Search

Around 10 % of renal cell carcinomas (RCC) are cystic, while some benign cysts have complex appearance in conventional diagnostic tests such as computed tomography (CT) or magnetic resonance imaging (MRI). These renal complex cystic masses (RCCMs) are a challenging entity in urological practice and sometimes have a difficult management, requiring surgical removal. Contrast-enhanced ultrasound (CEUS) is a very sensitive test detecting microvascularization in real time, and it has been used in the diagnostic workup of these kinds of lesions. The aim of our study was to assess the diagnostic power of CEUS in the evaluation of RCCM. This is a prospective observational study between April 2011 and July 2014. A total of 66 patients with 67 RCCMs were enrolled (Bosniak 2–4). Twenty-four patients underwent surgical removal of the RCCM. All participants underwent CEUS (experimental) and CT (control). All CEUS procedures were performed by a single high-experienced observer (urologist). Benign lesions were defined as those Bosniak 2–2F, and malignant were Bosniak 3–4. Statistical analysis was made measuring consistency (kappa index and Landis-Koch scale) and validity (sensitivity, specificity, positive and negative predictive values) of the study. Median size of RCCM measured by CEUS and CT was 3.8 cm (interquartile range (AIQ) 3.2–4.6) and 3.9 cm (AIQ 3.2–4.5), respectively. Kappa index shows good agreement between both tests (0.71; 95 % CI 0.57–0.85), both overall and stratified by categories according to Bosniak classification. CEUS has a sensitivity 100 %, specificity 81.4 %, positive predictive value 70.4 %, and negative predictive value 100 %. A total of eight RCCMs were discordant, and seven of eight classified as malignant by CEUS and not by CT. Of those seven lesions classified as malignant by CEUS, six (six of seven, 85.7 %) were malignant in the pathological exam. CEUS is a very useful tool for assessing RCCM, with good results in terms of consistency and validity. It has a good diagnostic power, with a sensitivity of 100 % and a negative predictive value of 100 %. Its main limitations are the experience required, a special software, and being observer-dependent.

Strict imaging follow-up is mandatory after cryoablation of small renal masses (SRMs). Although it uses ionizing radiation and nephrotoxic iodinated contrast, computed tomography (CT) is still the gold standard test. Contrast-enhanced ultrasound (CEUS) is a novel technique that informs in real time about renal perfusion avoiding radiation and nephrotoxicity. The objective of this study is to compare outcomes between CEUS and CT in the follow-up of SRMs treated with cryoablation, as well as to assess degree of agreement between them. This is a prospective observational study (May 2012 to December 2013) comparing CEUS and CT in 16 patients with SRMs cryoablated. The on-going protocol of the study includes a CT and CEUS 3 months after treatment and then every 6 months during 5 years. Local relapse was defined as the presence of contrast enhancement in the mass. All the CEUS were performed by a single experienced observer (E.S.). Degree of agreement was measured with kappa index. CEUS detected contrast enhancement in three patients (3/16, 18.8 %) and CT in two patients (2/16, 12.5 %). Degree of agreement between CEUS and CT, according to Landis-Koch classification, was 0.76 (CI 0.33–1.19; p = 0.0165), which is excellent and higher than expected by random. Sensitivity of the test is 93.75 % (15/16). Median time of follow-up after cryoablation is 22 months (15.5–36.5). CEUS has an excellent agreement with CT and a high sensitivity in the follow-up of SRMs treated with cryosurgery, demonstrating its usefulness. Due to these encouraging results, it could become a reference test in the near future for monitoring SRMs after ablative treatment.