Contrast-enhanced ultrasound using a time-intensity curve for the diagnosis of renal cell carcinoma.

OBJECTIVE

• To evaluate the usefulness of contrast-enhanced ultrasound (CEUS) for the diagnosis of renal cell carcinoma by employing a time-intensity curve (TIC).

PATIENTS AND METHODS

• From May 2008 to October 2009, CEUS was performed prior to surgery in 30 patients with renal masses. • In all, 10 of the 30 patients had cystic renal masses. The final diagnoses of all patients were pathologically confirmed. Contrast enhancement as a function of time was measured in two (tumour or solid component of cystic lesions and normal parenchyma) regions of interest (ROI) and TICs were obtained. • The time to the contrast enhancement peak (TTP), intensity change from the baseline to peak (ΔI) and ΔI/TTP of the tumour and the normal parenchyma were measured from the TIC.

RESULTS

• Pathological diagnoses were renal cell carcinoma in 30 patients. • The TTP of the cancer was shorter than that of the normal parenchyma in all cases (6.0 ± 2.0 vs 10.4 ± 3.0 s; P < 0.0001). • The ΔI did not differ between the cancer and normal parenchyma [21.3 ± 5.9 vs 20.9 ± 7.0 decibels (db); P= 0.68]; the ΔI/TTP of the cancer was significantly higher than that of the normal parenchyma (3.9 ± 1.4 vs 2.2 ± 0.94 db/s; P < 0.0001). • TIC patterns of solid cancer and cystic cancer were very similar.

CONCLUSIONS

• An objective and quantitative diagnosis of renal cell carcinoma by CEUS using a second-generation ultrasound contrast agent can be made by employing a TIC. • The TIC patterns of solid and cystic cancers were very similar, despite their morphological and vascular differences. • CEUS using TIC is a promising tool in the diagnosis of cystic renal cancer.