Identification of benign from malignant small renal tumors: Is there a possible role of T1 mapping?

Background: Differentiating benign from malignant small renal tumors can help to guide clinical decision-making. T1 mapping enables quantitative assessment of T1 relaxation time and may help to evaluate tumor properties. This study aimed to investigate the possible utility of T1 mapping for quantificationally distinguishing benign from malignant small solid renal tumors. Methods: The data set used in this retrospective study, consisting of 99 patients with 99 small renal masses (≤4 cm). 78 malignant small renal tumors and 21 benign tumors respectively. Quantitative variables (including pre- and post- T1 mapping) were calculated and compared between different renal tumors. The clinical features and image qualitative characteristics were recorded accordingly. Univariate and multivariate logistic regression models were used to identify independent influencing factors. The diagnostic accuracy of independent influencing factors was represented with the area under the receiver operating characteristic curve (AUC). Results : The pre-contrast T1 mapping (T1) and the ratio of T1 reduction in malignance were higher than those in benign small renal tumors, while post-contrast T1 mapping was lower (all P < 0.025). In the multivariable logistic regression, the patient’s gender (odds ratio (OR) = 4.987, P = 0.008), patient’s age (OR = 2.026, P = 0.020), and T1 (OR = 3.652, P = 0.001) were independent predictors. For the identification of benign renal tumors, the T1 demonstrated moderate diagnostic efficiency with an AUC of 0.697 (0.596-0.785), a sensitivity of 51.28%, and a specificity of 100% ( P < 0.000). The T1+ gender + age model achieved an AUC of 0.832 (0.743-0.899), a sensitivity of 60.26%, and a specificity of 95.26%. Conclusion : Quantitative T1 mapping parameters may provide an added value in noninvasively distinguishing small benign renal tumors from renal cell carcinoma (RCC).