Contrast-enhanced Harmonic Sonography: Study In Renal Masses

Obiective: The purpose of this study was to characterize the image morphology of renal masses on contrast-enhanced harmonic sonography and to correlate the imaging findings of renal cell carcinoma on contrast-enhanced harmonic sonography with microvessel density and histopathological grades.Materials and methods: A total of 69 patients with 70 renal masses were enrolled in this study prospectively. The renal masses included renal cell carcinoma (RCC, n=47), angiomyolipoma (AML, n=11), pseudotumor (n=5), transitional cell carcinoma (n=3), acidophile cell adenoma (n=2), nephroblastoma (n=1), focal infection (n=1). All patients were evaluated by traditional gray-scale sonography, color Doppler sonography and contrast-enhanced harmonic sonography. Imaging findings and time-intensity curves (TIC) of all renal masses were analyzed. The contrast-enhancement features between RCC and AML, the enhancement extent of RCC, microvessel density, and histopathological grades were analyzed statistically.Results: (1) RCCs were mostly hyperechoic (57.4%) or isoechoic (27.7%) masses with intra-tumoral cystic area in some tumors (27.7%), and peripheral surrounding vessels and / or penetrating vessels were noted in most RCCs (83.0%) on color Doppler sonography. As for AMLs, mostly were hyperechoic (54.5%) or markedly hyperechoic (36.4%) masses with posterior attenuation (9.1%), while peripheral surrounding vessels and / or penetrating vessels were only noted in 27.3% of AMLs on color Doppler sonography. (2) On contrast-enhanced harmonic sonography, hyper- or iso-enhancement were noted in 83.0% of RCCs, while as hypo-enhancement were noted in 81.8% of AMLs (p<0.00001). (3) Statistically significant differences were noted between RCC and AML in the values of PT (peak time) (p=0.036), WT (wash time) (p=0.0165), AA (peak intensity-basic intensity) (p=0.010), ΔA T/R (ΔA tumor/ΔA renal) (p=0.0025), k (p=0.0249), and ΔA*k (p=0.020). (4) A significant positive correlation was observed between MVD (3.0~58.7, mean: 40.9±12.6) and the enhancement extent (2.28~29.36dB, mean 14.94±6.14dB) of RCC (r=0.782, p<0.0001 ), and also between MVD and histopathological grades (G1=20,G2=16,G3=11) of RCC (r=0.319,p=0.029).Conclusion: Contrast-enhanced sonography is very useful in the differentiation of renal masses. And the assessment of tumour enhancement parameter is of prognostic significance for patients with RCC.