J Korean Soc Ultrasound Med.  2010 Jun;29(2):105-113.

Ultrasonographic Differentiation of Small Angiomyolipoma from Renal Cell Carcinoma by Measuring Relative Echogenicity on PACS

• Lee MS
• Cho JY
• Kim SH

Abstract

PURPOSE
To retrospectively evaluate the diagnostic value of ultrasonographic differentiation of small angiomyolipomas (AMLs) from renal cell carcinomas (RCCs) by measuring relative echogenicity (RE) on PACS.
MATERIALS AND METHODS
Thirty-six cases of < 3 cm, pathologically-proven RCCs and 42 cases of size-matched AMLs were enrolled. We measured the grayscale representing echogenicity of the mass, the renal cortex, and the sinus fat on PACS using a ROI cursor. The RE of the tumor was calculated by setting the grayscale of the renal cortex and sinus fat as 0% and 100%, respectively. We compared REs of AMLs and RCCs, including subgroups of each tumor. ROC analyses between RCCs and AMLs or non-fatty AMLs were performed for obtaining diagnostic performance (Az value) of RE measurement and for extracting sensitivities of RE with fixed specificities of 90% and 95%.
RESULTS
The RE of AMLs was higher than RCCs (p < 0.05). The RE of non-fatty AMLs was significantly lower than fatty AMLs, and higher than any subgroups of RCCs (p < 0.05). RE measurement provided good diagnostic performance (Az > or = 0.840, p < 0.05) with competitive sensitivity/specificity for differentiating AMLs from RCCs regardless of AML subgroups.
CONCLUSIONS
RE measurement on PACS can be helpful in the differential diagnosis of small AMLs and RCCs with the intrinsic merits of ultrasonography.

Keyword

Kidney; Angiomyolipoma; Renal cell carcinoma; PACS; Ultrasound

MeSH Terms

Angiomyolipoma
Carcinoma, Renal Cell
Diagnosis, Differential
Kidney
Retrospective Studies
ROC Curve