Objective:

To investigate the ability of attenuation measurement and histogram analysis in differentiating minimal-fat renal angiomyolipoma (AML) from papillary and chromophobe renal cell carcinoma (RCC) on unenhanced CT.

Methods:

Unenhanced CT images of 18 minimal-fat AML

15 chromophobe RCC and 22 papil

lary RCC were analyzed. The mean attenuation and relative histogram parameters (10th

25th

50th values and 10th/mean value) of the lesions were measured and calculated. The parameters were compared among AML

chromophobe RCC

and papillary RCC. The parameters with significant difference would be applied in differentiating of minimal-fat AML from two RCCs. The effeciency of the parameters for differentiation was assessed by receiver operating characteristic (ROC) curve.

Results:

The mean and 10th

25th

50th values of the attenuation of minimal-fat AML were significantly higher than chromophobe and papillary RCCs

but no significant difference was found in 10th/mean value. The values of area under ROC curve (AUC) of the parameters for differentiating AML from chromophobe RCC were 0.80

0.76

0.78

0.82

respectively

and no significant difference was observed among them. The AUC values of the parameters for differentiating AML from papillary RCC were 0.69

0.70

0.68

0.72

respectively

and no significant difference wasobserved among them.

Conclusion:

On unenhanced CT attenuation measurement and histogram analysis provide more parameters for distinguishing minimal-fat AML from papillary and chromophobe RCCs

but the efficiency should be further improved.