EAU 2018: Follow Up of Small Renal Masses Treated with Cryoablation: Role of Contrast Enhanced Ultrasound
Dr. Sanchez Gallego of the Hospital Ramon y Cajal Department of Urology in Madrid, Spain presents a prospective observational study of 34 patients with small renal masses treated with cryoblation, with a primary objective in comparing outcomes of follow-up between the traditional CT versus novel CUES.
The primary outcome measure was defined as a local recurrence, or the growth and presence of contrast enhancement in the mass. Inter-rater reliability (read: agreement between the two scans) was evaluated with the Kappa statistic. Further, reliability and validity measures were assessed via positive and negative predictive values, sensitivity, and specificity.
Overall, the 34 patients with a median tumor size of 2.6cm acted as their own matched controls, which resulted in a total of 89 pairs of CT and CUES. Post-cryotherapy recurrence (true positive rate) was observed in nine out of the 34 patients (26.5%) at a median follow-up of 7.8 months post-cryoablation.
Given these outcomes, the sensitivity and specificity of the CEUS was 88.9% and 95.2%, respectively. In comparison, the sensitivity and specificity of the CT was 66.7% and 100%, respectively. Similarly, the positive predictive values for CUES versus CT was 88.9% versus 100% and negative predictive values were 95.5% and 87%, Disagreement between the two scans was found to be approximately 8% in this patient cohort, yielding an agreement degree of 0.78 (95% CI 0.63-0.93), demonstrating moderate agreement between the two scans.
In discussion, Dr. Sanchez Gallego emphasized the trade-offs of sensitivity and specificity in CT versus CUES. If the purpose of measurement is to correct identify those with recurrence (i.e. true positive), the CT is recommended due to its high positive predictive value. In contrast, if the test’s objective is to “rule-out” recurrence (i.e. true negative), the CUES should be recommended due to its high negative predictive value.
Regardless of these trade-offs, however, this study confirms a comparable agreement between the two techniques of follow-up scans. As such, further considerations of morbidity associated with radiation exposure and nephrotoxicity can also be considered and weighed against reported sensitivity and specificity values.
Presented by: Sanchez Gallego M.D. Hospital Ram.n y Cajal, Dept. of Urology, Madrid, Spain
Co-Authors: Sanz Mayayo E., G.mez Dos Santos V., Rodriguez-Patron Rodriguez R., Lorca Alvaro J., Alvarez Rodriguez S., Hevia Palacios V., Burgos Revilla F.J.
Author Information: Hospital Ram.n y Cajal, Dept. of Urology, Madrid, Spain
Written by: Linda M. Huynh, BS, Department of Urology, University of California-Irvine at the 2018 European Association of Urology Meeting EAU18, 16-20 March, 2018 Copenhagen, Denmark