Comparing Sonazoid contrast-enhanced ultrasound to contrast-enhanced CT and MRI for differentially diagnosing renal lesions: a prospective multicenter study

Purpose To evaluate the diagnostic performance of contrast-enhanced (CE) ultrasound using Sonazoid (SNZ–CEUS) by comparing with contrast-enhanced computed tomography (CE–CT) and contrast-enhanced magnetic resonance imaging (CE–MRI) for differentiating benign and malignant renal masses. Materials and methods 306 consecutive patients (from 7 centers) with renal masses (40 benign tumors, 266 malignant tumors) diagnosed by both SNZ–CEUS, CE–CT or CE–MRI were enrolled between September 2020 and February 2021. The examinations were performed within 7 days, but the sequence was not fixed. Histologic results were available for 301 of 306 (98.37%) lesions and 5 lesions were considered benign after at least 2 year follow-up without change in size and image characteristics. The diagnostic performances were evaluated by sensitivity, specificity, positive predictive value, negative predictive value, and compared by McNemar’s test. Results In the head-to-head comparison, SNZ–CEUS and CE–MRI had comparable sensitivity (95.60 vs. 94.51%, P = 0.997), specificity (65.22 vs. 73.91%, P = 0.752), positive predictive value (91.58 vs. 93.48%) and negative predictive value (78.95 vs. 77.27%); SNZ–CEUS and CE–CT showed similar sensitivity (97.31 vs. 96.24%, P = 0.724); however, SNZ–CEUS had relatively lower than specificity than CE–CT (59.09 vs. 68.18%, P = 0.683). For nodules > 4 cm, CE–MRI demonstrated higher specificity than SNZ–CEUS (90.91 vs. 72.73%, P = 0.617) without compromise the sensitivity. Conclusions SNZ–CEUS, CE–CT, and CE–MRI demonstrate desirable and comparable sensitivity for the differentiation of renal mass. However, the specificity of all three imaging modalities is not satisfactory. SNZ–CEUS may be a suitable alternative modality for patients with renal dysfunction and those allergic to gadolinium or iodine-based agents. Key Points This prospective multicenter study demonstrated that the diagnostic performance of SNZ–CEUS was comparable to CE–CT and CE–MRI. The three imaging modalities displayed desirable sensitivity, while the specificity needs to be further improved. CE–MRI may have better specificity than SNZ–CEUS for differentiating renal masses bigger than 4 cm