Application value of superb microvascular imaging for diagnosis of different size renal solid tumors

Abstract

Objective: To discuss the diagnostic value of superb microvacular imaging (SMI) in renal solid tumors of different sizes. Methods: A total of 142 patients with 146 renal tumors detected by ultrasound in Tianjin Medical University Cancer Institute and Hospital from September 2017 to March 2019 were retrospectively analyzed. The maximum diameter of lesions was 0.8-7.3 cm, and patients were divided into the maximum diameter ≤3.0 cm group (61 patients, 64 lesions) and the maximum diameter >3.0 cm group (61 patients, 82 lesions). All of the tumors were separately evaluated by SMI and color Doppler flow imaging (CDFI) with Adler grade, vascular morphology and peripheral blood flow. Results: In the group with maximum diameter ≤3.0 cm, 50 lesions were malignant and 14 were benign. In the group with maximum diameter >3.0 cm, 62 lesions were malignant and 20 were benign. In the group with maximum diameter ≤3.0 cm, there were no significant differences in location, boundary, echo, homogeneity and small cystic area between malignant tumors and benign tumors (P>0.05). In the group with maximum diameter >3.0 cm, there were significant differences in echo, homogeneity and small cystic area between malignant tumors and benign tumors (P<0.05). For all of the benign tumors, there were no significant difference between CDFI and SMI in evaluating Adler grade, vascular morphology and peripheral blood flow (P>0.05). For malignant tumors with maximum diameter ≤3.0 cm, 43 lesions with Adler grade 2-3 were detected by SMI, which was higher than CDFI (32, P<0.05). There were 38 lesions with dendritic and irregular vascular morphology detected by SMI, which was higher than CDFI (7, P<0.05). The detected rate of peripheral annular or semi-annular blood flow in lesions was 80.0% (40/50), higher than CDFI (18/50, P<0.05). While in malignant tumors with maximum diameter >3 cm, the lesion with peripheral annular or semi-annular blood flow detected by SMI was 38, higher than 22 of CDFI (P<0.05). The area under the receiver operating characteristic (ROC) curve for CDFI and SMI diagnosis of renal solid tumors with the maximum diameter ≤3.0 cm was 0.627 (sensitivity: 54.0%, specificity: 71.4%) and 0.791 (sensitivity: 94.0%, specificity: 64.3%), respectively, with statistically significant difference (P=0.039). The area under the ROC curve for CDFI and SMI diagnosis of renal solid tumors with the maximum diameter>3.0 cm was 0.852 (sensitivity: 85.5%, specificity: 85.0%) and 0.860 (sensitivity: 91.9%, specificity: 80.0%), respectively, without statistically significance (P=0.858). Conclusions: SMI is superior to CDFI in detecting low-velocity blood flow and microvessels in both malignant and benign renal tumors, and can effectively improve the display rate of peripheral blood flow in malignant tumors. Otherwise, SMI can provide better diagnostic efficiency for renal tumors with the maximum diameter ≤3.0 cm.