  FIG. 1 Receiver operating characteristic (ROC) curves for the degree of contrast enhancement as a distinguishing factor between small malignant masses and small benign masses. The area under the curve for the corticomedullary phase (CMP) was 0.785 (95% confidence interval [CI], 0.667 to 0.902), which was statistically significant, and that for the nephrographic phase (NP) was 0.717 (95% CI, 0.579 to 0.854). CMP, corticomedullary phase; NP, nephrographic phase.

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