Differentiation of small hyperechoic renal cell carcinoma from angiomyolipoma: computer-aided tissue echo quantification.

Abstract

idespread use of ultrasonography and abdominal CT has increased the detection of small renal neoplasms, often found incidentally in asymptomatic patients. 1,2 RCC and AML are the most frequently occurring malignant and benign renal parenchymal tumors, respectively. Frequently small RCC are hyperechoic 1-3 and may mimic AML. Efforts were made to differentiate the two conditions on the basis of ultrasonographic characteristics such as intratumoral cysts, hypoechoic rim, and posterior acoustic shadowing. [3][4][5][6] These findings were fairly specific but not sensitive enough. 6,7 In our experience as well as that of others, AML tend to be more echogenic than RCC. 3,7,[8][9][10] Some investigators tried to differentiate these two tumors using a visual assessment of echogenicity alone without satisfactory results. 3,6 The purposes of this study were to evaluate the echogenicity of renal masses objectively and quantitatively by using CATEQ technique and to assess the value of this technique in differentiating small hyperechoic RCC from AML. To assess the value of computer-aided tissue echo quantification in differentiating small hyperechoic renal cell carcinomas from angiomyolipomas, we studied ultrasonographic images of 15 renal cell carcinomas and 20 angiomyolipomas. After digitizing the images, we measured the absolute gray scale values of the renal cortex, central echo complex, and mass. The relative gray scale value (%) of the mass was calculated by setting the gray scale value of the cortex as 0% and the central echo complex as 100%. The relative gray scale value of renal cell carcinomas was in the range of 12 to 73% (mean, 28%), whereas that of angiomyolipomas was 30 to 204% (mean, 130%). The differentiation between small hyperechoic renal cell carcinomas and angiomyolipomas can be facilitated by computer-aided tissue echo quantification.

Ultrasound of renal tumors

“…Ultrasound tissue characterization based on either USfrequency-dependent attenuation [14] or relative grayscale values measurements (compared with renal cortex) [15] have been recently evaluated in the diagnosis of solid renal tumors. Both tissue echo quantification techniques yield promising diagnostic aid in differentiating hyperechoic RCCs from AMLs.…”

Characterization and Diagnostic Confidence of Contrast-Enhanced Ultrasound for Solid Renal Tumors

“…Most solid RCCs revealed lower echogenicity than AMLs in conventional US (Sim et al 1999). In the present study, solid RCCs in subjective analysis showed intense contrast enhancement at the arterial phase, whereas typical AMLs revealed a dotlike appearance at the arterial phase.…”

“…Most RCCs are hypoechoic on US, but approximately 30% of small RCCs appear hyperechoic, similar to small angiomyolipomas (AMLs) (Forman et al 1993;Jinzaki et al 1998;Yamashita et al 1992), which typically appear very bright, homogeneous and sharply marginated (H el enon et al 2001;Jinzaki et al 1998). Incidence of atypical iso-hypoechoic and slightly hyperechoic AMLs account for 6% and 29%, respectively (Taniguchi et al 1997;Jinzaki et al 1998;Sim et al 1999). …”

Der Beitrag der Bildanalyse für die Differenzialdiagnose der fokalen Nierenparenchymveränderungen

“…), wurde die Echointensi- tät des Tumors in Relation zu der zugehörigen Nierenrinde gesetzt. Im Gegensatz zu Sim [28] haben wir auf den Vergleich mit dem Nierensinus verzichtet, da die Echointensität des Nierensinus eine stärker variable Größe ist. Die Standardabweichungen wurden in Varianzen umgerechnet und dienten als Maß der Inhomogenität (I).…”

“…Bei der Untersuchung mit höherfrequenten Sonden sowie bei der Arbeit mit Harmonic Imaging wurden tendenziell höhere Echoquotienten gemessen. Die Echointensität kleiner Angiomyolipome und Nierenzellkarzinome wurde in Relation zu der Nierenrinde und dem Nierensinus gemessen [28]. Die Methode wurde auch mit verschiedenen Geräten zur Analyse von Nierenrinde und Markpyramiden evaluiert [29].…”