Characterization of histological subtypes of clear cell renal cell carcinoma using contrast-enhanced ultrasound (CEUS).
BACKGROUND
The aim of this study was to analyze the histological subtypes of clear cell renal cell carcinoma (RCC) examined by means of contrast-enhanced ultrasound (CEUS) and a second generation blood pool agent (SonoVue®, Bracco, Milan, Italy) during the pre-operative phase.


METHODS
29 patients with histologically proven subtypes of clear cell RCC were examined. A total of three patients were diagnosed with highly differentiated clear cell RCC, 21 out of 29 cases with moderately differentiated clear cell RCC and five out of 29 patients had insufficiently differentiated clear cell RCC. An experienced radiologist examined the patients with CEUS. The following parameters were analyzed: maximum signal intensity (PEAK), time elapsed until PEAK is reached (MTT), local blood flow (RBF), area under the time intensity curve (AUC) and the signal intensity (SI) during the course of time. For the groups all comparisons are made based on healthy renal parenchyma.


RESULTS
In the clear cell RCC significant differences (significance level p < 0.05) between cancerous tissue and the healthy renal parenchyma were noticed in all four parameters. Therefore, the clear cell RCC stands out due to its reduced blood volume. However, it reached the PEAK reading relatively rapidly and its signal intensity was always lower than that of the healthy renal parenchyma. In the arterial phase retarded absorption of the contrast agent was observed, followed by fast washing out of the contrast agent bubbles.In all three histological subgroups no significant differences were noticed in PEAK and SI. However, the diagrams showed the possible bias, that the group of the insufficiently differentiated clear cell RCC had the highest PEAK-value and the highest signal intensity when compared with highly and moderately differentiated clear cell RCC.


CONCLUSIONS
Our study suggests that CEUS may be an additional tool for non-invasive characterisation and differentiation of the three histological subtypes of clear cell RCC. Furthermore, it seems to have an additional diagnostic value in daily clinical.
Department of Clinical Radiology, Ludwig-Maximilians-University of Munich-Grosshadern Campus, Marchioninistr., Munich, Germany.
R
R
Reimann
Department of Clinical Radiology, Ludwig-Maximilians-University of Munich-Grosshadern Campus, Marchioninistr., Munich, Germany.
J
J
Rübenthaler
Department of Clinical Radiology, Ludwig-Maximilians-University of Munich-Grosshadern Campus, Marchioninistr., Munich, Germany.
P
P
Hristova
Department of Urology, Ludwig-Maximilians-University of Munich-Grosshadern Campus, Marchioninistr., Munich, Germany.
M
M
Staehler
Department of Clinical Radiology, Ludwig-Maximilians-University of Munich-Grosshadern Campus, Marchioninistr., Munich, Germany.
M
M
Reiser
Department of Clinical Radiology, Ludwig-Maximilians-University of Munich-Grosshadern Campus, Marchioninistr., Munich, Germany.
D A
DA
Clevert
D000368:Aged; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000473:pathology; D003287:Contrast Media / Q000627:therapeutic use*; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male
D003287:Contrast Media